contaminant loads from household appliances - CiteSeerX

Sources of critical contaminants in domestic wastewater: contaminant loads from household appliances C Diaper, G Tjandraatmadja, C Pollard, AC Tusseau, G Price, L Burch, Y Gozukara, C Sheedy and M Moglia

December 2008

Water for a Healthy Country Flagship Report series ISSN: 1835-095X Australia is founding its future on science and innovation. Its national science agency, CSIRO, is a powerhouse of ideas, technologies and skills. CSIRO initiated the National Research Flagships to address Australia’s major research challenges and opportunities. They apply large scale, long term, multidisciplinary science and aim for widespread adoption of solutions. The Flagship Collaboration Fund supports the best and brightest researchers to address these complex challenges through partnerships between CSIRO, universities, research agencies and industry. The Water for a Healthy Country Flagship aims to provide Australia with solutions for water resource management, creating economic gains of $3 billion per annum by 2030, while protecting or restoring our major water ecosystems. The work contained in this report is collaboration between CSIRO and Smart Water Fund. For more information about Water for a Healthy Country Flagship or the National Research Flagship Initiative visit www.csiro.au/org/HealthyCountry.html

Citation: Diaper C, Tjandraatmadja G, Pollard C, Tusseau AC, Price G, Burch L, Gozukara Y, Sheedy C and Moglia M 2008. Sources of critical contaminants in domestic wastewater: contaminant loads from household appliances. CSIRO: Water for a Healthy Country National Research Flagship. Copyright and Disclaimer © Commonwealth of Australia 2008 All rights reserved. This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from the Commonwealth.

Important Disclaimer: CSIRO advises that the information contained in this publication comprises general statements based on scientific research. The reader is advised and needs to be aware that such information may be incomplete or unable to be used in any specific situation. No reliance or actions must therefore be made on that information without seeking prior expert professional, scientific and technical advice. To the extent permitted by law, CSIRO (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this publication (in part or in whole) and any information or material contained in it. Cover Photograph From: iStockphoto.com Description: Close-up of kitchen sink with water running away Copyright: Jan Rysavy 2008

Acknowledgements CSIRO would like to thank the Smart Water Fund for the funding to support this research and the project Trade Water Reference Group members (Michelle Carsen, Lidia Harvey, John Dennis, Hieu Dang, Adam Kazi, Mick Anderson and Robina Westblade) for their input and recommendations to the project. Matthew Inman and his research team, particularly Xiaoming Wang, and the Smart Water Fund Smart Metering project are also gratefully acknowledged for their cooperation and flexibility in working arrangements at the Mini-house.

Priority contaminants in household appliances

Page iii

Executive Summary The Smart Water Fund and CSIRO are conducting research aimed at understanding the origin and distribution of priority contaminants affecting water reuse and recycling (total dissolved solids, colour, arsenic, copper, cadmium, lead, mercury, nickel and zinc). Increasing the understanding of the contribution of domestic households to the quality of wastewater is an important step to more effective water reuse and the development of contaminant management strategies. Wastewater produced from households is comprised of grey water and black water. The characteristics of household grey water are complex as flows are variable and the composition of grey water is typically dictated by local household features such as water supply, surrounding infrastructure and inhabitant lifestyles. In addition, as individual appliances have different discharge patterns, monitoring of wastewater streams from a household constitutes a technical challenge. This report Contaminant loads from household appliances describes the analysis of household appliance streams in a laboratory study. It is part of the Smart Water Fund project Round 3 – Project 5 Household sources of priority contaminants in domestic wastewater. The aim of this work is to characterise flows and contaminant profiles from different household appliances that require MINIMAL human interaction (i.e. washing machines, dishwashers or shower and sinks) under controlled conditions. This work will generate data which will create a better understanding of the temporal quality variation of wastewater flows from appliances and also identify significant contributors to contaminants identified as priority by the Smart Water Fund. It provides the basis for comparison for the next stage of the overall study which will measure and characterise human inputs and assess contaminant inputs from tap water. Research method Experiments were conducted at the CSIRO Mini-house laboratory at Highett, which contains a range of appliances including: front loading and top loading washing machines, a dishwasher, high and low flow showers, a bathroom sink and a kitchen sink. Wastewater flow and quality profiles of each appliance were characterised. The washing machine, dishwasher and shower flows were characterised prior to operating the appliances with a range of household products, using only water and having minimal human input (clean clothes, etc). Priority parameters were monitored at the outlet of all appliances by collecting multiple samples during wastewater discharge for large volume appliances and by collecting all discharged grey water and composite samples for low volume appliances (dishwasher and sinks). Conductivity, oxidation reduction potential (ORP), pH and flow were monitored for the warm and cold washes of the washing machine, normal and rapid washes of the dishwasher and high and low flows of the shower. Samples from the washing machine and shower were collected automatically and analysed for total dissolved solids (TDS) and colour. The dishwasher samples from each wash or rinse cycle were collected manually and analysed for TDS and colour. Bathroom and kitchen sink samples were analysed as composite samples only. The composite samples for each complete appliance operation were analysed for TDS and specific elements as follows: silver (Ag), aluminium (Al), arsenic (As), barium (Ba), beryllium (Be), calcium (Ca), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), potassium (K), magnesium (Mg), manganese (Mn), molybdenum (Mo), sodium (Na), nickel (Ni), phosphorus (P), lead (Pb), sulphur (S), antimony (Sb), selenium (Se), silicon (Si), tin (Sn), strontium (Sr), titanium (Ti), thallium (Tl), vanadium (V), zinc (Zn) and zirconium (Zr). Tap water was also analysed for conductivity, TDS, pH, ORP and all elements. This list includes a number of elements which are additional to those identified as priority contaminants by the Smart Water Fund. Priority contaminants in household appliances

Page iv

TDS was measured by APHA standard method 2504c at a NATA accredited laboratory. Colour was measured in CSIRO laboratories using a HACH DR/2000 spectrophotometer and elemental analysis was carried out by ICP-AES or ICP-MS. Key findings The tap water used in the laboratory was found to have high pH and detectable levels of aluminium, barium, calcium, copper, magnesium, sodium, sulphur, silicon, tin and strontium. The temporal and composite sample data generated in this study is extensive and required methodical analysis to identify the following key outcomes: •

Washing machines generated the highest TDS load (82.2 g/wash maximum), except when used with environmental friendly brand liquid detergent.

•

Dishwasher grey water contained the highest range of elements in detectable concentrations, but used less water than washing machines.

•

Conductivity proved to be a reasonable indicator of TDS for the majority of grey water generated by appliances when used with products that had high inorganic content in its formulation. The relationship should be used with caution when products of high organic content are used because the deviation between TDS measured and TDS calculated from conductivity was larger for samples with high organic content.

•

Manufacturers’ recommended dosages of dishwasher and laundry products varied, with environmentally labelled brands using the least amounts.

•

Enviro label products: enviro label washing machine and dishwasher detergents had the lowest TDS among the products tested for each application. In particular, the enviro label liquid laundry detergent exhibited the lowest TDS load of the laundry detergent products tested and had the least impact on water quality (pH, ORP, EC).

•

All wastewater streams had more intense colour than tap water. The strongest colour detected was for the dishwasher, followed by the washing machine, kitchen and bathroom sinks and shower. The volume of the discharge, in addition to colour intensity, will also affect the overall impact.

•

No cadmium or mercury was detected in any water or appliance outlet samples.

•

Arsenic, copper, lead, nickel and zinc were detected in a number of appliance outlets.

•

Sodium and sulphur were present in all streams at significantly higher concentrations than tap water.

•

The experiment highlighted some of the difficulties associated with the monitoring of wastewater at the household level: o

A number of the products used were known to contain traces of elements of interest; however when used in the appliances, concentrations below the detection limit are generated which can lead to false negatives.

o

The wastewater flow pattern for small volume appliances (e.g. vanity unit, kitchen sink and dishwasher) is characterised by rapid and short discharges and is not suitable for automatic sample collection. The whole volume discharge is required instead

o

Temperature of the stream affects ORP and in some cases EC readings which might need to be considered when comparing readings from different studies.

Recommendations These findings suggest a number of recommendations for future work and further discussion:


Page v

•

Of the domestic sources, laundry detergent formulations and amount of product usage should be the main target for reduction in wastewater TDS load. This is dependent on whether reducing the estimated loads of TDS from washing machines is determined to be able to make a significant difference to overall wastewater TDS concentrations.

•

Further investigate dishwasher product formulations in order to determine their potential for element reduction in wasterwater, as the dishwasher contained the largest number of priority elements in detectable concentrations and dishwasher product formulations are the most likely sources.

•

Investigate the relationship between TDS and conductivity for products with organic components and the validity of TDS as an indicator for dissolved mono and divalent ions;

•

Understand dosage recommendations and their relation to feed water quality, machine type, wash type and washability through discussion with product manufacturers.

•

Investigate the impacts of high uptake of enviro-labelled brands on wastewater quality and treatment.

•

Further investigate the impact of human input on appliance outlet quality.

•

For all elements analysed, obtain additional information on loads in wastewater in order to identify if particular appliances or products are significant contributors.


Page vi

Table of Contents ACKNOWLEDGEMENTS ............................................................................................. III EXECUTIVE SUMMARY ............................................................................................... IV TABLE OF CONTENTS ............................................................................................... VII INDEX OF FIGURES ..................................................................................................... IX INDEX OF FIGURES ..................................................................................................... IX INDEX OF TABLES ...................................................................................................... XI 1

INTRODUCTION...................................................................................................... 1

2

METHODOLOGY..................................................................................................... 2

2.3

Mini-house laboratory .................................................................................................................... 2

2.4 Equipment ....................................................................................................................................... 4 2.6.1 Sonde and flowmeter................................................................................................................ 4 2.6.2 Auto-sampler ............................................................................................................................ 5 2.5 Sampling Methodology .................................................................................................................. 6 2.6.1 Washing machine ..................................................................................................................... 7 2.6.2 Dishwasher ............................................................................................................................... 9 2.6.3 Shower.................................................................................................................................... 10 2.6.4 Kitchen and bathroom sinks ................................................................................................... 10 2.6 Analytical methodology ............................................................................................................... 11 2.6.1 Physical-chemical parameters................................................................................................ 11 2.6.2 TDS analysis........................................................................................................................... 11 2.6.3 Colour ..................................................................................................................................... 11 2.6.4 ORP (oxidation reduction potential)........................................................................................ 11 2.6.5 Elements ................................................................................................................................. 11

3 3.3

RESULTS AND DISCUSSION .............................................................................. 13 Tap water ....................................................................................................................................... 13

3.4 Washing machine ......................................................................................................................... 15 3.6.1 Top loader............................................................................................................................... 15 3.6.2 Front loader ............................................................................................................................ 22 3.5 Dishwasher.................................................................................................................................... 32 3.6.1 Water usage and flows ........................................................................................................... 32 3.6.2 On line monitoring – Conductivity, pH and ORP .................................................................... 32 3.6.3 Sample analysis – Colour in rapid and normal washes......................................................... 39 3.6.4 Sample analysis – Elements in rapid and normal washes ..................................................... 39 3.6 Shower ........................................................................................................................................... 44 3.6.1 Water usage and flows ........................................................................................................... 44 3.6.2 On line monitoring – conductivity, pH and ORP ..................................................................... 44 Priority contaminants in household appliances

Page vii

3.6.3

Sample analysis – TDS, colour and elemental analysis......................................................... 50

3.7 Kitchen and bathroom sinks ....................................................................................................... 53 3.6.1 Elements ................................................................................................................................. 54 3.8 Appliance comparison discussion ............................................................................................. 57 3.6.1 Water usage and flows ........................................................................................................... 57 3.6.2 Conductivity ............................................................................................................................ 58 3.6.3 pH and ORP ........................................................................................................................... 61 3.6.4 Colour ..................................................................................................................................... 65 3.6.5 Elements ................................................................................................................................. 65 3.6.6 General issues........................................................................................................................ 70

4

CONCLUSIONS AND RECOMMENDATIONS...................................................... 71

REFERENCES ............................................................................................................. 74 APPENDIX 1 ................................................................................................................ 75 APPENDIX 2 ................................................................................................................ 89


Page viii

Index of Figures Figure 1: Picture of Mini-house laboratory located as CSIRO Highett ..........................................3 Figure 2: Mini-house outlet pipe network ......................................................................................3 Figure 3: Sonde and flow meter setup ..........................................................................................4 Figure 4: Manifold, flowmeter, sonde and autosampler ................................................................6 Figure 5: Flow diagram of mini house setup and sampling procedures........................................7 Figure 6: Flow rate profile for top loading washing machine.......................................................15 Figure 7: Average conductivity for product brands - Warm wash, top loading machine .............16 Figure 8: Average conductivity for product brands - Cold wash, top loading machine ...............16 Figure 9: Average pH values for each product brand top loading machine cold wash ...............18 Figure 10: Average ORP values for each product brand top loading machine cold wash ..........19 Figure 11: Typical discharge profile from the top loading machine using No-name brand .........19 Figure 12: TDS each product brand for a warm wash top loading machine ...............................20 Figure 13: TDS each product brand for a cold wash top loading machine .................................20 Figure 14: Flow rate profile for front loading washing machine ..................................................22 Figure 15: Average conductivity each product brand for a warm wash front loading machine ...23 Figure 16: Average conductivity each product brand for a cold wash front loading machine .....24 Figure 17: Average pH values for each product brand Front loader Cold wash .........................25 Figure 18: Average ORP values for each product brand Front loader Cold wash ......................25 Figure 19: Typical discharge profile - Front loading washing machine, No-name brand ...........26 Figure 20: TDS each product brand for a warm wash front loading machine .............................27 Figure 21: TDS each product brand for a cold wash front loading machine ...............................27 Figure 22: Detected true colour from Washing Machine.............................................................28 Figure 23: Flow rate profile dishwasher- normal wash setting....................................................32 Figure 24: Average conductivity for each product brand for dishwasher- normal wash (no prewash) ..............................................................................................................................33 Figure 25: Average conductivity for each product brand for a dishwasher- rapid wash..............33 Figure 26: Average pH values for each product brand dishwasher normal run (no prewash) ....35 Figure 27: Average ORP values for each product brand dishwasher normal run (no prewash).36 Figure 28: Typical discharge profile for dishwasher- normal wash (prewash included)..............36 Figure 29: TDS each product brand for dishwasher- normal wash.............................................37 Figure 30: TDS each product brand for a dishwasher- rapid wash.............................................38 Figure 31: Detected true Colour from Dish Washer....................................................................39 Figure 32: Flow rate profile for both shower heads.....................................................................44 Figure 33: Typical discharge profile for shower with low flow showerhead ................................45 Figure 34: Conductivity each shower wash- low flow shower head with product release...........46 Figure 35: Conductivity for each shower wash – high flow shower head with product release 46 Figure 36: pH values throughout low flow shower run ................................................................48


Page ix

Figure 37: pH values throughout high flow shower run...............................................................48 Figure 38: ORP profile for low flow shower run .........................................................................49 Figure 39: ORP profile for high flow shower run .........................................................................49 Figure 40: TDS results for each wash for both low and high flow showerheads.........................50 Figure 41: Detected average true colour from mini house low flow shower ...............................51


Page x

Index of Tables Table 1: Information on appliances, water usage and ratings ......................................................2 Table 2: Dose rates of laundry detergents....................................................................................8 Table 3: Operational parameters for washing machines ..............................................................8 Table 4: Operational parameters for dishwasher..........................................................................9 Table 5: Analysis of tap water at the mini house (Average 9 samples) ......................................13 Table 6: Average conductivity for warm and cold wash – top loading machine..........................17 Table 7: Estimate of TDS contribution from tap water and detergents for the top loader washing machine ...............................................................................................................................21 Table 8: Average conductivity for warm and cold wash – front loading machine........................23 Table 9: Estimate of TDS contribution from tap water and detergents for the front loader washing machine .................................................................................................................28 Table 10: Summary of ranking of products used in the washing machine..................................31 Table 11: Average conductivity for normal and rapid dishwasher wash cycles ..........................34 Table 12 - Estimate of TDS contribution from tap water and detergents for dishwasher............38 Table 13: Ranking of products used in dishwasher ....................................................................42 Table 14: Concentrations of elements found in shower water ....................................................52 Table 15: Analysis of grey-water from kitchen sink.....................................................................53 Table 16: Analysis of grey-water from bathroom sink.................................................................54 Table 17: Concentrations of elements found in kitchen sink.......................................................55 Table 18: Concentrations of elements found in bathroom sink...................................................56 Table 19: Average and peak flows of individual appliances .......................................................57 Table 20: Typical product concentrations ...................................................................................58 Table 21: Results of ANOVA analysis for washing machine ......................................................58 Table 22: Results of ANOVA analysis for dishwasher ................................................................59 Table 23: Average conductivities of individual appliances and different brands .........................60 Table 24: Average pH and ORP of individual appliances and different brands ..........................61 Table 25: Measured TDS load of individual appliances and different brands .............................63 Table 26: Comparison of predicted and measured TDS for different appliances .......................64 Table 27: Maximum colour observed for all appliances..............................................................65


Page xi

1 Introduction Increasing the understanding of the contribution of domestic households to the quality of wastewater is an important step to more effective water reuse and the development of contaminant management strategies. Wastewater produced from households is comprised of grey water and black water. The characteristics of household grey water are complex as flows are variable and the composition of the grey water is typically determined by local household features such as water supply, surrounding infrastructure and inhabitant’s lifestyle. Monitoring of wastewater streams from a household also poses a challenge due to the different grey water discharge patterns from appliances. This report focuses on the evaluation of grey water streams generated by major household appliances with minimal human interaction and aims to understand the distribution of contaminants and the flow patterns of individual streams for: •

washing machines – front and top loader (no human interaction, clean sheets used)

•

dishwasher – rapid and normal washes (no human interaction, no dishes)

•

shower – high and low flow (minimal human interaction, prescribed product use) and

•

bathroom and kitchen sinks (no human interaction, with the relevant products).

The analysis of on-line monitoring results shows the temporal distribution of flow, electrical conductivity (EC), pH and ORP for the washing machines, dishwasher and shower cycles. Analysis of composite and individual cycle samples shows the primary sources of TDS, colour and specific elements. Black water streams were not included in this report due to OHSE issues pertaining to the collection of samples. The contribution from these sources will be included in a future report, Contaminant loads from human activities which details monitoring of appliances with human interaction. This report is part of the Smart Water Fund project Round 3 – Project 5 Household sources of critical contaminants in domestic wastewater. The overall project aims to identify the contribution of domestic activities to the load of specific contaminants in wastewater as these can impact effluent reuse and biosolids disposal practices.


Page 1

2 Methodology The aim of this work was to characterise flows and contaminant profiles from different household appliances with MINIMAL human interaction (e.g. clean clothes in washing machine, and household products) under controlled conditions. Six household appliances, two washing machines, a dishwasher, a shower, a bathroom and kitchen sink were used with market share household products in a controlled laboratory set up which simulated a household scenario.

2.3 Mini-house laboratory The laboratory (or mini-house) simulates a typical household and is located in the CSIRO Highett laboratories. The house is fitted with a laundry, top and front loading washing machines, a shower, high and low flow shower heads, a dishwasher, a manual wash kitchen sink and a vanity unit or bathroom sink (Figure 1). All the appliances were brand new and were flushed with tap water at least five times before use. The specifications of appliances used at the mini-house are shown in Table 1. Table 1: Information on appliances, water usage and ratings

Appliance type

Brand

Average volume

Water consumption rating

Washing Machine – Top Loader

LG – Turbo Drum 5.5kg Capacity

63.3 L/wash (normal cycle)

1 star energy efficiency

Washing Machine – Front loader

Whirlpool 293-600 5kg Capacity

84 L/wash

Information not available

Dishwasher

Conia CDW1211

15.7 L/Wash (normal cycle)

2 ½ stars energy rating

10 L/min

2 star water rating

Shower – Low

N/A

4 star water rating

2 ½ stars water rating. (Water efficient)

Shower – High

N/A

13.5 L/min

0 star water rating (Water wasting)

The water pipe infrastructure in the mini-house is copper. The pipe type and materials prior to the mini-house were not investigated. Hot water is provided using a 25 L Rheem electric hot water service. All water flows entering the mini-house are measured using an inflow meter which was used to cross check water usage of appliances as recorded by the automatic sampling equipment installed at the outlet of individual appliances. The wastewater collection in the mini-house is comprised of 50 mm internal diameter PVC pipe (Figure 2). The orange boxes represent the appliances from which outlet flows were analysed. The grey boxes indicate the outlet point where the samples were collected using the automatic sampling equipment. The collection pipes are connected to a common outlet pipe, where the monitoring equipment was installed. The pipe-work underneath the house was designed to allow easy access for the grey water sampling equipment. Samples from the vanity unit, kitchen sink and dishwasher were collected at the outlet discharge of each appliance into the wastewater network.


Page 2

Shower Washing machine

Vanity unit Kitchen sink

Dishwasher

Figure 1: Picture of Mini-house laboratory located as CSIRO Highett

Figure 2: Mini-house outlet pipe network


Page 3

2.4 Equipment 2.6.1 Sonde and flowmeter The sonde is a multi probe in-line monitoring device designed to measure pH, electrical conductivity (EC), oxidation reduction potential (ORP), dissolved oxygen (DO) and temperature in flows of water, stormwater and wastewater. The flowmeter is an in-line monitoring device that measures the flow of wastewater at any given time. The flowmeter is an ABB Magmaster with an internal bore of 40 mm. The apparatus consists of a PVC barrel through which water can freely move, and electromagnetic radiation is used to measure the flow. The flowmeter is built into a waterproof housing and connected to a wall mounted LCD display that displays positive or negative flow Ls-1, % flow or total net volume. A PVC manifold was designed to accommodate the sonde, flowmeter and sample point (Figure 3 and Figure 4). The sonde was mounted in the pipe-work within a small section of PVC tube sealed with a rubber mounting cover which was inserted into the open PVC pipe in the manifold and sealed with hose clamps. Both the sonde and flowmeter were connected electronically to the auto sampler and the manifold sampling line was physically connected to the auto-sampler inlet. Conductivity and flow readings were used to trigger start-up of the auto-sampler. To tank overflow

PVC pipe with incoming grey water

Flowmeter

Sampling line to Auto-sampler

Conductivity probe Sonde Cable

Rubber Housing

PVC cover

Figure 3: Sonde and flow meter setup


Page 4

Calibration Procedures

The sonde was calibrated regularly using standard solutions as reference. The parameters calibrated and calibration procedures were: •

pH:

a two point calibration using pH 6.88 and 10 buffers

•

EC:

a single point 1412μS/cm conductivity standard

•

DO:

oxygen saturated in water for 1 hour (minimum)

•

ORP:

a single point standard 240 mV solution

Calibration of the sonde to specifications provided the following accuracy: •

pH:

•

ORP:

±20mV with an operating range of -999 mV to +999 mV

•

DO:

±2% or ±0.2 mg/L whichever is greater. Operating range of 0 to 50 mg/L

•

temperature:

±0.15 °C with an operating range of -5 to 50°C

±0.2 units with an operating range of 1 to 14 pH units

• conductivity: 100mS/cm

±0.5% of reading +0.001mS/cm with an operating range of 0 to

The flowmeter was factory calibrated with a three point calibration, the upper limit of flow being 0.99999 Ls-1. At lower flow rates, below 15% calibrated potential, the accuracy of the meter is limited and flows less than 0.0167 Ls-1 are out of the acceptable range of accuracy and will not give reliable results. Therefore for appliances with outlet flows below this limit, no flow data was collected (pH, temperature and conductivity could still be measured) and the autosampler was not triggered to take samples automatically. The sampling of the dishwasher, kitchen and bathroom sinks were all completed manually by discharge into a storage container capable of holding the total grey water volume. Samples were taken from this collected grey water for further analysis and readings were taken by manually inserting the sonde into the storage tank.

2.6.2 Auto-sampler The auto-sampler, an ISCO model No. 6712 (Figure 4), is an automated sampling device that is activated by changes in various water parameters, such as flow, time or physical parameters. The activation mechanisms used in this project were flow and conductivity. The auto sampler carries 24 bottles, each of which is 1000 mL in volume.


Page 5

Figure 4: Manifold, flowmeter, sonde and auto-sampler

2.5 Sampling Methodology The experimental set-up and the sampling processes adopted for the mini-house are shown in Figure 5. Outlet streams were sampled either in-line (real time) or from batch samples. Batch samples were used for low flow or volume appliances due to technical limitations (Section 2.1.1). The shower and the washing machine were sampled automatically. These appliances utilised the auto-sampler, triggered by water flow and conductivity, and individual programs that recorded water flow and quality profiles throughout operation of the appliance. Samples were obtained sequentially once the flow was above a selected trigger value. After samples were taken automatically, flow, conductivity, temperature, ORP and pH data were downloaded from the auto-sampler. Samples were then transferred to appropriate sample bottles and sent for analysis. For appliances with flows less than 0.0167 Ls-1 (kitchen sink, vanity unit, and dishwasher) outlet samples and analysis were undertaken manually by collection of each cycle or composite in a storage container. For the dishwasher, on-line recording of conductivity, temperature, ORP and pH was undertaken but samples were taken manually. For manual sampling, the volume was recorded with a measuring cylinder and analysis of physical-chemical parameters performed with appropriate probes. Samples were transferred to appropriate sample bottles and sent for analysis. Prior to every experimentation session, mains water taps were flushed of stagnant water by running water for 5 to 10 minutes and a sample of tap water was taken. For all appliances the composite water samples were taken from a large storage container which collected all appliance outlet flow. Samples were then preserved according to requirements for each analysis type (i.e. unpreserved, sulphuric acid for nitrogen and phosphorus and nitric acid for metal analysis). Samples were stored in a cool room at Enviro liquid Figure 11 shows typical flow and conductivity values for a top loading washing machine run. The sampling events which were triggered by flow > 0.25 Ls-1 are indicated by the yellow triangles on the diagram. There are temporal misalignments between flow, sampling and conductivity peaks; for example, the sampling events only occur during flow but the highest conductivity was reached during the decreasing flow of pump out and samples were taken during the highest flow phases. The graph also suggests that there may be residual detergent in the pipe-work after pump out, which slowly dissolves, increasing the conductivity at times of no flow. These errors could affect the interpretation of results, particularly the correlations between conductivity (measured on- line) and TDS (measured on samples taken).


Page 18

250

200

ORP (mV)

159

Rinse

176

150 ORP = 145 mV Wash cycle

Rinse

111

100

105 84

50

86

61

Enviro Powder Enviro Liquid No-name Brand Leading Brand Avg Tapwater

59

0 0

5

10

15

20

25

30

35

40

45

Time (min)

Figure 10: Average ORP values for each product brand top loading machine cold wash

30

2000 Conductivity (uS/cm) Sample Event Avg Tapwater Correct Flow (L/min)

1800

25

Wash cycle

1400

20

1200 15

1000 Rinse 1

800

Rinse 2

Flow (L/min)

Conductivity (uS/cm)

1600

10

600 400

5

200 Tap water

0

0 0

10

20

30

40

50

60

70

Time (min)

Figure 11: Typical discharge profile from the top loading machine using No-name brand

3.4.1.3

Sample analysis – TDS

Analysis of the TDS from samples taken for each of the cycles and for the composite sample for a warm and cold wash shows that the environmental labelled brand powder does exhibit lower TDS than the leading and no-name brands (Figure 12 and Figure 13). The majority of the TDS is released during the first wash cycle, with 82 to 85% of the total TDS released for the leading, enviro powder and no-name brands and 47% for the enviro liquid brand in the cold wash. Priority contaminants in household appliances

Page 19

Results for the warm wash are similar, except the enviro liquid contribution increases to 63% (Appendix 3). 1400 Leading commercial brand No-name Brand Enviro Powder Enviro Liquid

1200

TDS mg/L

1000

800

600

400

200

0 wash

rinse 1

rinse 2

composite

Phase

Figure 12: TDS each product brand for a warm wash top loading machine

1400 Leading commercial brand No-name Brand Enviro Powder Enviro Liquid

1200

TDS mg/L

1000

800

600

400

200

0 wash

rinse 1

rinse 2

composite

Phase

Figure 13: TDS each product brand for a cold wash top loading machine


Page 20

Significant variations were observed in TDS results between the warm and cold washes, when using the leading brand as shown in the following series:

TDS warm wash (composite) No name brand ≅ Enviro powder ≅ Leading brand > Enviro liquid TDS cold wash (composite) Leading brand > No name brand > Enviro powder > Enviro liquid This is potentially explained by differences in solubility of the detergents used, although all were stated as being suitable for both hot and cold washes on product labelling. At higher temperatures more of the product will dissolve in the wash, leading to higher TDS concentrations. The explanation is confirmed by the conductivity results for all products except the leading brand which exhibited lower conductivities for the cold wash, although these results were not statistically significant. The results imply the leading brand dissolves well in both warm and cold washes, whereas noname, enviro powder and enviro liquid brand solubilities are affected by water temperature. If the leading brand solubility is not affected by temperature and the other brands are, a change in temperature is likely to affect the position of the leading brand in the overall ranking. The anomaly between conductivity and TDS results may also be influenced by differences in the contribution of organic components of laundry components to TDS and EC. Organic components of laundry detergents comprise two parts, a cation – usually sodium - and an anion which is the organic part of the molecule. TDS measures all dissolved solids which pass through a 0.45 μm filter paper, whereas conductivity measures the ability of a solution to conduct an electric current. Differences in ion mobility and contribution to conductivity for ions of the organic components would require further investigation to understand the impacts of these differences on measured TDS and EC. Table 7 shows the maximum TDS contribution from tap water and detergents based on the mass of detergents used, the measured TDS of each stream and the volume of water used in each wash. In powder formulations, the detergent was the major relative contributor to TDS (>80%), whilst in the liquid formulation the TDS contribution is minimal and tap water was the source of more than 88% of the TDS measured. Table 7: Estimate of TDS contribution from tap water and detergents for the top loader washing machine

Wash temperature Cold

Warm

Product

Leading brand

Enviro powder

%TDS from product

77.4

68.9

11.5

72.9

% TDS from tap water

22.6

31.1

88.5

27.1

%TDS from product

91.5

91.2

1.6

88.9


8.5

8.8

88.4

11.1


Enviro liquid

No-name brand

Page 21

3.6.2 Front loader 3.4.2.1

Water usage and flow

The water consumption for the front loader washing machine was less than the top loader, with an average usage of 84 litres per total normal wash. The machine operated using one wash cycle and three rinse cycles. Figure 14 shows the average outlet flow rates for the four separate cycles of the front loading washing machine. The results were averaged over eight runs and the initial wash was followed by three rinses. The graph shows the corrected flow based on readings from the inlet flow meter as there were discrepancies in the readings from the outlet flow meter due to foaming in the pipe work. 14 12

Flow Rate (L/min)

10

Wash cycle

8

Rinse 1 Rinse 2

6

Rinse 3

4 2 0 0

5

10

15

20

25

30

35

40

45

Time (min)

Figure 14: Flow rate profile for front loading washing machine

3.4.2.2

On line monitoring – Conductivity, pH and ORP

The conductivity trends in the front loading machine displayed similar behaviour to the top loading machine, although the outcome in terms of comparison of individual brands was different. Grey water with the leading brand exhibited the highest and with the environmental liquid brand the lowest conductivities during the wash cycle, whilst grey water with the Enviro powder and No-name brands were very similar in conductivity. In summary the conductivity results are as follows;

Conductivity Leading brand > Enviro Powder ≅ No-Name brand > Enviro Liquid This result in the ranking of the different detergent types is different to that observed for the top loading machine, where the no-name and enviro powder brands produced the highest conductivity. This is explained by the fact an increased dose was recommended for the leading brand product in the front loading machine, 80 g for top loading machine and 100 g for front


Page 22

loading machine (Table 2). All other product doses were significantly less for the front loading machine compared to the top loader. There is no obvious difference in conductivities when the warm (Figure 15) and cold (Figure 16) washes are compared. For the averages and standard deviations of the warm and cold wash conductivities, cold wash results are generally lower, but this difference is not statistically significant. Lower conductivities in the cold wash suggest products are not dissolved completely. For grey water with the leading and no-name brands, the variability in results was higher for the cold wash compared to the warm wash.

Table 8: Average conductivity for warm and cold wash – front loading machine

Conductivity (μS/cm) Brand

Warm wash

Cold wash

Average St Dev Average St Dev Leading

3729

358

3691

496

No-name

1893

131

1814

158

Enviro powder

1914

210

1904

82

Enviro liquid

126

5

128

8

4500 Leading Commercial Brand No-name Brand Enviro Brand Powder Enviro Brand Liquid

4000


3500 Wash

3000 2500 2000

Rinse 1

1500 Rinse 2

1000 500 0 0

5

10

15

20

25

30

35

40

45

Time (min)

Figure 15: Average conductivity each product brand for a warm wash front loading machine


Page 23

4500 Leading Brand Powder No-name Brand Enviro Powder Enviro Liquid

4000


3500 Wash cycle

3000 2500 2000

Rinse 1

1500 Rinse 2

1000 500 0 0

5

10

15

20

25

30

35

40

45

Time (min)

Figure 16: Average conductivity each product brand for a cold wash front loading machine

For all detergents used in the front loading machine, the pH remained in the basic range. The environmental liquid showed less than 5% variation from the pH of the tap water (Figure 17), with the leading brand exhibiting the next highest variation and the home brand and enviro powder the largest increase in pH. The results can be summarised as follows:

pH No-Name brand ≅ Enviro Powder > Leading brand >> Enviro Liquid


Page 24

11.5 10.9

11

10.8

10.5

10.3 10.4 Wash cycle

Rinse

10.2

pH Units

10

10.0

Rinse

9.5

Rinse

pH = 9.3 9.1 8.9

9 8.5


8 7.5 0

5

10

15

20

25

30

35

40

45

Time

Figure 17: Average pH values for each product brand front loader cold wash

200 180

173

165

155

160 ORP = 145 mV

140

144 131

ORP (mV)

Wash cycle

120

124 Rinse

100

103 96

Rinse

83

Rinse

90

80

70

60

69


40 20 0 0

5

10

15

20

25

30

35

40

45

Time (min)

Figure 18: Average ORP values for each product brand front loader cold wash

The data in Figure 18 shows the ORP values for each cycle and the effects of each laundry detergent brand. The environmental brand produced the least change in ORP and increased the ORP above that of tap water. The no-name brand and enviro powder caused the greatest reduction in the oxidizing potential. In summary, the impact of the different brands on ORP was as follows:


Page 25

ORP Enviro powder ≅ No name brand > Leading brand >> Enviro liquid

18

2500 Conductivity (uS/cm) Sample Event Avg Tapwater Correct Volume (L/min)

14 12

1500

10

Wash cycle

8

1000

Rinse 1 Rinse 2

Flow (L/min)


2000

16

6

Rinse 3

4

500

2 Tap water

0 0

5

10

15

20

25

30

35

40

0 45

Time (min)

Figure 19: Typical discharge profile - front loading washing machine, no-name brand

The flow, conductivity and sampling parameters for the front loading washing machine show a similar trend to that observed for the top loading washing machine (Figure 19). The sampling protocol used for the front loader was different to that used for the top loader in that the sampler would activate when the flow exceeded 0.15 Ls-1 or when the conductivity exceeded 200 μS/cm (sample time indicated by the yellow triangles). The graph shows the same lag in conductivity reading as with the top loader, with the conductivity peak not necessarily occurring during maximum flow. 3.4.2.3

Sample analysis – TDS

The front loader runs were analysed for TDS, and the results produced were comparable to the conductivities obtained. The leading brand gave the highest TDS, whereas the enviro liquid gave the lowest. There were some differences observed between the cold and warm washes at the detail of individual cycles, particularly in regards to the leading brand detergent which had a higher TDS in warm water as seen in Figure 20 and Figure 21. As with the top loading machine, the majority of the TDS from the front loader was released during the first wash cycle, with 71% of the total TDS released for the no-name brand, 64% for the leading brand, 56% for the enviro powder and 49% for the enviro liquid brand in the cold wash. Results for the warm wash were similar, except the enviro powder contribution, which increased to 71% (Appendix 3). The TDS results for the composite samples where as follows:

TDS hot and cold wash (composite) Priority contaminants in household appliances

Page 26

Leading brand > Enviro Powder ≅ No-Name Brand > Enviro Liquid 3000 Leading commercial brand No-name Brand Enviro Powder Enviro Liquid

2500

TDS mg/L

2000

1500

1000

500

0 wash

rinse 1

rinse 2

rinse 3

composite

Phase

Figure 20: TDS each product brand for a warm wash front loading machine

3000 Leading commercial brand No-name Brand Enviro Powder Enviro Liquid

2500

TDS mg/L

2000

1500

1000

500

0 wash

rinse 1

rinse 2

rinse 3

composite

Phase

Figure 21: TDS each product brand for a cold wash front loading machine


Page 27

As in Section 3.6.1.3, the powder detergent was the major relative contributor to the TDS of the grey water (>80%), whilst for the liquid detergent, TDS contribution was minimal (Table 9). Table 9: Estimate of TDS contribution from tap water and detergents for the front loader washing machine

Wash temperature Cold

Warm

3.4.2.4

Product

Leading brand

Enviro powder

Enviro liquid

No-name brand

%TDS from product

72.3

95.5

2.5

102.4


7.7

4.5

97.5

0

%TDS from product

97.2

85.3

-1.8

103.5


2.8

4.7

100

0

Front loading and top loading machine colour analysis

Colour varied throughout the top loading washing machine operation, from 28 to 11 PCU, (Figure 22) with the most intense colour observed during the wash cycle. The tap water colour input was 6.3 PCU on average, equivalent to between 23% to 58% of the total colour in the grey water produced in each cycle.

30 Avg Tap Water No Soiled Clothing

25

Colour (PCU)

20

15

10

5

0 Wash

Wash

Rinse 1

Rinse 1

Rinse 1

Rinse 2

Rinse 2

Rinse 3

Rinse 3

Rinse 3

Washing machine cycle

Figure 22: Detected true colour from washing machine

3.4.2.5

Front loading and top loading machine elemental analysis


Page 28

Results for elemental analysis for the different appliances are presented in Appendix 1. The results presented in this report represent the composite samples from the washing machine cycles and are the averages of the grey water data for each brand tested (four runs, warm and cold washes for front and top loaders), except where otherwise stated. Elements that were not detected in any of the washing machine samples or in those present in similar concentrations as detected in tap water included: silver, barium, beryllium, cadmium, cobalt, chromium, copper, magnesium, manganese, molybdenum, nickel (except leading brand when used in front loader only, average 0.006 mg/L) lead, tin, titanium, thallium, vanadium, zinc (inconclusive results for leading brand in both front and top loader), zirconium (except leading brand in front loader only, average 0.008 mg/L), arsenic (except leading brand in front loader only, average 35 μg/L), selenium, antimony and mercury. The highest concentrations of aluminium were detected in the washing machine outlet stream when using the leading brand detergent. For the front loader, 3.63 and 7.63 mg/L Al were detected for the cold and warm washes respectively. The average outlet concentration for the environmentally friendly powder was 0.51 mg/L Al, for the environmentally friendly liquid 0.48 mg/L Al and for the no-name brand 0.14 mg/L Al, giving an overall ranking of:

Aluminium Leading brand > Enviro powder and Enviro liquid > No-name brand For the washing machine outlet the concentrations of calcium for the different brands were: leading brand 14.7 mg/L Ca and No-name brand 13.1 mg/L Ca. The enviro washing machine liquid and powder showed no significant increase in concentration when compared to tap water, giving an overall ranking of:

Calcium Leading brand > No-name brand There were significant increases in the concentration of iron compared to tap water for both leading brand of laundry detergent at 0.200 mg/L Fe and the environmentally friendly liquid laundry detergent at 0.176 mg/L Fe giving a ranking as follows:

Iron Leading brand > Enviro liquid The concentration of potassium in the leading brand laundry detergent was found to vary greatly ( All other brands (below LOD for other products) The washing machine outlet exhibited the second highest concentrations of sodium (dishwasher had the highest) for all appliances as follows: leading brand 433 mg/L Na, no-name brand 342 mg/L Na, enviro powder 324 mg/L Na and enviro liquid 91 mg/L Na, although the latter included one outlier result (319 mg/L) which may be due to a contaminated sample. The average of the readings, not including this outlier, for the enviro liquid was 15 mg/L Na.

Sodium Leading brand > No-name brand ≅ Enviro powder > Enviro liquid


Page 29

High concentrations of phosphorus were observed for the leading brand laundry detergent only at 118 mg/L. All other laundry detergents were all below 2 mg/L with the enviro liquid brand at 0.037 mg/L.

Phosphorus Leading brand >> No-name brand > Enviro powder ≅ Enviro liquid The concentrations of sulphur from the different laundry detergent brands ranged between 127 mg/L for the leading brand to 7.3 mg/L for the enviro powder brand, with an overall ranking as follows:

Sulphur Leading brand > No name brand > Enviro liquid > Enviro powder The results for sulphur for the liquid laundry detergent were very variable with one sample result almost ten times that of the other two samples analysed, and requires further analysis for clarification of results. The leading brand laundry detergent exhibited the highest concentration of silicon at 22.9 mg/L. All other products showed averages of 2.3 to 2.4 mg/L, thus the ranking was as follows:

Silicon Leading brand > No name brand ≅ Enviro Liquid ≅ Enviro powder Small increases above tap water concentrations of strontium were observed for the leading and no name brand laundry detergents (0.037 and 0.034 mg/L Sr averages respectively), but these were not significant. A small but significant decrease was observed for the enviro labelled washing machine powder, which had an average concentration of 0.0068 mg/L Sr. A summary of the rank of the leading, enviro and no-name brands of detergents used in the washing machines is provided in Table 10.


Page 30

Table 10: Summary of ranking of products used in the washing machine

Parameter

Ranking of product

Conductivity

FL: Leading brand > Enviro Powder ≅ No-Name brand > Enviro Liquid TL: No name brand > Enviro powder ≅ Leading brand >> Enviro liquid

pH

FL and TL: No-Name brand ≅ Enviro Powder > Leading brand >> Enviro Liquid

ORP

FL and TL: Enviro powder ≅ No name brand > Leading brand >> Enviro liquid

TDS

FL (warm and cold wash): Leading brand > Enviro Powder ≅ No-Name Brand > Enviro Liquid TL (warm wash): No name brand ≅ Enviro powder ≅ Leading brand > Enviro liquid TL (cold wash) : Leading brand > No name brand > Enviro powder > Enviro liquid

Aluminium

Leading brand > Enviro powder and Enviro liquid > No-name brand

Calcium

Leading brand > No-name brand

Iron

Leading brand > Enviro liquid

Sodium

Leading brand > No-name brand ≅ Enviro powder > Enviro liquid

Phosphorus

Leading brand > No name brand > Enviro liquid > Enviro powder

Sulphur

Leading brand > No name brand > Enviro liquid > Enviro powder

Silicon

Leading brand > No name brand ≅ Enviro Liquid ≅ Enviro powder

Note: FL – Front loading washing machine TL - Top loading washing machine


Page 31

3.5 Dishwasher 3.6.1 Water usage and flows The dishwasher had two separate programs: a rapid cycle and a normal cycle that utilized different amounts of water for each. The normal cycle included a pre-wash stage whereas the rapid cycle did not. The normal cycle used an average of 15.2 litres per complete wash, which differed to the manufacturer’s details that stated 15.7 litres per complete wash. For the rapid cycle 11.1 litres was used on average. Figure 23 shows the average results from four separate runs. Each run included a pre-wash, a subsequent wash and two rinses. The peaks for these are clearly identified in Figure 23. The multiple discharge peaks that are apparent in the cycles are due to the dishwasher pumping the water out in stages over each cycle. This flow analysis indicates that most of the flows from the dishwasher were below the threshold of accurate detection of the flowmeter (0.0167 Ls-1). For this reason sampling was not carried out automatically, but individual cycles were collected manually for further analysis.

3.5 3

Flow Rate (L/min)

2.5 2

Pre- Rinse

Rinse 2

1.5

Wash cycle Rinse 1

1 0.5 0 0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

Time (min)

Figure 23: Flow rate profile dishwasher- normal wash setting

3.6.2 On line monitoring – Conductivity, pH and ORP As no changes in conductivity, pH or ORP were observed during the prewash of the normal cycle, prewash data is NOT displayed on any of the results graphs, unless otherwise stated. The conductivity profile of the dishwasher outlet showed large differences in conductivity for three different dishwashing products and the normal and rapid washes, (Figure 24 and Figure 25). The conductivity was highest during the wash cycle.


Page 32

12000 Leading Commercial Brand No-name brand tablet Environmental Brand


10000

8000 Wash

6000

4000 Rinse 1 Rinse 2

2000

0 0

5

10

15

20

25

30

35

40

45

50

Time (min)

Figure 24: Average conductivity for each product brand for dishwasher- normal wash (no prewash)

12000 Leading Commercial brand No-name Brand Tablet Environmental Brand


10000

8000

Wash

6000

4000 Rinse 1

2000

Rinse 2

0 0

5

10

15

20

25

30

35

Time (min)

Figure 25: Average conductivity for each product brand for a dishwasher- rapid wash


Page 33

In summary the conductivities recorded for the all wash and rinse cycles, for both normal and rapid wash were:

Conductivity Leading brand > No name brand > Enviro powder The maximum conductivity of grey water containing each of the three brands during the normal wash cycle were 10,321μS/cm for the leading brand, 5,315μS/cm for the no-name brand and 3,282 μS/cm for the enviro labelled brand. The conductivity of the final rinse was small, less than 10% of that from the wash cycle for all brands, compared to that recorded for the other cycles. For normal and rapid cycles, the conductivities recorded at the outlet from the dishwasher were similar (Table 11). A higher maximum conductivity was observed for the initial normal wash with the leading brand but the average conductivity was higher for the rapid wash (Table 11), although this was not statistically significant. All conductivities exhibited similar variability throughout the wash cycle and no statistically significant differences were observed between the normal and rapid washes. Table 11: Average conductivity for normal and rapid dishwasher wash cycles

Conductivity (μS/cm) Brand

Normal wash

Rapid wash

Average

St Dev

Average

St Dev

Leading brand

9022

948

9409

1036

No-name

4320

460

4566

491

Enviro labeled

2549

102

2829

283

In the dishwasher the pH remained basic during the wash with the leading brand exhibiting the highest change in pH and the no-name brand gave the least change (Figure 26). The results are summarised below:

pH Leading brand > Enviro powder > No-name brand


Page 34

11

10.8 10.7

10.5

10.5

10.5

10.1 Wash cycle

pH Units

10

10.0 Rinse

9.5

Rinse

pH = 9.3

9

8.5 Leading Brand No-name Brand Environmentally Labelled Avg Tapwater

8

7.5 0

5

10

15

20

25

30

35

40

Time

Figure 26: Average pH values for each product brand dishwasher normal run (no prewash)

The average ORP values show the leading brand reduced the ORP by the most, to 7 mV as shown in Figure 27. The environmentally labelled brand had a lesser effect and the no-name brand had the least effect on ORP values, with the minimum ORP at 56 mV. The reduction ORP is greater than that observed for the washing machine.

ORP Leading brand > Enviro powder > No-name brand


Page 35

250 Leading brand No-name Brand Environmentally Labelled Tapwater

ORP (mV)

200

ORP = 145 mV

150

Rinse

Rinse

116

100

Wash cycle 98 56

50

42 42 7

0 0

5

10

15

20

25

30

35

40

Time (min)

Figure 27: Average ORP values for each product brand dishwasher normal run (no prewash)

6 6000

Conductivity (uS/cm) Flow (L/min)

5

4 4000

Pre-Rinse Wash cycle

3

3000

Rinse 1 Rinse 1

Flow (L/min)


5000

2

2000

1

1000 0 0

10

20

30

40

50

60

70

80

90

0 100

Time (min)

Figure 28: Typical discharge profile for dishwasher- normal wash (prewash included)

Figure 28 shows the conductivity and flow profile for a normal wash with no-name product brand. There is minimal change in conductivity during the pre-wash cycle and the majority of high conductivity outflow occurs during the wash cycle.


Page 36

3 Sample analysis – TDS For the TDS concentrations of the normal and rapid washes (Figure 29 and Figure 30:), the concentration of the leading brand is higher during the rapid wash cycle. TDS concentration of other brands for all cycles is similar when comparing rapid and normal washes. However, the TDS of the composite samples is higher for all the brands examined for the rapid wash, primarily due to the reduced water volume of the rapid wash program (in total 16L compared to 11L). Calculation of the percentage distribution of TDS for each cycle showed similar results for all products in the normal wash, with around 1 to 4% of TDS load appearing in the pre-rinse, 83 to 86% in the wash cycle, 10% in the first rinse and 2 to 3% in the final rinse (Appendix 2). These results changed for the rapid wash with less TDS from the leading brand and enviro labelled brand appearing in the wash cycle.

7000 Leading commercial brand No-name Brand Enviro Brand

6000

TDS mg/L

5000

4000

3000

2000

1000

0 prewash

wash

Rinse1

Rinse2

Composite

Phase

Figure 29: TDS each product brand for dishwasher- normal wash


Page 37

7000 Leading commercial brand No-name Brand Enviro Brand

6000

TDS mg/L

5000

4000

3000

2000

1000

0 wash

rinse 1

rinse 2

composite

Phase

Figure 30: TDS each product brand for a dishwasher- rapid wash

The detergent was the main contributor to TDS in the grey water generated (Table 12). The estimated contribution of the leading brand in the rapid mode was lower than in the normal mode, this might be caused by either incomplete dissolution of sample or error in the reading. Table 12 - Estimate of TDS contribution from tap water and detergents for dishwasher

Program

Normal

Rapid

Product

Leading brand

Enviro brand

No-name brand

%TDS from product

88.0%

87.4%

64.2%


12.0%

12.6%

35.8%

%TDS from product

66.2%

105.8%

83.6%


33.8%

0%

16.4%

The ranking of dishwashing detergent with regards to TDS of composite samples is as follows:

TDS (composite) Leading brand > No-name brand > Enviro powder TDS of composite samples ranged between 740 mg/L and 1800 mg/L for the normal wash and 1100 mg/L and 3100 mg/L for the rapid wash. All rapid wash concentrations were higher than those observed for the top and front loading washing machines which were all less than 1000 mg/L. The dishwasher produces significantly less volume of grey water in comparison to the Priority contaminants in household appliances

Page 38

washing machine, 15.2 L for a normal wash compared to 165 L and 84 L for the top and front loaders respectively.

3.6.3 Sample analysis – Colour in rapid and normal washes The dishwasher outlet stream recorded colour values in the range of 26 to 66 PCU for the different cycles. These values were higher than those observed for the washing machine (15 to 28 PCU). The most intense colour was observed in the wash cycle (Figure 31). Hence, detergent use increased the colour of the grey water produced by the appliance. However, as the volume of water released by the dishwasher is small ( No-name brand Barium was recorded at significantly higher concentrations than tap water from the dishwasher, whereas all other appliance outlets showed a similar concentration to tap water (0.0132 mg/L). The highest observed concentration of barium was for the environmentally labelled dishwasher brand at 0.0226 mg/L. The leading brand and no name brands were both similar in concentration at 0.0157 and 0.0162 mg/L respectively, giving a ranking as follows:

Barium Enviro powder > Leading brand ≅ No-name brand Calcium concentrations in the dishwasher outlet were significantly higher than those observed in tap water (7.1 mg/L) with the leading brand the highest at 16.9 mg/L and the enviro brand the lowest at 9.14 mg/L.

Calcium Leading brand > No-name brand ≅ Enviro powder There were significant contributions to copper concentrations above that observed in tap water (0.109 mg/L) with an overall average of 0.434 mg/L. The leading brand contributed the most (0.75 mg/L) and the enviro labelled brand the least (0.23 mg/L), giving an overall ranking:

Copper Leading brand > No-name brand ≅ Enviro powder The variation in copper concentrations observed for the different brands suggests that the copper originates from the products and not the infrastructure and component parts of the dish washer. The dishwasher products were found to contribute additional iron to the outlet stream with an average outlet concentration of 0.199 mg/L, compared to 0.115 mg/L for tap water. For the individual products the averages values were similar, no-name brand 0.214 mg/L, enviro brand 0.196 mg/L and leading brand 0.187 mg/L

Iron Leading brand ≅ No-name brand ≅ Enviro powder The similarity in iron concentrations observed for the different brands suggests that the iron could originate from the infrastructure and component parts of the dish washer and not the products used. The leading brand dishwasher detergent potassium composite sample concentration was 5.67 mg/L and the no-name brand 1.86 mg/L. Analysis for the enviro powder was inconclusive, with


Page 40

one sample less than LOD and one recording 0.104 mg/L. No potassium was detected in the tap water.

Potassium Leading brand> No-name brand > Enviro powder The highest concentration of sodium for all appliances was observed in the outlet from the dishwasher with the different brands showing the following concentrations: leading brand 2160 mg/L, no-name brand 1053 mg/L and enviro brand 585 mg/L

Sodium Leading brand> No-name brand > Enviro powder Phosphorus concentrations of the dishwasher outlet were also the highest observed for all appliances with the following concentrations for the different products: no-name brand 505 mg/L, leading brand 389 mg/L and enviro labelled brand 1.18 mg/L.

Phosphorus No-name brand >Leading brand >> Enviro powder The highest sulphur concentration of all appliances was observed in the dishwasher outlet for the leading brand dishwashing detergent (292 mg/L). The no-name brands and the enviro labelled brand showed 84 mg/L and 4.6 mg/L respectively. The sulphur concentration in tap water was 0.79 mg/L.

Sulphur Leading brand> No-name brand > Enviro powder The average concentration of silicon observed in tap water was 1.5 mg/L. The highest silicon concentration was observed in the enviro labelled dishwashing detergent outlet at 122 mg/L, with the no-name and leading brand exhibiting similar concentrations of 37.5 mg/L and 31 mg/L respectively:

Silicon Enviro brand> No-name brand ≅ Leading powder Low concentrations of titanium were observed for the enviro labelled and no name dishwasher brand outlets at 0.037 and 0.057 mg/L respectively. The concentration of titanium in tap water was below the limit of detection of < 0.02 mg/L.

Titanium No-name brand > Enviro powder All samples collected from the outlet of the dishwasher contained zinc in detectable concentrations For the leading brand, concentrations of 0.25 mg/L were observed; for the noname brand the concentration was 0.12 mg/L and enviro labelled brand had a much lower concentration at 0.03 mg/L, although there was a variation between the two samples for the noname brand and further analysis is required to verify this result.

Zinc Leading brand> No-name brand > Enviro powder


Page 41

Concentrations of zirconium observed in the enviro labelled and no-name brand dishwasher samples were 0.0067 and 0.0078 mg/L respectively. The leading brand dishwasher samples were variable in zirconium concentration at 0.0089 and 0.0179 respectively. A summary of the ranking of results for zirconium is as follows:

Zirconium Leading brand >≅ No-name brand ≅ Enviro powder A summary of the rank of the leading, enviro and no-name brands of detergents used in the washing machines is provided in Table 13. Table 13: Ranking of products used in dishwasher

Element

Rank of products based on concentration in grey water

pH

Leading brand > Enviro powder > No-name brand

Conductivity

Leading brand > No name brand > Enviro powder

ORP

Leading brand > Enviro powder > No-name brand

TDS

Leading brand > No-name brand > Enviro powder

Aluminium

Leading brand ≅ Enviro powder ≅ No-name brand

Arsenic

Leading brand > No-name brand

Barium

Enviro powder > Leading brand ≅ No-name brand

Copper

Leading brand > No-name brand ≅ Enviro powder

Iron

Leading brand ≅ No-name brand ≅ Enviro powder

Potassium

Leading brand> No-name brand > Enviro powder

Sodium


Phosphorus

No-name brand >Leading brand >> Enviro powder

Sulphur


Silicon

Enviro brand> No-name brand ≅ Leading powder


Page 42

Zinc


Zirconium

Leading brand >≅ No-name brand ≅ Enviro powder


Page 43

3.6 Shower For the shower the auto-sampling and on-line monitoring was carried out closer to the shower outlet (Figure 2) due to pipe work configuration.

3.6.1 Water usage and flows The reduced flow shower head installed in the Mini-house used an average volume of 36.9 litres per four minute shower compared to 54.2 litres per four minute shower for the high flow shower head. 18 Average Low Flow Average High flow

16 14

Flow Rate (L)

12 10 8 6 4 2 0 0

1

2

3

4

5

6

7

8

9

10

Time (min)

Figure 32: Flow rate profile for both shower heads

Figure 32 Compares the flow profiles of the low and high flow showerheads, an average of eight and five runs respectively. The low flow showerhead showed a peak flow of 11.88 L/min whereas the high flow peak was 16.3 L/min.

3.6.2 On line monitoring – conductivity, pH and ORP The data for conductivity, pH and ORP profiles for the five high flow and the eight low flow shower runs were adjusted so meaningful comparison could be made. Peak values did not necessarily occur at the same time in each run, and so timelines were adjusted in order to overlay the results and allow comparison between runs. All results presented here were adjusted in this way. 3.6.2.1

Conductivity

The differences in conductivity during the shower experimentation were small compared to those observed for other appliances (Figure 34 and Figure 35). A small increase in conductivity


Page 44

was observed during the first one to two minutes of the profile, but following this, conductivity decreased, returning to the original tap water conductivity at the end of the shower. There was a correlation between time when products were used and conductivity, this was observed throughout the shower run. The results from the high flow showerhead showed slightly higher variation in conductivity between runs with an average maximum conductivity of 131 μS/cm and a standard deviation of 15 μS/cm compared to the low flow with an average min of 49.25 μS/cm and standard deviation of 18.73 μS/cm (Figure 34 and Figure 35). High flow runs resulted in conductivity maxima ranging between +23% to +77% of the initial tap water value, whilst for the low flow showerhead the maxima ranged between +23% to +31% for four of the runs, followed by a dip in conductivity of -41% to -74% for the following minute. This reduction could be caused by the combined action of the lower dissolution of the products and sequestering of ionic species by ingredients such as EDTA present in shampoo. A factor that may contribute to this conductivity profile is the flow profile in the shower, in that flows increase to a peak two to three minutes into the shower, increasing the dilution of products that are used (Figure 33). Further analysis of the products and their potential contribution to conductivity will also be required in order to help explain the minimal contribution from shampoo and conditioner compared to liquid soap. The water was discharged for up to six minutes, with residual flow after the four minute shower coming from water remaining in the shower unit. This may be another contributing factor to the observed conductivity profile in that product may be retained in the shower tray, being further diluted prior to flowing to the conductivity meter.

14

120

12

100

8 Flow (l)


10 80

60 6 40 4 Average Conductivity (uS/cm) Sample event

20

2

Average Flow (l)

0

0 0

2

4

6

8

10

12

14

16

18

Time (min)

Figure 33: Typical discharge profile for shower with low flow showerhead


Page 45

160

140

Conductivity(uS/cm)

120

100

80 Wash 1 Wash 2 Wash 3 Wash 4 Wash 5 Wash 6 Wash 7 Wash 8 Tapwater

60

40

20

0 0

1

2

3

4

5

6

7

8

9

10

Time(min)

Figure 34: Conductivity each shower wash- low flow shower head with product release

160 Wash 1 Wash 2 140

Wash 3 Wash 4 Wash 5 Tap water Average


120

100

80

60

40

20

0 0

1

2

3

4

5

6

7

8

Time (min)

Figure 35: Conductivity for each shower wash – high flow shower head with product release


Page 46

3.6.2.2

pH

The pH at the outlet from the shower was decreased for both high and low flow showers (Figure 36 and Figure 37), although more pronounced for the low flow showerhead. An average minimum pH of 8.96 was observed for the low flow showerhead compared to 8.8 for the high flow showerhead. The pH varied between 8 and 10 and values returned to those of tap water towards the end of the shower. The observed changes in pH between washes at the start of the shower are due to changes in tap water quality. Overall, dissolution of products in the shower resulted in a relative reduction in pH of less than 20% of the original water pH.

10.2

10

9.8 9.65

pH(units)

9.6

9.4

9.2

9

Wash 1 Wash 2 Wash 3 Wash 4 Wash 5 Wash 6 Wash 7 Wash 8 Tapwater

Average Min - 8.96

8.8

8.6 Min pH 8.5 8.4 0

1

2

3

4

5

6

7

8

9

10

Time(min)


Page 47

Figure 36: pH values throughout low flow shower run

10

9.3

9.5

pH Units

9 Average minimum 8.8 Minimum 8.6

8.5

Wash 1 Wash 2 Wash 3

8

Wash 4 Wash 5 Avg Tapwater

7.5 0

1

2

3

4

5

6

7

8

Time

Figure 37: pH values throughout high flow shower run

3.6.2.3

ORP

The ORP values for the shower varied between runs for both the low and high flow showerheads with a general increase in initial ORP (Figure 38 and Figure 39). Variability in the initial ORP at the start of the shower was due to variations in tap water quality. The high flow runs showed some differences in the ORP profile, potentially due to the probe sensitivity to temperature, with the ORP baseline readings fluctuating at the higher temperatures (30 to 40°C). However, whilst the absolute value may have been affected by temperature, the relative trends in ORP over the four minute time interval of the shower were similar. The change in ORP during the showe’s run was less than for the washing machine or dishwasher. Figure 38 shows the comparison of shower runs with hot (~30°C) and cold (~12°C) water. It is apparent that temperature influences the ORP readings. Grey water at the higher temperature (30°C) was characterised by negative ORP values (reducing solution), whilst in cold water the ORP was positive (oxidizing solution). Hence, analytical comparison of results needs to consider the temperature of the water as this affects the dissolution of products and the ORP readings.


Page 48

150

Cold 1 Cold 2 Cold 3 Warm 4 Warm 5 Warm 6 Warm 7 Warm 8

100

ORP(mV)

50

0 0

1

2

3

4

5

6

7

8

9

10

-50

-100

-150 Time(min)

Figure 38: ORP profile for low flow shower run

250 Wash 1 Wash 2 Wash 3

200

Wash 4 Wash 5

ORP (mV)

Avg Tapwater

150 145.

100

50

0 0

1

2

3

4

5

6

7

8

Time (min)

Figure 39: ORP profile for high flow shower run


Page 49

3.6.3 Sample analysis – TDS, colour and elemental analysis 3.6.3.1

TDS

Figure 40 shows the TDS concentrations for composite samples of five low flow and high flow showerhead runs. There is one outlier in wash two, possibly due to sample contamination or operator error. The TDS of the low flow runs is generally higher than that observed for the high flow runs, potentially due to dilution. Average TDS of the low flow runs was 51.8mg/L and for the high flow runs 59 mg/L (this result excludes the outlier). The respective standard deviation for the low and high flow shower runs was respectively 16.2 mg/L and 13.95 mg/L. These results are within the same range as tap water.

350 Low Flow Profile Hi Flow Profile

300

TDS (mg/L)

250

200

150

100

50

0 1

2

3

4

5

Tapwater

Wash#

Figure 40: TDS results for each wash for both low and high flow showerheads


Page 50

3.6.3.2

Colour

The colour for the composite grey water released for the low flow shower runs is shown in Figure 41. As seen in Figure 41, similar amounts of product were used in each run. The observed colour was on average 12 + 6 PCU. This was less intense than both the dishwasher and the washing machine which had respective colour ranges of 20 to 66 PCU and 12 to 28 PCU. 14 Shower Colour (PCU) g/L Product consumed 12

10

8

6

4

2

0 Wash 1

Wash 2

Wash 3

Wash 4

Wash 5

Wash 6

Figure 41: Detected average true colour from mini house low flow shower

3.6.3.3

Elements

Results for each element for the different appliances are presented in Appendix 1. The results presented here represent the composite samples from the shower, an average of ten high and low flow shower runs combined. The following elements were not detected in the outlet from the shower or were not significantly different from tap water during high and low flow runs: silver, barium, beryllium, calcium, cadmium, cobalt, chromium, copper, iron, potassium, magnesium, manganese, molybdenum, nickel, phosphorus, lead, tin, strontium, titanium, thallium, vanadium, zinc (except one sample at 0.011 mg/L), arsenic, selenium, antimony and mercury. The concentrations of those elements found in detectable concentrations are shown in Table 14, along with the recorded values for tap water. The average concentration of aluminium was higher from the shower than from the dishwasher, bathroom and kitchen sinks and the no-name brand detergent outlet water from the washing machine. There was a small decrease in magnesium concentration when compared to tap water, a trend that was also observed for all other appliances. The increase in sodium concentration of the shower water above that of tap water (