Resource guidelines for greywater use and management

Transcription

1 Resource guidelines for greywater use and management Dr Kirsty Carden, University of Cape Town 18 April 2016 Water Research Commission project K5/2592 Development of resource guidelines for greywater use and management

2 Agenda for workshop 1 1. Welcome 2. Background to project status quo 3. Introduction to greywater harvesting assessment tool 4. Identification of thematic areas / issues to be addressed 5. Way forward 6. Closure

3 Strategic planning 2 South Africa is a water-stressed country, bordering on water scarce water may become a binding constraint on development, at least in some parts of the country. There is a need for urgent attention to be given to the management and conservation of water resources, especially in stressed water catchments Addressing supply and demand in the context of unevenly distributed and variable resources is a matter of central importance in national planning. (National Planning Commission, 2011) In many parts of the country, we are fast approaching the point at which all of our easily accessible freshwater resources are fully utilised. All South Africans must recognise this situation so that necessary steps are taken to assess current and future demands for water. This will not be an easy task, but with the necessary resolve to plan and implement the required interventions, a secure water future can be achieved. NWRS2, 2013, page 4

4 Water security issues 3

5 Predicted total water withdrawals 4 (Source: Hedden, 2016)

6 Resilience-based water management 5 Evolution from the 1990s to present day realisation WSUD Blue water Sector approach dominated by economics and engineering, emphasis on supply IWRM / IUWM Integrated blue water An economic approach to freshwater including environmental flows SuDS Integrated blue and green water Adding land interactions, surface runoff and infiltration to food, energy, and ecosystem services Green and blue water with social and ecological interactions Resilience based, addressing the need to sustain rainfall, capture resource value, and cross scale interactions and feedbacks Adapted from Rockstrom et al., 2014

7 Diversifying household water sources 6 Precipitation Evapo-transpiration Rainwater Harvesting Groundwater Reduced Municipal potable water demand Greywater reuse Increased Infiltration Reduced volumes of runoff Reduced wastewater discharge Stormwater Harvesting

8 Greywater recycling 7 Source: Ana Delétic

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10 Household greywater system 9 Image from

11 Simple home-based greywater systems 10 Photos courtesy of Kevin Winter

12 Combined rain- and greywater harvesting 11

13 Greywater irrigation in rural areas 12

14 Greywater tower gardens 13

15 Draft National Sanitation Policy (2016) 14

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17 Quality issues 16

18 Greywater management in informal settlements 17

19 Greywater management in informal settlements 18

20 Project aims 19 Address (and mitigate) the risks associated with the management and use of domestic greywater, and support the wider uptake of this practice in South Africa, in order to realise diverse benefits such as: building resilience into the water supply system; managing water demand; reducing volumes of greywater to wastewater systems; reducing diffuse pollution loads from un-serviced settlements

21 Technical background report 20 Definition of terms and concepts Role of greywater management in water supply and food security Applicable regulations / policy / guidelines on greywater use and management Existing greywater use and management systems Recommendations for sustainable greywater use and management

22 Greywater guidelines 21 Greywater quantity / quality and fitness for use / application Managing risks and uncertainty in greywater use / reuse Use of greywater to supplement irrigation activities Greywater management options, including: treatment, disposal and reuse

23 Method 22 Compile relevant research findings Survey greywater system users at household scale Local and national stakeholder workshops Review of legislative and health aspects Focus group discussions Develop guideline document, including a simple operations and maintenance manual, as well as the strategic technical background document

24 Quantifying risk in a guideline Lloyd Fisher-Jeffes Greywater harvesting Workshop 1 18 April

25 Overview 24 We know greywater can be dangerous Micobiologically Chemically SA Water Quality Guidelines Old Generalised Relevance? New approaches to risk management DALY Is it easily understood? What parameters should we focus on Environmental Legal implications

26 Varying Quality of greywater 25 Reference Eriksson et al., 2003 Rose et al., 1991 Cassanova et al., 2001 Source Composite Shower Laundry wash Laundry rinse Composite Composite Concentration (mg/l unless otherwise stated) Range Range Range Faecal coliforms (CFU/100ml) Faecal Streptococci (Enterococci) (CFU/100ml) E. coli (CFU/100ml) < For formal fully serviced residential houses greywater in informal settlements will have very different characteristics

27 SAWQG Whats an appropriate standard? 26 According to the South African Water Quality Guidelines (DWAF, 1996), gastro-intestinal and other illnesses can be expected to rise when people are in contact with E. coli counts above 400 counts / 100 ml

28 Managing risk internationally 27 WHO Australian guidelines for water recycling

29 Can it work in SA? 28 What does a DALY mean? The disability-adjusted life year (DALY) is a measure of overall disease burden, expressed as the number of years lost due to ill-health, disability or early death. It was developed in the 1990s as a way of comparing the overall health and life expectancy of different countries.

30 Can it work in SA? 29 Typical reference microorganisms used by WHO include: Campylobacter - bacteria Rotavirus - viruses Cryptosporidium parvum - protozoa and helminths Some studies have used E.coli as a reference microorganism for bacteria Howard et al.

31 Greywater Harvesting Assessment Tool 30 GWRR = MAX UTR TRRS 1 + TRRS n +

32 Thematic mapping session Kirsty Carden Greywater harvesting Workshop 1 18 April

33 Timeline of greywater research 32

34 Legislative issues 33 What legislation is relevant? How important is a legislative framework? Should legislation be developed? What about enforcement? Are there any relevant building codes? What about plumbing sign-off on home-based systems?

35 Socio-cultural issues 34 Are socio-cultural-religious considerations important? What are the most important socio-cultural concerns? What are the most important influencers of social acceptance? Who are appropriate users? What are the likely behavioural impacts?

36 Appropriate applications / uses 35 What are appropriate uses? What are inappropriate uses? Is scale important when designing a greywater system? How do you decide which risk preventative barriers to adopt? Is greywater harvesting appropriate in both serviced and un-serviced settlements?

37 Health aspects 36 Is greywater a health risk? What are the pathways to infection? What preventative barriers are there? What about treatment options? Is hygiene education important?

38 Key design considerations 37 What are the key technical design considerations? Centralised or decentralised systems; i.e. scale? Are there specific considerations related to quantity and quality? Are there basic handling rules for greywater? What are the operation and maintenance issues? Is economic viability important? Are there potential impacts on other water services?

39 Risk Management / Quantification 38 Why have previous guidelines not been widely adopted? Are guidelines useful for managing risk? Is the WHO approach to risk management useful? What are the simplest ways to manage risk? Is the Greywater Harvesting Assessment tool a good idea in principle?

40 Thank you To add to the debate go to