Copyright is owned by the Author of the thesis. Permission is given for a copy to be downloaded by an individual for the purpose of research and private study only. The thesis may not be reproduced elsewhere without the permission of the Author. Investigating Environmental and Health Risks of Greywater use in New Zealand A thesis presented in partial fulfilment of the requirements for the degree of Master of Science In Soil Science At Massey University, Manawatu, New Zealand Morkel Arejuan Zaayman 2014 Abstract Many countries, including New Zealand, are investigating alternative water management practices to address increasing demands on freshwater supply. One such practice is the diversion and reuse of household greywater for irrigation. Greywater is a complex mixture containing contaminants such as microbes and household chemicals. These contaminants may present an environmental and public health risk, but this has never been characterised in a New Zealand context. This thesis aims to reduce this knowledge gap by characterising the fate and effects of a representative chemical contaminant, the antimicrobial triclosan (TCS); and the microbial indicator, E. coli, in three soils. It also investigated public attitude towards the fate of household products in the environment. In Chapter 4, microbial biomass was used to determine an EC50 for TCS in one soil type (silty clay loam: EC50 = 803 ppm). This determined the loading rate of TCS for the lysimeter study in Chapter 5, where triplicate cores of 3 soil types were irrigated with greywater treatments (good/bad quality) or a freshwater control. Leachate samples throughout the study and soil samples from three horizons at the end of three months irrigation were analysed for TCS and E. coli. The results indicate that regardless of soil type, E. coli and TCS leached from the lysimeters posing a risk for groundwater contamination. Escherichia coli levels in the leachate were as high as 4.71 x 106 CFU/100ml for the GQGW treatments (Lincoln soil) and 6.97 x 107CFU/100ml in the BQGW treatment (Gisborne soil). Triclosan concentrations between 0.03ppb and 3.17ppb were measured in the leachate from the GQGW treatment and 0.03ppb - 42.3ppb for the 10ppm TCS treatments. Soils with high clay content had even larger potential for leaching through preferential flow as the average levels of E. coli found in the leachate from the BQGWD were at least on log10 lower than the average found in the BQGW leachate (Gisborne & Katikati). In contrast the levels of E. coli detected in the Lincoln soil were similar for both treatments. The effects of TCS on soil health parameters in the top horizon were also investigated, but were not found to be significant at concentrations used in this study. To address the source of greywater contamination, i.e. use of household products, I engaged with school children to investigate if awareness of household-contaminants will support behaviour change with respect to what products are used (Chapter 6). With my scientific guidance, the children successfully designed and implemented a greywater experiment and presented their results at a local hui. i The results from this study provide New Zealand specific, scientifically-robust information on potential environmental and public health risks associated with domestic greywater reuse for soil irrigation. ii Acknowledgements Firstly I would like to express my sincere gratitude to my supervisors Dr Jacqui Horswell, Dr Alma Siggins and Dr Dave Horne for providing me with this magnificent opportunity, for their sturdy guidance and abundant support throughout this project. My debt in chocolate runs in kilograms. Also my other ESR colleagues, Andrew van Schaik for answering endless questions, teaching me analytical techniques and humouring me when I got on my soap box about life. To Sarah Quaife for laughing at my jokes (your laughter only encourages me) and popping in every now and again to see if I was doing well. I’d like to express my gratitude to Jennifer Prosser and Virginia Baker for always encouraging me and the amazing chats we had (at tea times or otherwise), and Vanessa Burton for helping with the lysimeter setup (and suggesting that I never to do another lysimeter study again). To Grant Northcott for assisting me with my analysis and giving guidance. To all my friends who believe in me, encourage me and so frequently offered advice. (I’m looking at you Marie and Emily…) A couple of reds then, hey? Without the upbringing I received from my parents (Morkel and Julie) and my elder sister, Linda, I would not have been able to dream the big dreams I do, and I’d like to thank them for investing their time, care, love and trust in me over the years. In particular to my late mother who sang to me “Hold on tight to your dreams” too many times to count and inspired me to accomplish anything I apply myself to. And lastly to my better half, Emile. Thank you for your support, encouragement, pragmatism and all those coffees in the morning keeping me on track and my eyes on the goal-post. I hope to one day support you in the same amazing way you have done for me. iii Contents Abstract ........................................................................................................................................... i Acknowledgements ....................................................................................................................... iii List of Figures .............................................................................................................................. viii List of Tables ................................................................................................................................. xi 1. Introduction and Aims .......................................................................................................... 1 1.1 Introduction .................................................................................................................. 1 1.2 Aims............................................................................................................................... 3 1.3 Research approach........................................................................................................ 3 2. Literature review ................................................................................................................... 6 2.1 What is greywater? ....................................................................................................... 6 2.2 Greywater reuse drivers ............................................................................................... 7 2.2.1 Water shortages .................................................................................................... 8 2.2.2 Surplus water ....................................................................................................... 8 2.3 Risks and benefits associated with greywater reuse .................................................... 9 2.3.1 Risks....................................................................................................................... 9 2.3.2 Benefits ............................................................................................................... 10 2.4 Greywater composition .............................................................................................. 10 2.4.1 Microbiological quality ........................................................................................ 10 2.4.2 Nutrients in greywater ............................................................................................... 12 2.4.3 Chemicals in greywater .............................................................................................. 12 2.5 Triclosan (TCS), Chemical properties ................................................................................ 13 2.5.1 Fate of TCS in soil ................................................................................................ 14 2.5.2 Effects of TCS in soil ............................................................................................ 16 3. Methods .............................................................................................................................. 18 3.1 Moisture content, dry matter content and water holding capacity ................................. 18 3.1.1. Moisture and dry matter content: ............................................................................ 18 3.1.2 Water-holding capacity (WHC): ................................................................................. 19 3.2 pH ................................................................................................................................ 19 3.3. Substrate induced respiration .................................................................................... 19 3.4 Sulphatase enzyme activity ......................................................................................... 20 3.5 Microbial biomass ....................................................................................................... 21 3.6 Microbial metabolic quotient ..................................................................................... 22 3.7 Triclosan analysis ........................................................................................................ 22 iv 3.7.1 Extraction from soil ............................................................................................. 22 3.7.2 Soil sample concentration and derivatisation