municipal wastewater treatment in central and eastern

PRESENT SITUATION AND COST-EFFECTIVE DEVELOPMENT STRATEGIES

Public Disclosure Authorized


MUNICIPAL WASTEWATER TREATMENT IN CENTRAL AND EASTERN EUROPE


may .-

19qq


l--

LASZLO SOMLYODY AND PETER SHANAHAN

A REPORT

FOR THE ENVIRONMENTAL FOR CENTRAL

ACTION

AND EASTERN

PROGRAMME

EUROPE

Municipal Wasterwater Treatment in Central and Eastern Europe PresentSituation and Cost-EffectiveDevelopmentStrategies Laszlo Somlyody and Peter Shanahan

The World Bank Washington, D.C.

Copyright © 1998 The International Bank for Reconstruction and Development/THE WORLD BANKC 1818 H Street, N.W. Washington, D.C. 20433, U.S.A. All rights reserved Manufactured in the United States of America First printing May 1998 The findings, interpretations, and conclusions expressed in this paper are entirely those of the author(s) and should not be attributed in any manner to the World Bank, to its affiliated organizations, or to members of its Board of Executive Directors or the countries they represent. The World Bank does not guarantee the accuracy of the data included in this publication and accepts no responsibility whatsoever for any consequence of their use. The boundaries, colors, denominations, and other information shown on any map in this volume do not imply on the part of the World Bank Group any judgment on the legal status of any territory or the endorsement or acceptance of such boundaries. The material in this publication is copyrighted. Requests for permission to reproduce portions of it should be sent to the Office of the Publisher at the address shown in the copyright notice above. The World Bank encourages dissemination of its work and will normally give permission promptly and, when the reproduction is for noncommercial purposes, without asking a fee. Permission to copy portions for classroom use is granted through the Copyright Clearance Center, Inc., Suite 910, 222 Rosewood Drive, Danvers, Massachusetts 01923, U.S.A. Library of Congress Cataloging-in-Publication

Data

Somnly6dy, L. (]Laszl6) Municipal wastewater in Central and Eastern Europe present situation and cost-effective development strategies / Laszl6 Somly6dy and Peter Shanahan p. cm "A report for the Environmental Action Programme for Central and Eastern Europe." Includes bibliographical references. ISBN 0-8213-4085-9 1. Sewage disposal-Europe, Eastern. 2. Sewage disposal-Europe, Eastern-Cost effectiveness. I. Environmental Action Programme for Central and Eastern Europe. V. Title. TD555.S63 1997 97-42033 363.72'84'0947-dc2l CIP

Contents

Preface

vii

Acronyms

ix

Executive Summary Introduction

xi

1

Chapter 1

Water Supply, Sewerage, and Municipal Wastewater Treatment Poland 8 The Czech Republic 10 The Slovak Republic 11 Hungary 12 Bulgaria 13 Issues common to allfive countries 14

Chapter 2

An Approach to Develop Wastewater Treatment Strategies

Chapter 3

Evaluation of Wastewater Treatment Alternatives 25 The purpose of ivaste7vatertreatment 25 A brief overvie7vof treatment methods 26 Sludge disposal and treatment 27 Removal rates and costs of technology alternatives 28 Comparison of various cost estimates 29 A summary of treatment technologies proposedfor CEE countries The application of chemical upgrading to existing treatment plants Cost-effectiveness and multistage development 31 The role of receiving 7waters 33 Concluding remarks 35

iii

7

21

30 30

iv

Municipal Wastewater Treatment in Central and Eastern Europe

Chapter 4

Lessons from Case Studies

43

A highly overloadedplant: Zvolen, the SlovakRepublic 43 A highly overloadedplant with significantindustrialpollution: Novi Zamky, the SlovakRepublic 44 A new treatmentplant: Szeged,Hungary 45 Wastewatermanagementproblemsin a metropolis:Prague,the CzechRepublic 46 The applicationof natural treatmentsystems:Szugy, Hungary 47 Sludge treatment:HradecKralove,the CzechRepublic 47 48 Regionaleutrophicationof a degradedwater body:Lake Tata,Hungary Developmentof a regionalleast-costpolicy: the Nitra River Basin,the Slovak Republic Chapter 5

49

Costsof Controlling Municipal Effluents in the CEE Region and Country-Specific Strategic Issues

51

Estimatesof costs and water quality effectsof municipal7wastewater treatment- alternativesfor thefive countries 51 Country-specificstrategicissues 53 Chapter 6

Conclusions and Recommendations

57

Major elementsof cost-effectivedevelopmentstrategies 58 Wastewatertreatment 58 Costs of controllingmunicipaleffluent in the regionand country-specificstrategicissues Issues of implementation 60 Policyimpactsand education- demonstrationprojects 60

59

Annexes 63 A Biographical Sketches of Report Authors B European Community Environmental Directive Requirements for Wastewater Discharges 67 C Unit Costs of Wastewater and Sludge Treatment Alternatives 69 D Natural Treatment Systems and the Issue of Rural Areas 73 E Maps and Figures 75 1 Countries and towns included in the CEE data base 2 Population in towns in the Vistula River basin, Poland 3 Total wastewater discharge in towns in the Vistula River basin, Poland 4 Total BOD load in wastewater in towns in the Vistula River basin, Poland 5 Level of wastewater treatment technology in towns in the Vistula River basin, Poland 6 Influent and effluent BOD load in wastewater in towns in the Vistula River basin, Poland 7 Influent and effluent total nitrogen load in wastewater in towns in the Vistula River basin, Poland 8 Per capita domestic wastewater production in towns in the Vistula River basin, Poland 9 Per capita total and industrial wastewater production in towns in the Vistula River basin, Poland 10 Projected BOD concentration in receiving water at towns in the Vistula River basin, Poland 11 Population in towns in the Odra River basin, Poland 12 Total wastewater discharge in towns in the Odra River basin, Poland 13 Total BOD load in wastewater in towns in the Odra River basin, Poland 14 Level of wastewater treatment technology in towns in the Odra River basin, Poland 15 Influent and effluent BOD load in wastewater in towns in the Odra River basin, Poland 16 Influent and effluent total nitrogen load in wastewater in towns in the Odra River basin, Poland 17 Per capita domestic wastewater production in towns in the Odra River basin, Poland 18 Per capita total and industrial wastewater production in towns in the Odra River basin, Poland 19 Projected BOD concentration in receiving water at towns in the Odra River basin, Poland

Contents

V

Population in towns in the Czech Republic Total wastewater discharge in towns in the Czech Republic Total BOD load in wastewater in towns in the Czech Republic Level of wastewater treatment technology in towns in the Czech Republic Influent and effluent BOD load in wastewater in towns in the Czech Republic Percentage of population connected to public water supply and wastewater sewers in towns in the Czech Republic 26 Per capita domestic and total water supply in towns in the Czech Republic 27 Per capita water supplied versus wastewater collected and treated in towns in the Czech Republic 28 Projected BOD concentration in receiving water at towns in the Czech Republic 29 Population in towns in the Slovak Republic 30 Total wastewater discharge in towns in the Slovak Republic 31 Total BOD load in wastewater in towns in the Slovak Republic 32 Level of wastewater treatment technology in towns in the Slovak Republic 33 Influent and effluent BOD load in wastewater in towns in the Slovak Republic 34 Percentage of population connected to public water supply and wastewater sewers in towns in the Slovak Republic 35 Per capita domestic and total water supply in towns in the Slovak Republic 36 Per capita water supplied versus wastewater collected and treated in towns in the Slovak Republic 37 Population in towns in Hungary 38 Total wastewater discharge in towns in Hungary 39 Total BOD load in wastewater in towns in Hungary 40 Level of wastewater treatment technology in towns in Hungary 41 Influent and effluent BOD load in wastewater in towns in Hungary 42 Percentage of population connected to public water supply and wastewater sewers in towns in Hungary 43 Per capita domestic and total water supply in towns in Hungary 44 Per capita water supplied versus wastewater collected and treated in towns in Hungary 45 Projected BOD concentration in receiving water at towns in Hungary 46 Population in towns in Bulgaria 47 Total wastewater discharge in towns in Bulgaria 48 Total BOD load in wastewater in towns in Bulgaria 49 Level of wastewater treatment technology in towns in Bulgaria 50 Influent and effluent BOD load in wastewater in towns in Bulgaria 51 Percentage of population connected to public water supply and wastewater sewers in towns in Bulgaria 52 Per capita domestic and total water supply in towns in Bulgaria 53 Per capita water supplied versus wastewater collected and treated in towns in Bulgaria 54 Projected BOD concentration in receiving water at towns in Bulgaria 55 Distribution of population by number of towns 56 The effect of scale on the cost of traditional biological wastewater treatment 57 Multistage upgrading of an existing primary treatment plant 58 Multistage upgrading of an existing primary and biological treatment plant 59 Evaluation of multistage upgrading of wastewater treatment plants 60 Aggregated pollutant load reduction for CEE countries as a function of wastewater treatmnentcosts 61 Investment cost versus annual operation, maintenance, and repair cost for treatment technology alternatives 20 21 22 23 24 25

vi

Municipal

62 63 64 65 66 67 68

Wastewater Treatment

in Central and Eastern Europe

Wastewater treatment plant expenditures for the Czech Republic Percentage completion of wastewater treatment plants in Vistula River basin, Poland Costs of planned wastewater treatment plant improvements in Vistula River basin, Poland Percentage completion of wastewater treatment plants in Odra River basin, Poland Costs of planned wastewater treatment plant improvements in Odra River basin, Poland Percentage completion of wastewater treatment plants in the Slovak Republic Costs of planned wastewater treatment plant improvements in Hungary

Bibliography

145

Tables 1.1 Summary for the five countries 19 1.2 Summary of population distribution in towns considered in this study 20 3.1 Treatnent alternatives used in analysis 36 3.2 Effluent concentrations,removal rates, and sludge production for technologyalternatives 37 3.3 Comparison of relative investment costs of different treatment plants 38 3.4 Comparison of unit treatment costs 39 3.5 Unit costs of different treatment technologies 39 3.6 Cost-effectivenessof technology development 40 3.7 Comparison of single-stage and multistage treatment plant development 41 3.8 Dilution rate (Q/q) for various treatment technologies and ambient BOD improvements in rivers 41 B.1 Requirements for discharges from urban wastewater treatment plants 67 B.2 Requirements for discharges from urban wastewater treatment plants to sensitive areas subject to eutrophication 68 C.1 Annualized unit costs for village wastewater treatment plants in US$/m3 69 3 C.2 Annualized unit costs for township wastewater treatment plants in US$/m 70 C.3 Annualized unit costs for city wastewater treatment plants in US$/m3 71 C.4 Annualized unit costs of sludge treatment in US$/m3 72

iS1 T

Preface

he Central and Eastern European (CEE)

ing a technicallyfeasible,cost-effectivepolicy raises a

countries are undergoing dramatic economic changes that significantly (but to varying degrees) influence water pollution originating from different economic sectors. Decliningproductionin industry and agriculture have led to (temporary) water quality improvements, showing clearly the opportunity to couple environmental management with economic transformation. Municipal discharges, which are the subject of this report, are a rather different problem. The investment needed to improve the existing water resource systems in the CEE countries are so great that they would be burdensome for stable economies, let alone the CEE economies in transition. Thus, there is the issue of how to develop a strategy that can be implemented under severe financial constraints in a way that does not impede the current economic restructuring. The current state of woatersupply and sewverage collection in urban areas in the CEE countries is generally adequate; however, wastewater treatment is substantially less developed. Thus, the primary concern of this report is how cost-effective treatment strategies can be developed at both the local and river basin level from the existing infrastructure and facilities. In this sense, the major objective is to explore the technical possibilities and associated cost savings. The present report offers a number of rather generic ideas and technologies in this respect, the application of which always depends on site-specific conditions. Technical and economic details of a strategy is a required preliminary step for eventual implementation. Develop-

host of associated issues, including the ongoing and desired changes in the institutional setting, financing mechanisms, and decisionxaking. These other issues must be considered in light of the increasingly important role of local govermnents, privatization, and other changes. While these issues are recognized, it is beyond the scope of this report to address them in detail. Although the report deals solely with municipal discharges, it is stressed that in fact control of municipal emissions cannot be considered in isolation from other sources of pollution such as agriculture and industry. Ultimately, an integrated management strategy must be developed and implemented. The reader should realize that the present study was prepared in 1992/1993 as a contribution to the Environmental Action Programme for Central and Eastern Europe. The data collected represent the state of water supply, sewerage, wastewater treatment, sludge management and receiving water quality in the late eighties. During the past few years many changes took place in the CEE countries considered herein, which should be kept in mind when reading the report. Economies started to recover, though depending on which countries, at variable extents. Reduction of water consumption and wastewater generation has been continued. The overload of sewage plants has been further reduced and the underload emerged as an issue due to conservative design practices in estimating flows and capacities of newly constructed plants. Significant amount of investments were made. There were many changes and developments in legisvii

viii Municipal Wastewater Treatment in Central and Eastern Europe lation, institutions and financing. In spite of all these alterations, issues addressed in this report remain as relevant as before. For different reasons, this applies

to those CEE countries which already entered the EU accession process and the rest of the CEE and CIS region alike.

iiE ASP BAT BOD Cd CEE CIS COD DO EU ECE GDP IIASA N P TN TP TSS

Acronyms

Activated-Sludge Process Best Available Technology Biological Oxygen Demand Cadmium Central and Eastern Europe Commonwealth of Independent States Chemical Oxygen Demand Dissolved Oxygen European Union (formerly European Communities) Economic Commission for Europe (U.N.) Gross Domestic Product International Institute for Applied Systems Analysis (Laxenburg, Austria) Nitrogen Phosphorus Total Nitrogen (in water) Total Phosphorus (in water) Total Suspended Solids (in water)

ix

i T

Executive Summary

his report presents an evaluation of munici-

the five countries, a national team was formed to col-

pal wastewater treatment in five countries in Central and Eastern Europe (CEE): Poland, the Czech Republic, the Slovak Republic, Hungary, and Bulgaria. The objectives of this report are: (i) to evaluate the present status' of water supply, sewerage, and municipal wastewater treatment; (ii) to demonstrate cost-effective wastewater treatment strategies; and (iii) to estimate the cost to implement such wastewater treatment strategies. The report focuses on municipal wastewater treatment for three reasons: * An analysis of economic scenarios and associated environmental consequences indicates that emissions of BOD and several other water pollutants decline only at a small extent as a result of economic transformation, even if large reductions in industrial emissions occur. Households and small sources dominate the discharge of these water pollutants.

lect data, develop case studies, and evaluate present conditions in the country. In addition, several international experts on wastewater treatment provided detailed analysis of technology alternatives. The data from all five countries were assembled into a single computerized data base which was used with the results of the technology analysis to evaluate the present status in the countries and to develop and determine the cost of different approaches to upgrading existing wastewater treatment facilities.

• The investment requirement to improve the existing situation would be an enormous burden even for stable economies. * As described below, the current state of water supply and sewerage collection is generally adequate. In some countries, new investments in water supply are proposed mostly for industrial purposes rather than improving the quality of water resources. Focusing on the principal causes of water pollution therefore has the potential for alleviating water supply constraints. The work on which this report is based was organized by assembling teams of specialists. In each of

10,000. The information in the data base characterize the existing' water supply, sewage collection, and

Data collection

and reliability

Data were assembled for 362 municipalities with a total population of 35 million representing roughly half the total population of the five countries (73.2 million) and70percentofthetotalurbanpopulation. Thedata cover all towns with populations greater than 25,000 and in Poland some additional towns greater than

wastewater treatment systems as well as the receiving water qualit and flow downstream of each municiq a pal discharge. Included for each wastewater treatment plant are the flow capacity, the level of treatment, influent and effluent concentrations, quantity of untreated flow, and degree of overloading. For some municipalities, certain data are missing or conflicted with other data. For these, reasonable estimates were substituted based on typical per capita emnissionand population equivalent values or experience. Nonethexi

xii Municival WasteuwaterTreatment in Central and Eastern Europe less, data reliability may compromise some figures for some towns although the overall conclusions of the study are not significantly affected. Current status The current situation faced in the CEE countries is one in which change and uncertainty affect the country's economies, institutional frameworks, and legislation, all of which influence the ability to deal with environmental issues. The country-by-country analysis completed in this study indicates that significant improvements are needed in wastewater treatment but that the current state ofwater supply and seweragecollection is generallyadequate. The economic transition has also affected water and wastewater management by eliminating some industrial discharges where factories have been closed and by reducing domestic water consumption (and wastewater generation) as water prices are raised. The foliLowingoverall conclusions are based on a compilation and analysis of a large quantity of data on existing wastewater treatment: The level of wastewater treatment is generally poor. Approximately 50 percent of the wastewater comes from domestic sources, 30 percent from industrial, and the rest from groundwate:r infiltration, stormwater, illegal connections, and other sources. Less than half of the wastewater produced receives secondary biological treatment. Bilologicaltreatment plants are often overloaded, leading to unacceptably low BOD removal. A substantial fraction of the wastewater is discharged without trealment. Thus the removal of influent BOD is no more than 25 percent in the entire region. Sludge is inadequately treated and often contaminated by metals from industrial wastes. The metals content in sludge threatens sludge use for agriculture and other means of disposal. The following conclusions are based on an analysis of data for each of the five CEE countries individually: Polandis the most populous of the five countries considered and contains nearly half of the total number of towns of greater than 25,000 population. In Poland, 40 percent of the collected wastewater is untreated while 29 percent receives only mechanical treatment, and 36 percent receives secondary treatment. Many lteatment plants are affected by large hydraulic overloads, resulting in BOD removal rates

which vary between 5 percent and 95 percent and which average 70 percent. A program of treatment plant construction was begun in the 1980s but faltered for lack of funds. Only 54 of the planned 258 largecapacity plants have reached 70 percent completion. As the result of the large population and poor level of wastewater treatment, the water quality is poor in most streams and rivers. Water and wastewater infrastructure in the Czech Republic approaches Western standards. More than 90 percent of the population in towns larger than 25,000 is served by public water supply and wastewater collection and 80 percent of the wastewater is treated. There is a long tradition of biological wastewater treatment using the activated sludge process, and 75 percent of the treated wastewater receives secondary treatment. River water quaility is affected by the relatively small dilution capacity in Czech rivers, the numerous industrial discharges, and agricultural loads. The Slovak Republic is the smailest of the countries considered in terms of population and has the fewest towns larger than 25,000. The population distribution is an important factor in water and wastewater management in Slovakia, with small communities playing a proportionally bigger role than in the other countries. The fraction of the population served by public water supply is the lowest of the five countries and 25 percent of the delivered water fails to meet drinking water quality standards. On a national basis, only 51 percent of the total wastewater is collected, creating a large water-wastewater utility gap (defined as the difference in service coverage between water supply and sewerage). Only about 42 percent of the collected wastewater is treated and many plants are highly overloaded. The average BOD removal rate is about 70 percent. River water quality is poor. The population distribution in Hungary is much like that in Slovakia with the exception that 20 percent of the country's population lives in Budapest. Public water supplies 92 percent of the domestic water demand and per capita consumption rates are the lowest in the five countries owing to Hungary's earlier introduction of realistic water prices. Public sewage is much less extensive, reaching only 51 percent of the total population and resulting in a large overall utility gap. The level of wastewater treatment is low: 55 percent is untreated, 12 percent receives only mechanical treatment, and 33 percent receives secondary treatment.

Executive Summary xiii

Approximately half of the country's wastewater is generated in Budapest. BOD removal rates in most secondary treatment plants approach 90 percent and overloading is less of a problem than in Poland or Slovakia. The water quality in Hungarian rivers is good overall due to the relatively high dilution rate in Hungarian rivers. For example, the wastewater from Budapest, most of which is untreated, is discharged to the Danube River, where it causes only minor water ' quality impairment in the large river flow (in terms of traditioal compnents).dards chen-cal cn Bueta is) Traditionalachetica Thei opuatin Bugara i farlyevely istibuted among the largest city, Sofia, moderate-size cities,~~~~ ~~ ra.Pbian'ua ae upysre bu ies, and rural areas. Public water supply serves about 95 percent of the population and per capita consumption is very high. Sewers service 66 percent of the population and the utility gap is large. Approximately 41 percent of the collected wastewater is untreated, only 6 percent receives just mechanical treatment, and the rest receives biological treatment. Virtually all biological treatment is by the activated sludge process although many plants are overloaded. The average BOD removal rate is below 70 percent. Water quality is very poor in Bulgarian rivers; 86 percent of the monitored length of rivers falls within the lowest water quality category. In all of the countries water supply and waste disposal in rural communities and sludge treatment and disposal are significant problems. Rural communities include about 30 percent of the total population. Shallow groundwater, which is used for drinking water supply, is often contaminated by bacteria and nitrate with consequent health risks,.hre All of the countries also face new enviromnental legislation and changing regulations and standards. In some cases laws are being passed hastily and have tended to adopt stringent European Union or other Western standards within an unrealistically short period of time. Often overlooked in the adoption of new environmental laws is the enormous cost to upgrade existing wastewater treatment or build new facilities, and the limited funds that are in fact available. A more realistic approach has been adopted in the former Czech and Slovak Federal Republic (CSiR), and later by the two countries formed from the C.S.F.R., where increasingly stringent standards will be phased in over more than a decade.

Developing strategies

wastewater

treatment

The main elements of the policy proposed in this report are to reduce water consumption; increase industrial pretreatment, reuse, and recycling; close the water-wastewater utility cycle by matching the capacity of sewerage and wastewater treatment; set receiving water quality standards and/or equivalent regional ~~~~~~~~~~effluent standards; establish realistic schedules for stanstimplementation and tfcuscostffectave implementation; and focus on cost-effective wastewater treatment technologies and their multistage development. Strategies for rural areas should be bednlosing thaterial cyclrona household be based on closing the material cycle on a household level. On-site disposal and natural treatment may be competitive alternatives to traditional technologies depending upon site-specific conditions. The report recommends a multistage approach to improving municipal wastewater treatment. This approach includes developing a sequence of wellproven technology alternatives with known costs and pollutant removal rates; structuring alternatives so that they can be implemented sequentially over time, upgrading individual treatment plants over periods of, say, 10 to 20 years; and controlling effluent discharges (and specifying minimum treatment plant performance) by setting ambient water quality standards (and/or regionally variable effluent standards). The latter is a practical necessity under the present pressing financial conditions to be able to develop regional least-cost policies. The proposed approach gives first priority to upgrading wastewater treatment to meet the capacity of existing wastewater collection systems as a cost-effective step to reduce pollutant loads disoteevrnet charged to the environment. This study focuses on the technical and policy requirements to improve wastewater management. Although the report discusses issues of implementation and institutions, the primary purpose is to identify the highest priority actions to be taken as a precondition of implementation. Wastewater

treatment

alternatives

This study developed a set of technology alternatives that form a logical and cost-effective progression for multistage wastewater treatment development. Out of many possible treatment technology alternatives and combinations, the following five technologies were se-

xiv Municipal



lected as steps in the multistage process: primary (mechanical) treatment (P); chemical treatment (CEPT or PC -see below); primary and (high or low load) biological treatment (B); biological/chemical treatment (BC);and biological/chemical treatment with nitrogen removal (BCDN). These technologies were selected in light of established practice in the CEE region (for example, mechanical treatment is used due to the existence of combined sewer systems, the high suspended solids concentrations, and the frequent lack of industrial pretreatrnent) as well as trends in wastewater treatment. Primary treatment (P) entails the removal of solids by gravity and removes approximately 60 percent of the influent suspended solids and 30 percent of the influent BOD5. As noted, the study recommends primary treatmnent as essential in CEE treatment plants because combined sewer systems are common and suspended solids are high. Two varieties of chemical treatment are evaluated in this study: chemically enhanced primary treatment (CEPT) in which a low dosage of metal-salt precipitant is added in the primary treatment unit to enhance TSS,BOD, and TP removal; and primnary precipitation (PC) in which high dosages of metal salts are added mainly to achieve substantial TP removal. Both CEPT and PC are highly cost-effective technologies for upgrading existing treatment plants in that they can be economically added to existing treatment facilities and significantly improve capacity and pollutant remnoval rates with low capital costs. Biological treatment (B) plants generally employ one of two main processes: the activated sludge process (ASP) - mostly high load - or biofilm processes. ASP has long been used in the CEE countries but biofilm processes are still unusual there. Biological/chemical (BC) treatment entails combining biological treatment and chemical treatment in either sequential or combined unit processes (a practical example is upgrading the first stage of a secondary biological plant by adding chemical treatmnent,which can significantly increase the existing plant capacity). Adding biological denitrification to biological/chemical treatment (BCDN) removes nitrogen in a two-step process of nitrification and denitrification. The process is generally expensive and the marginal cost of nitrogen removal is high. Cost estimates for the various treatmnentoptions were prepared by synthesizing costs developed dur-

ing this and other studies (costs and various analyses are tabulated in Chapter 3). The initial investment cost and its annualized cost (IC); the annual operations, maintenance, and repair cost (OMRC); and the total annual cost (TAC) were developed. From the total annual cost and investment cost, the cost-effectiveness of the various technology alternatives was computed as cost per mass of pollutant removed (it is noted that "cost-effectiveness" can be defined also differently, for instance in terms of ambient water quality improvement). Further analyses determined aggregated costs and receiving water quality benefits associated with each technology alternative. The studies showed that upgrading primary, and primary and biological treatment plants by adding chemical treatment is a costeffective alternative which requires modest investment to improve removal rates and/or extend existing capacities. It is noted that for future solutions, if the usage of a primary clarifier can be avoided, the construction of a high-load activated sludge biological unit can be an alternative first step of the phased development (particularly if the dilution rate is small and the focus is organic material removal). It is stressed that the technology selection all the time depends on the actual sitespecific conditions. The estimates of costs and cost-effectiveness permitted a comparative analysis of the various technology alternatives and the multistage development approach. The analysis showed that upgrading wastewater treatment in stages over time exacts some cost penalty compared to building the entire treatment plant at once. Nonetheless, the analysis shows that multistage development is a cost-effective approach. It further illustrates that proper technology selection and clever financing arrangements can increase the cost-effectiveness of the multistage approach. More generally, multistage development is recommended as a practical and realistic approach for the CEE countries, which lack the funds to accomplish wholesale wastewater treatment improvements within the next several decades. Ambient water quality will be more generally improved by building many treatment plants with medium BOD removal capabilities rather than a few plants with high removal rates. Designing plants to accommodate future upgrades and added unit processes will allow high removal rates to eventually be reached, but at a time when funds are available and

Executive Summary xv such construction is realistic. Due to its high cost, nitrogen removal is not recommended for the early stages of the development process except where water supplies are endangered or eutrophication of lakes and seas is a problem. Multistage development can be particularly effective when used in the framework of a regionalleastcost approach. Under this concept, receiving water quality models (or more simple loading and transmission coefficients) are used to evaluate the effectiveness of upgrading different treatment plants within a river basin in achieving overall water quality improvements. The approach provides a means to optimize expenditures in the cash-short CEE countries during the near term. Regional least-cost approaches, which are based on receiving water quality standards, can be implemented using equivalent regional effluent standards. Rural areas and natural treatment systems For rural areas, on-site waste disposal and natural treatment systems may be cost-effective and practical. However, a comprehensive evaluation of the performance of the many different systems available has yet to be completed, although a first step was done under this study. As a result, technology and system selection for a specific community may not be easy. Sitespecific factors such as soil composition, climatic conditions, and seasonal variations can significantly affect natural treatment system performance. The capital cost of natural treatment systems is variable, but generally comparable to (or less expensive than) traditional treatment systems. The cost of land is typically a major factor (land is often overpriced and in some cases, such as agricultural land, may be legislatively protected). In the final analysis, broad general recommendations are impossible because site-specific features are critical to the selection, design, and costeffectiveness of natural treatment systems. The capacities of such systems should not be over- or underestimated; rather, each case requires a careful evaluation before a decision. Case studies Eight case studies are provided to illustrate the application of cost-effective wastewater treatment strategies and role of site-specific features. Zvolen and Nove

Zamky (in the Slovak Republic) illustrate improvements to highly overloaded treatment plants (with different contribution from industrial sources). These case studies particularly illustrate the practicality and costeffectiveness of the multistage development approach. Szeged (Hungary) is an example of the construction of a new municipal wastewater treatment plant discharging to a river of acceptable quality and with high dilution capacity. Prague is used to demonstrate the problems of a large town with a long tradition of sewerage and wastewater treatment. In contrast, the applicability of natural treatment systems is discussed for the small village of Szugy in Hungary. Possibilities for sludge handling are demonstrated by the example of Hradec Kralove (the Czech Republic). Finally, regional aspects of water quality management are illustrated in case studies of Lake Tata (Hungary) and the Nitra watershed (Slovak Republic). This last case study demonstrates the utility and strength of a river basin planning approach in achieving regional leastcost wastewater treatment. Costs of controlling

municipal

effluents

Aggregated costs for wastewater treatment improvements in the 362 towns considered in this study are analyzed and presented in Chapter 5. Achieving the most stringent directives of the European Union would require approximately US$8,000 million. This cost includes upgrading treatment facilities up to the capacity of the existing wastewater collection network (sewer rehabilitation would require an additional investment of several billion U.S. dollars). Upgrading wastewater treatment in the 362 communities to a minimum of biological treatment would cost only about half this amount; upgrading to biological/chemical treatment would be slightly more expensive; upgrading to a minimum of primary treatment would cost about one-quarter. Chemically enhanced primary treatment would be slightly more costly than primary treatment only, but would be much more cost-effective, roughly doubling the BOD removal rate and significantly improving phosphorus removal. These results clearly illustrate that significant improvements in pollutant removal can be achieved in the first stages of the multistage approach. Examination of the approximate concentration of BOD5 downstream of the 362 communities shows that the existing water quality is strikingly poor. Approxi-

xvi Municipal Wastewater Treatment in Central and Eastern Europe mately 50 treatment plants discharge to very low flow streams which act effectively as sewage canals. Excluding these, the analysis shows that upgrading to a minimum of biological or biological/chemical treatment can achieve a water quality close to Class I (3 to 5 mg/l BOD5). The management of sewage canal type of streams of no water uses (except waste disposal) requires careful setting of priorities. If the present poor quality is no longer tolerable, a high level of (costly) treatment is immediately required. The above cost-effective short-term investment would roughly halve the total BOD emission in the region (and only about 50 percent of the organic material generated would be discharged to the environment). To achieve an additional 30 percent removal or so would be an order of magnitude more expensive due to the need to build new infrastructure (sewers, interceptors, pumping stations, more expensive treatment plants in smaller municipalities, and sludge handling facilities) and to deal with the waste disposal problems of rural communities. The per capita cost would be a few thousand U.S.dollars, an extremely large amount of money under the present economic conditions. Country-specific

strategic issues

Special considerations for the five individual CEE countries were also evaluated. The Czech Republic approaches Western standards with numerous activated sludge biological plants on line or under construction. However, the Czech Republic (and the entire CEE region) must address issues associated with sludge handling, sewer rehabilitation, and stormwater management. Poland faces many inadequate or highly overloaded treatment plants, as well as many unfinished and oultdated plants. Many of the unfinished plants can be cost-effectively upgraded but others would be best:abandoned and replaced. The effect of wastewater discharges in Poland on the Baltic Sea is a special consideration. The Slovak Republic also has many highly overloaded plants but faces relatively high upgrade costs due to its distribution of population in mostly smaller cities and towns. Bulgaria has limited existing treatment capacity and wastewater is

not treated in more than half of the towns considered in this study. The wastewater treatment situation would benefit from reduction of the country's very high water consumption rate. Hungary faces a unique situation among the five countries in that so much of the country's wastewater is generated in a single large city and because there is relatively high dilution in the country's receiving waters. Multistage development based on receiving water quality would be very effective in Hungary. Issues of implementation policy impact

and

The implementation of a cost-effective, regionally nonuniform municipal wastewater treatment strategy can draw upon legislative or institutional elements previously used in Western countries. A complicating difficulty in the CEEcountries is, however, the continuing transition in the broad sense. We recommend that effluent and ambient standards be used jointly to issue permits that achieve improved receiving water quality cost-effectively. The decisionmaking process by river basin agencies (which exist in most CEE countries) should rely upon a regional plan that is based on consideration and analysis of the economic as well as water quality implications of treatment alternatives. The policy should be enforced by effluent charges and grants. Grants should depend on how closely the discharger conforms with the technology recommended by the regional least-cost policy. A major recommendation of this report is that the multistage least-cost development approach be demonstrated in selected projects. Best would be a demonstration project in a small river basin in which there are a few existing overloaded plants. Such a case study could be used to illustrate all aspects of the approach recommended here: upgrading existing plants, multistage development, nonuniform standards setting, river basin planning, and methods of implementation. Endnote 1. Late eighties to early nineties.

ii T

Introduction

egy which does not hamper the economicand social

he Central and Eastern European (CEE)

transition without exacerbating existing social probcountries currently (early nineties when this lems such as the low per capita GNP (one-fifth to onereport was prepared) face economic changes, tenth that in developed Western European countries). and in some aspects crises, that significantly but variThe per capita cost to meet the effluent quality requireably affect water pollution from various economic secments of the European Union can be estimated to be tors. For instance, decreased use of fertilizer in about 2,000 U.S. dollars. Because the funds available Hungarian agriculture has reduced nutrient loads by for environmental management are far less than those 20 to 40 percent in some rivers. A decline in industrial required, there is a need to design a policy which is production and plant shutdowns have caused some cost-effective in the short run but which can be graduheavily contaminated rivers to improve by one or two ally adjusted to meet long-term objectives. Any such water quality classes. These changes, which have not strategy must, of course, be a part of an integrated that considers pollution fom all sources resulted from any systematic management actions, il-framework and in all media. lustrate the new opportunity to couple environmental Thus, the main purpose of this study, which is a contribution to the preparation of the Environmental Action Programme for Central and Eastern Europe, is to analyze the above issue. To this end, the study has these three specific objectives (as defined in the Terms of Reference for the project): * To evaluate the present status of water supply, sewerage, and municipal wastewater treatment in five countries of the GEE region: Poland, the Czech Republic, the Slovak Republic, Hungary, and Bulgaria * To demonstrate, using selected case studies, alternative wastewater treatment strategies that are economically feasible and cost-effective in the short term, but flexible and amenable to future improvements to meet long-term needs * To estimate costs associated with the development of alternative policies. The purpose of this study is to develop an approach for management of municipal emissions and demonstrate the approach with examples. Since the

management with economic transformation. Unlike agricultural and industrial pollution, urban and municipal pollution have hardly been affected by the current economic changes. Urban and municipal pollution are characterized by two major factors: * During the past 40 years, municipal water resources systems have been developed in a somewhat haphazard fashion and with only limited resources, resulting in systems far below standards elsewhere in Europe. * The investment needed to improve existing systems would be an enormous burden even for stable economies. These differences necessitate different approaches. For industry and agriculture the major question is how to take best advantage of the present opportunity through a carefully designed economic and environmental policy. But municipalities, although they may be influenced by industry, face a very different task. Here the dilemma is how to develop a strat1

2

Municipal Wasteuzater Treatment in Central and Eastern Europe

current state of water supply and sewage collection is generally adequate, the study has a strong focus on wastewater treatment and its scheduling, as well as on regional priorities. The objective of the study is not to identify a particular strategy, priority list, or investment program for given watersheds or regions. Other programs are addressing these specific issues; for example, for the BalticSea (including the Oder/Odra and Vistula), the Danube River, and the Black Sea. Nevertheless, relevant results from these other programs are utilized here (at least to the extent that they are available). Overall, there are many interrelated international studies of water pollution problems in the CEE region ranging from basin-, subbasin-, and country-specific projects to generic studies on setting standards and the economic implications of those standards. We strongly believe that an efficient integration of these various efforts and thieirfindings will help significantly in properly addressing the serious problems which exist in Central and Eastern Europe. Thus, the primary objective of this study is to explore major technical elements of cost-effective strategies (startng from the existing infrastructure and facilities) and to estimate the possible cost savings of this approach. Developing a cost-effective policy raises a iportat hos of oherisses suh as he ~the a host of other important issues such as the insotuionalsetting, decisionmaking,financing, and enforcement. While we touch upon these issues, it is beyond the scope of tlhs report to address them in detail. Thisreprt oganzedass fllos. hisIntodThion rpoutlins theorganization fofowsThe ic andidenifies the project contributors. It also discusses th daacleto*pormaddt data collection program and data bas base dvlopet development. Chapter 1 describes the existing status of municipal water supply, sewerage, and wastewater treatment. The chapter is built upon the overall evaluation of five country reports (which are provided as appendices to this report) and additional analysis of the data base created from the country-specific data. The information on each country is summarized in individual sections of Chapter 1, while common features related to technical issues as well as institutions, legislation, and financing are discussed jointly. Chapter 2 proposes a general approach to developing cost-effective wastewater treatment strategies for the CEE countries and analyzes major elements of the approach. Chapter 3 summarizes wastewater treatment technology alternatives which can be used in the CEE

region. The chapter draws on three background reports included as appendices, and assesses pollutant removal rates, costs, and other factors for each treatment method for various capacity ranges. The chapter discusses how these technologies can be designed and constructed in multiple stages over an extended period of time (one to two decades) and while best utilizing existing facilities. Chapter 4 presents a number of illustrative case studies for both the municipality and river basin level. The case studies are taken from the country reports with further analyses added. Chapter 4 considers country-specific strategic issues of controlling municipal effluents while Chapter 5 discusses aspects of implementing least-cost policies. Finally, Chapter 6 summarizes the main conclusions and recommendations of the study. Data issues Control of municipal wastewater treatment should be considered within a demand management framework, and thus data are required not only on wastewater discharges but also on water supply and use. Moreover, data are required on varying levels of aggregation. For example, detailed information on unit processes would be needed to design or upgrade wastewater treatment plants, while local and regional water quallty impacts predominate at a river basin or subbasin scale. Data from multiple countries must be considered for shared water resources such as the larger river basins. collectionniiultetetuis should cover such diverse btitreae Thus data eesa but interrelated levels as individual treatment units; individual municipalities; river basins and subbasins; and individual or multiple countries. The focus of this study was on municipalties with obvious linkages to higher and lower levels. For each municipality, data were collected mostly in 1991 for water supply, sewerage, and wastewater treatment. Major features of treatment plants were also characterized, but process details were considered only in the case studies. Data were organized according to major river basins such as the Oder/Odra, Vistula, Danube, or Tisza and according to the five countries. Streamflow and receiving water quality data were gathered, but no effort was made to represent stream water quality relationships as a function of discharges and other factors along the rivers or within river ba-

Introduction

3

sins. This was outside the scope and objectives of the present study. Nonetheless, where the objective is to develop a detailed strategy for an individual watershed, a river basin management approach is required. Data were assembled under this study for 362 municipalities (Figure 1) with a total population of 35 million. This represents about half of the total population in the five countries (73.2 million) and 70 percent of the total urban population. The data are current as of the late 1980s. Data were collected for all towns with populations greater than 25,000. In addition, partial data were gathered for a considerable number of towns in Poland with populations greater than 10,000 (water supply data were not collected). Information was assembled for 187 towns in Poland (96 in the Oder/Odra River basin and 91 in the Vistula River basin), 51 in the Czech Republic, 27 in the Slovak Republic, 52 in Hungary, and 45 in Bulgaria. Aggregated data were gathered for the remaining population in each coun-

data did not identify capacities that were only partially used (due, for example, to unfinished sewer networks). Discrepancies between water supply and sewerage flows arose for many technical reasons, including lack of flow meters, inadequate or inaccurate monitoring, transmission losses, ground-water infiltration, stormwater runoff, industrial discharges, illegal connections, and so forth. In other cases, water supply quantities may have included exports outside the city or wastewater may have included discharges from selfsupplied industries. For these, a reliable evaluation of the water consumption cycle is almost impossible without detailed data collection at the site. Data reliability may compromise some figures. In the past, data were often manipulated or distorted to present a more favorable impression on water losses,

Data limitations

phosphorus (P) and nitrogen (N) emissions were often missing. Similarly, total phosphorus (TP) and total

Data collection faced several hindrances. The greatest was the simple fact that the information outlined above has practically never been assembled in an integrated fashion in the past. Hydrologic, water quality, water supply, and wastewater treatiment data were stored at supply, andwastewationr teatmcountry, ata wevere s uniat variousysti.Uftutnsainteach c of these instatutioneveral fled system. Unfortunately, several of these institutions have ceased to exist and valuable information was lost or came to be treated as an institutional or private strategic asset. The absence of integrated data collection and evaluation in the past was evidenced by numerous contradictions in the figures, only a portion of which could be resolved. One relatively minor difficulty was the fact that the various kinds of information did not necessarily correspond in time or duration. Confusion in the definition of quantities was another problem. For example, historical records sometimes failed to identify whether wastewater flows were annual averages, dry weather means, daily averages, peak values, or something else. The designed capacities of treatment operations were often not distinguished from the flows actually experienced. In some cases, upgrades had increased the actual capacity beyond the original design capacity. In other cases, the

nitrogen (TN) were seldom measured in receiving y als, which are an important component of polution by municipal discharges. Few data were collected on existing sludge handling. Even capacity figures were missing for most municipalities, reflecting serious problems with respect to this aspect of municipal pollution and the data to describe it. Considerable effort and numerous analyses were made to reduce data uncertainty. In many cases, additional information was collected, which often raised new doubts. Where it was impossible to resolve discrepancies in data, estimates were based on experience and "rules of thumb." For example, average per capita quantities for water consumption, and population equivalent values of BOD, P, and N in influent wastewater, were used. The same strategy was employed to fill in missing data. There is no other way to develop a useful data base from the information which can be collected in the CEE countries.

degree of treatment, or receiving water quality. These distortions are very difficult to repair now. With regard to wastewater quality data, ifluent and effluent biochemical oxygen demand (BOD) data were relatively reliable. However, such critical data as

Data organization Data are organized into several main categories of information. The first identifies each location by the town

4

Municipal

Wasteuwater Treatment in Central and Eastern Europe

name and by coordinates of latitude and longitude. The second includes information on the flow and water quality of the receiving water for the town. The third assembles parameters related to water supply and wastewater collection (distinguishing domestic and industrial contributions.) The fourth characterizes the wastewater treatment plant according to the age of the plant, its flow capacity, influent and effluent concentrations, degree of overloading, quantity of untreated flow, sludge production, and other factors. Finally, the last category assembles information on future plans to upgrade exisling plants and/or construct new facilities. Detailed information characterizing population, water supply, sewerage, and wastewater treatment for the larger cities in each country are illustrated in Figures 2 through 54. These figures show the collected data as well as values derived from the data. The charts were prepared with a commercial mapping computer program. Note that in figures where circles characterize a particular characteristic, the area of the circle is proportional to the quantity (and thus the scale is nonlinear). For all maps, including bar charts, the software automatically scales symbol size to the highest value; thus, symbol scaling varies from map to map. The water supply and wastewater treatment data base was constructed using the Microsoft Excelspreadsheet software. Each row of the spreadsheet represents an individual town. For a few large cities, separate rows are also included for individual wastewater treatment plants within a town. The columns of the spreadsheet contain data for the various receiving water, water supply, sewerage, and wastewater treatment parameters. In addition, the town's population and coordinates of latitude and longitude are also included. A separate spreadsheet was constructed for each country, with Poland separated into two spreadsheets for the Odra and Vistula River basins. The data base spreadsheets contain only the raw data received as part of the individual country reports. Data gaps are left unfilled and there are no secondary statistics calculated from the data. All numerical calculations and data analysis are performed in other spreadsheets in order to keep data manipulation aLndanalysis separate from the raw data. Data analysis As indicated above, the numerical data from the water supply and wastewater treatment data base were

analyzed in Microsoft Excel spreadsheets separate and apart from the data base spreadsheets. An analysis spreadsheet was constructed for each country. Data values from the raw data in the data base spreadsheets are provided to the analysis spreadsheet via dynamic links. This organization leaves the raw data intact and unmodified by any data analysis or manipulation. The data analysis spreadsheets perform three major functions: * Gaps in the original raw data are filled using other data to the extent possible, and otherwise using typical population equivalent or per capita values. * The cost to upgrade the existing level of treatment is computed for five levels of treatment: mechanical, chemically enhanced mechanical, biological, chemically enhanced biological, and the latter with nitrogen removal (Chapter 3). Within this framework, two scenarios are developed. The first assumes that missing capacities would be corrected by constructing new treatment units and adding volume; the second is based on expanding capacity (up to a certain limit) by chemical enhancement. * The "benefits" of upgrading to the five levels of treatment are computed in terms of reduction in BOD, TP, and TN loads, as well as the improvement in the corresponding receiving water quality concentration. The filling of data gaps is largely concerned with substituting for missing effluent data and correcting discrepancies between wastewater treatment capacities and the actual wastewater flows. Where effluent data are missing, concentrations appropriate to the level of existing treatment are substituted. The flow corrections are more difficult. Many of the treatment plants are highly overloaded, with the result that flow exceeding the mechanical (or biological) capacity is effectively untreated or only partially treated. Thus, for each city the quantity of "effectively untreated" flow is determined as the sum of the actual untreated flow plus the amount of treated flow that is in excess of the treatment plant's capacity. Costs of treatment plant upgrades are computed in terms of total capital cost; annual operation, maintenance, and repair (OMR) cost; and total annual cost. For each city, the cost of upgrading to successive levels of improved treatment is computed from unit costs prepared based on the wastewater treatment reports. Two approaches are developed. The first calculates the cost to upgrade treatment to a certain level in a single

Introduction

5

step. The second computes the incremental costs of upgrading from one phase to the next in a multiphase development process. The "benefits" of wastewater treatment are computed using water quality concentrations representative of each level of treatment. The weighted total effluent concentration is used to compute the total effluent load and that load is then assumed to be fu,y

as well as water quality problems and aspects of legislation. The task for each country report was threefold: * To evaluate present conditions, identifying major problems and outlining possible solutions and associated costs * To provide detailed data for larger municipalities * To prepare selected case studies which illustrate specific problems and, utilizing the findings of the

diluted in the receiving water low flow defined in the data base in order to compute a representative receiving water concentration. This concentration is a greatly simgpwaerconcentration. Thisthat concentratione gtherea simplified approximation in that it assumes no other soures f tothe wsteateecevin waer.Theefsources of wastewater to the receiving water. The effluent load, change in effluent load from the existing load, the receiving water concentration, and change in receiving water concentration are computed for each major wastewater pollutant: BOD, total nitrogen, and total phosphorus.

wastewater treatment review described below, show how cost-effective wastewater treatment showtegiecost-eofecthoe wastems. strategies may solve those problems. Several international experts in wastewater treatmn rvdddtie nomto ntcnlg l ment provided detailed information on technology alternatives. H. 0degaard and M. Henze evaluated different physical, chemical, and biological treatment technologies and technology combinations. They provided estimates (based primarily on Norwegian and Danish experience) of pollutant removal rates and costs for different technology alternatives and capacities.

Organization

D.R.F. Harleman and S.E. Murcott evaluated the applicability of chemical enhancement as a means to up-

of the study

National teams were created in all of the five countries considered. They were led by J. Dojlido in Poland; P. Grau and I. NesmerAk in the Czech Republic; J. Namer and L. Hyanek in the Slovak Republic; Gy. Botond and L. Somly6dy in Hungary; and I. Dobrevsky and V. Nenov in Bulgaria. Annex A contains short biographical descriptions of the contributors. The country reports, which are available separately as Working Drafts, analyze water supply, sewerage, and wastewater treatment and sludge handling

grade the performance of existing municipal treatment plants. They also provided cost estimates for different technologies based on U.S. experience. F. SzilAgyi reviewed the state of the art in natural treatment systems with special attention to their applicability to rural communities. The three reports on treatment technologies are also available separately as Working Drafts. This synthesis report summarizes the entire study and integratesfindings fromthenationalreports with those from the treatment technology reports. It includes further analyses of the integrated data base and other issues.

i

Chapter1 Water Supply, Sewerage, and Municipal Wastewater Treatment

D

ramatic political, economic, and institu-

ministries (water, environment, public health, fi-

tional changes in CEE countries since early 1990have affected every aspect of life including water resources management by municipalities. An extreme example is that of the Czech and Slovak Republics, which were a single country when this study started. Some of the key elements of the continuing transition are listed below. These elements illustrate the overall conditions which must be understood to develop effective policy and meaningful analyses: s Centralizes: strategic and financial planning by the * Centralized strategic and financial planning by the state has been almost completely abandoned and there is a strong movement toward decentralization and privatization. * The institutional system is undergoing significant change, both abrupt and gradual, leading to a strongly increased role for local governments, the creation of new river basin authorities (for example in Poland) and environmental agencies, the disappearance of state-owned regional water and wastewater companies (often without adequate replacements), and division of water quantity and water quality management functions into separate water and environmental ministries and district authorities (for example in Hungary). * Decisionmaking has been largely decentralized. Due to a lack of experience and institutional structure, decentralization can lead to rather peculiar schemes, particularly if financing is also involved. For example, the planned construction of a wastewater treatment plant may now involve decisionmaking by the state and local governments, several

nance, etc.), their inspectorates and regional authorities, waterworks, and so on. New environmental legislation is being gradually introduced. Responsibility for water supply and water treatment and ownership of the infrastructure is being transferred to municipalities. State subsidies are by subsibut may be replaced generally ending, funs. enl andwt diesaoryloansfromuevioma bund thesta te from Thes fn ars These funds are separate from the state budget and are planned to be sustained in the long run by the inoefmswaecrgsndpluonie. income ftom sewage charges and pollution fines. The state institutions formerly responsible for collecting and evaluating data on water, wastewater, and water quality have become largely ineffective due to institutional changes, lack of funding, and loss of personnel to the private sector. The state companies formerly responsible for engineering and design have fragmented into smaller enterprises which are now being privatized. Many new companies are now involved in planning and designing municipal water supply, wastewater collection, and treatment systems. Foreign companies and capital have entered the market in different ways, including the accelerating formation of joint ventures. These have both positive and negative repercussions. Transfer of knowledge in certain fields (management, operation, environmental impact assessment, auditing, financing, etc.) and provision of well-proven technologies are beneficial. On the other hand, outdated, cheap, and unreliable methods are sometimes sold, with negative consequences.

* *

*

*

*

7

8

Municipal

Wastewater Treatment in Central and Eastern Europe

This list was assembled to provide a "flavor" of the ongoing changes in institutions, decisionmaking, and technology transfer. These changes will influence the implementation of a strategy that promotes costeffective future development. With this as background, the following turns to the technical and statistical evaluation of the status of water supplv, wastewater collection, and wastewater treatment in Poland, the Czech Republic, the Slovak Republic, Hungary, and Bulgaria. For each country, an overall evaluation is offered. In addition, the existing situation of individual municipalities and regions is illustrated by the sequence of maps prepared from the computer data base. Those features which are similar for all countries (for example, sludge handling) are discussed in the last section of this chapter. Poland Poland is divided between two major river basins: the Vistula River and the Odra River. In addition, a small portion of the country drains directly to the Baltic Sea. The population of Poland is 38.2 million people, of which 62 percent live in cities and towns while 38 percent live in rural villages. The total number of cities and towns is 641, distributed as follows: 390 have populations larger than 10,000; 218 are larger than 20,000;and 33 are larger than 100,000. The largest 182 were considered in the data collection and analysis for this study. Figures 2 through 4 show population, total wastewater discharge, and the total load of five-day biochemical oxygen demand (BOD5) for different municipalities in the Vistula basin. The corresponding charts for the Odra basin are Figures 11 through 13. The Katowice area, in which a large population is concentrated, is characterized as an aggregated figure in the main rnap with individual cities shown in the enlarged insert. The area is near the Odra-Vistula divide, but the majority of the wastewater is discharged to the Vistula basin. Overall, Figures 2 through 4 and 11 through 13 help to identify the larger population centers, their discharges, and their possible local and regional effects. About 90 percent of the town population is connected to public water supply (only 32 communities lack central systems). The total water intake for all municipalities is 8.2 million cubic meters per day (1990

data), taken roughly equally from surface-water and groundwater although most of the largest towns depend upon surface water. PMunicipaluse in 390 cities with over 10,000 inhabitants is 5.5 million cubic meters per day, corresponding to 280 liters per capita per day on average. Inclusion of industrial use raises the per capita consumption by a factor of 2.5, to 700 liters per capita per day as a countrywide average (with much higher consumption in some individual municipalities -see below). The utility gap is an important consideration with respect to the completeness of water infrastructure development. We define the utility gap as the percentage of the population connected to public water supply less the percentage of the population connected to public sanitary sewers. In Poland, the percentage of the population connected to the water supply is practically 100 percent in towns larger than 20,000 population. Of the population served by public water supply, 89 percent is connected to the wastewater collection network. Thus the utility gap is relatively small on average, approximately 10 percent. However, it is 65 percent for communities smaller than 5,000. The situation is much worse in rural areas where only 20 percent of the population is supplied with piped water (compared with about 95 percent in Westem Europe). Proper wastewater collection (either on site, or off site with a collection network) is almost nonexistent. Shallow groundwater if often highly contaminated by bacteria and nitrate (concentrations of 100 mg/l are not rare). Because shallow wells are often used for drinking water supply, contaminated groundwater raises potentially serious health risks. The situation is similar in the rural regions of most of the other CEE countries. Wastewater treatment in towns lags water supply and sewerage. 302 municipalities have secondary (biological) waste treatment in 367 treatment plants; 165have only primary (mechanical) treatment; and 365 do not have any treatment. Of the 365 municipalities without treatment, 203 have capacities less than 5,000 cubic meters per day. The total quantity of sewage collected in towns is 6.2 million cubic meters per day of which slightly less than 30 percent originates from industry. Of the total sewage collected, 36 percent is treated biologically, 29 percent is treated mechanically, and 40 percent is untreated. In the 390 cities with more than 10,000 inhabitants, a total of 5.0 million cubic

Water Supply, Sewerage, and Municipal

meters per day of industrial wastewater is generated, of which 2.1 million is treated by industrial plants and 1.2 million is untreated. Considering municipal and industrial systems together, 56 percent of the wastewater is untreated, 19 percent is processed mechanically, and only 24 percent is treated biologically. There is as well a small percentage of industrial wastewater treated chemically. Figures 8, 9, 17, and 18 demonstrate the amount of wastewater discharged in liters per capita per day from domestic, industrial, and all sources. While domestic production exhibits a relatively narrow range, industrial production is highly variable. For example, Swiecie (Figure 9) is an example of what is also seen in other CEE countries: a large industry in a relatively small community. Industrial plants often obtain their water from the public water supply system, typically priced at a (negotiated) premium of 50 to 100 percent above the domestic water price. These arrangements raise important management and pricing issues for the future. From our data collection it is not possible to identify the industrial component within the "domestic" supply; therefore, per capita figures should be evaluated carefully (see also Figures 18,36, and 52). A similar caveat may apply to some of the per capita sewage data for municipalities where the public sewer also receives wastewater from industries which supply their own water (see, for example, Figures 18, 27, 36, or 53). Treatment plant operations are hindered by numerous problems, including large hydraulic overloads. BOD removal rates vary over a broad range (5 to 95 percent). Removal is less than 70 percent on average and less than 50 percent for one-quarter of the plants. The latter plants are effectively acting as mechanical units with no realistic expectation of effective sludge handling. Some of the treatment plant operational problems can be seen in the figures produced from the data base. Figures 5 and 14 show the level of wastewater treatment while Figures 6 and 15 illustrate the relationship between influent and effluent BOD loads (including untreated wastewater). Figure 5 is seen to be consistent with Figure 6, and Figure 14 with Figure 15, by the fact that the removal rate by mechanical treatment does not exceed 30 percent (Chapter 3). Figures 6 and 15 are based on actual removal rates, overloads, and untreated flows - quantities which are more informa-

Wastewater

Treatment

9

tive than the nominal treatment system type as indicated in Figures 5 and 14. Figures 7 and 16 illustrate total nitrogen loads which are crucially important to. the water quality of the Baltic Sea. These figures are very consistent with Figures 4 and 13, the total influent BOD loads. It can be seen that existing treatment technologies remove practically no nitrogen. Construction of 787 treatment plants, including 258 plants with capacities greater than 2,000 cubic meters per day, was started in the 1980s. The total planned capacity of these plants is 8 million cubic meters per day. However, funding difficulties even prior to the political changes had extended projected completion times 7 to 10 years. As a result, only 54 of the planned 258 large-capacity plants have reached 70 percent completion. The fate of these plants is currently uncertain (see further discussion below and in Chapter 5). In the discussion of water quality for Poland and the countries to follow, we define water quality classes in a general way. Numerical water quality classifications and evaluation systems vary from country to country. Here we present the percentages of stream length within each water quality classification solely to illustrate the overall state of water quality and not to characterize specific problems. In general, a Class I stream is suitable for drinking water supply (for example, dissolved oxygen (DO) greater than 6 to 7 mg/ I and BOD5 less than 2 to 5 mg/I). The poorest classes (III to V depending on the country) are waters which could not be used for any purposes (BOD5greater than 10 to 15 mg/l). A medium-class water can generally be used for industrial water supply. The water quality of Polish rivers is generally poor. Only about 2 percent of the total monitored length (approximately 9,000 km) belongs to highest water quality class, Class I. Thirty-three percent are in Class II; 30 percent in Class III, and 35 percent in Class IV. Bacteriological and lake classifications show even worse water quality. Out of the 390 towns with over 10,000 inhabitants, 3 percent discharge to Class I river reaches and 64 percent to Class IV. Organic matter and nutrients discharged to the Vistula, Odra, and their tributaries, or directly to the Baltic Sea, cause varying problems, depending upon their location. The most noteworthy problems include: * Oxygen depletion

10 Municipal Wastewater Treatment in Central and Eastern Europe * High BOI) levels (>20 mg/l for larger rivers and sometimes >150 mg/l for smaller streams which effectively act as sewage canals; see Figures 10 and 19) * High algail biomass (several hundred milligrams per cubic meter of chlorophyll-a) * High ammonia concentrations endangering water supplies * Bacterial contamination * Large nutrient load to the Baltic Sea. This is far from an exhaustive list of the nation's water quality problems, however. Several other problems unrelated to municipal discharges (for example, high salinity) are not discussed here although a comprehensive water quality management program would need to consider these problems as well (together, for example, with the contribution of agriculture to nutri-

The data reported here cover 51 towns larger than 25,000 which include 43 percent of the population. The regional distributions of population, wastewater discharge, and BOD load are illustrated in Figures 20 through 22. The level of development of water and sewerage infrastructure is significantly higher than in Poland or any of the other CEE countries studied. In the 51 towns evaluated, the percentage of the inhabitants connected to municipal water supply systems is 96 percent. The source of water supply is mostly surface water primarily relatively well protected river reservoirs; surface water accounts for 72 percent of total supply. The average per capita water supply to households is about 200 liters per capita per day represent-

ent loads and receiving water concentrations). To illustrate receiving water quality, Figures 10

users (8 percent). Processed water which is not accounted for (and presumably lost) is approximately 27

and 19 show five-day biochemical oxygen demand (BOD5). The BOD5 "concentration" is that which would be experienced under low flow conditions downstream of the discharge in the stream directly receiving the wastewater discharge. In order to clearly associate the receiving water impact with the municipal discharge, the mapping symbols are placed at the community although the receiving water station may actually be located downstream. The high concentrations observe!d at many sites indicate situations in which small streams act essentially as sewage canals; the lower concentrations in larger rivers show the effect of dilution and BOD decay in the receiving water. To summarize, the data presented in the text and figures illustrate that rural areas and municipalities of widely different size equally create critical problems with respect to sanitation and water quality management. However, they require quite different future development strategies (see Chapters 2 through 5). Another important consideration is the trade-off between the solution of local problems and the internatonal problern of the Baltic Sea.

percent. In Prague alone the water loss is about 250,000 cubic meters per day, which is roughly equal to the amount accounted for. All water use and loss sums to a per capita water supply that is greater than 400 I/ cap/d. In towns greater than 25,000 population, 94 percent percent of the inhabitants are connected to sewers and the utility gap is negligible (Figure 25). Due to

The Czech IRepublic The population of the Czech Republic is 10.3 million out of which 73 percent live in communities larger than 2,500 population. There are roughly 5,800 such communities, but only 6 cities larger than 100,000. Prague (Praha) is the largest city, with over 1.2 million people.

mg percent of the water processed. The rest is water in43 supplied to industry (22 percent) and to other water

groundwater infiltration and inflow from local small streams (clean water), the collected dry- weather flow requthin tewat treaten isaotercent higher than the total processed drinking water (5401/ cap/d). Figures 26 and 27 characterize water supply, sewerage, and wastewater treatment. Republic is much higher than in Poland or the other CEE countries: 82 percent of the population is connected to wastewater treatment plants. Out of the almost 2 million cubic meters per day collected, 1.5 million is treated biologically. The percentage receiving only mechanical treatment is not significant and is quickly vanishing. Figures 23 and 24 demonstrate in detail the much higher levels of treatment than are seen in the corresponding figures for Poland (note, however, that there are some discrepancies between the loads in Figure 24 and the types of treatment in Figure 23 due to contradictory data). The most common technology for biological (secondary) treatment is the activated sludge process, even

Water Supply, Sewerage, and Municipal

in small communities not included in the detailed data gathered for this study. There are over 400 activated sludge plants operated by public water and wastewater companies. BOD5removal efficiencies often exceed 90 percent. The overall removal rate is 71 percent for the 51 towns considered in this study, incorporating the untreated fraction of dry-weather sewer discharges. There are a number of plants under construction, reconstruction, or upgrading (for example, there are 51 in the Elbe River watershed alone). Although the speed of construction is limited by financial constraints, no significant plant construction has been suspended for a long period of time. Rivers in the Czech Republic typically have limited dilution capacity and industrial pollution (from the food, chemical, metal, machinery manufacturing, and other industries) plays an important role in affecting surface water quality. The headwater reaches of mountain streams have good or acceptable water quality (Class I, II, and III). However, most of the Odra and Morava Rivers is Class V, the lowest water quality class. The quality of the Elbe and its tributaries varies from Class I to Class V; on average, it is Class IV. Unlike Poland, stream BOD levels do not exceed 25 mg/l in streams with greater than 1 m3 /s flow. The overall average stream BOD concentration is around 10 mg/I, as is illustrated in Figure 28. Nevertheless, nutrient concentrations are high. Total phosphorus can exceed 1 mg/l and inorganic nitrogen 10 mg/l in even the larger rivers (to which agricultural nonpoint source pollution also contributes significantly). These high concentrations arise from the relatively low river flow rates, which carry roughly half the flow of Polish rivers on a per capita basis. In summary, we find that the level of water supply, sewerage, and wastewater treatment in the Czech Republic approaches that of developed Western European countries. The size of communities is distributed more homogeneously than in Poland, with fewer large cities. For these and other reasons, preparing a strategy for municipal water pollution control in the Czech Republic is a rather straightforward task. Nonetheless, the expense of carrying out even such a strategy will be considerable. The Slovak Republic The population of the Slovak Republic is 5.3 million in 2,800 communities. Of these, 27 are larger than 25,000


11

(representing 35 percent of the country's population) and only Bratislava and Kosice are larger than 100,000 (Figures 29,30, and 31). There are 2,475 communities with fewer than 2,000 inhabitants, making up 31 percent of the total population. Domestic water is supplied to only 76 percent of the Slovak population (about 70 percent of the households) in about 1,600 communities. In towns over 25,000 population, water supply reaches 97 percent of the populace (Figure 34). The total water supply capacity is 3.2 million cubic meters per day. Industry draws most of its supply from surface watercourses; industrial supply exceeds 2 million cubic meters per day. Municipal consumption is 1.2 million cubic meters per day, of which 85 percent comes from groundwater. Approximately 60 percent of the municipal consumption is used for domestic supply. Per capita water consumption averages close to 4001/ d (Figure 35). Household use alone is about 180 l/cap/d, but may be as much as 50 percent higher in large cities. As in the Czech Republic, unaccounted water is high, approximately 20 percent of the total supply. Drinking water quality is a serious problem: 25 percent of the delivered water fails to meet drinking water standards. Only 51 percent of the total wastewater produced in Slovakia is collected, although 89 percent is collected in the towns with populations larger than 25,000. Thus, the countrywide utility gap is rather high at 25 percent. In the larger towns considered in detail in this study the utility gap is less: 10 percent (Figure 36). In several districts, the fraction of the population connected to sewers is below 30 percent. Overall, only 10 percent of the communities are served by public sewer systems. Several towns with populations greater than 10,000 have no collection network. Groundwater infiltration and leakage are similar problems to that reported for the Czech Republic. For example, in the towns with populations larger than 25,000 the per capita water supply is 350 l/d while 530 l/d of wastewater are collected. The difference is not fully explained by industries which supply their own water but discharge to the municipal sewer. Only about 42 percent of municipal wastewater is treated countrywide (Figures 32 and 33). Altogether 172 plants are operated by public waterworks. Nearly 60 percent of the plants have capacities greater than 5,000 cubic meters per day, but less than 4 percent of the plants exceed 50,000 cubic meters per day.

12 Municipal


Municipal wastewater treatment plants typically employ seco:ndary (mechanical and biological) treatment using the high load activated sludge process. The portion of plants with only mechanical treatment is greater than in the Czech Republic. As in Poland and elsewhere in the CEE countries, chemical treatment is employed ordy in industry. Industrial contribution to municipal wastewater is significant. This can be seen in the figures for communities with large industrial operations, such as Partizanske, Ruzomberok, and L. Mikulas, which are characterized by large per capita wastewater discharges which greatly exceed the water supplied (Figures 35 and 36). A large fraction of wastewater treatment plants are significantly overloaded in terms of both flow and organic load. Not infrequently overloads exceed 100 percent; that is, flow or load is more than twice the design capacity (see Chapter 4 for details). As a result of overloading, the average BOD removal rate is about 70 percent and only one-third of the plants operate at the designed level of efficiency. More th,an100 treatment plants are not completed or are under reconstruction, and about 300 additional plants have been designed. Owing to the community structure in Slovakia, 60 to 70 percent of the latter are small plants with capacities between 20 and 1,000 cubic meters per day. Water quality in Slovak rivers is rather poor although the data collected do not properly reflect the actual situation. For example, on certain stretches of the Nitra River, BOD5 exceeds 30 mg/l and oxygen is depleted under low flow conditions. The most polluted rivers iare the Vah, Nitra, and Slana. However, stream water quality is largely determined by agricultural and industrial sources; their contribution in terms of BOD load is estimated to be larger than that from municipal sources. Approximately 8,200 kilometers of river are monitored in the Slovak Republic. BOD5 exceeds 15 mg/l over more than 2,000 kilometers. Most of the Vah River basin, including the Nitra River, falls in the lowest water quality classification, Class IV. A significant portion of the Bodrog and Hornad system, as well as the Slana River, are in Class III or IV. We surmimarize by observing that municipal infrastructure 'in the Slovak Republic is much less developed than in the Czech Republic and many more operational problems, such as overloading, exist. Small

communities play a much greater overall role in water management in Slovakia than in the countries discussed above, and it appears rivers may be more highly contaminated. These various factors make it difficult to specify future development goals for the Slovak Republic.

Hungary The population of Hungary in 1991 was 10.4 million of which 62 percent lives in the 177 largest towns and the remaining 38 percent lives in 2,915 smaller communities - a population distribution much like that in Slovakia (see Figures 37, 38, and 39.) Twenty designated "priority" cities (Budapest and the county capitals) include 38 percent of the population. Slightly more than 2million, roughly 20 percent of the country's population, live in Budapest alone. The 52 towns greater than 25,000 population which are in the data base developed for this study represent half of the total population (Figure 37). There are nine towns with populations greater than 100,000. Among the smaller communities, 2,270 towns have a population less than 2,000. In Hungary, 92 percent of the domestic water demand is supplied by public water supply in about 2,500 communities (Figure 42). However, the level of service is variable and only 78 percent of the total population lives in dwellings connected to a supply network (14 percent of the population takes its water outside the actual dwelling, such as at outdoor taps or communal supplies in apartments). Eight percent of the population is not served by piped water. In 442 communities bottled water is distributed on a temporary basis. The average domestic water consumption is 160 liters per capita per day (including services outside of dwellings). In the 52 towns included in the data base the per capita consumption is 200 l/d; in Budapest it is 240 I/d (Figure 43). The total quantity of water supplied in these municipalities, including industrial supplies and transmission losses, is 340 liters per capita per day. All of these consumption rates are less than those in the other CEE countries studied. The current total municipal water demand is 2.4 million cubic meters per day. Surface waters are used to only a limited extent (9 percent of total supply). Most of the supply comes from groundwater of some sort:

Water Supply,

43 percent from bank-filtered waters (groundwater withdrawn at or very near surface watercourses); 38 percent from non-karst groundwater aquifers; and 7 percent from karstic groundwater. Public sewerage extends to an area inhabited by 51 percent of the total population, but only 42 percent of the dwellings in these areas are connected to the system. This is less than half the service connections for water supply and the utility gap is greater than in any of the countries discussed above (Figure 44). The utility gap is more completely closed in Budapest and larger towns: 6 percent of the water supplied in Budapest does not return as wastewater and 13 percent is not returned in total in the towns greater than 25,000 population. All 177 of the larger towns are sewered. In contrast, sewerage exists in only 15 percent of the 2,915 small communities, showing the underdeveloped nature of rural settlements. Only 20 percent of the population living in unsewered areas is serviced by acceptable local waste disposal methods. The quantity of wastewater collected in public sewer systems is about 2.5 million cubic meters per day corresponding to about 450 liters per capita per day (Figure 38). Approximately half of the total sewerage, 1.2 million cubic meters per day, is in Budapest alone. Domestic sources account for about 40 percent of the total; industry 25 percent; institutions 12 percent; and stormwater and groundwater infiltration, 20 percent. The technology level of wastewater treatment shows a striking pattern: 12 percent of municipal sewage receives only mechanical (primary) treatment; 33 percent receives biological (secondary) treatment; but 55 percent receives no treatment at all (Figure 40). The total number of treatment plants is 328 in 374 communities. Only 58 plants have capacities larger than 5,000 cubic meters per day while 181 are smaller than 700 cubic meters per day. As in the other CEE countries, the activated sludge process is the dominant method of treatment. BOD removal rates are generally close to 90 percent except in overloaded plants or where operational problems occur. Plants are overloaded both hydraulically and by organic loads though to a lesser extent than in Slovakia. Despite the relatively low percentage of treated wastewater, the overall quality of surface waters is good and generally better than in other CEE countries

Sewerage, and Municipal

Wastewater

Treatment

13

(Figure 45). This arises from the relatively high dilution rate: for example the total per capita river outflow from the country is an order of magnitude greater than in the Czech Republic. Small natural streams which act essentially as sewage canals can be found in the vicinity of towns with inadequate or no treatment (Figure 45), but the high dilution rates in the Danube, Tisza, and their first-order tributaries significantly reduce receiving water concentrations. As an example, the BOD5 concentration is less than 8 mg/l over the entire length of the Danube and Tisza and dissolved oxygen (DO) levels are higher than in the countries discussed above (although DO is raised to some extent by oversaturation caused by algal photosynthesis). Inorganic nitrogen can exceed 5 mg/I, which is large relative to the loads generated within the country. However, a significant portion of the nitrogen originates from outside of Hungary, which lies downstream of other countries. In general, Hungary's receiving water quality is strongly influenced by transboundary pollution. Most of the rivers fall in Class II. The Saj6 (Slana in Slovakia), the rivers entering from Romania (such as the Szamos and Maros), and smaller rivers lying entirely within Hungary have poorer quality (Class Ill, which is the lowest class). Most of the lakes (including Balaton, Velence, and Tata) have experienced artificial eutrophication. Bank-filtered waters are drawn along 700 kilometers of the Danube, Drava, Raba, Mura, and Tisza Rivers. Increasing concentrations of nitrate, ammonia, iron, and manganese have raised serious concerns for these supplies. In addition, methane and arsenic have been problems for other groundwater supply sources. To summarize, transboundary pollution, the importance of rural settlements, the huge complex at Budapest, high dilution capacities, the need to protect groundwater resources, the large utility gap, and the extremely low level of sewerage and wastewater treatment are key elements to be considered in developing a future water management strategy for Hungary. Bulgaria The population of Bulgaria in 1990 was 9 million, 68 percent living in towns and 32 percent living in villages. The population distribution is thus similar to

14 Municipal Wastewater Treatment in Central and Eastern Europe that in Poland, Slovakia, and Hungary. There are 237 towns and about 4,200 villages. There are 9 towns with populations greater than 100,000 and 45 larger than 25,000. Population and corresponding wastewater and BOD loads a:reillustrated in Figures 46, 47, and 48. Water supply service reaches 98 percent of the total population. The total water supply is close to 2 million cubic meters per day, of which 21 percent is supplied in villages. All of the towns have central water supply systems (Figure 51). The average per capita water consumption is about 260 liters per day in towns (150 I/cap/d in households) while it is close to 100 l/cap/d in villages. Figure 52 illustrates water consumption. Surface water furnishes virtually all supply, including that for industry and agriculture. Sewers service 67 percent of the towns (Figure 51) but only :2percent of the villages. Overall, 66 percent of the population is connected to sewers. The utility gap is greater than 30 percent, which is less than in Hungary bul: greater than in Slovakia (Figure 53). As a rule, sewer systems are combined storm and sanitary sewers. Most large industrial enterprises have their own wastewater collection and treatment or pretreatment before discharging to receiving waters or municipal sewers. The total sewered municipal wastewater discharge is 2.2 million cubic meters per day and the industrial discharge is 2.7 million. Out of the industrial discharge, 45 percent percent is discharged to the public sewer system. Total per capita municipal wastewater production, including all sources, is 550 liters per day. Somewhat more than half, 59 percent, of the municipal wastewater is treated (see Figures 49 and 50 for informLationon towns larger than 25,000 population). Most of the plants (94 percent) employ the activated sludge process after primary clarification. Only 6 percent of the treated wastewater receives mechanical treatmenl: alone. Chemical treatment is employed for 19 percent of industrial wastewater. Out of 237 towns, only 42 are serviced by 47 wastewater treatment plants. There are also 5 plants at resorts and 41 in villages. However, more than 4,100 small commntities have no treatment at all. There are 9 plants providing only mechanical treatment in the towns and resorts. Of the industrial facilities, 62 percent provide only mechanical treatment. Treatment plants are often overloaded. The ratio of industrial to domestic sewage is usually large and

there are significant operational problems. As a result, the efficiency of BOD removal ranges from 50 to 75 percent. The average value is below 70 percent, which is similar to that in several other CEE countries (Figure 50). In 1988 a program was launched to develop sewer systems, upgrade existing treatment plants, and construct new plants. Full information is not available, but six plants have been completed to roughly the 90 percent level. Water quality is monitored along 3,441 kilometers of river. Water quality is extremely poor; 86 percent of the sampled length is classed in the lowest category, Class IV. There are almost no reaches in the highest two water quality classes. Figure 59 illustrates the severity of the stream water quality problem with respect to BOD. In summary, the problems facing municipal water management in Bulgaria are similar to those of Slovakia and Hungary. A stronger emphasis on surface water quality is needed due to the nearly complete reliance on surface water supplies. Issues common to all five countries This section addresses issues common to all countries and discusses a variety of topics important to the development of a strategy for water and wastewater improvements in the CEE countries. Generalobservations.Table 1.1 summarizes water supply, sewerage, and wastewater treatment statistics for the five individual countries and the totals over the five countries. Table 1.1, and the preceding sections, support the following conclusions. The overall level of water supply is quite good (at least insofar as quantity is concerned) and, on average, sewerage is adequately developed. However, the level of sewage treatment is poor, particularly if one considers that less than 50 percent of the collected wastewater receives secondary treatment. As determined above, the average treatment system efficiency over the five countries is approximately 70 percent. Thus, considering the fraction of wastewater not receiving secondary treatment and the efficiency of treatment for wastewater receiving treatment, we can estimate that only about 35 percent of the collected influent BOD is removed in the five countries. This is not more than 25 percent of the total BOD generated.

Water Supply, Sewerage, and Municipal Wastewater Treatment 15 Nutrients are retumed to the environment with practically no reduction. The Czech Republic approaches Western standards in all respects considered here. The fraction of the populace served by public water supply is the lowest in Slovakia while the level of sewerage and wastewater treatment is the poorest in Slovakia and Hungary. On the other hand, the utility gap is the greatest in Hungary, evidence of strongly unbalanced past policies favoring water supply development over sewer construction. Per capita water supply (both total and domestic) is particularly high. This arises from large losses from aged pipe networks and low water prices. The lowest per capita use is found in Hungary, where water prices were raised earlier than in the other countries. The domestic supply rate is extremely high in Bulgaria. In some municipalities the per capita consumption can be several thousand liters per capita per day due to usage of potable water by industry, a factor which raises serious demand management and pricing issues. The overall quantity of wastewater collected is practically equal to the amount of water supplied, however large differences are shown on a municipality level in the maps included as figures. As indicated above,

For example, in Hungary half of the wastewater is collected in Budapest. About half of the total population of the five countries lives in towns with fewer than 25,000 inhabitants. This indicates the need for a large number of small treatment plants. Rural communities, which number near 20,000, form at least 30 percent of the total population but possess only a primitive level of water infrastructure development. Drinking water is often obtained from shallow wells that are highly contaminated due to the lack of (adequate) wastewater disposal. There is no current strategy for addressing rural water development. There is generally a tendency to focus on water supply for rural villages and to neglect the more costly wastewater disposal. Such one-sided development tends to increase pollution in these areas. On-site wastewater treatment was rarely designed or constructed adequately. Often, systems were constructed without a wastewater disposal system (infiltration system) or as "tight tank" systems. However, the septic tank walls were often illegally perforated to avoid the cost of removing and transporting septage to wastewater treatment plant, a practice which led to groundwater contamination. These past abuses create difficulties for the present by diminishing accep-

reliable comparison between water supply and waste-

tance of even properly designed and constructed on-site treatment systems as a safe, competitive solution. Moreover, land for on-site treatment and disposal

augmlntaciof accu wanterisimpossiblerdue tlow storments esewerage foaugtratio

nftrate-

by iFithra

is often unavailable

or overpriced.

Overall, the prob-

stormwater flows, and industrial discharges. Further-

lems of water and wastewater management in small

more, many waterworks supply not only the immediate municipality but also neighboring areas. The sewerage systems often collect from different areas and also from industries with separate water supplies, and thus the water supply district and sewerage district often do not coincide. Overall, only half of the wastewater collected comes from domestic sources while industry produces about 30 percent. Wastewater treatment needs of rural areas versus towvns.Table 1.2 and Figure 55 show the distribution of population in the towns considered in this study. Most of the towns (approximately 70 percent) are in the 25,000 to 100,000 population range, representing 35 percent of the population considered in the study. Towns of this size would require medium-size wastewater treatment plants, with capacities in the range of 10,000 to 40,000 cubic meters per day. The population distribution varies significantly from country to country.

communities is a major strategic issue facing the CEE countries. Wastewatertreatmentand sludgehandlinginfrastructure. Regarding existing inftastructure for wastewater treatment and sludge handling, the following conclusions can be drawn. In all countries there is strong tradition of using the activated sludge process in secondary wastewater treatment, which is a considerable influence on technology selection in the near future. The age of plants is not generally an issue: more than half were constructed after 1970. There are practically no plants providing nitrogen removal and few providing phosphorus removal (the region around Lake Balaton in Hungary is a notable exception in providing phosphorus controls). Per capita emission-equivalent values of BOD, nitrogen, and phosphorus load are generally similar to

16

Municipal

Wasteuwater Treatment


those of Western Europe. Average influent values are around 260 rng/l BOD, 38 mg/l TN, and 9 mg/l TP (under current water consumption rates). Countryspecific concentrations depend on the rate of water supply, the composition of detergents (low phosphorus detergents are used in the Czech and Slovak Republics), the contribution by industry, and data uncertainty. The latter is particularly problematic for TP and TN which, for example, are unrealistically low in the Bulgarian data. The level of nutrients in wastewater, and the uncertainty in those levels, will be important considerations in any future decisions to introduce nutrient removal. The hig:h industrial water consumption and lack of adequate pretreatment, reuse, and recycling is a problem in all of the countries. In some cases, industrial wastes cause BOD or TP influent concentrations that are 5 to 10 times higher than in typical municipal wastewater. I[ndustrial wastewater often contains toxic or other undesirable components, such as heavy metals, oils, toxic organic compounds, extremely acid or alkaline wastes, and so forth. A particularly undesirable aspect of some industrial wastes is their toxicity to the microorganisms which carry out biological waste treatment. There are many wastewater treatment plants which are overloaded by 100 percent or more. Upgrading these facilities is an important strategic consideration for the near term. At the same time, there are a significant number of plants which are not fully utilized for lack of supporting sewer systems, interceptor sewers, or pumping stations. The Northern Wastewater Treatment Plant in Budapest, Hungary, is an example! of an underutilized facility. This shows another strategic consideration: the need to extend or upgrade missing infrastructure, including water distribution networks and sewer collection systems, such that existing systems as a whole can operate at their full, theoretically existing capacities. Many tr,eatment plants are compromised by poor design, low qlaality, outdated equipment with high energy demand (for example, aerators), inadequate control and monitoring systems, inadequate maintenance, and poor operations. There are more than 1,000 partially constructed treatmnentplants in the five countries considered. Most are significantly oversized - sometimes by as much as 100 percent- due to past practices in forecasting treat-

ment needs. Forecasts were typically made by linearly extrapolating prior growth trends and with the assumption that water was free; strategies to control water use and wastewater production were absent. With today's political and institutional changes, water and wastewater fees are being increased, the industrial structure is being altered, and the composition of detergents and other products is changing. Thus, there are dramatic shifts in the quantity and quality of wastewater from what was assumed at the time of design. As well, new goals for future water management are evolving, and budgets are seriously constrained. Thus, there is a clear need to reevaluate planned treatment plants and redesign many of the plants selected for continued construction. Renovation of water supply and sewer networks is a major and difficult expense for Western municipalities. The financial burden is much greater in the CEE countries, but infrastructure improvements are sorely needed. Water loss from water distribution networks is about 20 to 30 percent, at a cost equivalent to US$500 million annually in the five countries. The wastewater collection network typically includes combined storm and sanitary sewers, is aged and poorly maintained. For example, half the sewers in Budapest were constructed before the second World War and according to various estimates have accumulated more than 1 million cubic meters of sludge. Stormwater flows, groundwater infiltration, and illegal discharges contribute approximately 20 to 30 percent of the wastewater flow at a cost similar to the US$500 million annual loss on the supply side. This study has identified an increasing gap from water supply through wastewater collection to treatment. The gap widens further with respect to the treatment of sludge. Data are insufficient to perform a systematic analysis, however an educated guess is that about half of the sludge produced is not adequately treated and properly disposed of. Often, sludges find their way back into the environment, reversing the environmental benefit intended from wastewater treatment in the first place. The availability of sludge treatment facilities is limited. Anaerobic stabilization facilities exist at only the larger wastewater treatment plants. Aerobic treatment is the typical technology at smaller plants. Dewatering capacity is generally insufficient. Sludge is disposed of in sludge fields, lagoons, landfills, agri-

Water Supply, Seuwerage,and Municipal Wastewater Treatment 17 culture, and elsewhere (for instance, in the Odra River basin alone about 10,000tonnes of sludge are produced annually). For example, in Hungary, about 50 percent of the sludge disposal is described as "temporary" without further specification. Inadequate industrial pretreatment means that sludges are often contaminated by heavy metals and classified as hazardous waste, preventing final disposal. The various factors impairing the quality of sludge prevent its use as fertilizer or in energy production. Moreover, changes in environmental legislation also reduce sludge disposal options. For example, in Slovakia approximately half of the sludge now produced is used in agriculture (40 percent is disposed of in landfill). However, new environmental guidelines and legislation will practically prohibit agricultural use without considering the lack of an available alternative. The major problem is caused by cadmium, which is limited to 13 milligrams cadmium per kilogram of dry solids (DS) in sludges to be composted. This limit can rarely be met under present conditionsrduent thelaco itria pretreatment. As a comparison, the same limit is 5 mg Cd/kg DS in Hungary (an unrealistically low value at present) while the natural background concentration is below 1 mg Cd/kg DS. The standard in Scandinavian counwries was 10 mg Cd/kg DS. The viarent c luniesws 10 mg Cd/kg DS untithegoal 9. Twer current value is 4 mg Cd/kg DS with the goal to lower it to 2 mg Cd/kg DS by 1995. Legislation. Water tariffs and wastewater collection charges were increased significantly in all five of the countries studied during the last few years (although they remain low in Slovakia and Bulgaria). Charges in Hungary have now reached levels which realistically reflect the costs of the services, and have led to 20 to 30 percent reductions in water consumption (despite inadequate water metering). The same is expected to happen soon in the Czech Republic. Reduced consumption is decreasing the hydraulic overload of existing wastewater treatment facilities and municipal wastewater is becoming more concentrated. Sewage charges and fines have seen less change except in Poland. At the time of this writing, new environmental legislation has yet to be passed into law in most of the countries and enforcement is minimal. Lax enforcement is a result of the ongoing institutional changes discussed in the first section of this chapter. Within this enforcement and legislative void, decentralization, industrial restructuring, and privatization

continue but with great need for well-designed policies and strong enforcement. Parliaments in the CEE countries are overloaded by the need to pass new laws addressing all aspects of governance, not just environmental and water policy. Under these circumstances, hastily passed laws sometimes cause inconsistencies and new difficulties. For example, laws passed in Hungary in 1991 established goals requiring towns to show substantial progress by 1994 in developing water supply systems. However, there were no corresponding requirements concerning wastewater collection or treatment; those requirements are contained in draft environmental legislation. Developing water supply systems without simultaneously addressing wastewater will further open the utility gap in Hungary, already the highest among the five countries considered here. A consequence will be further contamination of groundwater. New systems of water quality tnad n y standards and stream classification are under discussion in all of the countries. The outcome will significantly influence future management practices. The former Czech and Slovak Federal Republic (C.S.F^R.) and Bulgaria depended upon receiving water standards for control of wastewater discharges. However, lenient standards and a lack of monitoring and enforcement provisions made these rules ineffective. Reacting to these earlier failures, the tendency today is to avoid ambient water quality standards and instead adopt the very stringent effluent standards recommended by the European Union (91/271/EEC). Unfortunately, the budgetary consequences of these standards have not been fully realized and there is the widespread but mistaken belief that EU standards can be met "immediately." This attitude misses the process concept of the EU recommendations but moreover ignores the practicality of what is likely to be a decades-long process to approach the EU recommendations. The process concept is well reflected by new standards approved in the C.S.F.R. and later adopted by both of the subsequently separated countries. The standards set limits for municipal discharges that are staged over time. Prior to the end of 2004, effluent concentrations must be less than 30 mg/l of BOD, 10 mg/l of ammonia-nitrogen, and 3 mg/l of total phosphorus in municipal discharges greater than 100,000population equivalent (1 P.E. = 60 g/cap/d). Beginning in 2005, limits are tightened to 25 mg/I, 5 mg/l, and 1.5 mg/l, respectively (note that the nutrient removal prescribed

18 Municipal Wasteu'ater Treatment in Central and Eastern Europe by the new legislation will increase the amount of sludge produced). Standards are less stringent for smaller communities, and are perhaps less stringent than the EU recommendations. No limits are set for TN, but are set for ammonia due to concern for drinking water supplied from surface water. The new permit system is based on the concept of combined standards: receiving water as well as effluent standards were set, with priority given to effluent standards. However, it is not yet clear how this rather flexible policy will work in practice. The management of municipal discharges requires tremendous investment. For example, in the Czech Republic, about US$200 million (U.S. dollar equivalent) is planned to be spent to continue the ongoing construction of wastewater treatment plants.

The immediate need in Poland to complete construction of the most important plants is about US$1,000 million. The estimate for Bulgaria for the short term (until 1995) is also US$1,000 million, and US$4,000 million through 2010. The estimate for Hungary is close to US$6,000 million. Longer-term needs (including the development of the collection network, interceptors, disposal systems in rural areas, protection zones, etc.) are, however, much higher-probably close to 100 billion U.S. dollars for the five countries. Unfortunately, none of these countries can afford to make the required investments, particularly over the next few years. Despite, or because of, these constraints there is critical need for a well-designed, realistic, and cost-effective development strategy. This issue is discussed in subsequent chapters.

Water Supply, Sewerage, and Municipal Wastewater Treatment 19

Table 1.I Summaryfor the five countries Poland I Population [millions]

38.2

2 WaterSupply

90

Czech Republic 10.3

Slovak Republic

Hungary

Total Bulgaria (average)

5.3

10.4

9

73.2

96 3)

76

92

98

90

80

94 3)

51

51

67

7412)

60

82

42

42

59

59

[152]8

SI

27

52

45

362

18.4

4.5

1.9

5

5.3

35

5702)

440

350

340

530

500

40 2)

59

67

59

80

42

500

5404) 4505)

530

430

430

490

42

20

38

55

38

38

38

10

20

27

25,000popLiatiorL Forthe390towr (Appendix 2). Fortowrs >25,000popLiation. Estimated. Discharged to thecciIection networ Rough estirTates. Industrial contribution ory (for 187tcwnscorsidered). Estimate(indLstry, rairmsater, infiltration, ec.).

9)

Irndustrial.

10) II) 12)

Industrial, rairmater,andothers. Very ncitainvalue(forallthetowra). OCerestinates.

0

Table 1.2 Summaryof populationdistributionin townsconsideredin this study

Poland Population range (millions)

>1

CzechRepublic

SlovakRepublic

Hungary

Bulgaria

Total

Numberof Population Number of Population Numberof Population Numberof Population Numberof Population Numberof Population towns (millions) towns (millions) towns (millions) towns (millions) towns (millions) towns (millions)

I

2.02

-

-

-

-

-

2

1.23 0.78 1.00

-

52

0.5- 1.0 0.25 - 0.5

1 5 9

1.70 3.42 2.96

1 2

0.72

1

0.1- 0.25 0.05- 0.1 0.025- 0.05

29 48 59

4.34 3.18 2.06

3 18 27

0.38 1.27 0.88

1 9 16

0.44 0.23 0.64 0.55

8 12 31

0.01 - 0.025 )

36

0.73

-

-

-

-

Total

187

18.39

51

4.46

27

I) Datawithinthisclasswere partially collectedin Polandonly.

1.21

-

-

-

1.86

1

1.20 0.76

4 5 14

6.13 3.42 4.88

11 16 15

1.57 1.22 0.50

52 103 148

7.75 7.09 4.99

-

-

-

36

0.73

5.03

45

5.25

362

34.99

i!i

Chapter2 An Approach to Develop Wastewater Treatment Strategies

P

resent wastewater treatment practices in de-

Directivesof the European Union approximately

veloped Westem countries are the result of enormous social, economic, and technological development during the past decades. The two most important factors in achieving the present level of urban water infrastructure and wastewater treatment are: First, ambitious goals were set to develop urban water infrastructures which maximized consumer convenience and comfort and minimized public health risk and adverse environmental effects (all considered to be benefits). Today the general expectation is that 95 percent of the urban population will be served by public water supply and 85 percent of the produced wastewater will be treated. There is generally a "willingness to pay" for such a service. ay Sacon, standards wereaysetorwsuch lservimied wsea * Second,standards weTeset which limited wastewater effluent concentrations, usually on the basis of well-proven, available technologies. For example, in the United States the 1972 Federal Clean Water Act mandated a technology-based standard of secondary treatment of municipal wastewater. Secondary treatment was defined as 85 percent removal of total suspended solids (TSS) from the influent wastewater and a monthly average effluent concentration of 30 mg/l of TSS and BOD5. The U.S. law institutionalized two-stage systems employing conventional primary treatment followed by biological secondary treatment, usually the activated sludge process. The advantage of this legislation is that standards can be safely met while the disadvantage is that this conventional system is expensive.

correspond to the U.S. standards. However, for sensitive areas subject to eutrophication (including freshwater bodies, estuaries, bays, and other coastal waters) additional requirements to remove nutrients must also be fulfilled. For treatment plants greater than 100,000 population-equivalent the effluent limits are 1 mg/l total phosphorus and 10 mg/l total nitrogen (and/or load reductions of 80 percent and 70 - 80 percent, respectively). These nutrient standards were set to address increasing concem over ecological problems in European seas. They can be met by applying nutrient removal, which is at least 30 percent more expensive than biological secondary treatment. Generally the budget is available and the ful plant (primary, sec-

3

ondary, and tertiary treatment units) is constructed in one step. As can be seen, present Western wastewater treatment policies are based primarily on effluent standards and much less on solving site-specific receiving water quality problems. The legislation forces a uniform minimum level of load reduction by all dischargers. Because the effluent standards are rather stringent, water quality is improved overall (at least where point sources are the dominant source of pollutants). This policy is far from cost-effective. In fact, costeffectiveness (and benefits which are usually hard to evaluate) is not an evaluation factor in the legislation or standards. Rather, the strategy expresses the wish of decisionmakers (and presumably of society in general) to assure environmental quality at "whatever" cost. It is not only a safe strategy but, owing to its 21

22

Municipal



uniform nature, enforcement is attractively simple. However, the cost of such a strategy is so great that the majority of CEE countries cannot afford it under the present (and near future) economic conditions. A different approach is therefore required. Unlike air pollution, damages and benefits of water quality management are difficult to quantify in the CEE region or elsewhere. Short-term benefits can be identified in regions of high recreational values or for resources used for drinking water supply. But water resource systems were developed during the past 40 years in ways that compensate or correct for poor water quality (for example, by water transfers or more treatment). Aesthetic values, impairment of recreational uses, damage to aquatic ecosystems, irreversible damages, and loss in quality were not real considerations. "Benefits" are often expressed in practice by load reductions (important, for example, from the standpoint of restoring the Baltic Sea) or river water quality improvements (see Chapter 3), where even the definition of the key water quality improvement may change from problem to problem, including also elements of subjective judgment (for example, "chemical" versus "biological" quality or short-term versus long-term changes). A benefit analysis would be further complicated by the fact that "willingness to pay" does not equa] the market values of the service in question (particularly not currently in the CEE countries.) Thus, most of the time only costs are considered in water quality management. Under the currently pressing financial constraints, the best that can be done is to try and minirmize costs. (We note that benefits can be expressed in monetary terms, that is the gain in the sum of treatment costs and charges by introducing costeffective technologies.) In such a context- and absent pressing needs due to water uses - ambient water quality goals shou:ld be set on the basis of long-term considerations (and associated costs) in a sensitivity fashion to see the immediate cost requirements. Although such an approach would not overcome the difficulty of not being able to quantify benefits, it remains a more sensible alternative for the CEE countries than the straight application of a uniform policy based on effluent standards. Chapter 1 showed that the level of water supply and wastewater collection in urban areas of the CEE countries is quite acceptable. This is not true, however, for the quality of the water distributed: the num-

ber of standards violations is increasing due to the lack of adequate wastewater treatment and increasing contamination of receiving waters and drinking water resources. Based on the findings of Chapter 1 and the fact that population is stagnant and urbanization has slowed in most of the CEE countries, short-term goals of municipal wastewater management should incorporate: * The reduction of domestic and industrial water consumption as well as increased industrial pretreatment, reuse, and recycling through efficient incentives * The development of the collection network if excess wastewater treatment capacity exists and, primarily * Theupgradingofwastewaterandsludgetreatment facilities to meet the capacity of existing sewer systems. The precondition of water supply development should be the simultaneous solution of waste disposal. This should be the major principle also for rural settlements with a strong focus on. water-wastewater cycle control at the household level. Priority should be given to areas where public health risk is high. For municipal wastewater treatment, methods should be sought which are cost-effective in the short run but which can be further extended and improved as resources become available in the future (this is an idea which is repeated throughout this report). Thus a strategy which can be applied in the CEE countries has at least three preconditions as follows: (i) To have a sequence of well-proven technological alternatives for which costs and removal rates of pollutants characterizing municipal discharges (primarily BOD5, TSS,TP, and TN) can be evaluated for various capacity ranges (ii) To structure alternatives (at least partially) such that one alternative can be upgraded to another that is more effective and thus allow multistage development over an extended period of time (say, 10 to 20 years) (iii) To specify water quality goals and corresponding ambient water quality standards for future time horizons. The third condition contrasts with policies based on effluent standards which a priori fix investment costs. An approach based on achieving ambient water quality goals allows least-cost regional policies to

An Approach to Develop Wastewater Treatment Strategies 23 be developed. These policies would be updated as standards are made more stringent over time and, it is hoped, as financial resources become increasingly available for multistage treatment plant construction. The enforcement of such a least-cost, nonuniform strategy raises a number of issues related to institutions, financing, economic instruments, and others. The development of a regional (country-, basinor subbasin-wide) policy requires a proper methodology that can handle the river network, hydrology, hydraulics, water quality, wastewater treatment technology alternatives and their costs, and nonmunicipal pollutant sources (industrial, agricultural, atmospheric, etc.). Such methodologies are generally available or can be relatively easily developed, In the past, three objections have been raised to such a river basin approach. The first criticism is that the methodology is too complicated. While this may have been true 10 years ago, it is no longer so: the analysis tasks can be easily handled on personal computers using publicly available software. The second criticism is that it is difficult to enforce a policy based on receiving water standards. This may be the case, however the water quality management policy can be translated into regionally varying effluent standards (based on technology alternatives) which are straightforward to enforce (in fact, regional standards exist in some of the CEE countries). The third objection is that it is better to solve the problem of a particular municipality once, rather than by incremental development over time. But if there are no funds, this argument is irrelevant. Attempting to solve the problem a single time will simply require postponement of all action, leading to further contamination of the envirornent dur-

struments should be applied? How is the project cost to be distributed equitably? Some of these questions are discussed in Chapter 5. Municipal wastewater treatment is usually considered on the individual plant level. The previous discussion makes clear that the development and evaluation of alternative treatment strategies requires consideration of other scales as well. At the scale of the municipality it is important to consider the water consumption cycle and its control in an integrated way. The river basin view is crucial because of water quality impacts and water resource issues. The country scale is important insofar as legislation, institutions, and financing is concerned. Finally, for shared water resources and European seas, several countries and different international agencies can'be involved. Thus, the problems of each treatment plant and municipality are embedded in a sequence of planning tasks of increasing scale (subbasin, basin, country, and countries) and communication between the various levels is extremely important. Several international projects addressing river basins in the CEE region are currently under way. Examples are the Vistula and Oder/Odra studies under the Baltic Sea Environment Programme, and the Danube program. These studies use methodologies that show both similarities and dissimilarities to the approach outlined here. A brief comparison is given in the following: * Technological alternatives are discussed only briefly. The present study is much more detailed in this respect, particularly with regard to focusing on the idea of multistage development. * For the Danube, an emission management decision

ing the interim. Of course, multistage development raisesanumber of issues. First, the level of development of existing treatment facilities must be evaluated. The amount and schedule for financing must be determined. Particularly in light of the changing politcal structure, including the increasing powers of local governments, overall governmental decentralization, and general institutional changes, the question must be addressed as to which budget is limited: is budget constrained at the state level or the town level? Furthermore: What are the roles of the state, river basin authorities, and municipalities in planning, decisionmaking, and financing? Who is actually paying? Which policy in-

support system (DEMDESS)is being developed by the Water and Sanitation for Health program (WASH) team and will be implemented on four subbasins (USAID/WASH, 1992b). The major objective is to evaluate a sequence of emission control strategies although the issue of regional least-cost policy is not addressed directly. The system incorporates elements outlined here including developing an emissions data base, evaluating treatment options, modeling water quality, and analyzing the applicability of economic instruments. * The style of the Vistula and Oder (Odra) pre-feasibility studies is slightly different (BCEOM, 1992; SWECO,1992). Although transmission coefficients

24 Municipal Wastewater Treatment in Central and Eastern Europe (or simplie water quality models) are used, their purpose is solely to estimate nutrient loads reaching the Baltic Sea. Cost-effectiveness is defined on a plant level in terms of ECU/kg BOD and ECU/ kg N removed and used, respectively, to define priority projects that provide local "benefits" and "benefits" to Baltic Sea nutrient load reduction. Because of the localized "hot-spot" focus of the study, regional cost- effectiveness and improvements in ambient water quality are not addressed. In summnary,the development of innovative water quality mLanagement strategies in the CEE coun-

tries requires the setting of realistic ambient water quality standards, scheduling those standards in light of local/regional water quality problem improvements and their economic implications, specifying treatment technologies which can be constructed over time as water quality standards are tightened, and developing a control policy model that integrates emissions, treatment alternatives, costs, standards, receiving water quality, and other factors. The implementation of such a policy requires innovative institutional settings, financing schemes, economic instruments, and enforcement.

i= =-il

Chapter 3 Evaluation of Wastewater Treatment Alternatives

W o

orking documents were prepared on

comprehensivecomparison of treatment methods was

wastewater treatment technologies to examine various treatment methods (mechanical, chemical, biological, natural, etc.) and wastewater management strategies for settlements of different sizes, from rural villages to large cities and metropolitan areas. Wastewater treatment selection and design criteria including effluent concentrations, sludge disposal, cotreatment with industrial wastewater, upgrading of existing facilities, space requirements, and useful economic life are discussed. Removal rates and costs are evaluated for different capacities and alternatives, and multistage development is discussed in detail. The applicability of chemically enhanced primary treatment (CEPT) to upgrade existing municipal plants is analyzed on the basis of U.S. experience. A methodology is offered to estimate the optimal dosage of chemicals and the amount of sludge produced. The effect of chemnicalenhancement on biological treatment is also assessed. In addition to technologies for full-size treatment plants, a review of natural treatment systems for rural communities is given in Annex D. The discussion covers various aquatic- and solid-based systems. Information on removal rates, public health issues, economic life, and costs are gathered and evaluated. This chapter summarizes and uses the major findings from working drafts. In addition, a survey was made on the removal rates and costs associated with various treatment technologies. Cost functions developed by the country teams were incorporated. A

also performed, considering results from the Baltic and Danube studies as well as those generated in the present study. Detailed design evaluations were made for three different treatment plant capacities to isolate investment cost components which are critical to realizing the multistage development concept. Finally, an engineering economic analysis was performed to evaluate the cost-effectiveness of various treatment technologies. All of these issues were discussed during the course of a two-day task force meeting in which the majority of the key contributors to this study participated. The purpose of wastewater

treatment

The goal of municipal wastewater treatment is to improve the quality of receiving waters expressed in bacteriological parameters, suspended solids, indicators of oxygen and nutrient balances, and biological indices (the latter are hard to quantify as a function of emission reductions). If, however, organic nitrogen compounds and their oxidation (characterized as nitrogenous BOD, or NBOD) play a significant role as well, nitrification is also required. Because nitrogen compounds may have toxic effects that compromise drinking water quality, nitrification may be needed to reduce ammonia and nitrite. If the nitrate level is high (whether from nitrification in the treatment plant or in the receiving water) nitrogen removal is required to ensure a safe drinking water supply. Finally, phosphorus and nitrogen removal may be required to con25

26 Municipal Wastewater Treatment in Central and Eastern Europe trol eutrophication of inland waters and coastal seas, respectively. To address the above needs, a large number of wastewater treatment technologies have been developed based o:nWestern experience and emerging methods within the context of the traditions and financial limitations of the CEE region. They combine different physical, chemical, and biological processes leading to different remLovalrates of BOD, TP, TN and their fractions, and different investment and operation, maintenance, and repair costs. A brief overview

of treatment methods

Mechanicaltreatment. Mechanical treatment is the first step in almost every wastewater treatment plant. It includes a screen, grit chamber, and settling tank. The objective is to remove particles of various sizes and composition. About 60 percent of influent suspended solids are removed but only about 30 percent of the influent BOD5. The process is not complicated and is applicable at all community levels. The treatment needed for the sludge includes stabilization and dewatering. Chemicaltreatment. Chemical treatment of wastewater is done in order to remove suspended solids, BOD and COD, and phosphorus. This process is always combined with others. In the process a precipitant (normally a metal salt) is added to cause the formation of a precipitate. The precipitate is a mixture of suspended solids particles, colloidal matter, a phosphorus rnetal compound, and a metal hydroxide compound. The precipitate is removed in a separation process such as settling or flotation. There are many variations on the basic chemical treatment concept, with differences in the location of chemical addition (precipitation, simultaneous precipitation, postprecipitation, and contact filtration), the composition of the chemicals, and chemical dosage. If chemical treatment is used as the sole treatment, two methods are distinguished: (i) Chemically enhanced primary (mechanical) treatment (CEPT) (ii) Primary (or direct) precipitation chemical treatment (PC). The first lype is used in the United States to increase the capacity and/or BOD removal at existing mechanical plants, while the second is employed extensively in Scandinavia primarily to remove phosphorus.

In CEPT plants a metal coagulant is dosed prior to the settling tank, for example in the grit chamber. Because the primary intention is to coagulate suspended matter, the dosage is relatively low (less than 50 mg FeCl 3 /l). An organic anionic polymer is added after the metal salt to cause flocculation. A cationic polymer may also be applied if coagulation is insufficient under the low metal salt dosage. CEPT significantly improves removal rates compared to conventional primary treatment. Under normal conditions, TSS removal is increased from 60 to 80 percent; BOD5 from 30 percent to 50-60 percent; and TP from 15 percent to 60-80 percent. In primary precipitation plants a metal coagulant is added prior to the flocculation tanks with a relatively high dosage (150 to 250 mg FeCI3 /l or 100 to 200 mg Al2 (SO4 )3 /l) because the goal is to remove phosphorus in addition to suspended solids. Flocculation is accomplished by mechanical stirring and may be enhanced by adding 0.25 to 0.5 mg/l of anionic polymer. As the result of the higher chemical dosage, a primary precipitation plant achieves higher removal rates than CEPT: about 90 percent, 70 percent, and 90 percent for TSS, BOD5, and TP, respectively. The higher chemical dosage leads to greater production of sludge. The direct energy consumption of chemical plants is very low, but the cost of chemicals may be considerable. The sludge contains large quantities of organic matter and requires stabilization. There is also a considerable potential for gas production at larger plants (there is no indication that the use of aluminum or iron has any adverse effects on the properties or production of the gas). Biological treatment. The purpose of biological treatment is to reduce the organic load. The treatment can be done on raw, or mechanically or chemically treated wastewater (that is, not all biological treatment plants include a primary clarifier). The process, where organic matter is partly oxidized to carbon dioxide and partly converted to biomass, may be by either of two different technologies: activated sludge or biofilm. The microbiological processes are identical, but the reactor designs are quite different. In either design, the reactor provides for oxygen transfer to supply the oxygen needed for the oxidation of organic matter. In both processes, the wastewater is brought into contact with a large biomass, from which the wastewater must be separated after treatment (usually by settling). Activated sludge plants (ASP) can be designed for high or low loading (low and high sludge age).

Evaluation of Wastewater Treatment Alternatives Low-load plants also provide nitrification (except during cold weather). The surplus sludge is stabilized, thus no digestion is needed. In contrast, high-load plants require sludge digestion as well as closer controls of treatment operations. An activated sludge plant can also be designed as a two-stage process, with a high-load first stage (biosorption) and a low-load second unit. The second unit requires a smaller volume than it would otherwise because load is reduced in the first stage. Biofilm plants can configured as trickling filters, submerged aerated filters, or rotating disks. Pretreatment is always needed. Biofilm plants are preferred for medium to high organic load. An advantage of biofilm reactors is that they require smaller residence times and thus smaller area for reactors. A disadvantage is their greater sensitivity to load fluctuations. Biological/chemicaltreatment. Combining biological and chemical treatment significantly improves phosphorus removal (to 90 - 95 percent) and also slightly and BOD5 TSS removal. However, the quansighty of sludge increases and itrequiresconcentration, hity of sludge increases and it requires concentration, stabilization (if pre-precipitated), and dewatering. This meho anasobeuedt epadcaait.Use method can also be used to expand capacity. Nitrogen removal. None of the methods discussed

27

Sludge disposal and treatment

biofilm or activated sludge process. Biological phosphorus removal can also be incorporated into the deni-

Wastewater treatment sludge has a high content of suspended solids, organic matter, nutrients, and bacteria. The sludge may also contain undesirably high concentrations of heavy metals and organic chemicals dependatwtrcnrbtdb h muto iguo Fo iprtreated the degree o whht indusyn even wih example, the dmium contetco a s a between beteen 4iand indus cancan vary ota he industrial 4 and input out a heavy 12 mg Cd/kg DS for all types of treatment, causing disposal problems in agriculture. There are three basic possibilities for sludge disposal: * Disposal in landfill a Use in agriculture * Incineration with disposal or reuse of ash. Landfill disposal is still widely used, but in many places creates a considerable nuisance due to odor and secondary pollution. Often land is unavailable. However, if suitable disposal areas such as closed mining areas exist, then landfiuling may be the optimal sludge disposal option and may only require sludge dewateigaprramn. tering as pretreatUsent. of sludge in agriculture is a more sensible disposal method as municipal wastewater sludge can uiia atwtrsug a dsoa ehda be a good soil conditioner and contains valuable soil nutrients. Its use may be limited if the sludge is contaminated by heavy metals, organic chemicals, other toxic materials, bacteria, viruses, or other undesirables, or if land is unavailable. Legislation also plays a significant role. In many countries, contamination by undesirable components has led to an unfortunate general ban on sludge use in agriculture. Sludge should in fact be used on farmland provided that its content is well monitored and controlled within acceptable limits. A particularly crucial need in this respect is control of industrial discharges to the municipal sewer system. Depending on the type of agricultural use, sludge may need to be disinfected to prevent microbial pollution. Sludge incineration is becoming increasingly

trification process design. Biological denitrification can be used to improve the performance of nitrifying (low-load) treatment plants. Denitrification restores about half of the alkalinity removed by nitrification and energy is also partially regained (since nitrate acts as an electron acceptor during denitrification).

common in Western countries - despite its substantial cost-because landfil sites are lacking and agricultural use is prohibited. Disadvantages of incineration include the potential for air pollution and the problem of ash disposal. Treatment requirements for sludge depend on its final disposal. Thickening and dewatering (to achieve

above removes nitrogen efficiently. Nitrogen is removed in two steps: first, nitrogen is oxidized to nitrate in the presence of oxygen (nitrification), and second, reduced to free nitrogen gas in the absence of oxygen (denitrification). A prerequisite for biological denitrification is an organic carbon source, which can be supplied either from the wastewater itself or from organic chemicals like methanol or acetate (these are sometimes supplied by industrial wastes). If wastewater is the carbon source, prenitrification is usually specified; if organic chemicals, postnitrification is typical. Both alternatives can be designed for use with the

28

Municipal


at least 20 percent dry solids) are required for land disposal. Additional stabilization and disinfection is a prerequisite for use in farming. If incinerated, sludge must be thickened, dewatered, and dried. Incineration itself carnbe thought of as both a treatment and a disposal process. As stressed in Chapter 1, lack of adequate sludge handling is one of the major shortcomings in CEE countries. This situation developed in the past mainly because the flocculants used in sludge treatment were expensive and were often purchased with scarce hard currency. The solution of the sludge problem is rather straightforward today if money is available. Limited construction would be required to accommodate sludge treatment in existing plants and dewatering equipment (centrifuges, belt-filter presses, etc.) is available and thus can be replaced quickly. Flocculants of good quality are now being produced in several CEE countries. Thus, the major strategic question concerns instituting industrial pretreatment. This is the precondition for using sludge in agriculture. Agricultural use is the most cost-effective solution for sludge excepting in the large cities, where incineration appears to be the best alternative (for a case study see Chapter 4). In the absence of proper pretreatment, the cadmium and chromium content of the sludge can exceed 100 mg/ DS and 1,000 mg/DS, respectively- one to two orders of magnitude greater than realistically set standards for agricultural use. Removal rates and costs of technology alternatives

alternatives to be considered in dealing with a particular problem is much larger. For instance, if there is no need for a primary clarifier (as a result of the composition of the raw wastewater), partial biological treatment can be an efficient starting solution (particularly if the dilution rate is small). Among the process combinations listed above, two variations on process have been considered for each of the groups except for mechanical treatment. The treatment alternatives considered are described in Table 3 and corresponding treatment efficiencies (for BOD5, SS, TP, and TN) and sludge production rates are summarized in Table 3.1. Two influent wastewater scenarios were considered based on a specific pollution load (BOD5 = SS = 62.5 g/P.E./d, TP = 3.0 g/ P.E./d, and TN = 12.0 g/P.E./d) and two hydraulic loads (250 I/P.E./d and 400 l/P.E./d). The cost data for three capacities (2,000,10,000, and 100,000 P.E.) are tabulated in Annex C. The data presented are based on analyses carried out in Scandinavia and Denmark. The primary purpose of the cost estimates is to show the relative differences between various technologies. Thus, the cost estimates should not be considered to be accurate estimates for any particular installation, because site-specific conditions are very important in determining actual costs (see below). Annex C includes tables which give unit costs in U.S. dollars (US$) per cubic meter of wastewater treated. Three cost components are provided: the annualized capital cost; annual operation, maintenance, and repair (OMR) cost; and total annual cost. The annualized capital cost is computed assuming a 12 percent interest rate and 20-year life, leading to a capital

Five different groups of treatment process combinations were considered in light of the needs of the CEE

recovery factor of 0.133 (that is, the annualized cost should be divided by 0.133 to obtain the initial investment cost). The costs in Annex C correspond to a hy-

countriMechasiical(primary)treatmendraulic (i) Mechanical (primary) treatment (ii) Mechanical/chemical treatment (iii) Biological treatment (high and low load)

load of 400 1/P.E./dd. Costs associated with a load of 250 l/P.E./d are at rnost 10 to 15 percent less.

removal Biological/chemical treatment with nitrogen removal. All the above methods incorporate a mechanical stage due to the overall usage of combined sewer systems in CEE countries, the high suspended solids concentration and the low level of industrial pre-treatment (see also below). Of course, the number of treatment

country's lending policies and the attitude of the state toward infrastructure development and environmental management have an important impact on the choice of technology and the associated costs. A low interest rate (for example, a "nominal" one) would make alternatives involving high investment costs "more attractive" than suggested by the tables in this report. However, the overall lack of financial resources

(v)

The interest rate plays an important role in comparing different treatment methods. In this sense, a

Evaluation of Wasteu7ater Treatment Alternatives 29 should preclude low interest rates in the medium term, and it is therefore more appropriate to compare investment costs rather than total annual costs. Unit costs in terms of US$ per unit kilogram dry solids (DS) of sludge are given for three sludge treatment alternatives: (i) Dewatering only

EPA cost summary; other literature data; cost estimates derived by country teams; and systematic design data for three treatment plant capacities (40,000,9,000, and 3,000 m3 / day) prepared as a part of the present study. Relative investment costs of technologyalternatives. The different treatment technologies discussed above can be developed stepwise over time. For instance, if

(ii) Anaerobic stabilization and dewatering (iii) Dewatering and incineration. costsarensummarized inciAnnupgraded EstimDewateding Estimated costs are summarized in Annex C. Only 10,000 and 100,000 P.E. plants were considered. For the smallest capacity range, trucking the sludge to a larger treatment plant is probably the most cost-effective solution. Furthermore, costs are not estimated for incineration at 10,000P.E. plants as this sludge treatment method is unlikely to be used at small plants. Table 3.1 and Annex C summarize the information needed to evaluate municipal wastewater treatment strategies and their cost-effectiveness. They illustrate that the: * Treatment costs vary approximately in a range of 1:3 depending on treatment goals and levels * Unit cost of nutrient removal is about an order of

there is an existing primary treatment plant, it can be

magnitude higher than that of BOD (see below) * Effect of economies of scale (note that when the size of the hreatment plant is selected the economy of of te pantis tratmntsleced te eonom of transportation costs should also be accounted for). A more detailed evaluation follows based on a comparison of cost data from Annex C to other estimates. The outcome of this evaluation is a slightly modified set of treatment alternatives and cost estimates which are used in further analyses in this report.

from different elements of the present study, the U.S.

Comparison

of various cost estimates

The following three issues are considered in this section: (i) The relative cost of different technology alternatives, which has significant effect on the effectiveness of multistage treatment plant development The effect of treatment plant scale ...i Th.ag otetmts (iii) The range offaslt absolute cost estimates. Removal rates are not discussed here as literature data are very similar to those shown in Table 3.1. In comparing cost estimates for different technology alternatives, costs are derived from the working drafts, which discuss U.S. cost estimates; results from the Vistula, Oder/Odra, and Danube studies; a U.S.

to chemically enhanced or biological treatment. The upgrade decision depends primarily on the investment cost of the proposed upgrade; its cost-effectiveness expressed, for example, in US$/kg BOD removed (see below); and the water quality improvement achieved. Thus, one needs to know the ratio of costs of technologies which can be consecutive elements in a multistage development. A summary is provided in Table 3.2 which illustrates costs of six technologies relative to traditional activated sludge biological treatment (including primary treatment). Costs of sludge treatment (anaerobic stabilization and dewatering) are included. The comparison is made for a 100,000 population equivalent plant. Data were used

EP oto ehooycotdgs 18) h prefeasibility study of the Vistula River basin (SWVECO, p 1992),the Danube study (USAID/ WASH, 1992a), and Roman (1992). As can be seen, the cost estimates deviate from each other by 10 to 15 percent depending on the technology, local conditions, whether internal infrastructure is included (approximately 25 to 30 percent of the total investment cost), and several other factors. The cost estimates of primary treatment (P), chemically enhanced primary treatment (CEPT), and primary precipitation treatment (PC) (based on Scandinavian experience) are consistently higher than the others due to greater estimates for the investment cost of primary treatment (61 percent versus 43 to 55 percent in the other estimates). Detailed designs reflecting Czech and

(ii)

Hungarian conditions revealed that primary treatment cost is about 50 percent of the biological treatment cost for a 100,000 P.E. plant. This ratio increases with decreasing capacity as the relative importance of the internal infrastructure grows. Based on these findings, 55 percent was accepted and used to modify the costs of CEPT and PC in the original estimates from the

30 Municipal Wastewater Treatment in Central and Eastern Europe working documents. The accepted estimate is shown in line 8 of Table 3.2. The effect of scale. A comparison of the effects of scale is presented in Figure 56. In addition to previously cited sources, the figure uses results of the Oder/ Odra River basin prefeasibility study (BCEOM, 1992). As can be seen, there is good overall agreement between the various estimates. There is greater scatter for plants of less than 40,000 P.E., but this has insignificant effect on our further analyses. Comparisonof various cost estimates. The expectation is that estimates will vary substantially depending on the country, local conditions, degree of price competition, and so forth. A summary is given in Table 3.3. As can be seen, the first four values are similar. Local estimates obtained from the Slovak and Czech Republics show lower unit costs, reflecting different and changing price structures and market conditions. Nonetheless, it is interesting to note that the investment cost of 30 bid tenders received for a recent 20,000 P.E. treatment plant bidding in the Czech Republic varied between 28 million and 95 million KC (US$10 million - 33 million), with the average investment costs from Western bidders being about 50 percent higher than the average from domestic bidders. A summary of treatment technologies proposed for CEE countries Among the technologies outlined in the Overview of Treatment Methods we selected only those which include a primary sedimentation tank (at least for the >10,000 P.E. r ange). Primary sedimentation is needed because combined sewer systems are prevalent in the CEE countries, leading to high solids content in the raw wastewater and the need for solids removal. The (high load) activated sludge process was assumed for all biological treatment plants as this is a widely used methodology in all of the countries at present. The biofilm process has many advantages, including small space requirements, but its application would still be unusual in the CEE countries. This situation will most likely change significantly within the coming 10 years, however. The technologies chosen are all well designed. None would be considered to be "high tech" and all are relatively simple to operate and do not require unrealistic levels of training. Depending on sitespecific features, other methodologies could also be considered in dealing with a local problem. Under such

conditions, the results presented here could be useful background for comparison. The summary of treatment methods including removal rates, effluent concentrations, and costs is given in Table 3.4. The individual technologies are all discussed above with the exception of BClDN and BC2DN. These are the same as BC1 and BC2,but with only partial denitrification and thus lower costs than BCDN (Table 3.4). In the course of preparing the costs, downsizing of the primary sedimentation tank was considered for the CEPT and PC processes due to their higher overflow rates (3 m/h versus 1.5 m/h). Lower costs than estimated may be possible, but cost calculations would require more detailed analyses of design standards and methodology with speciaLl attention to handling stormwater overflows. Costs obviously incorporate increased sludge treatment as a result of adding chemicals which enhance BOD, SS, and TP removal. Costs of technologies BC1 and BC2 involve moderate downsizing of the aeration tank due to increased BOD removal by the upgraded first stage (this is why, for instance, BC1 is less expensive than B). The actual downsizing can be greater. It depends on the type of chemical treatment (low or high dosage) and the P removal required. PC allows greater reduction in the volume of the aeration tank, however increased sludge treatment cost can counteract this effect. Thus a detailed design is needed for each individual case. Sludge treatment costs are included in Table 3.4; anaerobic digestion and dewatering were assumed for all treatment technologies. In the forthcoming analyses, the values in Table 3.4 were employed together with Figure 56 to represent the economic effect of treatment plant scale. The application of chemical existing treatment plants

upgrading

to

As is demonstrated in Chapter 1, there are many plants with only primary treatment or with overloaded secondary treatment in the CEE countries. Chemical enhancement is an attractive, cost-effective method to upgrade these plants (Table 3.4) and is therefore discussed here in more detail. CEPT has been used frequently in the United States during the last 15 years to retrofit existing primary treatment plants. The main goal has been to increase the solids and BOD removal rate and thus the

Evaluation of Wastewater Treatment Alternatives

chemical dosage is small. In contrast, in Scandinavian countries four to five times higher dosage is applied in order to meet stringent effluent standards for TP (so as to control eutrophication of lakes and seas). For the CEE countries, low chemical addition could be used to increase significantly BOD (and TP) removal rates at little additional investment and sludge treatment cost. U.S. experience with CEPT has shown significant improvements in BOD, SS, and TP removal rates compared to conventional primary treatment (Table 3.4). As mentioned above, surface overflow rates can be practically doubled. The amount of sludge produced is 1 kg solids/ kg TSS removed for primary treatment and approximately 50 percent more for CEPT. Whereas for conventional primary treatment, the settled solids consist only of the TSS removed, for CEPT the settled solids include both the solids capture and the added chemicals. The amount of sludge can be estimated from stoichiometry as a function of influent and effluent concentrations of TSS and TP, and the type and concentration of metal salt added. The U.S. experience shows that the sludge production rate by CEPT is approximately equal to that of an activated sludge plant (roughly 1.8 kg solids/kg TSS removed or 1 kg solids/kg BOD5 removed). Because of its low cost, relative ease of implementation, and effectiveness, CEPT is attractive as the first step of a multistage wastewater treatment plant development, particularly if the dilution rate is high. Cost-effectiveness

and multistage

development

31

in which T is the economic life of the project and r is the interest rate (which may be replaced by an apparent interest rate if the effect of inflation is also considered). The multiobjective nature of cost-effectiveness is obvious: if money is scarce the indicator IC/kg mass removed is much more important than TAC/kg mass removed. This is the situation faced in the CEE currently. The problem is also multiobjective in the sense that different treatment technologies serve different purposes. For instance, the goal of traditional biological treatment is BOD removal (with or without nitrification). Chemically enhanced treatment (CEPT) also efficiently removes phosphorus while in a primary precipitation plant (PC), phosphorus removal is considered more important than BOD removal. BCDN treatment (Table 3.4) more or less balances the attention given to BOD, P, and N removal. Thus, when evaluating cost-effectiveness, appropriate weights should be applied to the different pollutant removal capabilities. The situation becomes more complex if one considers impacts on biological indicators such as the saprobic index used in some countries. Mechanical (and probably also chemical) treatment has a smaller impact than biological treatment but quantification is not possible given our current level of understanding. However, for rivers with small dilution rates, biological treatment is preferable. Table 3.5 summarizes the cost-effectiveness of the technologies described in Table 3.4. Two cases are considered in Table 3.5: (i) the technology is constructed at once, and (ii) the same treatment plant is developed

in a multistage fashion. A 100,000P.E. plant was con-

Cost-effectiveness is usually expressed in terms of cost per mass of pollutant removed, where cost may be either the total annual cost (TAC) and/or the investment cost (IC). TAC is the sum of the annualized investment cost and the annual operations, maintenance, and repair cost (OMRC):

TAC = (CRF)IC + OMRC where the capital recovery factor is: rT

CRF

+ r) (I + r) T-1

=r(

sidered with the assumption that the life of all the projects is 20 years (further analysis of the project life is provided below) and the interest rate is 12 percent. As weighting factors are considered, it was assumed that technologies P and B provide BOD (and SS) removal, while CEPT, PC, and BC also provide phosphorus removal. For upgrading a plant from B to BC it is assumed the primary aim is to improve P removal; from BC to BCDN, N removal (Table 3.5). As stated above with respect to CEPT, P and BC can be effectively applied to modify highly overloaded plants and/ or, for BC, to intensify nitrification in the aeration tank. As can be seen in the upper part of Table 3.5, primary treatment alone is expensive. Traditional bio-

32 Municipal Wastewater Treatment in Central and Eastern Europe logical treatrnent is more effective, but investment requirements aLrehigh. Despite the costs of sludge treatment, primary precipitation, chemically enhanced primary treatment, and biological/chemical treatment are attractive from the standpoint of both investment cost and total annual-cost. Cost-effectiveness remains better than for biological treatment alone even if all weight is pul: on BOD removal. Table 3.5 shows at the same time that unit removal costs of nutrients are much higher than for BOD. The cost-effectiveness of P removal decreases as effluent standards are made more stringent. The lower part of Table 3.5 demonstrates the costeffectiveness of multistage development. The table excludes cost reductions due to downsizing in the PC, CEPT, and BC costs because the volumes are already determined i:nthe existing plant (as noted above, there can be a benefit in treating more wastewater [see first two case studies in Chapter 41 or in increasing nitrification). The table shows that in terms of investment costs upgradiing a primary treatment plant to a chemically enhanced plant is more than three times more effective than upgrading to a traditional biological treatment plant. If phosphorus removal is excluded from the comparison, PC and CEPT are still 70 percent more cost-effective than B. The teclhnical realization of multistage development is illustrated in Figures 57 and 58. In the first case, an existing primary treatment plant (Figure 57a) is upgraded to a mechanical/chemical plant (Figure 57a and 57b), the first requiring less investment cost. The second step is an extension to a biological/ chemical plant (Figure 57c) which may be one of several alternatives, depending on the type of precipitation. Finally, the third and final step is adding a postdenitrification unit (Figure 57d). Figure 58 illustrates the corresponding two-stage development for an existing primary-biological treatment plant. The concept of multistage development is shown in Figure 59. The overall economic life, T, of a wastewater treatment plant is about 30 to 40 years assuming that machinery and equipment are replaced every 10 to 15 years (say, three times during the plant life). Thus, the typical plant life and repair schedule are fully compatible with two or three plant upgrades during its lifetime. Tlhestarting time and duration of upgrading (to and TR, respectively) depend upon many factors, including the machinery replacement timetable, availability of funds, and regulatory requirements. If

for instance the time horizons specified in the Czech and Slovak legislation are considered, new effluent standards must be met by 2005, allowing at most 12 years for plant development. However, budgetary constraints will probably drive this time period longer in most of the CEE countries. Table 3.6 further analyzes the cost-effectiveness of the single- and multistage development strategies, assuming that the final treatment level and effluent criteria will be the same. Two cases are considered: (i) an existing, 10-year-old primary plant which is upgraded in three steps as in Figure 57 (to = 10 y); and (ii) no existing plant (to = 0 y). For both scenarios the annual average removal rates and costs are calculated for a 100,000 P.E. plant; see Table 3.4 for the basic data and assumptions. All indicators (removal rates, investment cost, and TAC/kg mass removed for BOD, TP, and TN) are expressed as the percentage of the singlestage construction value. In contrast to Table 3.5, for the first step in upgrading (P to CEPT), 10 percent of the investment cost was assumed to be needed for additional repairs to the existing plant. No such cost component was included for the next two steps (CEPT to BC1,and BC1 to BCDN). Machinery replacement costs were disregarded because they would be the same for the two scenarios. Four subcases were considered: 10- and 20-year upgrade times and 6 and 12 percent interest rates. The second stage is assumed to be constructed at to + Tr/ 2 in all four cases. The results summarized in Table 3.6 show that the average BOD and TP removal rates hardly differ from those of the single-stage development (97 percent and 95 percent, respectively). Nonetheless, investment cost at the start is only 14 percent of the full construction costs for the first case (in which primary treatment exists) and it is 41 percent for the second case (no current treatment). The N removal rate is more strongly influenced by multistage development, being reduced to 60 to 80 percent of single-step development. Based on the results in Table 3.6, cost-effectiveness depends on the scheduling of the plant expansion, interest rate, existing treatment level, and the component considered. Weighting the various pollutants does not play a role, however. For the baseline case, T. = 10 years and r = 12 percent, the improvement, averaged over the two configurations (existing primary treatment and no existing treatment) is around 34 percent, 45 percent, and 19 percent for BOD, TP,

Evaluation of Wasteu?ater Treatment Alternatives 33 and TN, respectively. In general, increasing the interest rate and lengthening the upgrade period increases the cost-effectiveness. Among all the cases considered in Table 3.6, the only reduction occurs in the average TAC per kg TN removed for 20 years at 6 percent interest. Inflation increases the apparent interest rate and thus the cost-effectiveness. However, if a loan is guaranteed by an international bank (or the government) at a fixed interest rate, inflation does not really influence the above analysis. In this section, it is shown that cost-effectiveness can be significantly improved by selecting proper technology alternatives. Secondarily, cleverly designed multistage development (and associated financing) not restricted to the technologies analyzed here is shown to further enhance cost-effectiveness (provided the hypothesized upgrade schedule is met which calls for effective enforcement). The advantage of the multistage approach is that time is available to monitor and evaluate the impact of the first stage (and changes in water consumption) before taking the next action. The approach is flexible and can accommodate new technologies and innovations which evolve over time (for example, biofilm processes in the CEE region). A required feature in the original design is that sufficient space be left available for different later extensions, whether ASP or biofilm processes. Cost-effectiveness has been expressed in this analysis in terms of cost/kg mass removed without regard for the concentration levels in the receiving waters and the benefits or risks that derive therefrom. This issue iS addressed below.p

kinetics can be assumed along the river considered. For example, for total phosphorus:

The role of receiving

the cost-effectiveness of wastewater treatment becomes very small; this is the case for municipalites far from

waters

This section addresses the issue of cost-effectiveness by considering effects on receiving waters rather than just the cost per* unit of pollutant mass removed. The intent of this section is not to perform a detailed or rigorous analysis of receiving water, which is a complex subject in its own right. Rather, the intent is to indicate overall trends and the associated implications for receiving water assessment. Eutrophication of lakes and seas. If the receiving water impacts of concern are lake or sea eutrophication, the task is to achieve some pre-defined reduction in the nutrient load to the water body. This requires some translation of effluent load reductions at a given site to the lake or sea. As a simplification, first-order

Ep P = p0 exp(-ki

t*)

exp(-klt*)

-

Q+q where PO

TP in the river just below the discharge point, assuming complete mixing (mg/l); Ep = TP effluent load (kg/d); Q = river flow (m3 /d); q = wastewater flow (m3/d); k, = apparent settling rate (1/d); and t' = travel time in days (expressed as x/ U, where U = "average" velocity in km/d and x = distance in km). The above expression can be written by introducing the transmission coefficient TCP

Pj

=

exp(- k t)

=

=

E TCp

Q+ q where TCPi . expresses the impact of the load (and its reduction) at site i on the phosphorus level (or load) at the location j. The phosphorus removal rate, Ep. is a function of treatment alternatives X ,k: EPA(Xlk)where removal rates are discussed in the appropriate section above. The load reduction at the lake or sea will be only a fraction of the local load reduction, which is de-

fined by TCp

If TCi

= 1, cost-effectveness

is

i SEA not modified by receiving water considerations; this iS a typical situation for a wastewater discharge directly into or close to a sea or lake. However, if TCpiSEA

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Figure 14

Untreated

Level of wastewater treatment in towns in the Odra River basin, Poland

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Projected BOD concentration in receiving water at towns in the Odra River basin, Poland

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Figure 32

gm

Levelof wastewatertreatmenttechnologyin towns in The SlovakRepublic

m

Mechanical Biological

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Influentand effluentBODload in wastewaterin towns in The SlovakRepublic

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Figure 34 Percentage of population connected to

public water supply and wastewater sewers in towns in The Slovak Republic

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Figure 39 Total BOD load in wastewater in towns in Hungary

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Figure 48 Total BOD load in wastewater in towns in Bulgaria

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Figure 50

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Figure53 Per capitawater suppliedversuswastewatercollectedand treated in towns

in Bulgaria

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