Water and Waste Water Management in Food ...

SPINOFF ON

FRUIT AND VEGETABLE WATER AND WASTEWATER MANAGEMENT

ROY E. CARAWAN

JAMES V. CHAMBERS

ROBERT R. ZALL

PROJECT SUPERVISOR ROGER H. WILKOWSKE

EXTENSION SPECIAL REPORT No. AM-18E JANUARY, 1979

PREPARED BY: EXTENSION SPECIALISTS AT: NORTH CAROLINA STATE UNIVERSITY CORNELL UNIVERSITY PURDUE UNIVERSITY

WITH THE SUPPORT OF THE SCIENCE AND EDUCATION ADMINISTRATION-EXTENSION USDA - WASHINGTON, D.C.

WATER AND WASTEWATER MANAGEMENT In Food Processing Plants - An Educational Program The objective of this program is to increase the knowledge of food scientists, food processors, engineers, scientists, waste management specialists and other practitioners in the concepts and principles needed to properly control water use and product waste in food processing facilities. The materials are designed for individuals con cerned with management of food plants, with pretreatment of food processing wastewaters, with treatment of food processing wastewaters and with the utilization or disposal of food plant residuals. The modules in this program incorporate knowledge from food science and technology, food processing, sanitary and environmental engineering, agronomy, soil science, agricultural engineering, economics and law. The program consists of some 15 modules. Introductory material is presented in the Core Manual to introduce the program. Technical specifics are provided in 7 technical spinoffs. The application of water and waste management in specific food plants is related in 7 commodity Spinoff Manuals. Published by THE NORTH CAROLINA AGRICULTURAL EXTENSION SERVICE North Carolina State University at Raleigh, North Carolina Agricultural and Technical State University at Greensboro, and the U. S. Department of Agriculture, Cooperating. State University Station, Raleigh, N. C., T. C. Blalock, Director. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. The North Carolina Agricultural Extension Service offers its programs to all eligible persons regardless of race, color, or national origin, and is an equal opportunity employer.

F&V SPNOFF/PREFACE PREFACE

Purpose:

The main purpose of this FRUIT AND VEGETABLE WATER AND WASTEWATER MANAGEMENT SPINOFF is to be a primary reference document to aid the extension specialist in assisting fruit and vegetable processors in meeting water pollution requirements.

This document is intended as a guide, in that

it attempts to provide broad coverage, but cannot be totally comprehensive on all topics.

Instead, it gives general

information on a wide scale, and then directs the reader to additional specific data and bibliographic information. By presenting the fundamentals of water and waste management for fruit and vegetable processing, this booklet will enable the extension specialist to help fruit and vegetable processors develop effective water and waste control programs. Such programs can enable these processors to better meet current water pollution control regulations and prepare for future, more stringent regulations. Thus, this guide can be a tool to help extension specialists and food processors alleviate present misunderstandings and avoid future problems.

In addition, this guide can aid in bringing together

representatives from the food industry and regulatory agencies-to coordinate their mutual interest in reducing water pollution. Audience:

This guide should be valuable not only to extension specialists for which it was prepared, but also for food processors and regulatory officials charged with the review and approval of wastewater discharge from food plants not only to surface waters but also to municipal wastewater treatment systems.

F&V SPNOFF/PREFACE Scope:

The subject of this guide is the management and control of water use and waste discharge in fruit and vegetable processing, with emphasis on necessary legal, sanitary, environmental and energy factors.

In preparing this guide,

the committee has attempted to maintain a uniformity of recommendations and suggestions, despite the variety of processing plants and the disparity of requirements for pollution control throughout the country. Limitations:

No written material dealing with pollution control regulations can remain current and up-to-date with our rapidly changing regulations.

Therefore, the reader is advised to

check on current laws and local regulations before consideration of any pollution control project.

The vast differ-

ences and complexities that exist in fruit and vegetable processing do not allow for a detailed information that would be applicable to any plant without modification. Disclaimer:

The mention of manufacturers, trade names or commercial products is for illustration purposes and does not imply their recommendation or their endorsement for use by the Agricultural Extension Service.

Learning Objectives: 1.

Recognition of unit operations and, plant practices that can or do contribute to pollution.

2.

Understanding of the key elements in a water and waste control program for a fruit and vegetable processing plant.

3.

Identification of the key federal, state and local pollution laws and regulations that affect fruit and vegetable processors.

4.

Appreciation of the possible role of an extension specialist in assisting processors to meet water pollution control regulations.

ii

F&V SPNOFF/SUMMARY SUMMARY The important factors for extension specialists to consider in developing programs to assist the fruit and vegetable industries in meeting water pollution requirements are presented. includes the following:

This document

(1) role an extension specialist can play in

plant pollution problems, (2) components of an effective water and waste control program in fruit and vegetable processing, (3) methods for monitoring and analyzing fruit and vegetable wastewaters, (4) terminology and concepts of pretreatment and treatment of fruit and vegetable wastewaters, and (5) notes for developing an effective extension program for fruit and vegetable processing plants. Each fruit and vegetable plant has numerous operations that use water and discharge skins, juices, bits of flesh or rejects which can contribute to pollution and specific examples are reviewed for selected plants. The possible ways these operations can be modified or employee practices changed to reduce water use and waste are identified and discussed.

The

role of management in processing water and waste control is explained. Various practices to reduce pollution after the institution of inplant water and waste management procedures are presented.

These

practices include pretreatment, by-product recovery and/or treatment. The most important aspects of each of these are reviewed. The opportunities for wastewater discharge from a fruit and vegetable processing plant are recognized as either discharge to a municipal system or discharge directly to a stream, estuary or the ocean. The important factors to consider in municipal discharge of fruit and vegetable processing wastes are identified as sewer use ordinances, user charges and pretreatment. reviewed.

State, federal and local regulations for pretreatment are

State and local requirements for discharge limitations to meet

NPDES permits or water quality criteria are listed and discussed. Parameters of importance for fruit and vegetable processors for municipal or direct discharge are identified as BOD5, TSS, pH and flow.

The importance of proper sampling and analytical techniques are

explained.

iii

1 F&V SPNOFF/LAND DISPOSAL I N T R O D U C T I O N Fruit

and

Vegetable

Industries

The fruit and vegetable industries are as varied as the name implies - this industry processes in a number of ways the great variety of fruit and vegetables grown in the United States.

The categories of processing

include canning, freezing, dehydrating, and pickling and brining.

The 1972

Census of Manufacturers indicates there are over 3000 establishments in this SIC Code classification including 2032, 2033, 2034, 2035, 2037 and 2038. The Census also tabulated statistics showing that over 300,000 employees are employed by this industry.

The annual payroll in 1972

amounted to about $1.5 billion. The value of products produced by this group of industries in 1972 was over $15 billion.

The industries have plants all over the United States,

but California has the heaviest concentration of production of fruit and vegetable products. Water Water in its pure state is a simple molecule consisting of two hydrogen atoms attached to a single atom of oxygen. The greatest quantity of water on this planet is in the oceans which contain 97.13% of the supply.

The largest supply for human consumption exists as ground or

subsurface waters with an 0.612% of the supply. Only a relatively small portion of the supply exists as surface water in lakes (0.009%) or streams (0.0001%).

Most water pollution laws are designed to protect the water in

the streams, although newer legislation looks at the total water supply. Legislation Congress, on October 18, 1972, established PL 92-500, the Federal Water Pollution Control Act Amendments of 1972. This law was passed to create a successful mechanism to control water pollution.

Authority was

granted to the United States Environmental Protection Agency (EPA) to establish a permit system including pollutant discharge limitations to help

2 F&V SPNOFF/LAND DISPOSAL abate water pollution.

In fact, the law, establishes a national goal to

eliminate pollutant discharges into navigable waters by 1985. The limitations for industries were required to be established in three parts.

First a set of effluent limitations reflecting the

application of the "best practicable control technology currently available" (BPT) to be achieved by July 1, 1977. Second, limitations to be achieved by July 1, 1983 reflecting the application of the "best available technology economically achieveable" (BAT). Also, a set of effluent limitations were to be established for all new sources based on the "best available demonstrated technology."

Subsequently, Congress in 1977, passed

the Clean Water Act and EPA was required to replace BAT standards with "best conventional pollutant control technology" (BCT). To assure that the effluent limitations and water quality standards would be met, PL, 92-500 established the National Pollutant Discharge Elimination System (NPDES).

Although the program was developed by and is

the responsibility of EPA, the various states have in most cases assumed the responsibility for the NPDES program. Industrial facilities that discharge to municipal systems were also affected by PL 92-500.

User charges and industrial cost recovery (ICR)

were required of those industries in municipalities that receive federal funds.

Also, effluent limitations were established for publicly owned

treatment works (POTWS).

These increased standards require more costly

treatment processes and these costs are passed on to the users, including industrial discharges.

F&V SPNOFF/PROC PLANT SCHEMES

TYPICAL FRUIT AND PROCESSING PLANT

VEGETABLE SCHEMES

INTRODUCTION This chapter presents some flow diagrams and process descriptions of a few different fruit and vegetable commodities.

These flow charts will

give you a basic idea of the steps involved in processing fruit and vegetables.

Including flow charts for every fruit and vegetable commodity is

beyond the scope of this chapter.

The charts and accompanying texts were

taken from a publication by Soderquist.

GREEN BEANS As shown in Figure 1, the green bean canning process involves an initial washing followed by grading, snipping of the ends, cutting, blanching, canning and retorting.

The physical layout of a green bean processing plant

analyzed in the Soderquist study is presented in Figure 2.

The major con-

tributors to the total pollutant load were found to be the washing, grading, and blanching processes.

CHERRIES The Soderquist study investigated the processing of two different varieties of sweet cherries; Royal Anne and Lambert. appears in Figure 3.

The processing layout

A comparison of Figures 4 and 5 reveals that the pro-

cessing methods for both varieties are similar.

PEARS The plant layout for processing Bartlett pears appears in Figure 6. The pollutional effects of two different types of mechanical peeling systems were compared:

the older Ewald peelers, and the more modern contour peelers.

The Ewald peelers peel the fruit by slicing over a pre-set contour, while the more modern contour model follows the individual contour of each pear, abrading the peel and thereby increasing the yield of saleable product by as much as 10%.

The study noted that the more modern peeler was decidedly in-

ferior to the Ewald peelers in terms of waste management.

F&V SPNOFF/PROC PLANT SCHEMES

5 F&V SPNOFF/PROC PLANT SCHEMES

6 F&V SPNOFF/PROC PLANT SCHEMES

8 F&V SPNOFF/PROC PLANT SCHEMES

Figure 6.

Physical configuration of pear processing.

9 F&V SPNOFF/PROC PLANT SCHEMES Figure 7 depicts the pear canning process. After grading, the pears are peeled and then flumed in a sodium chloride brine (which retards the browning reaction on the peeled surface) to a fresh water rinsing tank for removal of excess brine solution.

After rinsing, the pears are conveyed to

trimming tables where blemishes are removed. After trimming, any severely disfigured pears are directed from the main process line to the "chopping" area where they are processed for incorporation into secondary products. CORN TWO corn processing plants were studied; both plants produced frozen whole kernel corn and frozen corn-on-the-cob.

The flow diagram depicting

the parallel corn processing lines in one plant appears in Figure 8. In this figure, solid waste generation is indicated by the heavier arrows and generation of liquid or waterborne wastes is indicated by the lighter arrows. About 85% (by weight) of the total production from this plant was packed as cut corn.

Fifteen percent of the total input remained on the cob.

As indicated in Figure 8 the first major unit operation in the process was the air blower.

The blower was used to remove the loose material which

was received at the plant along with the raw product.

The waste material

from this operation was collected dry and used as silage. No liquid wastes were generated at this point. The second major unit operation was the mechanical husker. Here the husks were removed and again the solid wastes were collected and used for silage.

No liquid wastes were generated here either.

The third major unit operation involved in the corn process was the de-silker, or "silker." study.

Two types of silkers were in use at the time of the

One consisted of a large tumbler into which water was sprayed from

the inside.

The second silker was of the roller type. In this type, the

corn passed over a set of hard rubber rollers while it was being sprayed from above.

Both types of silkers reused water which had been used in a

subsequent unit process; generally the water from the cooling operation was reused in the silkers. The steps described above were common to the cut corn process and onthe-cob process.

From this point on, it was necessary to consider separ-

ately the cut corn and corn-on-the-cob lines. the corn was sorted.

After the silk was removed,

As mentioned before, about 85% (by weight) of the in-

coming raw product was shunted to the cut corn line.

The yield for cut corn

10 F&V SPNOFF/PROC PLANT SCHEMES

Figure 7.

Bartlett pear canning process diagram.

11 F&V SPNOFF/PROC PLANT SCHEMES

Figure 8.

On-the-cob and whole-kernel corn processing flow schematic.

12 F&V SPNOFF/PROC PLANT SCHEMES was about 30% by weight. Referring again to Figure 8, in the corn cutting operation the kernels were mechanically removed and the cobs collected as solid waste.

Practically

no liquid waste was generated in the cutting operation during processing, but considerable amounts of highly contaminated liquid wastes were generated during the clean-up operation in the proximity of the cutter. After being cut, the corn was blanched in a conventional steam blancher. The only liquid waste generated at this point was the condensate. Following blanching, the corn was sent to flotation washers. These washers removed unwanted material by encouraging it to float to the surface.

The overflow from

the tank carried the waste solids away. After washing, the corn was transported by vacuum lines to large hoppers, and from there, flumed to the freezing tunnel where it was dewatered, frozen, and packaged. The corn-on-the-cob was processed in a separate line after de-silking. Following sorting it was steam blanched. After blanching, the cobs were passed beneath a series of overhead sprays for cooling. Some of the corn at this point was cut into uniform lengths and subjected to a second cooling process before passing to carbon dioxide coolers. The cob ends resulting from this trimming operation were collected as solid waste and used for silage.

The remainder of the corn, as indicated in Figure 8, passed directly

to the carbon dioxide coolers. BLACKBERRIES The Soderquist study observed one blackberry freezing plant in detail. The flow diagram for the blackberry freezing process in that plant is shown in Figure 9. The berries arrived from the field in plastic crates or trays, each tray holding about 15 pounds.

After the berries were dumped from the crates,

the crates were washed as shown in Figure 9.

After the crates were emptied,

the blackberries were passed through an air blower if the debris level in the incoming product was sufficient to warrant using the blower. If the berries were adequately clean and free of debris upon arrival at the plant, the blower was not used.

The blower normally had to be used when the berries

had been mechanically harvested.

Conversely, it was normally not used when

the berries had been manually picked. The next unit operation in the process was the washing step where the

13 F&V SPNOFF/PROC PLANT SCHEMES

Figure 9.

Blackberry freezing process schematic.

14 F&V SPNOFF/PROC PLANT SCHEMES berries were subjected to a wash by overhead sprays. This washing constituted the only point in the process where the product actually came into contact with water.

Consequently, most of the plant waste load was generated at this

point.

After washing, the berries were inspected, sorted, and conveyed

mechanically to the freezing tunnel.

The conveyor belt was continuously

cleaned using a small water spray. SUMMARY The flow charts in this chapter are by no means meant to represent a complete picture of all operations involved in processing various fruit and vegetable products.

As you might imagine, processing schemes for many dif-

ferent commodities have some unit operations in common. There are on the other hand, of course, many unit operations which are strictly commodityspecific. The flow diagrams and texts offered here represent a small sampling of the many and varied processing schemes that are associated with equally as many different fruit and vegetable commodities.

Their value is in intro-

ducing you to some general processing layouts which comprise the processing of fruits and vegetables.

References 1) Soderquist, M. R. Wastewaters. 1975.

Characterization of Fruit and Vegetable Processing

Water Resources Research Institute, Oregon State University.

15 F&V SPNOFF/WW CHARACTERIZATION W A S T E W A T E R I N

T H E

C H A R A C T E R I Z A T I O N

F R U I T

P R O C E S S I N G

A N D

V E G E T A B L E

I N D U S T R I E S

Introduction Whenever food, in any form, is handled, processed, packaged and stored, there will always be an inherent generation of wastewater.

The

quantity of this processing wastewater that is generated and its general quality (i.e., pollutant strength, nature of constituents), has both economic and environmental consequences with respect to its treatability and disposal. The economics of the wastewater lie in the amount of product loss from the processing operations and the cost of treating this waste material. The cost for product loss is self evident, however, the cost for treating the wastewater lies in its specific characteristics. Two significant characteristics which dictate the cost for treatment are the daily volume of discharge and the relative strength of the wastewater.

Other

characteristics become important as system operations are affected and specific discharge limits are identified (i.e., suspended solids). The environmental consequences i n not adequately removing the pollutants from the waste stream can have serious ecological ramifications. For example, if inadequately treated wastewater were to be discharged to a stream or river, an eutrophic condition would develop within the aquatic environment due to the discharge of biodegradable, oxygen consuming compounds.

If this condition were sustained for a sufficient amount of

time, the ecological balance of the receiving stream, river or lake (i.e., aquatic microflora, plants and animals) would be upset.

Continual

depletion of the oxygen in these water systems would also result in the development of obnoxious odors and unsightly scenes. This chapter will deal with those industries who utilize the processes of the canned and preserved fruits and vegetables industry to extend the shelf life of raw commodities through the use of various preservation methods including canning, freezing, dehydrating, and brining.

Fruit and

vegetable preservation generally includes the following unit operations: cleaning and sorting, peeling, sizing, stabilizing and processing.

16 F&V SPNOFF/WW CHARACTERIZATION Fruit and vegetable processing plants are major water users and waste generators.

Raw foods must be rendered clean and wholesome and food

processing plants must be sanitary at all times. For the most part these wastes have been shown to be biodegradable, although salt is not generally removed during the treatment of olive storage and processing brines, cherry brines, and sauerkraut brines. According to Standard Industrial Classifications of the fruit and vegetable industries, the following industrial categories and subcategories have been assigned: Note - the subcategories listed here are tentative (1978). The apple, citrus and potato processing segment of the industry has been subcategorized as follows: Designation

Subcategory Apple Juice

A

Apple Products

B

Citrus Products

C

Frozen Potato Products

D

Dehydrated Potato Products

E

The above subcategorization does not include caustic peeled and dehydrated apple products, and pectin and pharmaceuticals derived from citrus products.

The remaining part of the industry has been tentatively

subcategoried, but is still subject to change. The tentative subcategorization is as follows: Added ingredients Apricots Asparagus Baby foods Beets Broccoli Brussels sprouts Cranberries, Blueberries Carrots Cauliflower Cherries, sweet & sour Cherries, brined Corn Corn chips Cranberries Dehydrated onions & garlic Dehydrated vegetables

Dried fruits, prunes, figs Dry beans, canned Ethnic vegetables, Chinese & Mexican Grape pressing Grape juice Jams, jellies and preserves Lima beans Mayonnaise and salad dressings Mushrooms Olives Onions (canned) Peaches Pears Peas Pickles, fresh pack Pickles, process pack

17 F&V SPNOFF/WW CHARACTERIZATION Soups Spinach/leafy greens Strawberries Sweet potatoes Tomatoes, peeled Tomato products Tomato - starch cheese, canned specialties White potatoes, whole

Pimentos Pineapples Plums Potato chips Prune juice Pumpkin and squash Raisins Sauerkraut, cutting Sauerkraut, canning Snap beans (green & wax) Process

Description

In general, all subcategories have similar process operations as follows. Field to Plant The crop is harvested, separated from "trash" (stems, leaves), sorted, transported, and received at the plant.

No wastewaters are

generated. Washing and Rinsing Prior to processing the fruits and vegetables are washed and rinsed by means of flumes, soak tanks, water sprays, flotation chambers, or any combination of these methods.

Great quantities of water are used.

Detergents and ultrasonic techniques are also being tested for increased cleaning efficiency. Sorting (Grading) The commodity is sorted and graded by mechanical, optical, manual or hydraulic means.

Density graders employing brine of controlled density are

used to separate mature from over mature produce.

Weed seeds, chaff, and

stones may be separated by density and in froth separators. Stemming, Snipping, Trimming Steeming, snipping, and trimming are accomplished by a variety of mechanical means. No wastewaters are generated.

18 F&V SPNOFF/WW CHARACTERIZATION In-Plant Transport Various means have been adapted for conveying fruit or vegetable products at unloading docks into and through the processing plant. These include fluming, elevating, vibrating, screw conveying, air propulsion, negative air conveying, hydraulic flow, and jet or air blasting. Water, in one way or another, has been extensively used in conveying products within plants because it has been economical in such use and because it serves not only as conveyance but also for washing and cooling. It has been traditional to consider water an economical means to transport fruits and vegetables within a plant and to assume there was some sanitary significance to such use, not only for the product, but also for the equipment.

A significant disadvantage, however, may be leaching of

solubles from the product, such as sugars and acids from cut fruit; and sugars and starch from cut corn, beets, and carrots.

Alternative systems

to decrease such losses from water have been investigated, such as osmotically equivalent fluid systems. Peeling Many fruits and vegetables are peeled for processing. This serves the multiple purpose of removing residual soil, pesticide residues, coarse, fuzzy, or tough peeling with unpleasant appearance, mouth feel, or digestive properties. Peeling is accomplished mechanically by cutting or abrasion; thermally by puffing and loosening the peel-by application of steam, hot water, hot oil flame, or blasts of heated air; or chemically, principally using caustic soda (with optional surfactants) to soften the cortex so it may be removed by mechanical scrubbers or high-pressure water sprays. Pitting, Coring, Slicing and Dicing Pitting, coring, slicing and dicing are accomplished by a variety of mechanical techniques depending upon commodity used and end product desired.

No wastewaters are generated.

Pureeing and Juicing Widely varied techniques are used for pressing and separating fluid from fruits and vegetables.

Equipment includes reamers and a wide variety

of crusher-presses, either batch or continuous in operation.

19 F&V SPNOFF/WW CHARACTERIZATION The oxygen and other gases (nitrogen, carbon dioxide) present in freshly pressed or extracted fruit and vegetable juices may be effectively removed by deaeration under vacuum.

The liquids to be deaerated are pumped

into an evacuated chamber either as a spray or as a thin film. Modern deaerators operate at a vacuum of 29 inches or above. Deaeration properly carried out not only improves color and flavor retention, but reduces foaming during filling and also reduces separation of suspended solids. In the concentration of solutions by evaporation, the liquid to be concentrated continuously flows across a heat exchange surface which separates it from the heating medium. evaporators, including:

There are various types of

open kettles, shell-and-tube heat exchangers,

flash evaporators, rising and falling film evaporators, plate type evaporators, thin-film centrifugal evaporators, vapor separators, vacuum evaporators and heat pump evaporators.

The process involves heating the

product to evaporation and separating the vapors from the residual liquid. Size Reduction A wide range of size reduction equipment is required to produce different types of particulated solids.

Selection of a machine which can

most economically product desired results is affected by physical characteristics of the material and by the required particle size and shape. Blanching Blanching (scalding or parboiling) of vegetables for canning, freezing, or dehydration is done for one or more reasons: removal of air from tissues; removal of solubles which may affect clarity of brine or liquor; fixation of pigments; inactivation of enzymes; protection of flavor; leaching of undesirable flavors or components such as sugars; shrinking of tissues; raising of temperature; and destruction of microorganisms. Blanching is accomplished by putting the products in contact with water or steam.

In almost all cases for preparation of vegetables to be frozen,

it is imperative that the blancher processes be terminated quickly. Consequently, some type of cooling treatment is used. Typically, if the product has been water blanched, the vegetable is passed over a dewatering

20 F&V SPNOFF/WW CHARACTERIZATION screen and cooled either by cold water flumes or cold water sprays. Product to be canned is usually not cooled after blanching. The pollution loads from blanching are a significant portion of the total pollution load in the effluent stream during the processing of certain vegetables. Canning The sanitary codes of most states require that cans be washed before being filled.

There are usually three steps in the can cleaning operation.

First, the cans travel a short distance in the inverted position; second, they are flushed with a relatively large volume of water under high pressure; and third, they travel another short distance in the inverted position for the purpose of draining excess water. This is usually accomplished mechanically. The commodity is then filled into the can by hand, semiautomatic machines, or fully automatic machines, depending on the product involved. In some products, there is a mixture of product and brine or syrup. In other cases, brine or syrup is added hot or cold as top-off liquid. When the top-off is cold, it is necessary to exhaust the headspace gases to achieve a vacuum and maintain product quality. Exhausting in order to create a vacuum, is usually accomplished by one of the three methods: 1.

Thermal exhaust or hot filling.

The contents of the container are

heated to a temperature of 160o to 18OoF, prior to closing the container.

Contraction of the contents of the container after sealing

produces a vacuum. 2.

Mechanical.

A portion of the air in the container headspace is pumped

out by a gas pump. 3.

Steam displacement.

Steam is injected into the headspace to replace

the air, and sealed.

A vacuum is produced when the steam condenses.

Drying or Dehydration Continuous belt dryers are the most commonly used method for dehydration.

They are usually long and multi-staged with baffled chambers

which blow heated and sometimes desiccated air from over and under the bed-depth of the raw slices.

Residence time in this type of dryer is

21 F&V SPNOFF/WW CHARACTERIZATION usually ten to twenty hours, resulting in a product that has a finished moisture content of no greater than 4.25 percent of onions or 6.0 percent for garlic. Post-Drying Operations After dehydration the dried slices are usually screened, milled, aspirated, separated, and ground in various mechanical combinations to achieve the final desired piece size. Mixing and Cooking Certain commodities utilize additional ingredients in the manufacture of the finished products. For example, many frozen vegetables are prepared with butter, cheese, cream sauce, sugar, starch and tomato sauce added.

Equipment washouts and spills add an incremental waste load to the

total plant waste production. Freezing Freezing is accomplished in a tunnel freezer. The frozen commodity is then inspected, sorted and sized prior to packing. The only waste loads generated from this operation are from the clean-up operations and from cooling water. Clean-Up Clean-up operations vary widely from plant to plant and from product to product.

Normally the plant and equipment is cleaned at the end of the

shift, usually by washing down the equipment and floors with water. In some plants it is desirable to maintain a continuous cleaning policy so that end-of-shift clean-up is minimized. Clean-up begins with a dry collection of wastes followed by a washdown.

The washdown may be done with either water alone or with water

mixed with detergent.

Water is applied through either high-volume,

low-pressure hoses or low-volume, high-pressure hoses. In some operations, such as the mayonnaise processing operation, clean water is used to flush out the entire system at the end of the shift to remove any residues which might harbor bacteriological growth. The water used in clean-up operations generally flows through drains directly into the wastewater system.

22 F&V SPNOFF/WW CHARACTERIZATION Wastewater

Characterization

Characteristics Major wastewater characteristics of concern to the fruit and vegetable industries are the wide ranges of wastewater volume and organic strength generated.

The wastewater characteristics depend upon the

particular commodity being processed, the particular operation employed, and daily and seasonal variations.

Treatment facilities must be designed

to handle large volumes intermittently. Citrus wastes are highly putrescible and contain pectic substances which interfere with the settling of suspended solids. Pollutant parameters of significance to the fruit and vegetable processing wastewaters are biochemical oxygen demand (BOD) and total suspended solids (TSS).

These parameters dictate the level of waste treatment

required and define the limitations of the permit to discharge to a tributary stream (NPDES) or a municipal sewer (Sewer Use Ordinance).

These

parameters can be defined by monitoring the plant's processing flow. Sampling Of equal importance is the problem of obtaining a truly representative sample of the stream of effluent.

The samples may be required not

only for the 24 hr effluent loads, but to determine the peak load concentrations, the duration of peak loads and the occurrence of variation throughout the day.

Assuming that a sample can be taken from the effluent

drain which will be representative of the liquid in the weir or flume, there are a number of different ways of obtaining a 24 hr composite. (a) A time-proportional method, which involves taking a sample at a set time interval, e.g., every 1 min, or every 30 min; the greater the frequency of sampling, the more representative will be the sample; (b) A volume proportional method, in which a small sample is taken from the drain after a known volume, e.g., 1000 1, has passed through the flow measuring device; (c) A flow proportional method, in which a sample is taken from the drain at a particular time but proportional to the flow passing the particular device at the time the sample is taken; and (d) A combination method, in which the sample is taken proportional to both time and volume.

23 F&V SPNOFF/WW CHARACTERIZATION Obtaining good results will depend upon certain details. Among these are the following: (a) Insuring that the sample taken is truly representative of the wastestream. (b) Using proper sampling techniques. (c) Protecting the samples until they are analyzed. The first of these requirements, obtaining a sample which is truly representative of the wastestream, may be the source of significant errors. This is especially apparent in the case of "grab" or non-composited samples.

It must be remembered that waste flows can vary widely both in

magnitude and composition over a 24-hour period.

Also, composition can

vary within a given stream at any single time due to a partial settling of suspended solids or the floating of light materials.

Because of the lower

velocities next to the walls of the flow channel, materials will tend to deposit in these areas.

Samples should therefore be taken from the

wastestream where the flow is well mixed.

Since suitable points for

sampling in sewer systems are limited, numerous ideal locations are not usual. The usual method for accounting for variations in flow and waste constituents and minimizing the analytical effort is by compositing the samples.

Basically, sufficient samples should be taken so that, when mixed

together (before analysis), the results which are obtained will be similar to taking a sample from a completely-mixed tank which had collected all the flow from the stream in question.

Greater accuracy is obtained if the

amount of sample in the composite is taken in proportion to the flow. In general, the greater the frequency of samples taken for the composite, the more accurate the results. Obtaining a representative sample should be of major concern in a monitoring program.

A thorough analysis of the waste flows in the plant

must be made and a responsible staff member should be assigned to insure that the samples taken are representative. As a general rule, closer attention must be given to waste sampling than in the sampling of a manufacturing process stream. In many process operations, the wastes are pumped from sumps within the plant before the liquid goes into settling tanks. Where a liquid is being pumped through a pipe, flow monitoring and sampling are often

24 F&V SPNOFF/WW CHARACTERIZATION simplified, for in most cases the variations in pumping rate are minor and can either be calculated from the pump curves, or by calibrating pumps. Sampling under these systems involves using time-operated solenoid valves which open for a brief interval every minute or so.

The timers should be

attached to the pump motors so that samples are taken only when the effluent is being pumped. Once the samples have been obtained, analysis procedures should be initiated as soon as practical.

Table 1 summarizes the recommended storage

procedure for specific analysis. Process Waste Point Sources Figure 10 presents a simplified process flow diagram for both a fruit and vegetable process line.

Major wastewater generation occurs

during the washing steps and at plant clean-up as noted by the heavy arrows.

Because of the variation in wastewater characteristics found

throughout the fruit and vegetable industries, an attempt has been made to group the commodity oriented industry according to BOD strength of the wastewater.

Table 2 gives the raw waste characteristics for this

industry. The table has been grouped by the following formula: Group I

- Commodities with BOD less than 500 mg/l

Group II

- Commodities with BOD between 500-1000 mg/l

Group III - Commodities with BOD between 1000-2000 mg/l Group IV - Commodities with BOD between 2000-3000 mg/l Group V - Commodities with BOD between 3000-5000 mg/l Group VI

- Commodities with BOD greater than 5000 mg/l

Loading Factors and Their Estimates It is a well established fact that a given volume or quantity of production will have a direct effect on the level of waste generated. Tables 3, 4 and 5 present data gathered by the U. S. and Canadian federal environmental protection agencies as a result of plant surveys conducted for the fruit and vegetable industry. In the use of these tables, one can only develop a gross estimate of the loading factors for a given commodity operation. It should be emphasized that these tables should not be used as a substitute for an actual plant survey of sufficient duration to establish the loading factors based on actual production.

25 F&V SPNOFF/WW CHARACTERIZATION

Table 1.

Recommended Storage Procedure.

26 F&V SPNOFF/WW CHARACTERIZATION

Figure 10.

Food Plant process flow diagram (Fruit and Vegetables).

28 F&V SPNOFF/WW CHARACTERIZATION

29 F&V SPNOFF/WW CHARACTERIZATION

NOTE;

* The BOD5 loadings for small and large fruit/vegetable processing plants are low because the commodity mix indicates that tomatoes comprise of the bulk of the processing, and the average unit BOD5 loadings for tomatoes is comparitively lower at 4.7 kg/t.

F&V SPNOFF/WW CHARACTERIZATION

31 F&V SPNOFF/WW CHARACTERIZATION References CH2M Hill, Corvallis, Oregon. 1976. Wastewater Treatment - Pollution Abatement in the Fruit and Vegetable Industry. Prepared for Food Processors Institute and Sponsored by Office of Technology Transfer, Environmental Protection Agency. EPA. 1976.

Wastewater and Its Treatment.

Grants Programs.

Published by EPA, Construction

Environmental Protection Agency Technical Transfer

Series (EPA-43-9-76-017c), Vol. III, Appendix 8. Mulyk, P. A. and A. Lamb. 1977.

Inventory of the Fruit and Vegetable

Processing Industry in Canada - A report for Environment Canada, Environmental Protection Service, Ottawa, Ontario, Canada.

32 F&V SPNOFF/CONTROL OF WATER & WW

CONTROL OF WATER AND WASTEWATER IN FRUIT AND VEGETABLE PROCESSING INTRODUCTION Water is an absolute necessity in most fruit and vegetable process ing operations, and by practicing its conservation and reuse, the amount of liquid waste from these operations can be reduced.

Until recently, little con-

sideration has been given to water reuse because it was cheap and relatively abundant; reuse was considered hazardous because of bacterial contamination. This chapter is divided into three major parts. The first portion presents some basic concepts related to controlling water and wastewater.

The

second section presents some case studies which examine various water and wastewater control methods that have been applied to the processing of several different fruit and vegetable commodities.

The third section explores

reuse and recycling methods in more detail, and presents some commodityspecific information on by-product recovery and use. CONTROL

OF

WATER

AND

WASTEWATER

-

SOME

CONCEPTS

The type of waste management system suitable for a food processing operation will depend upon: the characteristics of the waste the location of the processing plant the degree of waste treatment required available points of discharge for the treated liquid wastes and for the collected solid wastes. As with almost all industrial waste situations, a unique waste management solution may exist for each operation. One of the first and best approaches to devising a fruit or vegetable processing waste management system is to investigate the opportunities for in-field and in-plant modifications.

Let's Took at some of these in-plant

and in-field techniques that help decrease wastewater strength and reduce water use.

These techniques include:

Using harvesting equipment that allows more of the stems, leaves and culled material to remain in the field. Washing and/or partially processing the crop in the field to allow return of any residue to the land,

F&V SPNOFF/CONTROL OF WATER & WW Using air blowers and water-filled flotation tanks to remove debris from the crop. Modifying peeling and pitting operations to use less water and waste less of the raw product. Recovering and reusing process water through the plant. Separating waste process streams at their sources for potential by-product use. Separate waste treatment and disposal of wastes with differing characteristics. A nationwide study of the preserved fruits and vegetables processing industry was conducted in 1974.About 500 processing plants were visited in the course of this study. Certain unit processes and/or technologies were readily identified as having an impact on reducing raw waste loads. Some of these were: Separation of low and high strength waste streams Installation of low-volume high-pressure clean-up systems Dry in-plant transport of products Countercurrent reuse of wash/flume/cooling waters Dry handling of solid wastes Dry caustic peeling Change-over from water to steam blanching (where possible) Air cooling after blanching An active and progressive waste management program. Two major streams contribute wastewater flows in a food processing plant: 1)

Water used in processing the product

2)

Water used for cooling.

Water conservation is practical in today's plants and can be practiced by the use of low-volume high-pressure sprays for plant clean-up, elimination of excess overflow from water supply tanks , use of automatic shut-off valves on water lines, and use of mechanical conveyors to replace the old style of water-gobbling flumes.

Reusing cooling water in counter-flow schemes to

wash the incoming raw fruits or vegetables is an example of a separation and reuse technique. Another water conservation method is the closed loop system for certain processing units, such as a hydrostatic cooker-cooler used for canned products.

The water is reused continuously; fresh makeup water is added only

to offset the minor losses from evaporation. Closed loop systems not only

34 F&V SPNOFF/CONTROL OF WATER & WW conserve water but also reclaim heat and can result in significant economic savings. Eliminating water in certain unit operations in turn eliminates attendant problems of treating the wastewaters which were generated by those operations.

Wherever possible, food should be handled by either a mechani-

cal belt or pneumatic dry conveying systems.

If possible, an air system in-

stead of a water system should be used for cooling the products.

Studies

comparing hot air blanching of vegetables with conventional hot water blanching showed that both the product and environmental quality were improved by using air.

Blanching is used to deactivate enzymes and produces a very

strong liquid waste when the hot water technique is used.

In a pea proces-

sing operation, for example, this small volume of wastewater is estimated to be responsible for 50% of the plant's entire BOD wasteload; for corn, the estimate is 60%; and for beets with peelings, 80%. Preliminary results have shown a reduced pollution load, while simultaneously providing a product quality improvement in terms of nutrient, vitamin and mineral content. Segregating wastes within a plant can be important in optimizing the least-cost approach to waste treatment.

For example in a typical brewery,

3% of the flow contains 59% of the plant's BOD load.

It is usually less ex-

pensive to treat this small flow separately than to mix it with the entire plant waste flow, and then attempt to treat this much larger volume. Other modifications to food processing operations for waste product separation become apparent when a mass balance is conducted at a plant and when by-product utilization opportunities are available. The development of dry caustic potato and fruit peeling methods has reduced both the volume and strength of wastes from these operations.

A waste survey of a food process-

ing facility, including a water balance and mass balances of product, BOD, solids, and nutrients can reveal other opportunities for in-plant waste management modifications. It has been determined that by controlling the pH of fruit fluming waters using additions of citric acid, it is possible to reduce the flume water volume without risk of increasing the size of the bacterial population, thereby avoiding contamination.

A pH of 4.0 will maintain optimum conditions

with cut fruit such as peaches.

This technique not only reduces the total

volume of water required and therefore the amount of wastewater discharged, but also increases the product yield by decreasing the loss of solids from sugar and acids which would otherwise have leached from the fruit. Consequently, there is a reduction in the total pounds of organic pollutants

F&V SPNOFF/CONTROL OF WATER & WW appearing in the wastewater.

Still another advantage offered by this process

is the improved flavor and color of the canned fruit due to better retention of soluble solids. Many factors determine the final effectiveness of proper water use. For example, tomatoes spray-washed on a roller belt where they are turned over are almost twice as clean as the same tomatoes washed on a belt of wire mesh construction.

Also, warm water is about 40% more effective in removing con-

taminants than the same volume of cold water. The last major source of liquid wastes is the washing of equipment, utensils and cookers, as well as washing of floors and food preparation areas. The wastewater from clean-up periods is likely to contain a large concentration of caustic, thus increasing the pH above the level experienced during processing. Use of waste monitoring equipment such as temperature recorders, conductivity measurements, flow measurement devices, and turbidity measurements can be used toconduct mass balances at a processing plant, and to pinpoint potential improvements in processing operations.

Such waste production indices

can be used to measure the performance of both management and production workers. By using these techniques, waste handling costs can be reduced, water conservation and reuse can be enhanced, and savings of raw materials may result. Proper management of processing wastes requires consideration of individual operations from harvest through waste disposal as integrated subunits of the total process.

Every effort should be made to eliminate wastes and

to avoid bringing wastes from the harvesting fields into the processing plant. Where possible, preprocessing should be done directly in the field to permit the return of organic materials to the land, Remember that in water reuse schemes, a delicate balance exists between water conservation and sanitation.

There is no straightforward or simple

formula to obtain the least water use.

Each case and each process scheme has

to be evaluated in terms of the equipment used in order to arrive at a satisfactory procedure for maintaining product quality while reducing wastage and water use. SOME

CASE

STUDIES

The previous section outlined some concepts and the general techniques which can put those concepts into practice.

This section presents various

36 F&V SPNOFF/CONTROL OF WATER & WW methods for controlling water and wastewater in commodity-specific processes. CARROT WASH

PROCESSING

WATER

MODIFICATIONS

RFCYCLING

Washing soil from root vegetables requires a lot of water. One large fresh carrot supplier in California used about 4,000 gal/min of wash water in the course of processing 500 T carrots/day the year round.

Because

of

short supplies of water and expensive waste disposal, wash water recycling became attractive.

The continuous water recycling system is described below

and depicted in Figure 11. Two settling ponds, each 60' by 150', serve as surge reservoirs.

From

here, water is pumped for use in fluming the carrots. The flume water is used for flushing the carrots from the trucks. the field soil.

This flushing removes 90% of

Carrots go through a brush washer, and then through sorting

stations, where small sizes and misshapen carrots are removed as culls. The desired sizes are hydrocooled, then sent through a second brush washer, Potable water is sprayed over the carrots in the final section. Part of the flume water is pumped through a patented, cylindrical, solids-liquid separator.

Here, water enters an annular space at the top; flow

velocities decrease as solids are spun inward through orifices toward the center, rather than outward as in conventional cone-shaped cyclone separators. The cleaned water exits at the top; solids settle to the bottom where they are continuously flushed out and returned to the settling pond. Trash is screened out through a stationary curved screen separator before entering the four centrifugal separators.

Flow through the four separators is 2OO-300

gpm total. Water in the hydrocoolers and in the final sprays is chlorinated at 100 ppm.

Chlorination of these flows, which cycle through the ponds, keeps the

reservoirs, flumes, and equipment free of bacterial, fungal or algal growth. RESULTS

ACHIEVED

The low-cost self-installed recycling system just described, effectively recycles all wash and flume water, excepting a small amount sprayed during final rinse, and the water carried out with the product. The system requires no extra energy except that for handling a pressure drop of about 8 psi to pump the water through the centrifugal separators, Separators remove 98% of

37 F&V SPNOFF/CONTROL OF WATER & WW

Figure 11.

Carrot wash water recycling system.

38 F&V SPNOFF/CONTROL OF WATER & WW the soil particles sized 44 microns (325 screen size) or larger. The best result of all is that there is no waste to treat. IN-PLANT

CHANGES

RESCUE

CARROT

PROCESSOR

Plant "A" processes frozen carrots.

The plant operates on a typical

schedule of 5 days per week, 10 to 11 months each year.

Normal production

is set for two shifts per day with additional clean-up time as needed. Average throughput is about 8 raw tons per hour. Figure 12 shows the typical flow diagram that plant A followed before any process modifications were made.

Carrots were delivered in bins either

directly from the fields or from a sorting shed. They were washed, trimmed, conventionally lye peeled and diced or sliced.

Blanching was accomplished

in a water blancher; post blanch cooling was also accomplished using water. Water use was high, approaching a daily average consumption of 1.5 mgd; BOD levels were correspondingly high, averaging about 2,400 mg/l. This plant, landlocked by city growth, was already paying a surcharge for its effluent disposal to the municipal waste treatment system. The city recognized that expanded treatment facilities were needed to accommodate industrial users.

So, the city proposed tentative revisions in its surcharge

system which if adopted, would cause monthly rates to approach $4,000. At this point, plant A's managers decided to institute changes in the form of capital investments.

When designing the plant modifications, the

engineers considered each waste contributing process within the processing scheme. Figure 13 shows the results of these efforts; Table 6 records the benefits gained. CARROT

WASHING

Water used to wash the incoming carrots had previously been combined with the main plant effluent stream.

However, observation and testing of

this stream indicated that its chief components were sand and dirt, some field debris, and occasional carrot particles. Because of the plant's location, it was decided that this stream should be isolated from the streams with higher waste concentrations and discharged separately under an NPDES permit.

A double screening system was installed (not shown on diagram) to

remove various solid particles from the waste stream.

This not only lower-

ed the suspended and settleable solids but also, in part, contributed to reducing the BOD discharge.

Freezer defrost water was also diverted to merge

39 F&V SPNOFF/CONTROL OF WATER & WW

Figure 12.

Original flow, carrot processor "A".

40 F&V SPNOFF/CONTROL OF WATER & WW

Figure 13.

Modified flow, carrot processor "A".

41 F&V SPNOFF/CONTROL OF WATER & WW

Table 6.

1

0.35

MGD

Carrot Process "A".

discharqed

under

NPDES

Parameter Differences

permit, 0.25 MGD to city

42 with this stream.

F&V SPNOFF/CONTROL OF WATER & WW The effect of this separation should not be underestimated.

These two components are responsible for about 60% of the total plant flow about 350,000 gallons per day.

The alternative discharge of this large water

volume to a municipal waste treatment system would have been extremely expensive. PEELING The peeling process was identified as the main source of BOD and SS generation.

The water required for peel removal was a substantial percentage of

the plant's total effluent.

A new lye peeler (ferris wheel type) was pur-

chased and installed. The conventional high-pressure water lye peel removal system was replaced with a Magnuscrubber. a holding tank.

The resulting peel waste slurry was pumped directly to

Ultimately this waste fraction is disposed of in sanitary

landfill. In addition to 'the water use and BOD reductions expected, the equipment modifications just described were responsible for improving finished product recoveries for both sliced and diced carrots,

These increased yields were a

direct result of the new peel removal system.

Plant personnel also noticed a

reduction in caustic soda consumption. DRY

SOLIDS

HANDLING

The engineers working on process modifications recognized that every attempt should be made to stop the introduction of solid wastes into the effluent stream.

The original plant flow allowed for trimmings and solid waste

to be flushed into gutters, followed by final screening before discharge to the city sewer system.

This allowed for additional leaching of soluble sol-

ids and was, in part, responsible for the plant's high BOD. To overcome this problem, a separate series of dry solids conveyors were installed to transport trimming table and other wastes directly to outside bins. Plant managers also made a concerted effort to instruct plant employees on proper methods of handling solid waste. BLANCHING As shown in Figure 12, this plant had used a hot water blancher for years. Water blanchers, however, have been shown to be major sources of water pollution.

Leaching solids, continuous spillage and overflow, all contribute

43 F&V SPNOFF/CONTROL OF WATER & WW heavily to a plant's BOD and SS loads.

The waste stream from the water blan-

cher was not only concentrated, but was of substantial volume.

So, the old

water blancher was removed and a steam blancher was installed. Now the only effluent from this unit process is a highly concentrated l-2 gpm condensate. The effect on total BOD and SS load has been considerably lessened, yet the desirable product quality characteristics have been retained. COOLING Similarly, post blanch hydrocooling, necessary to prepare carrots for freezing and to optimize freezer efficiencies, was found to contribute to the plant's effluent load.

The conventional hydrocooling system was replaced

with an ambient air cooler.

Working on a fluidized bed principle, the pro-

duct leaves the blancher and is blown and vibrated over perforated screens by the action of air jets blowing through and upward to contact the product. The action of the air and the mechanical vibrations of the screen move the product across the screen during which time the required cooling gradient is achieved.

Using air eliminates almost all water contact after blanching ex-

cept for one or two fine water sprays between the blancher and cooler.

Water

use at this stage was estimated at no more than 2 gal/min. CAPITAL

INVESTMENT

The plant estimated that their total expenditures for all the improvements and modifications amounted to about $90,000. Although no attempt was made to calculate paybacks on investment capital, it can be seen in Table 6 that savings accrued due to reduced discharged volume and pounds of pollutants sent to the city waste treatment system accounts for about $42,000 per year.

If one were to add a monetary value to the increased yeilds obtained,

the investment would become even more attractive. The changes just described were documented in a study by LaConde and Schmidt (1976). DRY

CAUSTIC

PEELING

Of the unit operations in the processing of fruits and vegetables which use water and generate waste, the most notable for magnitude of water use and waste generation is the peeling operation.

Whether product peeling is by

water, steam, caustic, or a combination of these, the operation has always generated a liquid waste troublesome because of its volume, organic load, and

F&V SPNOFF/CONTROL OF WATER & WW pH value.

For example, approximately 40 percent of the BOD from peach can-

ning comes from the peeling operation. In recent years interest in dry peeling of fruits and vegetables has increased because of the impact that this process has on reducing water pollution.

As a result of this interest, equipment manufacturers have explored

developing machinery for such peeling processes. This section will present the waste and water reduction results that have been achieved by using such processes. TOMATOES AND PEACHES Tomatoes, clingstone peaches and potatoes are the principal “target" commodities at which dry caustic peeling efforts have been aimed. The peeling machine is basically designed to gently remove the peel from soft fruits and vegetables without using water, and to collect the peel waste residue so that it does not enter the plant's wastewater effluent. This is done by collection, haulage, and separate disposal of concentrated peeling wastes. To gently wipe away peel softened by caustic, the machine uses very thin soft rubber discs.

These rubber discs are placed on rotating cylindrical

rolls arranged in a circular revolving cage containing a feed screen through the center.

The fruit moves parallel to the roll axis and perpendicular to

the surfaces of the roll discs.

The soft, moving disc surfaces provide gen-

tle, thorough scrubbing much like wiping the fruit with the palms of the hands.

The feed rate is accurately controlled by the central screw conveyor.

A final rinse to remove the last traces of peel and caustic is the only fresh water used.

During an EPA demonstration grant with the Del Monte Corp.,

water use in the peeling operation was reduced from 850 gal water/ton peaches to 90 gal water/ton peaches by using the dry peeling process. In conventional peeling, the peel is pre-softened by contact with dilute sodium hydroxide and then removed from the peach using large volumes of fresh potable water that comprise high-pressure sprays. Water from this peeling operation therefore contains essentially all of the removed peel. Dry caustic peeling in which mechanical rubbing is used to remove the softened peel was originally developed for the potato processing industry; however, peeling softer fruit such as peaches required the development of the new process just described. Peeling is the largest single source of waste from fruit processing, accounting for as much as 10 percent of the total wastewater flow and 40 percent of the total biochemical oxygen demand.

45 F&V SPNOFF/CONTROL OF WATER & WW The dry caustic peeling process also allows for collection of the peel as a pumpable slurry.

This slurry may have potential value as an animal

supplement or in reclaiming marginal farm land, Because the peel is not carried in the wastewater flow, the total organic and suspended solids loading of the wastewater from the peeling process is reduced by about 60 percent. Peach quality was judged to be equal to that of conventionally peeled peaches. The most striking result of the commercial tests of the dry caustic peeler is the 90 percent reduction in water use as compared to the conventional caustic peeler. imately 60 percent.

Significant pollution parameters can be reduced by approxTable 7 illustrates the average wastewater volumes and

pollution loadings for each process, based on 24-hour composite samples taken on each of the 21 days of the demonstration period. Table 8 sununarizes the characteristics of the peach peel solid wastes. The relatively high pH of the slurry and the low pH of the rinse water indicate that most of the caustic is removed with the peel. A commercial dry caustic peeler has also been operated successfully on freestone peaches.

There is additional economic incentive for use on free-

stone (as opposed to clingstone) peaches, since the mechanical action of the wiper effectively removes bruises and decreases the higher cost of hand inspection associated with freestone peaches. After having tested dry caustic peeling on peaches, Magnuson Engineers, Inc. decided to try the process on tomatoes. They established that a dry caustic peeling machine they designed would also very effectively peel caustically-treated tomatoes. Tomatoes peel very differently from peaches. Much stronger caustic solutions are required and caustic-compatible wetting agents must be used. While the tomato surface beneath the skin is attacked by the caustic, the skin itself remains intact and dislodges as sheets of tissue.

Other types

of tomato peelers have difficulty in thoroughly removing this peel tissue because it tends to transfer from tomato to tomato, or from tomato to equipment and back to another tomato.

Water sprays are generally used to try to

flush away these skins and hand labor is required to finish the skin removal. The dry caustic peeler that has been used on peeling tomatoes removes substantially 100% of the peel at capacities of 8 to 10 tons per hour without using any wash water.

This method has eliminated nearly all of the hand

labor required to remove the peel. About one gal/min of "lubrication" water is used in the machine.

46 F&V SPNOFF/CONTROL OF WATER & WW

Table 7.

Comparison of the Average Liquid Effluent from the Del Monte Dry Caustic Demonstration Project with Conventional Caustic Peeling

47 F&V SPNOFF/CONTROL OF WATER & WW BOD

REDUCTION In both the tomato and peach peeling operations, the dry caustic peeler

collects and delivers a full strength, essentially undiluted peel waste sludge. Since the peel waste is a major source of BOD, it is highly desirable to keep this peel waste out of a plant's wastewater.

Smith (1976) cited a 1974 study

that discovered that peel wastes accounted for 60% of the total plant BOD load in a peach cannery and 35% of the total BOD load in a tomato cannery. The plants comprising that study were generally typified by California processing methods.

Food processors now recognize that removing BOD loads from

wastewater is very expensive, both in terms of the plant investment for wastewater treatment facilities and the facilities' operating costs.

It is now

widely acknowledged that preventing wastes from entering the plant effluent is an excellent method for precluding wastewater treatment costs.

This is

especially true in seasonal operations where expensive wastewater treatment facilities would be used for only two or three months per year. INCREASED

PRODUCT

RECOVERY

Smith (1976) also noted that a California tomato processor who was using four dry peeling machines reported an increased product recovery of 2.5 cases per ton.

This product recovery was attributed to the reduction in product

losses made possible by the dry peeling units. The same processor also noticed a 44.7% reduction in the amount of caustic consumption as a result of installing the dry peelers.

Such savings were possible because the mechani-

cal wiping action of the-rubber discs can do an effective job while exposing the tomatoes to less caustic.

This product savings of course, means less

product loss in the spent caustic solution.

Similarly, since water washing

is not used during peel removal, the loss of tomato solids which in conventional peelers are normally carried away by the wastewater, is eliminated. SOME

BY-PRODUCT

POSSIBILITIES

Now that the mechanics of dry caustic peeling have been proven, much attention is being focused on the handling and disposal of peel waste sludge. So far, this sludge has been disposed of by spreading on land; sometimes it has been spread on pasture land where cattle are feeding. As this sludge material becomes available in greater quantities, possible uses for it will arise.

Brandy manufacture is one possible outlet.

Tomato peel waste offers promise for use as a by-product. The peel

48 F&V SPNOFF/CONTROL OF WATER & WW waste has a higher solids content than pureed whole tomatoes, because it is made up entirely of material from the outer cell walls of the tomatoes. This material is the most highly colored portion of the tomato, so it is very high in desirable red pigment.

Of course, the material contains caustic (NaOH),

but this can be neutralized with hydrochloric acid (HCl) and converted to common table salt (NaCl) and water.

Salt is usually added to tomato products

anyway, so it's very likely that the tomato peel fraction can be processed into high quality tomato products for human consumption. LEAFY-GREENS

WASH

WATER

RECYCLE

Industries that process leafy vegetables use large volumes of water, mainly during four unit operations: washing blanching cooling transporting product. Three types of washers are most commonly used in commercial operations: immersion, spray-belt, and rotary-spray.

Estimates of wash water requirements

per unit weight of product range from 50% of the total water requirement of 3 to 5 gal/lb necessary for complete processing, to 73% of a total 1.1 to 1.5 gal/lb cited elsewhere for complete processing requirements. One obvious way to conserve water in a greens-washing operation is to modify the system in some way to-permit recycling of the wash water itself. Of course the chief concern is that the recycled water be of good enough quality throughout the period of use to insure against degradation of the product quality beyond acceptable limits. To learn more about effects of water recycling on product quality, two full-scale, immersion-type washers that would permit wash water recycling during greens-washing operations, were designed and evaluated in a study whose description follows. The washers' performances were monitored during five trials, four when collard greens were being processed and one when spinach was being processed. THE

PROCESS

DESCRIPTION

Two washers were designed to wash 4,000 lbs of product per hour. The bottoms were comprised of three sections, each V-shaped to facilitate the

49 F&V SPNOFF/CONTROL OF WATER & WW collection and removal of grit when the washers were drained,

The maximum

depth in each washing tank was 3 ft., and the nominal capacity of each was 688 gallons.

Water from each washer was recycled through separate settling

tanks whose nominal capacities were 718 gallons. Both washers were identical and were operated in series. Each was equipped at the input end with three banks of sprayers (4 nozzles each); one bank placed at water level and two above the incoming product. One of the overhead banks of sprayers was later taken out of service in order to maintain high pressure on the nozzles while reducing the overall recirculation rate from 200 gpm (757 l/min) to about 125 gpm (473 l/min). This change was necessary because it was discovered that the washer drain system and the return sump-pump could not handle the larger flow. As product entered, it was spread out and vigorously agitated by the sprayers, and pushed toward the first of three center-mounted, paddle wheels covered with flattened expanded metal.

The three revolving paddle-wheel

drums propelled the product through the washer, alternately submerging and releasing it. Insects and leaf fragments floated to the surface inside each drum while the product was submerged, while water, forcefully dispensed through a stationary bank of three spray nozzles (positioned inside each drum), prevented leaves from becoming entangled in the expanded metal covering and provided additional cleaning. An exit conveyor - - made of an openmesh, plastic belting with flights every 2 ft - - carried product out of each washer. Water and floating trash that collected inside the rotating drums flowed out of the washers through surface side-drains into a trough leading to a box containing a submersible sump-pump.

This pump forced water into the settling

tanks through a moving-belt filter made of polyester screen that trapped trash and carried it to a collection box.

Streams of compressed air at the

end of the conveyor were directed upward through the belt across its width to force trash into the collection box.

The nominal capacity of each settling

tank was 718 gal, and provided a detention time of about 7 min for grit to settle when the recirculation rate was 100 gpm. Fresh, chlorinated water was added to the system at only one point: the second settling tank. first settling tank.

The overflow was carried through an H-flume into the The volume in excess of that required to make up for

losses in each washer, caused by carry-over on the product, was discharged as waste from the first settling tank through a second H-flume.

Flow meters

were installed to allow monitoring of fresh-water input and recirculation

50 F&V SPNOFF/CONTROL OF WATER & WW rates, which could be controlled by opening or closing gate valves through each washer-settling tank system.

The H-flumes were equipped with continu-

ous stage recorders and were calibrated so that depth of flow through the flumes could be converted to volume flow rates. The researchers concluded that the experimental washing system, as a whole, performed well during the four trials using collards and the one using spinach.

While the quality of the water as it was recycled through

the washers did deteriorate as more and more greens were processed, cleaning of the greens while they passed through the system was always evident. Reduction of bacterial population densities on the greens were observed in all five trials, probably because chlorine residuals were maintained at high levels and because of a detergent action in the wash water induced by dissolved organic compounds leached from the vegetables. Conclusions from this study were: 1)

Most of the actual cleaning of product occurred in the first washer and settling basin; an average of 71% of organic and inorganic wastewater constituents were present in the-first washer and settling basin.

2) The settling tanks were effective in removing small particles such as silt and fine sand. In one trial when sufficient grit for analysis was recovered, 63 percent of the total was found in settling tank No. 1. Washer No. 1 collected the most of the fine and medium sand (12 percent of the total weight of grit collected). Differences in total suspended solids concentrations in the wash water from the head to the back of a settling tank did not accurately reflect the actual solids removal that occurred. 3) There were distinct differences in final wash water quality when different cuttings of collards were processed, the differences most probably being a function of product maturity. 4) The water-usage rate in the experimental system, was, on the average, 15.6 gal/min (59.0 l/min), which is 77 percent less than that used by the conventional commercial washers. Water use per unit product was an average of only 0.56 gal/lb (4.66 l/kg) compared to an estimated usage of 1.5-2.5 gal/lb (12.5-20.8 l/kg) by conventional equipment. 5) The average chemical concentrations of the wash water being discharged from the system at the end of the trials were high, both in organic and inorganic suspended solids. When collards were washed, the organic suspended solids were concentrated at 110 mg/l while the inorganic suspended solids were at concentrations of 61 mg/l. When spinach was washed, organic suspended solids concentrations rose to 632 mg/l, and inorganic suspended

51 F&V SPNOFF/CONTROL OF WATER & WW solids concentrations occurred at concentrations of 57 mg/l. The magnitudes of the solids concentrations probably reflect the fact that there was considerable turbulence in the settling tanks because of the high recirculation rates within the system, and because the lighter particulates (clay and small leaf fragments, e.g,) did not settle well. 6) The average concentrations of COD and BOD5 in waste water being discharged from the system at the end of the trials were similar to those in weak municipal sewage. When collards were processed, COD values averaged 356 mg/l and BOD values average 80 mg/l. When spinach was washed, COD values averaged 211 mg/l while BOD values averaged 46 mg/l. 7)

Concentrations of both organic and inorganic compounds in wash water were much lower than those reported in another study, as were the waste loads generated per unit weight of product processed. The best agreement of data between the two studies was for total suspended solids. The other study's values for organic waste loads (COD and BOD, lb/ ton) were from 5 to 6 times higher than those calculated in this study.

8) Recirculation of wash water in immersion-type, leafy-green washing systems is a promising modification of existing processing methods for reducing water consumption and concentrating waste loads so that they can be more easily treated. INDIVIDUAL

QUICK

BLANCHING

(IQB)

Preparing vegetables for preservation by canning, freezing, or dehydration results in large volumes of high-strength organic waste streams. For the purpose of reducing total plant effluent and BOD, attention has been focused on the blanching operation.

Blanching serves several purposes in-

cluding: removing tissue gasses inactivating or activating enzymes reducing microbial load cleaning the product wilting the tissue to facilitate packing. These objectives are accomplished by heating the vegetables in either hot water or steam.

Both hot water and steam blanching produce liquid wastes

high in BOD, and both result in loss of water soluble nutrients, A report based on a study of two Wisconsin canning plants stated that a 90% reduction in blancher effluent volume would reduce total plant waste flow by 10 to 20%,

52 F&V SPNOFF/CONTROL OF WATER & WW and would reduce total plant BOD production by 20 to 50%. In an effort to approach

these

reductions, a study was made to design a blanching process

which would produce a wastewater flow of 10% of that from a commercial hot water

blancher.

The project resulted in a new concept of heating foods and

the application to blanching was demonstrated. The process, individual quick blanch (IQB), was used as a precanning process, and the results of that study are presented here.

EQUIPMENT

DESCRIPTION

The IQB unit used in the study consisted of two insulated chests, one heated by direct steam and the other heated indirectly. The IQB's capacity was about 300 lbs/hr.

The product, taken from the process line just prior

to entering the conventional pipe blancher, was distributed in a single layer on a mesh belt moving through the steam chamber.

The residence time in the

chamber allowed the mass average temperature of the product to reach desirable

blanching

temperatures.

The product was then transferred to a much slow-

er moving belt traveling through the second chamber. there

until

blanching

was

accomplished.

The product remained

The product was then hand-packed

into 303 x 407 cans to a given fill weight, brine and hot water were added, and the cans were sealed.

Then the cans were inserted into the plant's con-

veying line to go through the continuous retort process. Previous investigations by other researchers with the IQB unit showed that the reduction in waste flow from blanching was enhanced by slightly drying the product prior to steaming.

So, some of the experiments in this study

were conducted on the product which was dried by a 5 to 20% weight reduction in an alternating upflow-downflow hot (160-180°F) air dryer. The effluent from the IQB blancher was collected and analyzed for BOD, total

solids,

suspended

solids, total and soluble phosphorus, total organic-

nitrogen, ammonia-nitrogen, nitrate-nitrogen, and pH.

CONCLUSIONS

OF

THE

IQB

STUDY

The results of this study indicate that IQB can be used successfully for blanching vegetables prior to their canning.

The IQB process results in re-

duction of blancher effluent by 68 to 99% while maintaining product quality. Specific 1)

results

include:

Peas: Blancher effluent was reduced at least 68% in the IQB process compared to pipe-blanching. Excessive drying of the peas resulted in skin breakage with resulting cloudy brine and loss of product quality.

53 F&V SPNOFF/CONTROL OF WATER & WW 2)

Corn: IQB reduced blancher effluent between 77 and 99%. There was no product quality loss except under high temperature pre-drying conditions where the product was darker in color than the control.

3) Green Beans: An 86 to 95% reduction in blancher effluent was obtained using IQB. Product quality was comparable to pipe-blanched canned product except when pre-dried. With pre-drying, sloughing was evident. 4) Lima Beans: Reductions up to 99% were accomplished in the blanching operation using IQB. With drying, the loss of skins seemed to impair product quality. HEAT-COOL

SEQUENCE

FOR

TOMATO

PEEL

REMOVAL

A new process for commercial tomato peeling uses only heat and water, both of which can be recycled. amounts of heated caustic (lye).

Conventional peeling processes use large Caustic is expensive and requires large

amounts of energy for its production. The new process involves heating tomatoes with steam at about 315oC, then cooling them in a water bath or spray. Each step lasts about 10 seconds, and the heat-cool sequence is usually conducted three times for a total of 60 seconds. TOMATO

Peels can then be removed mechanically.

PROCESSING

Tchobanoglous et al. (1976) studied the effects of some in-cannery process modifications on reducing water use and waste at Hickmott Foods, Inc., a small independent tomato cannery.

The nature and results of their in-plant

water pollution control efforts are summarized here. Hickmott Foods, Inc. cans tomatoes in an 80-day operating season during the months of July through October.

Except for a week or two at the beginning

and end of the season, canning is a continuous, 'round-the-clock operation. To meet waste discharge requirements, the plant undertook a program of wastewater management to clean up its wastewater discharge to the San Joaquin River. Significant reductions in the wastewater flow rate and strength have been accomplished by modifying various operations within the cannery production area. These changes and their impact are discussed in this following section. WASTEWATER

FLOW

REDUCTION

The two principal components of the wastewater produced during the 1973

54 F&V SPNOFF/CONTROL OF WATER & WW and 1974 tomato canning seasons were the process water and the water from the evaporators and retorts (see Table 9).

Water used in the production process

is derived primarily from the municipal water supply; the water used to cool the evaporators and retorts is filtered San Joaquin River water. Several steps were taken between 1973 and 1974 to reduce the quantity of water used by the cannery and to reduce the wastewater flow rates.

The cool-

ing water was analyzed and found to be suitable for direct discharge to the river (COD less than 50 mg/l) after cooling.

Eliminating the cooling water

from the waste stream reduced the flow requiring treatment from 3.1 million gal/day to 1.14 million gal/day, while cannery production increased 20%. The installation of four dry peel removal machines reduced the total water needed for peeling from 306 to 124 gal/min. The quantity of peel sludge produced dropped from 150 to 25 gal/min while cannery production increased 20%. This reduced volume* of peeling sludge made it possible to isolate this material and process separately. All low pressure-high volume washdown hoses were removed and a high pressure hose system with nozzles that shut off upon release was installed. This change resulted in a washdown flow reduction of at least 80 gal/min (see Table 9). As low pressure hoses were usually left to run on the floor, the reduction was probably somewhat larger.

Some employees objected to the use of the

high pressure spray as it was harder to control, but they eventually became accustomed to using these nozzles.

No degradation in the quality of the pro-

duct or plant sanitation was observed. Cooling water discharge was reduced by 200 gal/min by reusing the retort cooling water for can washing.

Besides reducing the amount of water to be

cooled before discharge to the river, the amount of river water that required filtering and chlorination for use in the can washing system was also reduced. ORGANIC

WASTE

REDUCTION

The quantity of raw tomato constituents present in the process wastewater was reduced from the 1973 to 1974 season by modifications in the peeling operation and floor waste management. Dry Peeling.

The installation of four dry peel removal machines and mod-

ifications in the operation of the caustic peelers resulted in a reduction in caustic chemical use and in the quantity of waste generated that required treatment.

This was accomplished with no deterioration in product quality.

Dry caustic peeling, using rotating rubber discs to mechanically rub peel from

55 F&V SPNOFF/CONTROL OF WATER & WW

Table 9.

Daily Water Usage During 1974 Canning Season and Percent Reduction Data Over 1973 Canning Seasonal

56 F&V SPNOFF/CONTROL OF WATER & WW tomatoes dipped in sodium hydroxide, replaced the conventional water rinse peeling operation.

Effective peeling was obtained with this method while

reducing the concentration of caustic in the peelers.

Through a combination

of reducing the peeler speed (resulting in more tomatoes per bucket but a longer contact time with the caustic per tomato) and using mechanical peeling, it was possible to use a caustic solution of 7 to 10% in 1974 as opposed to an 18 to 20% solution in 1973.

This operation change resulted in

a reduction in caustic use (6.9 lbs/ton in 1974 as opposed to 11.7 lbs/ton previously) and reduced other chemical requirements for neutralization of the resulting wastewater.

As discussed later, reducing the pH value of the

caustic sludge can also make the possibility of product recovery more practicable. Dry caustic mechanical peeling requires about 80 gallons of potable water per ton of tomatoes as opposed to 720 gal/ton using conventional methods.

The 80 gal/ton which amounted to 24 gal/min of caustic sludge produced

in the operation is a small enough volume so that it can be disposed of in a land spreading operation.

Eliminating this sludge from the waste stream re-

duced the BOD load on the water pollution control plant by 46%. Floor Waste Management. Because tomatoes are, for the most part, a water soluble fruit, the longer they remain on the cannery floor or in a wastewater conveyance facility, the greater the amounts of tomato solids and juices contributing to the soluble COD and BOD of the wastewater.

If processing wastes

are picked up in solid form they can be fed to livestock or at least disposed of as solid wastes.

Manual collection of large solid tomato parts was stress-

ed during the 1974 season. ted down.

Gratings covering all floor drains were also bol-

Reliable solid waste per ton of data were not available for the

1973 season but it was estimated that considerably more solid waste was used for cattle feed during the 1974 season.

This is waste that does not reach

the treatment facility as fine suspended matter or soluble organics. FUTURE

IMPROVEMENTS

THAT

WILL

LEAD

TO

REDUCE

WATER

USE

Because Hickmott Foods no longer processes sweet potatoes and asparagus, daily water use could be reduced further by shortening the lengths of belts on which peeled tomato products must travel.

This change would eliminate

about 50 gal/min of water now used for belt lubrication.

In turn, this would

reduce the peak water use in the cannery to between 750 and 800 gal/min. This quantity is considered to be the minimum water use possible for maintaining sanitary conditions.

Heightened concern by the U.S. Department of Agri-

F&V SPNOFF/CONTROL OF WATER & WW culture over the issue of machine mold may ultimately result in increased per ton water use by Hickmott Foods. IN-PLANT

WATER

RECYCLE

WITH

OFF-LINE

MUD

REMOVAL

With the advent of mechanical harvesting of tomatoes, tomato processors noted an increase in the soil accumulations within fluming systems.

Most of

the soil accumulated in the initial flumes or bin dumps. Flow velocities within the bin dumps were insufficient to scour settled soil solids from the base. The resulting accumulation of soil in the bin dump eventually impaired product flow and required processing downtime to remove. There are two widely practiced procedures for alleviating the accumulation of soil in the bin dump.

The first is to employ a high overflow rate

from the bin dump, this overflow discharging to the plant's sewer system. The second procedure involves processing downtime to drain off excess liquids and to hand shovel the accumulated soil into an adjacent receptacle. Several-adverse impacts result from the current procedure for handling bin dump mud.

In the case of the high overflow rates, the excess water used

adds to the hydraulic surcharge to the sewer system from this seasonal industry. The high soil loadings discharged to municipal treatment systems result in operation and maintenance problems.

As a consequence of the necessity for

periodically shutting down the bin dump to remove accumulated soil, the time requirements for processing a given tonnage of tomatoes are extended, resulting in reduction of the plant's productivity. This, in turn, results in further excess water use through the down-time period and for the additional required clean-up and washdown. During the 1974 processing season, a study by Wilson, et al. (1976) was undertaken to evaluate alternative water recycle system configurations.

Bin

dump model studies were then undertaken in the spring of 1975 to develop design data on an efficient system for intercepting soil solids in the bin dump and transporting them to a solids removal system without interfering with product flow. The objective of the '75 season tomato water recycle project was to demonstrate a water recycle system which when used in conjunction w ith a normal bin dump operation, would significantly reduce the adverse impacts associated. with current practices.

An essentially closed loop recycle system was employ-

ed. The recycled water was used to maintain adequate scouring velocities within the bin dump without detrimentally affecting product flow. A solids

58 F&V SPNOFF/CONTROL OF WATER & WW removal system was constructed within the closed loop to remove the settleable solids and thereby prevent their accumulation within the bin dump. This recycle system was expected to eliminate excessive water use related to high bin dump overflow rates, as well as those rates related to clean-up down-time and extended operational period for processing a given tonnage of tomatoes. The researchers investigated four modes of operation aimed at minimizing wastewater-related costs.

These modes comprised the following:

conventional cleaning, without water recycle conventional cleaning with water recycle disc cleaner with water recycle disc cleaner with recycle and chemical coagulationflocculation. Water consumption and total solids balances were made on each mode. The conclusions of the study are discussed below. CONCLUSIONS Not surprisingly, the daily average tonnage of tomatoes processed increased substantially with disc cleaning and water recycle, as compared with the conventional system.

An increase of 26% in the tonnage of tomatoes processed

was realized with the disc cleaner combined with water recycle and chemical flocculation.

These increases in the daily tonnage of tomatoes processed may

be primarily due to the virtual elimination of solids accumulation in the dump tank with consequent impaired product flow. No incident of temporary shutdown of shift operation for dump tank clean-up was encountered during the modes of operation with water recycle. With respect to the water consumption, the following findings were established in this study: 1) The majority of daily water usage was operational (48-61%), followed by clean-up (31-44%) and filling (6-8%). There were no significant variations in percentage usage in the In all modes of operation, various modes of operations. approximately 7% was filling; approximately 55% operational; and approximately 39% clean-up. 2) A 26% decrease in the average total daily water use was realized when disc cleaner, combined with water recycle and chemical flocculation relative to the conventional system, was applied. 3) A decrease in the average unit water consumption rate relative to counter-current flow conventional cleaning, occured when water recycle measures were applied. A 41%

F&V SPNOFF/CONTROL OF WATER & WW decrease in average unit water consumption rate was realized when the disc cleaner, with water recycle and chemical flocculation (164 gal/ton), was applied relative to the conventional system (278 gal/ton). With respect to the total solids balances, the following conclusions were drawn: 1)

With the water recycle measures implemented, the soil solids removed from the dump tank per tonnage of tomatoes processed were significantly reduced; the soil solids lost to the sewer per tonnage of tomatoes processed were reduced substantially.

2)

The estimated soil solids incoming to the plant per unit weight of tomatoes processed ranged from 10 to 20 lbs/ton, and averaged 13 lbs soil solids per ton of tomatoes processed. The total soil loaded was estimated from the sum of soil solids which were collected from the dump tank, lost to the sewer, and removed from the sludge thickener. It appeared that the amount of soil reaching the plant varied considerably, depending on the type of soil in which the tomatoes were grown, the moisture content of the soil in which the tomatoes were harvested, and the method of tomato harvesting.

3)

Efficient clarification of the thickener overflow required surface loading rates of less than 1,000 gpd/ft2. Approximately one-half of the gravity settleable soil solids overflowed from the thickener at surface loading rates of 2,000 gpd/ft2.

Using performance parameter values found in this study, it was demonstrated that installation and operation of an in-plant water recycle system with off-line mud removal, would result in about a 50% savings in the total annual wastewater-related costs.

For the 35 tons tomatoes/hr plant evaluated

in this study, annual savings would amount to about $47,000.

F&V SPNOFF/CONTROL OF WATER & WW References 1)

Liptak, B. G.

Food Processing Wastes.

Environmental Engineer's Handbook.

Volume I - Water Pollution. 1974. 2)

Loehr, R. C. ches.

3)

Agricultural Waste Management, Problems, Processes, Approa-

1974.

LaConde, K. V. and C. J. Schmidt.

In-Plant Control Technology for the

Fruits and Vegetables Processing Industry.

Proceedings Seventh National

Symposium on Food Processing Wastes. EPA-600/2-76-304. December, 1976. 4)

Robe, K., associate editor.

Low-cost, total recycling of wash water.

Food Processing. December, 1977. 5)

Dry Caustic Peeling of Clingstone Peaches, Capsule Report. U.S. Environmental Protection Agency Industrial Demonstration Grant with Del Monte

6)

Corporation.

EPA Technology Transfer.

Smith, T. J.

Dry Peeling of Tomatoes and Peaches. Proceedings of the

Sixth National Symposium on Food Processing Wastes. EPA-600/2-76-224. December, 7)

1976. Changes in Organic and Inorganic Constituents of

Hoehn, R. C. et al.

Wash Water Upon Recycle in a Prototype Leafy-Greens Washer. Proceedings of the Seventh National Symposium on Food Processing Wastes. EPA/600-276-304. 8)

December, 1976.

Heat-cool sequence for tomato peel removal. Picks and Packs. Technical Notes for the California Fruit and Vegetable Processing Industry. Cooperative Extension, University of California.

9)

Tchobanoglous, G.

March, 1978.

Wastewater-Management at Hickmott Foods, Inc. Pro-

ceedings of the Sixth National Symposium on Food Processing Wastes. EPA-600/2-76-224. December, 1976. 10)

Wilson, G. E. et al. moval. Wastes.

11)

Tomato Flume Water Recycle with Off-Line Mud Re-

Proceedings of the Seventh National Symposium on Food Processing EPA-600/2-76-304. December, 1976.

Liquid Wastes from Canning and Freezing Fruits and Vegetables. U.S. Environmental Protection Agency Water Pollution Control Research Series. 12060 EDK 08/71. August, 1971.

12)

Mercer, W. A.

Conservation and Recycling of Water and Other Materials.

Food Industry Week Conference.

Proceedings Waste Management and Pollution

Control. 1971. 13)

Kamm, R. et al.

Evaluating New Business Opportunities from Food Wastes.

Food Technology, June, 1977.

61 F&V SPNOFF/RECYCLING & REUSE OF FD PROC WW RECYCLING

AND

REUSE

OF

PROCESSING

WASTEWATERS Sources

of

Potable

Water

Water can be obtained from two sources, surface reservoirs or streams, and underground reservoirs or streams. by a municipality or by a private party.

These sources can be tapped

If a food processor's water comes

from a municipal supply system, the water's quality is the responsibility of the municipality.

But, a food processor who supplies his own potable

water comes directly under the provisions of the Safe Drinking Water Act. Food processing plants must use water that is of potable quality. Potable water must also be used for cleaning all equipment which contacts the foods.

Water must meet Federally established quality standards in However, the standards set by any given

order to be classified as potable.

state may be even more strict than the Federal standards.

For this reason,

a food processor must know exactly what qualities the state expects of a Please turn to Chapter 5 of the Core

processing plant's water supply.

Manual entitled By-products, Reuse and Recycling for more information on this topic.

However, in some cases, it is possible to have multiple-use or

reuse of water as discussed in the following. Introduction

to

Recycling

and

Reuse

This section explores several aspects of recycling and reusing food processing wastewaters.

It is meant to give you an overview of the factors

affecting wastewater reuse and recycling. Keep the following basic concept in mind with regard to reusing wastewater.

Reusing wastewater basically involves collecting the effluent

from one or more unit processes, and then using that effluent as the influent for other unit processes.

The key to wastewater reuse lies in

matching the effluent from one unit process with the influent requirements of another unit process.

The "matchmaker" must be careful to take into

account the effluent's quantity and quality when examining the source requirements of prospective processes.

62 F&V SPNOFF/RECYCLING & REUSE OF FD PROC WW Legal Aspects of Water Reuse Water rights and related laws are under nationwide review. Scientists, economists and lawyers are evaluating current and future use of out water resources; constitutional rights as well as individual state laws may be involved before the present systems of water regulations can be applied to multiple-use water. Reusing water is not a new concept.

Published data estimate that 60

percent of the population presently reuses water. The intake water supply pipe of one city is often downstream from the discharge sewage pipe of another metropolis, and coastal municipalities have no choice but to commingle supply and wastewaters when tidal conditions return the sewage effluents into the water supply storage reservoir.

The use of interstate

streams is not only subjected to the laws of each user state but is also under regulations and control by federal authorities. Two basic systems of water law in the United States include riparian and appropriation.

Generally, those areas with abundant water supplies use

the common-law doctrine of riparian rights. Areas sparse in water resources found the first users and statutory prior appropriation doctrine more suitable.

Unfortunately, there are also some states that use combina-

tions of both systems with regional special interpretations. Pollution abatement programs have generally classified state waters according to use and thus have established standards of quality in accordance with these objectives.

It seems only prudent that the processor

should consult the stream classifications and standards that govern water purity in the state within which wastewater is to be reused. Public Health Aspects of Wastewater Reclamation Decision to reuse renovated wastewater for human consumption or in processes that normally require potable water (i.e., food processing), must be equated with potential health risk and hazards. The U.S. Public Health Service in a policy statement believes that renovated wastewater is not suitable for drinking water when other sources are available. Reclamation Methods Water is absolutely necessary in food processing, and by practicing conservation, reuse and recycling, the amount of liquid waste and conse-

63 F&V SPNOFF/RECYCLING & REUSE OF FD PROC WW quently the pollution load from food processing operations can be reduced. Reduction of water use through reuse of the same water can pay significant dividends in improving a waste disposal situation. Water reuse is beneficial because water is no longer a free commodity; it costs money to procure water; it costs money to pump water; and it costs money to dispose of water. Food processing waters cannot be reused indiscriminately. Their recirculation in contact with food products must allow satisfactory product and plant sanitation.

To offer more specific guidance in the use of

reclaimed waters, NCA offered the following recommendations: o The water should be free of microorganisms of public health significance. o The water should contain no chemicals in concentrations toxic or otherwise harmful to man, and no chemical content of the water should impose the possibility of chemical adulteration of the final product. o The water should be free of any materials or compounds which could impart discoloration, off-flavor, or off-odor to the product, or otherwise adversely affect its quality. o The appearance and content of the water should be acceptable from an aesthetic viewpoint. As an example of the possibilities for water reuse, a survey was made in a tomato and vegetable packing plant.

The effect of water reuse

was measured in terms of the percent reduction in water use per ton of product processed.

With no water reuse in can cooling, product washing, or

other operations, water use totaled 3,340 gal/ton of product.

When product

wash waters were recirculated, water use was reduced by 16%. Recirculation of can cooling water added a 22% reduction.

In the case of vegetable pro-

cessing these water reuses allowed a total water use reduction of 38%. When tomatoes were being processed, reuse of the excess water from the evaporative condenser system to wash product allowed a total overall reduction of 45% in water use/ton of product. Water is best saved by reducing its rate of consumption. Industries that routinely monitor their water usage and their waste effluent flows have been able to reduce the in-house uses of water by as much as 50%. Unfortunately, some water managers consider renovated wastewater to be acceptable only as a last resort alternative.

Such attitudes obscure the

64 F&V SPNOFF/RECYCLING & REUSE OF FD PROC WW real importance of wastewater as being potentially the most economical choice available as a source of water. Wastewater treatment and renovation can exist in varied forms. Direct reuse occurs in canneries when counterflow untreated streams are used stepwise.

Clean water is piped into the cooking areas where, following

use, it flows to blanching operations.

Having fulfilled its service here,

it discharges to water-conveying canals and finally to incoming washing troughs where it removes filed detritus from fruits and vegetables. Spent water handling can be simplified by segregating wastes into appropriate categories.

The commingling of fluids into common sewers

complicates reuse and reclamation programs. wastewater is to establish the objectives.

The first task in reusing A water demand inventory should

be taken to determine usage amounts with quality levels of purity. Subtotals of departmental (industrial plant sections) use should add to the total documented need required for the site. The dairy industry (Fig. 14) collects salvaged condensed milk vapors from vacuum pan evaporators and uses them for boiler water feed and for plant cleaning wash water.

Inline turbidity meters monitor the salvaged

condensate and divert contaminated milk and water vapors to the sewer in case of a malfunction. Salvageable Food Fractions Food wastes found in water can consist of particulate matter, dissolved solids and fats - either as an emulsion or in a free-floating state. Both the food and the water quality have an influence on deciding whether or not the salvaged fractions gathered from wastewater are suitable for human or animal consumption.

If wastes are channeled into sewer lines,

these materials become a treatment burden, at some cost to a waste treatment system.

Obviously, processes that reclaim human food-grade materials

must meet sanitary standards.

By-products for animal foods are continu-

ously being upgraded; thus, it may be prudent to furnish reasonable duplication in nonhuman food production of those techniques used in human food processing. Food as particulate matter is often separated from liquids by settling, screening, skimming, or centrifuging.

Automated continuous processes

suitable for cleaning in place are most attractive (as contrasted with

65 F&V SPNOFF/RECYCLING & REUSE OF FD PROC WW

Fig. 14.

Recovery of milk vapors in powdered milk production. The milk

evaporator functions much like steam generaged in boiler.

Because the

vacuum pan is subjected to a high vacuum through the air ejector system, milk boils at low temperature that rarely climb higher than 15OoF. Milk vapors change back to water, which collects against the cold condenser tubes.

Vacuum increases linearly to maximum with lowest temperature thus

vapors flow from A to B to C.

Malfunctioning milk evaporators tend to

foam, carrying over milk solids; hence, an inline turbidity meter safeguards the condensate purity for the salvaged water reuse.

66 F&V SPNOFF/RECYCLING & REUSE OF FD PROC WW batch methods) for both short-term and long-term goals. Careful planning with well-defined objectives is required to create resources from wastes. Toward the end of this text you will find a section entitled "By-Product Recovery Use."

This section outlines some commodity-specific recovery

schemes. Recovery of Chemicals While cleaning chemicals in waste matter often cause toxicity and poor performance of the biological treating processes, they also represent a BOD demand.

For example, surfactants or common acid detergents produce 0.65 lb

BOD5/lb of substance.

Table 10 shows the BOD demand of selected substances,

cleaners and sanitizers. Liquid detergents, sanitizers and other analogous products can be handled in bulk in a series of vessels.

These materials may then be piped

to reservoirs that can store and feed the cleaning solutions. Clean-inplace (C.I.P.) circuits can be designed to reuse fluids that are circulated by pumping through pipelines, bulk tanks, storage reservoirs and other media.

Final uses of captured liquids include floor cleaning or use as the

fluidizing liquid in sludge pumping. Heat Recovery Flow measurements are also necessary because the temperature alone is not adequate to reflect the magnitude of potential heat recovery.

Waste-

waters should be grouped according to purity and temperature, and the hot-test water should be without dilution to avoid heat dissipation. Steam condensate is returned to the boiler by deaerators because the water is soft as well as hot. Sometimes a water demand may be satisfied by preferential water makeup, where the idea is to use all the salvage water first with fresh water supplied only when the other sources are exhausted. Water Reuse Water reuse may be adopted with economical advantage when: o there is insufficient water available locally to maintain an open circuit system all year 'round. o valuable by-product materials can be economically recovered from the treatment processes.

67 F&V SPNOFF/RECYCLING & REUSE OF FD PROC WW

68 F&V SPNOFF/RECYCLING & REUSE OF FD PROC WW o treatment cost of recycling water is less than the initial cost of water, plus the cost incurred in discharging the effluent into the sewer. o cost of treating the effluent to a required standard is such that, for a little extra investment, the water quality can be made suitable for recycling. The practice of water reuse can be divided into sequential reuse, recirculation without treatment and recirculation with treatment. Sequential reuse is the practice of using a given water stream for two or more processes or operations before final treatment and disposal, i.e., to use the effluent of one process as the input to another.

Recirculation is

the practice of recycling the water within a unit process or group of processes.

A combination of these practices will probably be required for

an optimum reuse scheme. Table 11 indicates some of the cannery operations in which water may be reused indiscriminately.

Its recirculation in contact with food

products must allow for satisfactory plant and product sanitation. In an effort to optimize industrial water use and wastewater management, emphasis is now being given to decreasing the quantities of water used and the contaminants introduced during use.

Alternatives available

for volume and pollutant reduction include water conservation, good housekeeping, waste stream segregation, process modification and water reuse. Historically, little consideration was given to water reuse because of its abundance in nature and because it was considered to be hazardous due to bacterial contamination.

Contamination potential shows that, in washing

fruit, unless 40% of the water is exchanged each hour, the growth rate of bacteriological organisms becomes extremely high. In order to overcome this, other means of control, such as chlorination, must be used. When chlorination is discontinued, the bacterial count more than doubles. As soon as chlorination is resumed, the bacterial counts are again brought under control. Water conservation can be achieved through counterflow reuse systems. Figure 15 outlines a counterflow system for reuse of water in a pea cannery. At the upper right, fresh water is used for the final product wash before the peas are canned, and from this point the water is reused and carried back in successive stages for each preceding washing and fluming

69 F&V SPNOFF/WATER USE & REUSE

70 F&V SPNOFF/RECYCLING & REUSE OF FD PROC WW

Fig. 15. Four-stage counterflow system for reuse of water in a pea cannery. Key:

A. First use of water; B. Second use of water; C. Third use

of water; D. Fourth use of water; E. Concentrated chlorine water.

71 F&V SPNOFF/RECYCLING & REUSE OF FD PROC WW operation. As the water flows countercurrent to the product, the washing and fluming water can become more contaminated; therefore, it is extremely important (Fig. 15) to add chlorine in order to maintain satisfactory sanitation.

At each stage, sufficient chlorine should be added to satisfy

completely the chlorine demand of the organic matter in the water.

With

this arrangement, satisfactory bacteriological conditions should exist in each phase of the washing and fluming program. Water Conservation There may be several operations in a food processing plant where water is wasted continuously, thus causing an overload to subsequent collection and treatment systems.

Consideration should be given to steps that can be

taken within a plant to conserve water, thus enabling the liquid waste disposal system to operate more efficiently and thereby reduce water pollution.

As an example of water conservation methods the steps possible

in a food processing plant include 1) using automatic shutoff valves on all water hoses to prevent waste when hoses are not in use (a running hose can discharge up to 300 to 400 gallons of water/hour), 2) using low-volume, high-pressure nozzles rather than low-pressure sprays for cleanup, 3) avoiding unnecessary water overflow from equipment, especially when not in use, and providing automatic fresh water makeup valves, 4) avoiding using water to transport the product or solid waste when the material can be moved effectively by dry conveyors, and 5) reducing cooling water flow to the minimum to accomplish product cooling. Recently, it was determined that by controlling the pH of fruit fluming waters by the addition of citric acid, it was possible to reduce the water use without an increase in bacterial numbers. A pH of 4 will maintain optimum conditions with cut fruit, such as peaches.

The system

not only reduces the total volume of water required and therefore the amount of wastewater discharged, but also increased the product yield as a result of decreasing the loss of solids from leaching of sugar and acids. Consequently, there is a reduction in the total pounds of organic pollutants in the wastewater.

Another advantage is improved flavor and color of

the canned fruit because of better retention and soluble solids. Another water conservation method is using the closed loop systems on certain processing units, such as a hydrostatic cooker-cooler for canned

72 F&V SPNOFF/RECYCLING & REUSE OF FD PROC WW product.

The water is reused continuously, fresh makeup water being added

only to offset the minor losses from evaporation.

Closed loop systems not only conserve water but also reclaim much heat and can result in significant economic savings. It is not possible to describe all the concepts and ramifications inherent in various food processing industries to reduce water and waste loads while at the same time maintaining product quality. Many factors determine the final effectiveness of proper water use. For example, tomatoes spray-washed on a roller belt where they are turned are almost twice as clean as the same tomatoes washed on a belt of wire mesh construction.

Also, warm water is approximately 40 percent more effective in

removing contaminants than the same volume of cold water. A delicate balance exists between water conservation and sanitation. there is no straightforward or simple formula to obtain the least water use.

Each case and each food process has to be evaluated with the

equipment used in order to arrive at a satisfactory procedure involving water use, chlorination and other factors, such as detergents. Elimination of Water Use Eliminating water in certain unit operations in turn eliminates attendant problems of treating the wastewaters, which were generated by those operations.

Wherever possible, food should be handled by either a

mechanical belt or pneumatic dry conveying system.

If possible, the food should be cooled by an air system rather than by a water cooling system.

Recent studies by the National Canners Association in comparing hot air blanching of vegetables with conventional hot water blanching show that both product and environmental quality were improved by using air. Blanching, used to deactivate enzymes, produces a very strong liquid waste.

For

a pea processing operation, this small volume of wastewater is estimated to be responsible for 50% of the entire wasteload BOD; for corn, 60%, and for beets with peelings, 80%.

Preliminary results show a reduced pollution

load, while at the same time providing a product quality improvement in terms of nutrients, vitamins and mineral content. Waste Stream Segregation Waste segregation involves the separation of waste streams according to their wastewater load.

Noncontaminated streams offer the possibility of

73 F&V SPNOFF/RECYCLING & REUSE OF FD PROC WW being discharged directly to receiving bodies of water, whereas contaminated waste streams have to be treated. As a general rule, all plants should be provided with three water discharge systems, namely 1) storm and cooling water, 2) sanitary waste, and 3) industrial waste. The stormwater system should receive all surface and storm runoff. This system can also be used for discharging uncontaminated waters, such as cooling waters, that require no treatment prior to discharge. Although it is desirable to keep uncontaminated wastewater out of the treatment plant, the cost of installing separate collection systems for small, isolated streams may be so high that by-passing the treatment plant becomes uneconomical. The sanitary system should collect the wastewaters from all washrooms and shower rooms.

For most industrial plants it is desirable to send these

wastes to a municipal plant for treatment, rather than to treat them individually. Process Modification One alternative available for eliminating or reducing the wastes created during processing involves the modification or elimination of the step or steps which are producing the wastes. For example, since the peeling process is one of the greatest sources of wastes in most fruit and vegetable processing plants, efforts have been directed toward modifying the peeling process so that the peel waste can be removed without using excessive amounts of water.

One recent process modification, is the "dry"

caustic peeling process for potatoes.

In conventional steam or hot lye

peeling processes, potato peels may contribute up to 80 percent of the total plant wastewater BOD.

The new dry caustic vegetable peeling method

collects peels and caustic as a dry and semidry residue, thus preventing their entrance into plant wastewaters.

Dry caustic peeling is discussed in

more detail in Chapter 4. A Summary Reuse of wastewater is the utilization of a process waste stream one or more times before it leaves plant boundaries.

This can be accomplished

by piping the wastewater from one unit to another, by treating or diluting

74 F&V SPNOFF/RECYCLING & REUSE OF FD PROC WW effluents before reuse in other units, or by combining a few or all effluents, treating them and reusing the water. Incentives for water reuse involves the possibilities of reduction of wastewater treatment costs and raw water costs.

Although lower waste

treatment costs currently provide the major savings from reuse, in some areas the supply of acceptable raw water is decreasing, the price is rising, and reduced raw water usage may provide a significant incentive in the future.

The typical plant considering reuse seldom plans to completely

eliminate wastewater discharges since this would usually require very extensive modifications.

The important standard for economic reuse is that

an unused makeup process water can be replaced by a lower-quality water without harming the process.

So, reuse schemes should always be considered

in planning for pollution abatement. Ultimate requirements for water pollution control may be completely closed systems from which no discharges are permitted, and use of fresh water is only required as makeup for evaporation losses.

Closed water

systems as the final goal of pollution research has long been an ideal. Even though total reuse may not be legally required, it may be a viable alternative to meeting stringent discharge regulations. Possible steps for proceeding toward an intermediate or total reuse system are: o Determine the effluent qualities and quantities and makeup requirements for plant units. A waste stream survey is a must for such an analysis. o Study the lowest-cost treatments needed for various effluents to reach the required qualities of secondary users. Trends have been toward treatment of combined waste streams. Segregation of waste streams may offer better reuse possibilities. o Reduce wastewater volumes by increased maintenance and equipment modifications can reduce flows significantly. o Study the effects of reuse on existing treatment equipment because water reuse generally results in a lower volume, more concentrated waste stream. Commitment to total reuse requires an economic justification covering the expected future costs of fresh water and ultimate waste disposal.

In some areas of the world, the cost of fresh water is rising

75 F&V SPNOFF/RECYCLING & REUSE OF FD PROC WW and the cost for ultimate disposal may gradually decrease as technology improves.

The key to inexpensive reuse is volume reduction. The total-

reuse will be able to economically treat only a small waste stream for total removal of contaminants. The decision of whether to implement total reuse will be set by a comparison of costs of raw water and water treatments with and without discharges.

These include: water supply; treatment required before use of

fresh water; waste treatment required before discharge; treatment required for use of reused water; plant modification to accept lower quality or higher temperature reused water; extra piping and control valving; loss of flexibility due to integrated water system. A total reuse plan should begin at the individual process units, since In certain cases it may even be more

it will affect their operation.

economical to modify a process so that it requires little or no water.

The

economics of total reuse will vary from plant to plant. References 1) Mercer, W. A. 1971.

Conservation and Recycling of Water and Other

Materials. Food Industry Week Conference. Proceedings Waste Management and Pollution Control. 2) Liptak, B. G. 1974.

Environmental Engineer's Handbook. Volume I -

Water Pollution. 3) Morresi, A. C., et al. 1978. for Wastewater Reuse.

Cooling Water and Boiler Possibilities

Industrial Wastes, March/April.

76 F&V SPNOFF/BY-PRODUCT RECOV & USE

BY-PRODUCT

RECOVERY

AND

USE

Introduction Food processing plants inherently tend to generate significant quantities of waste material.

Frequently, the waste is believed to have

potential nutritional or industrial value, thereby representing a possible basis for a new business opportunity.

But turning these beliefs into new

business is often a complex technical and economic problem. Extracting the critical business and engineering parameters for decision making requires an analysis of the economic, technological, and marketing factors involved, as well as an ability to resolve problems arising from these factors. This section presents some recovery schemes by fruit and vegetable processors to transform hitherto waste products into useful by-products. This idea of recovering by-products from waste has been "catching on" throughout the food processing industry, but many of these recovery schemes have not been published.

The examples that follow are not meant to

represent a full-scale review of the state-of-the-art. SCP

From

Potatoes

A northern Maine potato processor is helping develop a new process of single cell protein (SCP) production as a part of the answer to meeting stricter wastewater discharge standards. the cutter deck in potato processing.

These plants reclaim starch from

Wash water solids, after sand-filter

screening and dewatering, go to the "tate meal" dryer for drying and subsequent sale as animal feed.

Up to 16% of such solids are added to

normal silage to provide the same amino acid level as other conventiona protein sources. This system is said to be best applicable to wet food processing operations, where high concentrates of soluble solids with a corresponding high level of biological oxygen demand (BOD) are present. Estimated protein output is one pound of protein for every 2 pounds of dissolved solids converted to SCP yeast. expected production.

The higher the BOD, the greater the

77 F&V SPNOFF/BY-PRODUCT RECOV & USE Size of treatment system is another consideration. Where a land disposal operation takes many acres, and even a settling pond, with primary and secondary treatment plants taking nearly as many acres as do conventional activated sludge water treatment systems, the SCP system fills the corner of a warehouse, taking up little more space (about 2,000 sq ft) than the processing equipment that comprises the unit, less than one hundredth the space occupied by any of the more traditional systems. Scrap

Potato

to

Molasses

At one Ore-Ida Foods vegetable processing plant a study revealed that converting scrap potato to molasses would raise the value of those wastes by a factor of seven; converting to alcohol would increase the value by a factor of thirteen.

However, both options were rejected in favor of

simpler sugar production and starch recovery because of a smaller capital investment and a-more stable market. Peel Sludge to Puree A California tomato processor attempted to recover causticallyremoved tomato peels as an edible by-product.

The processing plant was

losing about 120 tons of tomato constituents per day in the form of caustic peeling sludge.

A test run was conducted to investigate the feasibility of

recovering the tomato peeling sludge, after acidifying it, as products. The flow scheme used is shown in Figure 16. The quality of the puree made from a 1:1 blend of acidified caustic peeling sludge and fresh crushed tomatoes was judged to be good by the NCA with respect to both flavor and appearance.

The quantities of acid required to lower the pH value of the

caustic juice were kept to a minimum by operating the peelers at 8% caustic.

Further studies are being conducted to establish whether this

method can be accepted cannery practice.

If this peel recovery scheme can

be proven to be safe, the tomato processor would be able to recover and additional 4 tons/hr of usable tomato material, reduce the plant waste loss from 16% to 6%, and cut the volume of sludge that must be hauled for disposal by one-half.

78 F&V SPNOFF/BY-PRODUCT RECOV & USE

Figure 16.

Flowsheet for proposed recovery of waste peeling sludge.

79 F&V SPNOFF/BY-PRODUCT RECOV & USE BTU's From Olive Pits Every weekday at Lindsay Olive Growers plant, Lindsay, CA, about 27 tons of pits pour from the ripe olive-pitting machines. This continues seven or eight months a year.

Disposal was an expense, whether hauled to

the county disposal site, or to nearby orchards for use as roadbed material. The Lindsay plant ran tests and found that the pits, although half water, yielded nearly 400 BTU of heat per wet pound.

This potential heat

could supply part of the 450,000 lb of steam per day needed in the two-shift plant operation.

After considering all the possibilities, and in

view of fuel shortages in the future, the president of Lindsay Olive Growers and the Board of Directors gave the go-ahead to use the pits as boiler fuel. A furnace in use for burning wet sawdust was studied and adapted to Lindsay needs. bed unit.

The diagram and caption show the details of the fluidized-

Briefly, wet pits fall through a swirling-flame, vapor-removal

section into a fluidized bed of sand heated to 1,400°F. A gas flame heats the sand at start-up; after two to three hours, the pits themselves furnish the 1,400oF heat, and the burners shut off. The fluidized-bed furnace started up in January, 1977 with minimum mechanical difficulties.

It is capable of burning a wide assortment of

agricultural wastes, such as peach and apricot pits, and almond shells from nearby plants. Pits furnish about 25% of the steam used by the plant. The cost of hauling and disposing of pits is eliminated. There is no soot produced at the high burning temperatures and no air pollution problem. Payout on the installation through savings of fuel and haulage costs is difficult to determine because of the rapidly r ising cost of fuel oil, but the unit is expected to make a good profit.

80 F&V SPNOFF/BY-PRODUCT RECOV & USE References Dry Caustic Peeling of Clingstone Peaches. Capsule Report. U.S. Environmental Protection Agency Industrail Demonstration Grant with Del Monte Corporation.

EPA Technology Transfer.

Forwalter, J., Associate Editor. 1978.

Turns 3000 ppm food processing

waste into by-product, cuts sewage charges. Maintenance.

Sanitation and

Food Processing, May.

Heat-cool sequence for tomato peel removal. 1978. Picks and Packs. Technical Notes for the California Fruit and Vegetable Processing Industry.

Cooperative Extension, University of California, March. Changes in Organic and Inorganic Constituents

Hoehn, R. C. et al. 1976.

of Wash Water Upon Recycle in a Prototype Leafy-Greens Washer. Proceedings of the Seventh National Symposium on Food Processing Wastes.

EPA/600-2-76-304, December.

Kamm, R. et al. 1977.. Wastes.

Evaluating New Business Opportunities from Food

Food Technology, June.

LaConde, K. V. and C. J. Schmidt. 1976.

In-Plant Control Technology for

the Fruits and Vegetables Processing Industry. Proceedings Seventh National Symposium on Food Processing Wastes. EPA-600/2-76-304, December. Liptak, B. G.

1974. Food Processing Wastes. Environmental Engineer's

Handbook. Volume I - Water Pollution. Liquid Wastes from Canning and Freezing Fruits and Vegetables. 1971. U. S. Environmental Protection Agency Water Pollution Control Research Series.

12060 EDK 08/71, August.

Loehr, R. C. 1974.

Agricultural Waste Management Problems, Processes,

Approaches. Mercer, W. A. 1971. Materials.

Conservation and Recycling of Water and Other

Food Industry Week Conference. Proceedings Waste

Management and Pollution Control. Morresi, A. C. et al. 1978. Wastewater Reuse.

Industrial Wastes, March/April.

Pratt, M., Editor. 1977. Recovery.

Cooling Water and Boiler Possibilities for

AE Update.,

Food Processing Plant Wastes: The Economics of Agricultural Engineering, December.

81 F&V SPNOFF/BY-PRODUCT RECOV & USE Robe, K., Associate Editor. 1977.

Low-cost, total recycling of wash water.

Food Processing, December. Robe, K., Assistant Editor. 1977.

Lindsay turns wet olive pits into

profit, uses wastes to furnish 25% of plant steam requirements.

Food

Processing, May. Smith, T. J. 1976.

Dry Peeling of Tomatoes and Peaches. Proceedings of

the Sixth National Symposium on Food Processing Wastes. EPA-600/2-76-224, December. Tchobanoglous, G. 1976.

Wastewater Management at Hickmott Foods, Inc.

Proceedings of the Sixth National Symposium on Food Processing Wastes. EPA-600/2-76-224, December. Wilson, E. G. et al. 1976.

Tomato Flume Water Recycle with Off-Line Mud

Removal. Proceedings of the Seventh National Symposium on Food Processing Wastes.

EPA-600/2-76-304, December.

82 F&V SPNOFF/WW TREATMENT W A S T E W A T E R

T R E A T M E N T

Pretreatment The pretreatment of food processing wastewaters is commonly associated with discharges to a municipal waste treatment system.

The

degree of pretreatment required of the food processor is determined by the specified discharge limitations defined in the municipal sewer use ordinance. These limitations focus on wastewater characteristics which have, historically, caused either a hazardous condition for the waste treatment plant operators or have been responsible for detrimental influences on the waste treatment system's operation and waste removal efficiences. Another factor which has identified pretreatment as a necessity when discharging to a municipal waste treatment facility is the Federal Water Pollution Control Act. of 1972 which requires that before any grant is approved to a municipality for facility expansion or improvement, the EPA must be assured that provisions are made to prevent the municipal system from receiving pollutants that would inhibit the operation of the municipal treatment works, or that would pass through the system untreated. Therefore, if the municipality receives a federal grant, the food processor may be required to provide some form of pretreatment if the waste being discharged, "as is", to the municipality is judged detrimental to the system and modifications are indicated.

However, EPA has noted that fruit

and vegetable processing wastes are amenable to municipal treatment. Discharging of fruit and vegetable process wastewaters to a municipal sewer system and the possibility of requiring a pretreatment system are quite probable realities for the fruit and vegetable processing industries. Screening is one form of pretreatment often required by municipal sewer use ordinances.

Other forms of pretreatment required by these ordinances could

be flow equalization, neutralization, and soil removal.

In addition to

meeting the municipal ordinance requirements, pretreatment may help to reduce sewer use costs and accommodate production increases without exceeding discharge limitations (i.e., suspended solids).

83 F&V SPNOFF/WW TREATMENT Alternatives It is an obvious economic fact that before any food processor undertakes the task of building a pretreatment facility for discharge to a municipal sewer, pays a municipal charge for wastewater treatment, or builds a complete treatment plant for discharge to a receiving stream that he must initiate in-plant waste saving practices, along with water recycling and reuse measures.

Another consideration is the restrictions

that are placed on the food processing wastewater discharge. Principal limitations focus on substances that may be toxic, cannot be adequately treated or stabilized, or materials which cause obstruction to flow in the sewers.

While toxic substances are not commonly associated with fruit and

vegetable type process waste streams, certain wastes are present that are not amenable to treatment and can cause obstruction and maintenance requirements.

These troublesome wastes include those that contribute large

quantities of suspended solids or alkalinity to the waste treatment facility.

Thus, some form of isolation and pretreatment of the waste

stream becomes necessary prior to discharge to this facility. The third consideration the food processor must address is to the strength and volume of his processing wastewater.

These parameters are

influenced by the fluctuation in production volumes and production facility expansion programs.

As these activities take place, increasing waste loads

can occur which could, and frequently do, reduce the ability of the municipal's waste treatment system to adequately treat the added waste. Should this happen with regularity, then the food processor may be faced with a problem of pretreatment or supporting a municipal waste treatment plant modification or expansion program.

In either case, careful economic

considerations will need to be reviewed.

Since the food processor knows

what his sewer costs are, he can calculate the cost of the added sewage treatment load and determine whether the projected cost could better be handled by pretreatment or financially supporting a municipal expansion program. Cost Considerations Inherent in modification or expansion of a municipal's waste treatment facility is the federal requirement (if federal grant money is used) that should these activities include treatment capacity for industrial wastewaters, then some form of industrial cost recovery system must be

84 F&V SPNOFF/WW TREATMENT established.

Much of this cost recovery activity is accomplished through

the use of a surcharge system keyed to specific wastewater parameters. Common parameters used are BOD strengths, suspended solids and the fats, oils and grease category. Surcharge systems vary, and no one can predict whether pretreatment can be justified economically until costs are evaluated. A surcharge system should be based upon an evaluation, by the city's consulting engineer, of the cost of the elements of the municipal treatment plant necessary to accomodate the flow, remove the suspended matter, and treat the other ingredients of the industrial wastewater to the required levels all on a unit basis (cost per pound of constituent). Many surcharge systems start with a flow base rate and apply multipliers for concentrations of any or all such ingredients as BOD, suspended solids, and grease.

As an example, the flow base rate charged to all sewer

users may be 50 percent of the water bill, including flow from private water supplies.

Then, taking BOD as an example, assume that 250 mg/l has

been established as a bottom base for surcharges. Then a multiplier might be applied for BOD between 250 and 500 mg/l, and a higher multiplier between 500 and 1,000 mg/l.

Another set of multipliers might be appl ied

for suspended solids, another for grease, others for other factors. These multipliers are then added together to establish a single multiplier to be applied to the flow base charge to arrive at the total bill. An example of the cost formulation as developed by the Federal EPA and used as a general guideline is as follows: Ci=voVi+boBi+soSi where Ci = charge to industrial users, dollars per year V O = average unit cost of transport and treatment chargeable to volume, per gallon bo = average unit cost of treatment, chargeable to BOD, dollars per pound s o = average unit cost of treatment (including sludge treatment) chargeable to suspended solids, dollars per pound V i = volume of wastewater from industrial users, gallons per year B i = weight of BOD from industrial users, pounds per year S i = weight of suspended solids from industrial users, pounds per year

85 F&V SPNOFF/WW TREATMENT Note:

The principle applies equally well with additional terms e.g., chlorine feed rates) or fewer terms (e.g., voVi only).

The terms bo and so may include charges (surcharges) for concentrated wastes above an established minimum based on normal load criteria. Inasmuch as it is an objective of the guidelines to encourage the initiation and use of user charges, this general method of allocation is both preferable and acceptable. Since this guideline was published before enactment of the act, it serves only as an indication of possible procedures.

No guidelines

pursuant to the act have been developed at this time. However, the decision to provide extensive pretreatment for discharge to a municipal sewer system or to separate and treat the plant's wastewater should be based upon a thorough, after-tax analysis of the costs involved. Evaluating Needs After the plant has been surveyed completely, and all possible waste conservation and water reuse systems have been identified, the necessary pretreatment system must be designed and the cost estimated. Those parts of the treatment attributable to flow (such as grease basins and dissolved air flotation) should be totaled and reduced to a cost per 1,000 gallons. Similar breakouts in cost per pound can be carried out for grease, suspended solids, and BOD. Then each major in-plant expense for waste conservation and water recycle and reuse can be evaluated, based on the estimated reduction in flow, BOD, suspended solids, and grease.

From such data, priorities can be

established for each in-plant waste-conservation measure suggested in the survey. Pretreatment Processes:

Pretreatment can cover a broad range of

wastewater processing elements, including flow equalization, screening, gravity separation of solids and floatables, dissolved air flotation, chemical treatment as an adjunct to gravity separation or flotation, and biological treatment such as aerated lagoons or some other form of biological treatment. Before any pretreatment is considered, an adequate survey should be made, including flow measurement, composite sampling, and chemical analysis, to determine the extent of the problem and the possibilities for pretreatment.

Analyses may include BOD, suspended solids, suspended

86 F&V SPNOFF/WW TREATMENT volatile solids, settleable solids, pH, temperature and FOG. A permanent flow-measuring and composite-sampling arrangement are warranted if sampling is done regularly to determine municipal surcharges. Most common pretreament practices will include flow equalization, neutralization and the separation of floatables and settleable solids. In some instances lime and alum, ferric chloride, or a selected polymer may be added to enhance separation.

Paddle flocculation may follow alum and lime

or ferric chloride additions to assist in coagulation of the suspended solids.

Separation may be accomplished by gravity or by air flotation.

Screening, which could include vibrating, rotary or static type screens, may precede the separation process and may also be used to concentrate the separated floatables and settled solids.

These various systems will be

discussed under separate headings. Flow equalization and neutralization are important in reducing hydraulic loading and correcting pH deficiencies if needed in the waste stream.

Equalization and neutralization facilities consist of a holding

tank, aeration capability for mixing, and, pumping equipment designed to reduce the fluctuations of waste streams as well as a means to adjust pH. These facilities can be economically advantageous whether the industry is treating its own wastes or discharging into a city sewer after some pretreatment.

The equalizing and neutralization tank will store wastewater

for recycle or reuse, or to feed the flow uniformly to treatment facilities throughout the 24-hour day.

The tank is characterized by a varying flow

into the tank and a constant flow out.

Lagoons may serve as equalizing

tanks or the tank may be a simple steel or concrete tank, often without a cover. Removal of floatables and suspended matter will provide a satisfactory means of reducing BOD concentrations.

Frequently this degree of treatment

will reduce the waste load sufficiently to comply with municipal sewer use ordinance limitations.

If additional BOD removal is required, a study of

biological processes for pretreatment may be instituted, possibly in pilot scale.

Several biological treatment systems have been successfully adapted

to the treatment of food processing wastes. These include the lagoon arrangement, activated sludge, and land application.

87 F&V SPNOFF/WW TREATMENT Treatment

Alternatives

to

Meet

Regulations

In the treatment of fruit and vegetable processing wastewaters one should be cognizant that these wastewaters often contain high concentrations of organics and suspended solids. These wastes are amenable to municipal waste treatment processes but when treated separately possess inherent treatment problems.

In most cases the processing wastes are

nutrient deficient, often lacking sufficient nitrogen and phosphorus compounds essential to support adequate biological activity.

Table 12

presents a summary of BOD/Nitrogen/Phosphorus ratio relationships associated with common fruit and vegetable commodity wastewaters.

For

adequate biological activity to proceed without limitation, the BOD/Nitrogen/Phosphorus ratio should be at least 100/5/l, respectively, expressed in mg/l units.

Thus an examination of Table 12 reveals that

nutrient supplements are needed for nitrogen and phosphorus.

Common

wastewater fortification practices utilize anhydrous ammonia and phosphoric acid as N and P sources, respectively, with NaOH used to standardize the pH of the pretreated raw wastewater stream. In addition, the unit processes employed in commodity production may produce an acid or alkaline effluent stream, resulting in fluctuations in the pH of the final effluent.

Therefore, some form of neutralization is

needed to correct the pH of these waste streams to the compatible pH range (6-9). Treatment alternatives have been briefly mentioned in the pretreatment section of this chapter.

If additional information is required for the

treatment alternatives mentioned, the reader is encouraged to refer to the supplemental reference material provided in this manual series entitled "Wastewater Treatment of Food Processing Effluents". Basically, the treatment processes involve screening, sedimentation or dissolved air flotation. Perhaps the most commonly used process is screening. Screening may employ vibrating screens, static screens or a rotary screen. In pretreating specialty food processing waste streams, the vibrating and rotary screens are the most frequently used. These screening systems are used in a flow away (water in forward flow and passes through with solids constantly removed from screen) mode of operation and can vary widely both

88 F&V SPNOFF/WW TREATMENT

Table 12.

Available Nutrients Fruit & Vegetable Wastewaters.

89 F&V SPNOFF/WW TREATMENT in mechanical action and in mesh size.

Mesh sizes can range from 0.5 inch

in a static screen to 200 mesh in high-speed circular vibratory polishing screens.

Screening systems may be used in combination (i.e., prescreen-

polish screen) to achieve the desired solids removal efficiency. Sedimentation is another process form used to remove solids from the wastewater influent.

Sizing of the detent on vessel and providing a

quiescent state for the raw wastewater are important design considerations. Temperature variation of the wastewater is another important consideration because of the development of heat convect on currents and the potential interference with marginal settling particles.

Grease removal is also

accomplished with this unit process through removal of the surface scum. A more complete treatment of the fruit and vegetable processing wastewaters can be achieved through biological assimilation.

Frequently

used systems, after suspended solids removal, are: treatment in an anaerobic lagoon followed by an aeration lagoon and stabilization-polishing pond; activated sludge system; aerated lagoon followed by a stabilizationpolishing pond; trickling filters, utilizing plastic media, and rotating biological contractors; with land application used as an effluent polishing technique. Treatment

of

Fruit

and

Vegetable

Processing

Wastewaters

A number of waste treatment systems are available for treating fruit and vegetable processing waste streams.

These systems are summarized in

Table 13 which defines the unit process, its order of use in the waste treatment sequence and the expected waste reduction performances by these unit processes. Anaerobic Lagoons Anaerobic lagoons may be used as a primary biological process in order to reduce the organic and solids loadings on aerobic biological processes which may be more expensive to operate. The lagoons are usually 2.4 to 6.1 meters deep with 3:l side slopes. In most cases, the detention time is between 5-25 days and the lagoons are designed for high surface loadings, 34 to 112 g,BOD5/day/m2.

90 F&V SPNOFF/WW TREATMENT

Table 13.

Food Industry Wastewater Treatment Practices.

91 F&V SPNOFF/WW TREATMENT The operation depends on the activity of anaerobic bacteria which degrade organic materials in the absence of oxygen to form organic acids, methane, ammonia, hydrogen sulphide and carbon dioxide. The reaction is relatively slow, with an optimum temperature of approximately 33 to 35oC. However, there are a number of advantages: 1.

Low initial cost.

2.

Ease of operation.

3.

No energy consumption.

4.

Ability to handle shock loads.

5.

Low operation costs.

6.

Small land area requirement.

Odors may occur periodically but this problem can be minimized by good management.

In some cases plastic covers of nylon, reinforced hypalon,

polyvinyl chloride or Styrofoam are utilized to retain heat and odorous gases in the pond. Anaerobic lagoons are particularly suitable for treating the high strength biodegradable wastes characteristic of the fruit and vegetable processing industry. and suspended solids.

Anaerobic ponds have achieved 85% removal of BOD5 Typical values for BOD5 removal are given in

Table 14. The ponds must be designed with sufficient sludge storage capacity such that sludge removal is required only infrequently. Treatability studies are recommended to assess sludge accumulation rates for design purposes. The anaerobic process can be enhanced by the construction of enclosed, well mixed reaction systems.

The systems consist of flow equalization

tanks, anaerobic contact tanks (0.12 to 0.5 days' detention time), air or vacuum gas stripping units, and a clarifier with sludge recirculation pumps.

Loadings of 2.4 to 3.2 kg BOD5/day/m3 have been used with a waste

recycle rate equal to 30% of the average daily flow to achieve BOD5 and suspended solids removals of 90 to 97%. Methane gas produced in the process can be collected and burned.

The capital and operating costs are

high but the units are suitable for installations where odor emissions cannot be tolerated and where insufficient land is available for the installation of anaerobic ponds.

92 F&V SPNOFF/WW TREATMENT

Table 14.

BOD5 Loadings and Removal Efficiencies - Anaerobic Lagoons.

93 F&V SPNOFF/WW TREATMENT Aerobic Lagoons Aerobic lagoons or stabilization ponds are the most common biological treatment system used in the U.S. fruit and vegetable industry. The type of lagoons used are seasonal retention ponds, aerobic stabilization ponds, and aerated lagoons.

All these processes depend on

the action of aerobic bacteria on the soluble organics contained in the waste streams. The organic carbon is converted to carbon dioxide and bacterial cells. Algal growth is stimulated by incident sunlight which penetrates to a depth of 1 to 1.5 meters.

Photosynthesis results in the production of excess

oxygen which is available to the aerobic bacteria; additional oxygen is provided by mass transfer at the air/water interface. Aerobic stabilization ponds are 0.18-0.9 m deep to optimize algal activity and are usually saturated with dissolved oxygen throughout the depth during daylight hours.

The ponds are designed to provide a detention

time of 2 to 2O days, with surface loadings of 5.5 to 22 g BOD5/day/m2. The ponds are usually multiple cell units operated in series to eliminate the possibility of short circuiting and to permit sedimentation of dead algae and bacterial cells.

The ponds are constructed with inlet

and outlet structures located in positions to minimize short circuiting due to wind induced currents; the dimensions and geometry are designed to maximize mixing.

These systems can achieve 80 to 95% removal of BOD5

and approximately 80% removal of suspended solids, with most of the effluent solids discharged-as algae cells. During winter periods the degree of treatment decreases markedly as the temperature decreases and ice cover eliminates algal growth. In regions where ice cover occurs, the lagoons may be equipped with variable depth overflow structures in order that processing waste flows can be stored during the winter.

An alternative method is to provide long

retention storage ponds; the wastes can then be treated aerobically during the spring prior to discharge. Aerobic stabilization ponds are utilized where land is readily available.

In regions where soils are permeable, it is often necessary to use

plastic, asphaltic, or clay liners to prevent contamination of adjacent groundwater.

94 F&V SPNOFF/WW TREATMENT Typical BOD5 removal efficiencies for fruit and vegetable wastes are given in Table 15. Facultative Ponds Facultative ponds are usually 0.9 to 1.8 meters deep. The processes involved in aerobic stabilization ponds occur in the upper layers of facultative ponds.

Anaerobic bacteria operate at depths greater than one

meter and are important in the degradation of organic compounds contained in the suspended solids which settle to the bottom of the ponds. Seasonal retention ponds belong to this category. Detention times for facultative ponds range from 7 to 30 days at surface loadings of 2.2 to 5.6 g BOD5/m2. Considerably higher organic loadings and longer retention times are utilized in seasonal holding ponds which are generally deeper than two meters. Holding pond systems can generally produce an effluent of acceptable quality for discharge to receiving streams (BOD5 and suspended solids concentrations less than 30 mg/l and 70 mg/l, respectively). They are particularly suitable for use in conjunction with other forms of treatment such as spray irrigation, or as flow equalization basins prior to the disposal of wastes to municipal sewage treatment works. The quality of effluent from holding ponds treating various commodities is provided in Table 16. Aerated Lagoons Where sufficient land is not available for seasonal retention or aerobic lagoons, efficient biological treatment can be achieved by the use of aerated lagoons.

Air is applied to these ponds by fixed or floating

mechanical aerators or by compressors through air diffusers located on the bottom of the pond.

The ponds are between 2.4 and 4.6 meters deep, with 2

to 10 days retention time and achieve 55 to 90% reduction in BOD5. There are two types of aerated lagoons in common use: 1.

Completely mixed (all solids are kept in suspension and only aerobic oxidation takes place).

2.

Facultative-aerated lagoon (the contents of the pond only partially mixed and suspended solids settle to depths where anaerobic decomposition occurs).

95 F&V SPNOFF/WW TREATMENT

Table 15.

BOD5 Loadings and Removal Efficiencies - Stabilization Ponds.

96 F&V SPNOFF/WW TREATMENT

Table 16.

Effluent Quality - Holding Lagoons.

97 F&V SPNOFF/WW TREATMENT Loading rates for aerated lagoons vary considerably and are determined by rigorous laboratory or pilot scale testing carried out on the raw waste. Specific BOD removal rates for given commodities in an aerated lagoon under completely mixed conditions are given in Table 17. Aerated lagoons achieve good BOD5 removal.

Levels of suspended solids in the effluent

are usually high and therefore aerated lagoons are usually followed by quiescent settling to reduce the concentration of solids. Trickling Filters Trickling filters, utilizing plastic media in columns 4.5 to 6.0 meters high, have been used in the treatment of high strength fruit and vegetable wastes (3000 to 4000 mg/l BOD5). High liquid recirculation rates and forced air circulation are used to achieve BOD5 removals up to 90%. Wastewater is distributed by rotating arms at constant rates onto the top surface of packed columns of plastic media. A biological film is formed on the media and cellular material periodically sloughs-off when the thickness becomes sufficiently great that oxygen transfer cannot occur throughout its depth and anerobic conditions develop. Underdrains located beneath the column transport the effluent to settling tanks where the dense sludge is separated from the liquid effluent.

A portion of the effluent is

recirculated to seed the process with biological cells and to promote consisten sloughing. General design criteria for trickling filters are as follows: roughing filters may be loaded at rates of 4.8 kg BOD5/day/m3 filter media and achieve BOD5 reductions of 40-50%; high rate filters achieve BOD5 reductions of 40-70% at organic loadings of 0.4 to 4.8 kg BOD5/day/m/3 standard rate filters are loaded at 0.08 to 0.4 kg BOD5/day/m3 and achieve BOD5 removals greater than 70%.

Both high rate and roughing filters

are normally followed by additional treatment.

In general they are used to

reduce the loading on subsequent treatment processes because of cost and ease of operation.

Limited data shown in Table 18 are principally from

pilot plant operations. Activated Sludge In an activated sludge treatment system, an acclimatized, mixed, biological growth of microorganisms (sludge) is contacted with organic

98 F&V SPNOFF/WW TREATMENT

Table 17.

NOTE:

BOD5 Removal Rate Constants and Efficiencies - Aerated Lagoons.

Fraction of BOD5 removed = (1 - kt)-'

99 F&V SPNOFF/WW TREATMENT

Table 18.

BOD5 Loadings and Removal Efficiencies - Trickling Filters.

100 F&V SPNOFF/WW TREATMENT material in the wastewater in the presence of excess dissolved oxygen and nutrients (nitrogen and phosphorus).

The microorganisms convert the

soluble organic compounds to carbon dioxide and cellular material.

Oxygen

is obtained from applied air which also maintains adequate mixing. The effluent is settled to separate biological solids and a portion of the sludge is recycled; the excess is wasted for further treatment such as dewatering. Activated sludge systems utilized in the fruit and vegetable industry are the extended aeration types: that is, they combine long aeration times with low applied organic loadings. days.

The detention times are three to ten

The suspended solids concentrations are maintained at high values to

facilitate treatment of the high strength wastes. It is usually necessary to provide nutrient addition, pH control and flow equalization prior to the activated sludge process, to ensure optimum operation.

BOD5 and suspended solids removals in the range of 95-98%

have been achieved, using similar processes for many fruit and vegetable wastes.

However, pilot or laboratory scale studies are required to

determine organic loadings, oxygen requirements, sludge yields, sludge settling rates, etc. for these high strength wastes. The following information required for the design of activated sludge systems can be obtained from bench or pilot scale experiments: 1.

BOD5 removal rate data.

2. Oxygen requirements for the degradation of organic material and the degradation of dead cellular material (endogenous respiration). 3.

Sludge yield, determined from the conversion of soluble organics to cellular material and the influx of inorganic solids in the raw waste.

4. Solid/liquid separation rate; the final clarifier would be designed to achieve rapid sedimentation of solids which would be recycled or further treated. 3

A maximum surface

2

settling rate of 16.5 m /day/m has been suggested for fruit and vegetable waste. Activated sludge systems used in the fruit and vegetable processing industry may be batch ("fill and draw") or continuous flow.

The activated

sludge reactors and clarifiers are often lined earthen basins rather than concrete or steel tanks, the former involving lower construction costs.

101 F&V SPNOFF/WW TREATMENT These systems are more difficult to operate than lagoon systems or trickling filters but can consistently produce a specified effluent quality.

They are particularly suited for use in locations where there is

limited land available.

However, operational power costs and operation and

maintenance costs are relatively high. Typical design criteria and operating conditions for activated sludge systems treating fruit and vegetable wastes are as follows: - activated sludge concentration 2,000 - 4,000 mg/l - organic loading 0.1 to 0.5 kg BOD5/kg microbial solids, - aeration time 16 - 48 hours, dependent on organic loading and sludge age requirements, - depth 3.0 - 6.1 meters (2.1 m minimum), - return sludge rate 25 - 100% of plant inflow rate. Rotating Biological Contactors The use of rotating biological contactors is relatively new in North America but has been utilized in Europe for a number of waste treatment applications.

BOD5 reductions up to 90% have been achieved with multi-

stage units on citrus and apple processing wastes. Rotating contactors consist of closely spaced flat parallel disks mounted on horizontal shafts which rotate at 1 to 6 rpm perpendicular to the direction of waste flow.

The disks are partially submerged in the

wastes and a biological film consisting of a mixed population of bacteria, fungi and protozoans develops on the surface of the disks. The biological film is alternately contacted with the waste and with the atmosphere for oxygen exchange.

The rotational motion maintains solids in suspension and

entrains air in the liquid effluent.

As the biological growth increases, a

portion of it separates from the disks and is settled in a clarifier. The organic loading required for 90% BOD5 removal is specific to the waste being treated.

A high degree of treatment is possible since the

contactors are designed to provide plug flow and the bacterial growth changes with distance along the contactor.

The contactors may be used

subsequent to roughing treatment such as anaerobic or aerated lagoons; a number of contactors in series may be used without roughing treatment. Biological contactors can cope with fluctuating loadings and can provide consistently good quality effluent.

They are relatively simple to

102 F&V SPNOFF/WW TREATMENT operate, require little maintenance and consume relatively little energy. At the present time, economic consideration of high capital cost detract from their widespread use. References CH2M Hill, Corvallis, Oregon. 1976. Wastewater Treatment - Pollution Abatement in the Fruit and Vegetable Industry. Prepared for Food Processors Institute and Sponsored by Office of Technology Transfer, Environmental Protection Agency. Dornbush, J. N., D. A. Rollag and W. J. Trygotad. 1976. Investigation of an anaerobic-aerobic lagoon system treating potato processing wastes. IN Proceedings of the Sixth National Symposium on Food Processing Wastes. EPA - 600/2-76-224, p. 3, December. Hemphill, B. W. and R. G. Dunnahoe. 1977. Improved Biological Treatment of Food Processing Wastes with Two-Stage ABF Process. IN Proceedings Eighth National Symposium on Food Processing Wastes. EPA-600/2-77-184, p. 235, August. Mulyk, P. A. and A. Lamb. 1977. Inventory of the Fruit and Vegetable Processing Industry in Canada - A report for Environmental Canada, Environmental Protection Service, Ottawa, Ontario, Canada. Mulyk, P. A. and A. Lamb, of Stanley Associates Engineering Ltd. 1977. Review of Treatment Technology in the Fruit and Vegetable Processing Industry in Canada.

Economic and Technical Review Report EPS

3-WP-77-5, Water Pollution Control Directorate. Steffen, A. J. 1973. In-Process Modifications and Pretreatment Upgrading Meat Packing Facilities to Reduce Pollution, #l. EPA Technology Transfer Seminar Publication, October. Steffen, A. J. 1973. Pretreatment of Poultry Processing Wastes Up-grading Poultry-Processing Facilities to Reduce Pollution. #2. EPA Technology Transfer Seminar Publication (EPA - 625/3-73-OOl), July. Stephenson, J. P. and P.H.M. Guo. 1977. State-of-the-Art Review of Processes for Treatment and Reuse of Potato Wastes. Economic and Technical Review Report EPS 3-WP-77-7, Water Pollution Control Directorate.

103 F&V SPNOFF/LAND DISPOSAL L A N D

D I S P O S A L

Introduction Food processing wastewaters have been applied to the land through engineered systems for more than 25 years.

Major interest began in the

late 1940's with the objective being primarily waste disposal. Since then, a wide variety of food processing wastewaters has been applied to the land.

Many of the earlier installations were loaded on the basis of

successful experience elsewhere, without regard for differing soil and drainage characteristics.

As a result of this oversight, many systems

failed and land treatment systems began to acquire a poor public image. Today's PL 92-500 "zero discharge" goals, however, coupled with improved understanding of the capabilities and limitations of soil systems have renewed the interest in using land application. A 1964 survey resulted in the identification of 844 systems applying food processing wastewater to the land.

Pennsylvania had the most systems

(143) followed by Wisconsin (141) and California (131). In 1972 as a result of surveys and studies by the American Public Works Association (APWA) and Metcalf & Eddy, Inc., data on more than 84 operating systems were collected.

These reports serve as the basis for much of the

information presented here. This information is not meant to stand alone as the final work on the subject of land applied fruit and vegetable processing wastes.

Its

purpose is to provide a commodity-specific perspective of the suitability of land application systems for the fruit and vegetable processing industry. Wastewater

Quality

and

Pretreatment

Requirements

Wastewater Characteristics The characteristics of food processing wastewaters that must be considered with regard to land treatment include BOD and COD, suspended solids (SS), total fixed dissolved solids, nitrogen, pH, temperature, heavy metals, and the Sodium Adsorption Ratio (SAR). These characteristics vary widely among food processing wastes applied to the land.

104 F&V SPNOFF/LAND DISPOSAL BOD and COD.

The ratio of BOD to COD is a measure of a

wastewater's biodegradability.

Most food processing wastewaters are

readily degradable and exhibit a high BOD to COD ratio. Most soils are highly efficient biological treatment systems. So, liquid loading rates for land treatment operations are usually governed by the water holding capacity of the soil rather than by the organic loading rate.

This

operational independence from BOD loading can be a distinct advantage of land treatment systems over conventional systems in treating high-strength wastewaters.

There are limits, of course, to the organic loading that can

be placed on the land without stressing the soil system. The effects of organic overloads on the soil include damage to or killing of vegetation, severe clogging of the soil surface, and leaching of undegraded organics into the groundwater.

Defining the limiting organic loading rate for a

system must be done on an individual site-specific basis.

However,

rule-of-thumb rates have been developed based on experience.

A maximum BOD

rate of 200 lb/acre/day has been suggested as a safe loading rate for pulp and paper wastewaters.

A somewhat higher rate can normally be used with

food processing wastewaters containing a higher percentage of sugars rather than starchy or fibrous material.

Substantially higher loading rates

(greater than 600 lb/acre/day) have been used on a short-term seasonal basis for infiltration-percolation systems. For overland flow systems, organic loadings in the range of 40 to 100 lb/acre/day have been used successfully. Suspended Solids.

Solids are generally the major source of

operational problems such as clogged sprinklers and clogged soil surface. Pretreatment to remove solids will normally minimize these problems. Nitrogen.

Nitrogen in food processing wastewaters is normally

not of major concern because it is usually present in such concentrations that it is almost completely removed by bacterial assimilation or crop uptake.

Notable exceptions are feed-lot, dairy, potato processing, and

meat packing wastes.

The latter have been found to contribute a

significant nitrate load to groundwaters. pH. Wastewaters that have a pH between 6.0 and 9.5 are generally suitable for continuous application to most crops and soils.

Wastewaters

with pH below 6.0 have been successfully applied to soils that have a large

105 F&V SPNOFF/LAND DISPOSAL buffering capacity. "Beware of applying caustic wastes before diluting or neutralizing them. High temperature wastewaters from cooking

Temperature.

operations can sterilize the soil and prevent growth of cover vegetation. Heavy Metals. metals.

The soil has a large capacity to adsorb heavy

Once this capacity is exceeded, however, the metals may be

leached to the groundwater (under acid soil conditions) or inhibit plant growth. Salt Loading-Sodium Adsorption Ratio (SAR). The ratio of sodium to other cations, primarily calcium and magnesium, can adversely affect the permeability of soils, particularly clay soils. Wastewaters with a SAR below 8 are considered safe for most soils. Sandy soils can tolerate higher SAR values. Pretreatment Pretreatment is required in most cases to eliminate frequent operating difficulties and avoid adverse effects on the terrain environment. Screening. Screening with rotary or vibration screens has been almost universally employed as a form of pretreatment to separate coarse solids from food processing wastewaters.

Such solids can cause serious

problems with wastewater distribution, particularly with spray Fine screens at pump intakes or in-line screens in the

applications.

discharge piping have also been employed as an added precaution against sprinkler nozzle clogging. Lagooning.

The use of lagoons or settling ponds prior to land

application of industrial wastewaters has been prevalent.

Such lagoons

serve to remove silt and other suspended particles which may contribute to clogging of the distribution system as well as hasten the clogging of soil pore space.

This form of pretreatment is normally used when applying

wastewaters to vegetated fields by flood irrigation techniques.

This

practice does, however, tend to create noxious odors. pH Adjustment.

Industrial wastewaters with sustained flows

outside the pH range of 6 to 9.5 should be neutralized prior to land application if the site is to be vegetated. Wastewaters with widely fluctuating flows can be self-neutralizing if an equilization basin is

106 F&V SPNOFF/LAND DISPOSAL provided prior to land application.

In other cases a continuous pH

control system may be necessary. Cooling.

For wastewaters below 150°F, application by sprinkling

normally provides sufficient cooling to protect vegetation and soil. Such cooling may be enhanced by the use of sprinklers that produce small spray droplets or that have large spray diameters. Wastewaters with temperatures much above 150°F generally should be cooled prior to spraying if vegetation is desired. Nutrient Addition.

Nutrient addition in the form of nitrogen or

phosphates may be necessary for nutrient deficient wastes unless the fields are adequately fertilized. Land

Treatment

Processes

Land application systems for treatment and disposal of food processing wastes are normally categorized into three types of systems based on differences in the interaction of the wastewater with vegetation and soil.

These three catagories are referred to as (1) irrigation, (2)

overland flow, and (3) infitration-percolation.

Selection of the type of

system at a given site is primarily governed by the drainability of the soil because it is this property that largely determines the allowable liquid loading rate.

Schematic diagrams indicating the major process

characteristics of each 'of the systems are shown in Figure 17. A summary of the comparative characteristics of the three systems is presented in Table 19. Irrigation.

Irrigation is considered to include those systems

where wastewater is applied to land by either spray or surface techniques at normal agricultural irrigation rates or somewhat in excess of those rates. in./day.

Liquid loading rates generally range from about 0.1 in./day to 0.6 At these loading rates, land requirements range from about 60 to

370 acres/mgd of wastewater, plus a buffer zone. Within the food processing industry the most common method of liquid waste disposal on the land is spray irrigation.

The availability of

suitable land, soil characteristics, cover crop, the wastewater, and climatic conditions all affect this method of disposal.

Some irrigation

l07 F&V SPNOFF/LAND DISPOSAL

Figure 17.

Land Application Approaches

108 F&V SPNOFF/LAND DISPOSAL

Table 19.

Comparative Characteristics of Land Treatment Systems

*l acre inch = 27,154 gallons

109 F&V SPNOFF/LAND DISPOSAL systems operate with little or no run-off and remove practically all of the pollutional load (Table 20). Loamy, well-drained soil is most suitable for irrigation systems, particularly where crop production is a major goal of the operation. However soil depth of 5 feet above groundwater is preferred to prevent saturation of the root zone.

Underdrain systems have been used

successfully to adapt to high groundwater or impervious subsoil conditions. The objective of most irrigation systems for food processing wastewaters is to maximize hydraulic loadings rather than crop production. The result is that most systems use a water tolerant perennial grass as a cover crop.

A few systems use higher valued crops, such as alfalfa or

corn, for cover vegetation, but these have only been successful when standard irrigation practices have been followed. Cover vegetation plays an important role in irrigation systems. This is particularly true in spray application systems where the cover vegetation prevents soil erosion and sealing of the soil surface due to the battering action of water droplets. The root structure of cover vegetation also aids in maintaining the infiltrative capacity of the surface by expanding the soil and promoting dispersion of clogging materials.

Plants are also largely responsible for removal of nutrients

such as nitrogen and phosphorus.

Removal of the organic materials in the

wastewater is accomplished primarily by microorganisms residing in the soil. A few systems employing surface application techniques, such as border strip or ridge and furrow irrigation, do not use cover crops because the wastewater is either toxic to plants or contains a high suspended solids load that would be trapped by a cover crop at the head of an irrigated strip. Spray irrigation on slopes draining to lagoons appears to be very successful and adaptable to soils which limit lateral movement of underground water; 99% BOD reduction, total color removal, and 90% N and P reduction may be expected. In irrigation systems most of the applied wastewater is either consumed through evapotranspiration or percolates through the soil to become groundwater.

Evaporative consumption generally is equal to or

111 F&V SPNOFF/LAND DISPOSAL greater than percolation. as surface runoff.

A portion of the applied wastewater may appear

Failure to adequately control this runoff is a common

source of problems at existing systems.. These 1970 figures show the percentages of canners and freezers of the listed products disposing of effluents by irrigation in the continental

U.S.:

Overland Flow The overland flow technique is an adaptation of spray irrigation to impermeable or poorly drained soils.

The technique was pioneered in 1954

by the Campbell Soup Company at Napoleon, Ohio, and was studied in depth at the Campbell installation at Paris, Texas.

Until recent studies with

municipal wastewaters were performed, its application had been restricted to the food processing industry.

Overland flow differs from spray

irrigation primarily in that a substantial portion of the wastewater applied is designed to run off and must be collected and discharged to receiving waters, or in certain cases where wastewater is produced only during part of the year, stored for deferred application.

An overland

flow system therefore functions more as a land treatment system than a land disposal system. Wastewater is applied by sprinklers to the upper two-thirds of sloped terraces that are 100 to 300 feet in length, [see Figure 17(b)]. A runoff collection ditch or drain is provided at the bottom of each slope. Treatment is accomplished by bacteria on the soil surface and within the vegetative litter as the wastewater flows down the sloped, grass-covered surface to the runoff collection drains.

Ideally, the slopes should have a

grade of 2 to 4 percent to provide adequate treatment and prevent ponding or erosion.

The system may be used on naturally sloped lands (such as the

two Campbell Soup Company installations at Napoleon, Ohio, and Paris,

112 F&V SPNOFF/LAND DISPOSAL Texas) or it may be adapted to flat agricultural land by reshaping the surface to provide the necessary slopes. Higher liquid loading rates are possible with the overland flow technique than with conventional spray irrigation. These rates may range between 0.25 to 0.7 in./day, resulting in a land requirement of about 50 to 150 acres plus buffer zone for each mgd applied. As mentioned previously, the system is especially suited to use with slowly permeable soils such as clays or clay loams.

With this type of

soil very little water percolates to the groundwater. Most of it appears as surface runoff or is consumed by evapotranspiration. A cover crop is essential with the overland flow system to provide slope protection and media for the soil bacteria as well as to provide nutrient removal by plant uptake.

A water tolerant perennial grass such as

Reed canary grass or tall fescue has been found to be suitable to the high liquid loading rates. Infiltration-Percolation Infiltration-Percolation systems are characterized by percolation of most of the applied wastewater through the soil and eventually to the groundwater.

The method is restricted to use with rapidly permeable soils

such as sands and sandy loams.

This type of system is normally thought to

be associated with recharge or spreading basins although in food processing applications high-rate-spray systems have been used to provide distribution of the wastewater.

In actual practice there is not a

definite division between irrigation systems previously described and high-rate spray infiltration-percolation systems, but rather a complete spectrum of operations with liquid loading rates ranging from 0.1 in./day to 12 in./day.

For purposes of discussion, an average loading rate of 0.6

in./day is used as an arbitrary dividing point between the two types Of systems.

At this minimum loading rate, infiltration-percolation

systems

would require about 60 acres plus a buffer zone for each mgd applied. The use of recharge or spreading basins for treatment and disposal of food processing wastewaters has been limited primarily due to the high organic strength and high solids concentration of typical wastewaters. These constituents clog the soil surface and make it difficult to maintain consistently high soil infiltration rates.

113 F&V SPNOFF/LAND DISPOSAL Vegetation is essential in high-rate spray systems to protect the infiltrative surface.

For spreading basins, cover vegetation would

normally not be used for wastewaters containing a high solids concentration because it would tend to entrap solids and prevent satisfactory distribution in the basin. In infiltration-percolation systems, plants play a relatively minor role in terms of treatment of the applied wastewater.

Physical,

chemical, and biological mechanisms operating within the soil are responsible for treatment.

The more permeable the soil, the further the

wastewater must travel through the soil to receive treatment.

In very

sandy soils this minimum distance is considered to be approximately 15 feet. Existing

Land

Treatment

Systems

The design and management as well as common operating problems of the different types of systems described above are discussed through description of several selected existing operations. Irrigation Systems Under the category of irrigation the two basic techniques of wastewater application employed are spray irrigation and surface irrigation.

Under spray irrigation, variations that have been observed

include solid set sprinklers, portable sprinklers, and tower spraying. Surface techniques include border strip flood irrigation with or without crops and ridge and furrow irrigation also with or without crops. A selected list of spray irrigation systems handling a wide variety of food processing wastewaters is presented in Table 20 along with the major operating characteristics. systems is presented in Table 21.

A similar list for surface irrigation Typical systems employing each of the

various application techniques are described below. Solid Set Sprinkler Irrigation.

An example of solid set spraying

is the system of the Idaho Supreme Potato Company in Firth, Idaho. The distribution system is buried with risers spaced on 80-foot squares discharging at 80 to 100 psi.

The spray fields are planted to a mixture of

Reed canary grass, meadow foxtail, and alta fescue with the yield of hay

115 F&V SPNOFF/LAND DISPOSAL being 5 tons/acre annually.

Potato washing wastewater passes through

vacuum filters with the mud going to lagoons and the filtrate to the spray fields where it is mixed with screened wastewater from the potato peeling and cutting operations.

The system is well managed with wastewater applied

in 12 hours followed by 8 to 9 days of resting in the summer.

The system

continues to operate during the winter with ice mounds building up to heights of 5 feet.

The only change in operation is that spraying lasts for

24 hours followed by 16 to 18 days of resting. Portable Sprinkler Irrigation.

The spray system at Tri Valley

Growers tomato processing installation near Stockton, California, is a good example of a portable sprinkler system.

The spray field consists of 165

acres with 90 acres planted to water grass and 75 acres planted to Sudan grass.

The sprinkler system consists of 16-inch portable aluminum mains

and 4-inch portable laterals with sprinklers on a 60-foot grid. Although the system is portable, it is operated as a solid set system without moving the laterals prior to the end of the season. Pretreatment of the wastewater consist of coarse screening, holding pond for equalization and sedimentation, plus in-line screens in the discharge lines of the spray system pumps. Prior to the addition of the 75 acres to the spray fields in 1973, approximately 3 mgd of tomato processing wastewater was applied to 90 acres with each of nine lo-acre sections receiving full flow for The resulting average liquid loading

approximately 3 hours at a time.

rate was in excess of 1.2 inches per day on a clay loam soil. This application rate was far in excess of the infiltrative capacity of the soil and the evapotranspiration demand of the cover crop. Therefore approximately 30 percent of the applied water appeared as runoff. The runoff was collected and channeled back to the pumping station for recirculation over the system.

Runoff was not discharged to local

receiving waters because of particularly stringent discharge requirements of 15 mg/l BOD and 15 mg/l suspended solids. The recirculated runoff, therefore, accumulated and was actually stored on the field surface and in the drainage ditches.

The flooded conditions that developed led to odor

and mosquito propagation problems. the season and became quite tall.

The crop was allowed to grow throughout This tall grass impeded drying of the

soil surface and produced sheltered habitat for mosquito breeding.

116 F&V SPNOFF/LAND DISPOSAL The flooded condition was partially relieved in 1973 by the addition of 75 acres of spray field and regrading the existing 90 acres. resulting loading rate was 0.67 in./day.

The

In addition, the cover crop was

harvested as part of the field management. Prior to harvesting, the field was allowed to dry for a period of 7 days.

The grass was mowed and removed

as green chop in one cutting during the 1973 season.

For 1974, the

expected flow is 2 mgd as a result of the separation of cooling water and the resulting application rate would be reduced to 0.45 in./day. Tower Spray Irrigation.

A unique spraying system has evolved at

the Stokely-Van Camp installation at Fairmount, Minnesota. In the early 1950's a portable solid-set system was used, but the labor required to move the laterals proved too expensive.

This system was replaced by a boom-type

center pivot irrigation rig which also was too demanding of labor for maintenance.

Finally, a fixed tower system was designed with fog nozzles

operating at high pressure.

The system now operates successfully using

towers at 500-foot centers that are about 25 feet high. Flood Irrigation.

An example of flood irrigation is the Idaho

Fresh Pak system at Lewisville, Idaho.

The land has been graded into

2.5-acre plots for border strip irrigation.

Potato-peel wastewater passes

through a vacuum filter and the filtrate is pumped 4.5 miles to the site. In the summer, grass is grown and harvested for hay. In the winter the 50°F wastewater melts the snow and ice and percolates into the soil. Some odors exist and more land is being acquired by the company. Ridge and Furrow Irrigation.

This form of irrigation has been

replaced, for the most part, by spray irrigation.

Whereas Schraufnagel

reported about 50 ridge and furrow systems in 1962, Sullivan reported only one ridge and furrow system out of the 56 responding to the APWA questionnaire.

That system was the Green Giant Company installation at

Buhl, Idaho, where corn-processing wastewater is screened and used as supplemental irrigation water for corn.

Other systems reported in

existence by an APWA mail survey are five creameries in Wisconsin and three food processing plants in Indiana. Overland and Flow Systems. The overland flow systems described below are examples of how the system may be adapted to different site conditions. A list of existing systems with operating characteristics is presented in Table 22.

117 F&V SPNOFF/LAND DISPOSAL

Table 22 - Selected Overland Flow Systems

118 F&V SPNOFF/LAND DISPOSAL The Hunt-Wesson Foods cannery in Davis, California, employs the overland flow technique to treat approximately 3.25 mgd of tomato processing wastewater from July through September, plus smaller volumes of wastewater from other products during the remainder of the year.

The

system consists of a series of sloped terraces with collection ditches at the toe of each slope.

The terraces were constructed on a slope of 2.4

percent with a length of 175 feet.

A considerable amount of earthwork was

required to form the slopes (over 300,000 cu yd) since the site was originally flat agricultural land. The slopes were planted to a combination of Reed canary grass, tall fescue, Italian rye grass, and trefoil with the anticipation that Reed canary grass would eventually dominate.

The distribution system consists of a solid set sprinker system

with risers spaced at lOO-foot intervals and 65 feet from the top of each slope. Spraying is preceeded by coarse screening. The application of wastewater is controlled automatically by clock timers that actuate pneumatic valves in the field. During peak season, however, the spray rotation is controlled manually. Infiltration-Percolation Systems. tion-percolation,

Under the category of infiltra-

two methods of wastewater application are employed.

These are spreading basins or percolation beds and high rate spraying. Tri Valley Growers' Plant No. 2 near Modesto, California, is one of the few processing plants where classical spreading basins are employed for infiltration-percolation.

A waste-flow of approximately 2.5 mgd is

generated from the processing of tomatoes, peaches, and pears with the canning season normally extending from July through September.

The

infiltration-percolation site consists of 70 acres of spreading basins and 20 acres of wine grapes.

The grapes are irrigated with wastewater using

normal application rates with no adverse affects on grape quality. The soil at the site is primarily sand and loamy sand. The infiltration-percolation site is divided into one-acre basins. Most of the basins receive wastewater from concrete-lined ditches equipped with slide gates, while the remainder are served by a buried-pipe system with flood valves.

This pipe must be flushed with fresh water after each

application to prevent release of odors.

The application schedule and

loading rates have been developed by trial and error, since each basin was

119 F&V SPNOFF/LAND DISPOSAL found to have a different percolation capacity. The differences are due to hardpan layers in the subsoil.

This situation is a good example of why

subsurface soil conditions should be determined as part of a site investigation for infiltration-percolation systems.

Applications range

from 50,000 to 500,000 gallons per acre depending on the basin. Each application is followed by 7 to 10 days of resting. The applications are regulated to achieve elimination of standing water within 24 hours of the start of application.

This avoids both odor and mosquito problems.

During the summer no cover crop is used on the basins. After each application the basins are disked to allow the soil to aerate and maintain its infiltrative capacity. As the season proceeds, the infiltrative capacity drops somewhat due to clogging by solids in the wastewater. Following the canning season, the basins are planted to oats which are harvested in the following spring.

The oats serve to take up some of the

nitrogen that was contained in the wastewater and held in the soil structure, as well as to restore the infiltration capacity of the soil. Costs At present the availability of useful cost data on land treatment systems is limited.

The cost data presented herein are based primarily on

the APWA report and are supplemented with information on a few systems in California. Spray Irrigation Costs for selected spray irrigation systems are given in Table 23. Construction costs include costs for pumping stations, force mains, land preparation, and distribution systems, except as noted, and depend on the year constructed as well as many local conditions.

Land costs have been

separated because of the ir variab ility and are presented in Table 24. In addition to the cost of land when purchased, the estimated value of the land in 1972 is included in Table 24.

In all cases the value of the land

is at least as high as when it was purchased and in several cases land values have appreciated substantially.

The total capital cost is the sum

of the costs for land and construction plus easements, pretreatment facilities, monitoring facilities, and administrative, engineering, and

120 F&V SPNOFF/LAND DISPOSAL Table 23.

Construction and Operating Costs for Selected Spray Irrigation Systems

121 F&V SPNOFF/LAND DISPOSAL legal fees.

In the case of the Libby operation at Liepsic, Ohio, the land

for spray irrigation is leased. Operating costs are also given in Table 23. The annual budget was divided by the total annual flow to obtain the cost in cents per thousand gallons.

The period of operation ranged from 4 months for the Green Giant

Company operation at Montgomery, Minnesota, to 12 months for the Gerber operation at Fremont, Michigan. Surface Irrigation Costs for surface irrigation depend a great deal on the existing topography.

Consequently the cost-of preparing the land for irrigation

must be balanced against the purchase price of the land. For example, the Libby's system at Gridley did not entail any land preparation costs because the fields were leveled previously for irrigation. However, the land cost was $1,400 per acre.

On the other hand, for the California Canners and

Growers system at Thornton, costs for land preparation and the distribution system totalled $450 per acre (total construction cost shown in Table 25). Adding this to the land cost of $870 per acre yields a total of $1,320 per acre at Thornton, as compared to the $1,400 per acre at Gridley. Of course, many of the local conditions were different.

However, the

combination of land cost and land preparation cost is an especially important consideration for surface irrigation systems.

Additional land

costs are given in Table 26. The initial expenditure for a land application system is appreciably lower than that for a biological wastewater treatment plant. The primary investment of a land application system is the cost of land.

In the

midwest region of the United States, except for major metropolitan areas, land prices vary from $400 to $1,500 per acre. Equipment and installation costs are as high as $1,000 per acre, the major equipment expense usually being the piping.

Four-inch aluminum pipe costs roughly $1.30 per foot,

and 6" spiral-wound steel pipe costs about $1.50 per foot, including connections. Operating costs include the cost of pumping, maintenance and operation.

If the semipermanent system is used, two men are capable of

properly operating the system. operator's attention.

The permanent system requires only one

122 F&V SPNOFF/LAND DISPOSAL OF F&V PROCESSING WASTEWATERS

Table 25 - Construction and Operating Costs for Selected Surface Irrigations Systems

123 F&V SPNOFF/LAND DISPOSAL Overland Flow Construction cost items for overland flow include earthwork, pretreatment, transmission, distribution, and collection. Clearing of land, grading of slopes, and planting is generally equal in cost to the distribution system.

The available costs for distribution systems and land

preparation for two operating systems are given in Table 27. The operating costs shown are total costs not including the return from the sale of hay. The return on the sale of hay is approximately 8 to 10 percent of the total annual operating cost. Infiltration-Percolation For infiltration-percolation

systems, the costs per gpd, as shown in

Table 28, are relatively low compared to spray irrigation.

Similarly, the

operating costs are lower due also to the high-rate applications and low land requirements.

The only available land cost was $400 per acre in 1961

for the Hunt-Wesson system at Bridgeton, New Jersey. Applicability

and

Potential

of

Land

Application

It is apparent from the descriptions of the various existing systems that land application can be adapted to a wide range of soil types and site drainage conditions.

One of the keys to a successful system is

to determine the site characteristics--soil type, soil drainage, subsurface conditions, topography, and climatic conditions--and then adapt the most suitable technique to them.

Equally important to successful

operation is conscientious field management to avoid stressing or overloading the system. Of particular interest to the food processing industry is the ability of land application techniques to meet "zero discharge" requirements at a reasonable cost.

As more food processing activity becomes centered in

rural areas the economic advantages of land application will become more evident. Land application, however, is not a panacea. Many uncertainties still remain regarding long-term effects of wastewater on soils, plants, and groundwater.

Research in this regard is being carried on at several

124 F&V SPNOFF/LAND DISPOSAL

Table 27 - Construction and Operating Costs for Overland Flow Systems

a

Depends upon the period of operation.

125 F&V SPNOFF/LAND DISPOSAL locations.

Dr. Jay Smith of the USDA in Kimberly, Idaho, is conducting a

3-year study of land application of potato processing wastewaters in Idaho. EPA has sponsored considerable research on overland flow. The food processing industry has taken the lead in developing land application as an economic alternative to conventional treatment method. This is evidenced by the fact that over one-third of all the land application systems in the United States serve the industry. Active interest indicates that the industry will continue to be at the forefront of future development. References Bogedain, F., A. Adamczyk, and T. J. Tofflemire. 1974. Land Disposal of Wastewater in New York State. New York State Dept. of Environmental Conservation. Cole, L., B. Morris, and Wm. S. Stinson. 1977. Potato processor achieves 98+% BOD, 99+% suspended solids removal. Food Processing, Feb. Crites, R. W., C. E. Pound, and R. G. Smith. 1974. Experience with land treatment of food processing wastewater. Proceedings Fifth National Symposium on Food Processing Wastes. EPA.

Municipal Wastewater Treatment Works Construction Grants Program. references--Regulations, Guidance, Procedures.

Koo, R. C. J. 1976.

Back to the Tree, citrus processing plants use

wastewater for irrigation. Liptak, B. G. 1974.

Water Research in Action. Vol. 1, No. 7.

Environmental Engineer's Handbook. Vol. I and III.

National Canners Association. 1971.

Liquid Wastes from Canning and

Freezing Fruits and Vegetables (12060 EDK 08/71).

126 F&V SPNOFF/DIRECT DISCH DIRECT

DISCHARGE

Introduction Fruit and vegetable processing plants that discharge wastewaters directly to streams, bays, sounds, rivers, creeks and/or estuaries must have a permit for this discharge as required under the NPDES permit program.

In most cases, even small plants that have septic tanks for process

wastewaters must also have a state or local permit.

Plants that use

non-discharge systems such as land disposal will also probably need a permit. Permits for discharge or disposal are usually obtained from the state environmental control agency. Effluent

Guidelines

and

Limitations

Introduction In response to widespread public concern about the condition of the Nation's waterways, Congress enacted the Federal Water Pollution Control Act Amendments of 1972.

The 1972 act built upon the experiences of earlier

water pollution control laws.

The 1972 act brought dramatic changes.

What the 1972 law says, in essence, is that nobody - no city or town, no industry, no government agency, no individual - has a right to pollute our water.

What was acceptable in the past - the free use of waterways as

a dumping ground for our wastes - is no longer permitted.

From now on,

under the 1972 law, we must safeguard our waterways even if it means fundamental changes in the way we manufacture products, produce farm crops, and carry on the economic life of our communities. Congress declared that the objective of the 1972 law is "to restore and maintain the chemical, physical, and biological integrity of the Nation's waters." - The law requires EPA to establish national "effluent limitations" for industrial plants - including fruit and vegetable products plants. An "effluent limitation" is simply the maximum amount of a pollutant that anyone may discharge into a water body. - By July 1, 1977, the law required existing industries to reduce their pollutant discharges to the level attainable by using the "best

127 F&V SPNOFF/DIRECT DISCH practicable" water pollution control technology (BPT). BPT was determined by averaging the pollution control effectiveness achieved by the best plants in the industry. - By July 1, 1983, the law requires existing industries to reduce their pollutant discharges still more - to the level attainable by using the "best available" pollution control technology (BAT). BAT is based on utilizing the best pollution control procedures economically achievable. If it is technologically and economically feasible to do so, industries must completely eliminate pollutant discharges by July 1, 1983. - The law requires new fruit and vegetable plants to limit pollutant discharges to the level attainable by meeting national "standards of performance" established by EPA for new plants. A new plant must meet these standards immediately, without waiting for 1977 or 1983. These new plant standards may require greater reduction of pollutant discharges than the 1977 and 1983 standards for existing plants. Where practicable, zero discharge of pollutants can be required. However, for the fruit and vegetable industry, the standards are equal to the most stringent 1983 standards, with allowance not granted for plant size. - The law requires fruit and vegetable facilities that send their wastes to municipal treatment plants - as almost half the do - to make sure the wastes can be adequately treated by the municipal plant and will not damage the municipal plant.

In some industries, discharges to municipal

plants may thus have to be "pre-treated." That is, the portion of the industrial waste that would not be adequately treated or would damage the municipal plant must be removed from the waste before it enters the municipal system.

To date, the fruit and vegetable industry has not been

required by law to pretreat their wastewaters. - The law does not tell any industry what technology it must use. The law only requires industries to limit pollutant discharges to levels prescribed by law. - The law also says that if meeting the 1977 and 1983 requirements is not good enough to achieve water quality standards, even tougher controls may be imposed on dischargers. - And while the law requires industries to meet the national discharge standards set for 1977, 1983 and for new plants, the law also allows a state or community to impose stricter requirements if it wishes.

The

128 F&V SPNOFF/DIRECT DISCH national standards are thus minimum requirements that all industries must meet. The key to applying the effluent limits to industries - including the fruit and vegetable industry - is the national permit system created by the 1972 law. (The technical name is the "national pollutant discharge elimination system," or NPDES.) Under the 1972 law it is illegal for any industry to discharge any pollutant into the Nation's waters without a permit from EPA or from a State that has an EPA-approved permit program. Every industrial plant that discharges pollutants to a waterway must therefore apply for a permit. When issued, the permit regulates what may be discharged and the amount of each identified pollutant. effluent from each plant.

It sets specific limits on the

It commits the discharger to comply with all

applicable national effluent limits and with any State or local requirements that may be imposed.

If the industrial plant cannot comply

immediately, the permit contains a compliance schedule - firm target dates by which pollutant discharges will be reduced or eliminated as required. The permit also requires dischargers to monitor their wastes and to report the amount and nature of wastes put into waterways. The permit, in essence, is a contract between a company and the government. This combination of national effluent standards and limits, applied to specific sources of water pollution by individual permits with substantial penalties for failure to comply, constitutes the first effective nationwide system of water pollution control. Now what does all this mean to the fruit and vegetable industry? How does one determine the NPDES permit limitations for a plant discharge into a receiving stream? The U. S. Environmental Protection Agency prepared standards for fruit and vegetable plants under the 1972 law. many factors:

EPA did so, after considering

the nature of plant raw materials and wastes; manufacturing

processes; the availability and cost of pollution control systems; energy requirements and costs; the age of size of plants in the industry; and the environmental implications of controlling water pollution.

(For instance,

129 F&V SPNOFF/DIRECT DISCH we would gain nothing if, in controlling water pollution, we created a new air or land pollution problem.) The proposed regulations were issued by EPA in March, 1974 and October 1975. Then, they were sent to the industry and other interested organizations for review and comments. Federal Register.

They were made public by publication in the

Comments were submitted by companies and industry

organizations, by State agencies, and by Federal agencies.

EPA then

carefully analyzed the comments and made appropriate changes in the standards.

Then, EPA issued the final standards for the plants to follow

in order to meet the requirements of the 1972 law. The standards are contained in an official government regulation published in the Code of Federal Regulations. This regulation is supported by a detailed technical document called the "Development Document for Interim Final and Proposed Effluent Limitations Guidelines and New Source Performance Standards for the Fruits, Vegetables and Specialties Segment of the Canned and Preserved Fruits and Vegetables Point Source Category." Subsequent regulations and amendments have been made over the last several years. In brief, here is what the regulation does: - Sets limits on identified pollutants that can be legally discharged by plants in the sub-categories of the fruit and vegetable products industry. - Zeroes in on the major fruit and vegetable industry pollutants, it establishes maximum limitations for BOD and suspended solids that plants can discharge during any one day, on an average over a thirty-day period, and on an annual average based in terms of lbs pollutant that can be discharged per 1000 lbs of raw material processed. - Sets limits that can be met by using the "best practicable control technology currently available" - the 1977 requirement. - Sets more stringent limits that can be met by using the "best available technology economically achievable" - the 1983 requirment (Table 29 for fruits and Table 30 for vegetables). - Requires that the pH (acidity or alkalinity) of fruit and vegetable plant discharges be within the range of 6.0 to 9.5. - Establishes performance standards that new plants must meet without waiting for 1977 or 1983.

For the fruit and vegetable industry, the new

132 F&V SPNOFF/DIRECT DISCH plant standard is the same as the 1983 (BAT) standard for existing plants except that the limitations for the large plants are the new source standards regardless of plant size. However, regulatory officials shall be consulted for up-to-date information. - Does not require zero discharge of any pollutant by a fruit and vegetable plant.

Zero discharge may be technically possible in the

industry, but the cost would be prohibitive for most if not all plants in the industry. - Does not tell companies what technology to use to meet regulations. The standards only require fruit and vegetable companies to limit pollutant discharges to the levels required. In 1978, EPA reviewed the BAT standards in light of Section 304 (b)(4) of the Clean Water Act which established "best conventional pollutant control technology" (BCT).

BCT was intended to replace BAT. Congress

directed EPA to consider the: . . . reasonableness of the relationship between the costs of attaining a reduction in effluents and the effluent reduction benefits derived, and the comparison of the cost and level of reduction of such pollutants from the discharge of publically owned treatment works to the cost and level of reduction of such pollutants from a class or category of industrial sources The fruit and vegetable processing industry was studied and regulations were proposed in the August 23, 1978, Federal Register.

The

results of these studies lead EPA to concluded that BAT regulations were found to be established from insufficient data and they were recommended to be suspended.

Only the tomato and mushroom BAT regulations were found

acceptable for BCT. Despite the voluminous amount of material available in regard to the regulations, many fruit and vegetable processors will find they are facing state regulations more stringent than the BPT, BAT or BCT standards. When facing a permit situation, prompt contact with the proper regulatory officials is recommended.

133 F&V SPNOFF/MUNC DISCH MUNICIPAL

DISCHARGE

Introduction PL 92-500 and PL 95-217 have some subtleties that will increase costs for your fruit and vegetable plants discharging to municipal systems. The requirements for industrial cost recovery, user charges and sewer use ordinances will surely affect many plants.

Probably almost 50% of the

fruit and vegetable plants now discharge to municipal systems. However, with developing regulations and technologies, the future may find many more plants discharging to municipal systems. The sewer use ordinance as used is to refer to the "sewer ordinance" defined as an instrument setting forth rules and regulations governing the use of the public sewer system.

In most cases, the industrial cost

recovery and surcharges (user charges) may be a part of this instrument. Little can be reported about industrial cost recovery as few municipalities have imposed the same and an 18 month moratorium has been imposed in PL 95-217.

Surcharges will be treated as a section of the sewer use ordinance

although in reality some municipalities pass separate ordinances for user charges. Processors must ask themselves what is happening now and what will happen in the near future.

Although charges for industrial wastes began as

early as 1907, as late as 1969 only about 10% of United States municipalities collected these charges.

Most municipalities did not have a stringent

sewer use ordinance until after 1960.

Most municipalities do not have one

in 1978 although state and federal pressure and encouragement will surely force most municipalities to draft such an ordinance. Key questions that must be asked by industrial dischargers is how they can get a reasonable ordinance that gives both them and the city system protection -- them in having sewage treatment, at a reasonable cost and the city in preventing illegal or toxic discharges. PL 92-500 and EPA require that municipalities institute industrial cost recovery, a system of user charges and have a sewer use ordinance if they obtain federal funds for water or wastewater facilities. However, one must look carefully at exactly what is required. were modified substantially by PL 95-217.

The initial requirements

134 F&V SPNOFF/MUNC DISCH Industry should assist in the development of a "practical and sound regulatory ordinance fitted to local conditions".

Industry should want the

minimum number of restrictions that will protect the municipal system. These restrictions should be technically sound and rigidly enforced. Specific Requirements Sewer use ordinances are largely a matter of local and state jurisdiction.

However, many individuals have been to a town council

meeting and been told that "EPA insists and requires a 28 page document". There is a difference in what each EPA Regional Administrator requires. There are seven specific requirements for a sewer use ordinance if Federal monies are received. (1) 35.927-4

These include: Prohibit new connections from inflow sources into sanitary sewers.

(2) 35.927-4

Insure that new sewers and connections are properly designed and constructed.

35.925-11

System of user charges paying proportionate share of 0 + M.

(3) 35.935-13 X. (1976 a.)

User charge system must be incorporated. Equitable system of cost recovery. Note - all users pay user charge -- not just industrial users.

(4) 4.2.2 (1976 a.)

Users shall be required to immediately notify waste treatment plant of any unusual discharge (flow or waste parameters).

(5) x. (1976 a.)

Pretreatment of wastes that would otherwise be detrimental.

(6) Appendix B. (f) 3) (1976 a.)

User charges shall be reviewed annually to

(7) 35.905-6

Recovery from industrial users of the grant

assure 0 + M recovery. amount allocable to the treatment of their wastes.

Review of Proposed Sewer Use Ordinance The best and perhaps the only time that industry can get input into a sewer use ordinance is during the passage by the city council or the

135 F&V SPNOFF/MUNC DISCH sewer district board; i.e., the governing body.

Normally public hearings

are held but everyone must be most observant for the hearing notice. The study of a proposed sewer use ordinance requires time and expertise.

However, anyone can read and understand such an ordinance with

a little extra effort. A description of some key parts of a sewer use ordinance can be found in Table 31.

Each word and sentence can have a real meaning. Industry

management should not only ask the engineer or utilities director to explain what they meant to say but insist that the ordinance have language that clearly states the same.

For example, does "sample manhole" refer to

the manhole in the street or does it refer to a specially constructed box with a wier, flow recorder, sampler and sample refrigerator that might cost as much as $25,000.

Specific problems seen in ordinances for fruit and

vegetable plants have included: - Holding tanks or flow equilization being required - where are you going to. put the tank? - Control manhole or sampling facility costing more than $25,000. - Limitations or prohibitions on BOD, FOG, etc. i.e., BOD less than 300 mg/l, FOG less than 25 mg/l. - Surcharge for industrial users only with other contributing commercial customers not charged equally. Specific review points when considering a sewer use ordinance should include the following: - What's it going to cost as proposed - after enactment? - Are there defacto or real limitations prohibiting your discharge? - Who is the boss? - Who handles complaints and reviews decisions? - Will samples be representative and who pays for sampling and analysis? - Are there unrealistic limitations - pH, FOG, BOD5? - Did you review the ordinance before enactment? - Can you obtain split samples? - Can you object to unreasonable results? If so, how? Normally the ordinance is passed by a public body. This is industry's best chance of getting a receptive audience. They can more easily obtain changes then than later.

The procedures for obtaining changes are

presented in the "Municipal Discharge Spinoff".

136 F&V SPNOFF/MUNC DISCH Table 31.

Some Key Parts to A Sewer Use Ordinance

Definitions

All key words should be included in the definitions. For instance: Does representative sample mean a grab sample, an average of 4 grab samples at 15 minute intervals or a 24 hour, proportional composite sample?

Resampling

Does the ordinance contain the specifics of resampling if industry objects to a particular sample? What are the costs of the resampling?

Mock Bill

A clause in a new ordinance can require the city to sample for a period of 6-12 months to perfect their techniques while billing you on a "mock bill" which does not have to be paid. If there are high charges, you have time to institute in-plant changes or pretreatment.

Appeal Procedure

State law probably requires an appeal if an action is considered unreasonable or injust. However, if a procedure and time schedule for appeal is not specified, an industry may find themselves without water and sewer for an extended period while court action is followed.

Responsible Person

The individual(s) responsible for interpretation and enforcement should be specified. Everyone should be aware of any interpretable decisions that might be made.

Representative Samples (wastewater characteristics)

What method(s) is specified for sampling? Is the sample proportional to flow? What is the frequency of the samples? Does each sample period give a set of characteristics or are sample periods averaged to determine wastewater characteristics?

Waiver (Special Agreement)

Does the-ordinance have a special clause allowing a contract or agreement between industry and the municipality to allow otherwise prohibited flows or concentrations? Who okays such a pact ? Will you be able to get one approved?

When in the event that metered water does not equal wastewater

There should be a clause allowing plant records or metering or engineering studies to establish a percentage of metered water which actually leaves in the sanitary sewer which is sampled. Thus a "fair" wastewater load can be established.

Pretreatment

When, who and how is pretreatment or flow equilization required?

137 SEAFOOD SPNOFF/MUNC DISCH Municipal Charges Muni cipal charges for industrial plants include water, sewer, surcharge (user charge) and industrial cost recovery.

Most municipalities

compute water and sewage charges as follows: Water . . .

Based on water consumption metered into the plant. Often on a declining block scale so that the cost/ unit decreases as you use more water.

Note that

the bill is usually in hundreds of cubic feet (1 cu. ft. = 7.48 gal.).

Cost usually ranges from

$0.10 to $1.00 per 1000 gallons. Sewer Charge . . .

Based on computed water charge and usually represents 10 to 200 % of the water bill. Normally 100% is the most common figure seen in the Southeast.

Surcharge . . .

Based most often on metered water consumption and a parameter(s) measured in the wastewater. The most common factor is BOD5 and usually charged at a rate of $0.10 to $2.00 per pound for those pounds in excess of normal sewage.

Similarly, the

suspended solids (TSS) load is also used. A hydraulic load charge is sometimes included and is often used as a "demand charge" especially for seasonal operations. Industrial Cost Recovery . . .

Recovery by the grantee from the industrial users of a treatment works of the grant amount allocable

(Rules &

to the treatment of wastes from such users pursuant

Reg. 35.905-6)

to section 204 (b) of the Act and this subpart. (Note that ICR is under review and there may be some changes.)

Surcharges Surcharges are often included in a sewer use ordinance. However, they may be included in a separate ordinance. Surcharges are usually passed because of local government's problems such as:

(1) Waste treatment costs are rising, (2) More treatment is being

138 F&V SPNOFF/MUNC DISCH required, (3) Loads are often increasing, (4) Property tax is already overburdened, or (5) because the municipality has received federal funds and is required to institute user charges. Any food plant should keep careful records about their surcharge bill.

A plant should keep up with the following in respect to their

surcharge bills: - For which characteristics are you paying - Do these vary widely - Does your flow vary widely - How does your bill compare with similar plants Careful attention should be paid to the method the city uses for calculating the surcharge.

Careful attention should be directed toward the

sampling method, sample analysis procedures, flow measurement method and the validity of the results.

A surcharge calculation involves flow

measurement, sampling, sample preservation, sample analysis, laboratory calculation, and surcharge calculation. cause an error in the surcharge bill.

An error in any of these will However, remember that errors can be

in the plant's favor. Conclusions The lack of details is explained in part by the procedure a sewer use ordinance follows.

As a normal rule, the person in charge of the waste

treatment works and planning presents an ordinance drafted by an engineering firm for approval of the board or council. As the council members feel incompetent to review and discuss the same, rapid passage is the rule. Mr.

Rankine, an attorney, noted that it is the most important

matter that a sewer regulating authority can pass. The fruit and vegetable industry is affected because for health and sanitation, much cleaning and washing results in large amounts of organic wastes which equate to BOD5.

Also, much of the raw material is wasted

in fruit and vegetable processing due to peeling and trimming. The legal field of sewer use ordinance making is complex and ill reported. Challenges are usually settled out of court and legal records and precedents have not been established.

The best defense a plant has to a

badly drafted sewer use ordinance is a good lawyer and a friend(s) on the body responsible for voting on the same.

Industries faced with bad ordi-

139 F&V SPNOFF/MUNC DISCH nances must rally their forces and present a united front.

City managers

should consult industry when they draft sewer ordinances. A pact with the city fathers allowing specific exemption for your wastes is a realistic alternative if an ordinance is in existence with a clause for such a pact.

But, a fruit and vegetable processor should get

the best technical and legal advise before doing this. In conclusion, your fruit and vegetable plants will probably face the issues discussed herein within the next several years.

It would be to your

benefit to be ready to assist them in these most serious negotiations. You must tell them to be alert to any indication that a sewer use ordinance is being developed or revised.

ACKNOWLEDGEMENTS The development of this program and the preparation of the modules resulted from the collaboration of Drs. Roy E. Carawan, N.C. State University, James V. Chambers, Purdue University, Robert R. Zall, Cornell University and Roger H. Wilkowske, SEA-Extension, USDA. Financial support which supported the development of this project and the modules was provided by the Science and Education AdministrationExtension, U.S.D.A., Washington, D. C., and the Cooperative Extension Services of North Carolina, New York and Indiana. STAFF AND PART-TIME PARTICIPANTS An Advisory Committee made up of individuals from the food processing industry, equipment manufacturers, regulatory agencies and the legal profession assisted in the planning and development of these materials. The authors appreciate their advice and support. Much of the information presented in these documents has been gleaned from the remarks, presentations and materials of others. Their cooperation and assistance is appreciated. Ms. Torsten Sponenberg (Cornell University) provided support in developing several modules and chapters. The authors appreciate her interest, enthusiasm and dedication. Ms. Jackie Banks (Cornell University) provided many hours of typing and proof-reading needed to pull together the wide array of material in the different documents. The authors appreciate her contributions. Mr. V. K. (Vino) Chaudhary (Purdue University) provided support in developing the materials on pretreatment and treatment. Ms. Cindy McNeill (N. C. State University) provided support in the preparation of the final documents. Mr. Paul Halberstadt (N. C. State University) provided support in the development of many of the modules. He also was the principal reviewer and editor for these materials. The authors acknowledge his contribution to this program. Mrs. Gloria Braxton (N. C. State University) provided typing for several of the modules. Mrs. Judy Fulp (N. C. State University) served as secretary for the project. She is primarily responsible for typing the materials in the many modules. The authors deeply appreciate her invaluable contribution. Only through her interest, dedication and hard work were the authors’ notes turned into these documents.

Sets of the modules are available from: Publications Office N. C. Agricultural Extension Service Ricks Hall N. C. State University Raleigh, North Carolina 27650