Estimates of Unsafe Return of Human Excreta to the environment. Presented by Dr Musa Manga, on behalf of the team at UNC Water Institute

Transcription

1 Estimates of Unsafe Return of Human Excreta to the environment Presented by Dr Musa Manga, on behalf of the team at UNC Water Institute

2 Evolution and Range of Activities Phase I Origin: SDG language of safely managed waste what does this mean, how measured? A. National Estimates from JMP data Split san stats into pit latrine, septic tank, and sewer Follow crap through containment, emptying, transport, treatment and disposal Estimate % of hazard removed (incl through dieoff) at each stage Models calibrated and tested by local experts in Sénégal, Mozambique, Ghana and Indonesia Spreadsheets now cleaned-up, ready for circulation

3 Evolution and Range of Activities (cont d) B. Defining and Modelling Hazard and san technology (Lisa Fleming) Hazard risk Hazard is potential Burden of Disease but does not reflect exposure Hazard in waste changes over time and/or with treatment Not all pathogens are alike Die-off time Pathogenic load in waste and infectious dose Burden of disease Arrived at a weighted sum of pathogens, each with their own characteristics Modelled pathogen die-off and hazard reduction in a pit latrine What about in septic tanks? Biological treatment?

4 Lessons from Phase I Not enough data (of all kinds!) to go very far beyond common sense a lot of assumptions All sanitation is local national averaging difficult (Phase II focused on specific sites) Inverse hierarchy of technology In general Latrines leak less hazard than septic tanks, which leak less than sewers. (can discuss!)

5 Phase II:- Establish field validity of faecal and pathogen hazard concept - Identify leaks to environment (as in SFD) - Get baseline measurements of pathogen concentrations/load in these leaks/ sanitation outflows... Our big research questions :- a) How many faecal pathogens are being released to the community environment by key excreta return pathways along the sanitation chain? b) To what extent do common sanitation technologies inactivate pathogens in faecal waste before release to the environment?

6 Identified communities for field validity of faecal and pathogen hazard concept INDIA Study area: Trichy (TCC) and Coimbatore (NNP), Tamil Nadu,India

7 Data Collection methods Key Informant interviews with the sanitation service providers along the sanitation chain Community Transect walks Structured Observational surveys Sanitation technology users survey conducted on users and owners of the sanitation technologies enrolled in the study Field measurements/ environmental sampling the different sanitation technologies in the study community.and identified sanitation outflows/ leaks

8 FULLY LINED TANT NO OUTLET FULLY LINED TANT WITH NOWITH OUTLET Field measurements:- Sanitation technologies encountered in the study areas FULLY LINED TANKWITH OVERFLOW TO OPEN DRAIN FULLY LINED TANKWITH OVERFLOW TO OPEN DRAIN Community Toilet Facility Toilet Facility Toilet Facility Toilet Toilet Facility Facility Fully lined tank Supernatant Supernatant Fully Lined TankEffluent to Open Drain Fully Lined Tank Directionof offlow Flow Direction Direction of Flow Direction of Flow Effluent to Open Drain Fully lined tank Effluent to Open Drain Fully lined tank Supernatant Supernatant Sludge TANKWITH OUTLETTO OPEN LAND Sludge Toilet Facility Sludge Sludge HouseholdTank with FULLY LINEDTANKWITHOVERF LOWTOTHE RIVER no outlet sludge Fully lined tank DIRECT DISCHARGE sludge Supernatant (BLACKWATER DISCHARGINGTO OPEN Effluent To DRAIN) Open Land Household- Tank with outlet to open drain Toilet Toilet Facility DIRECT DISCHARGE Fully lined tank DIRECT DISCHARGE (BLACKWATER DISCHARGINGTO OPEN DRAIN) (BLACKWATER DISCHARGINGTO OPEN DRAIN) Effluent totheriver TANKWITH NO OUTLET Facility TANKWITH NO OUTLET Supernatant sludge Toilet Facility Community Toilet Facility Community Toilet Facility Toilet Facility Direction offlow Black water pipe to Open Black water pipedrain to Open Drain Black water pipe to Open Drain Fully lined tank Fully lined tank Open Drain Sludge Open Drain Household -Tank with outlet to river or open land Open Drain Blackwater pipes to open drain

9 Field measurements:- Sampling sites identified in the study communities More Sanitation technologies Underground drainage/ sewerage system Lined pits with semi-permeable walls and open bottom Lined tanks with open bottom Open drains Emptying and transportation operation Decanting stations Wastewater/ faecal sludge treatment plants Illegal damp sites, faecal sludge re-use sites

10 Sample collection: Blackwater pipes and Underground drainage Sample collection from blackwater pipes (using flexible bags -1000g polythene bags) Underground drainage points associated with overflows/ blockages

11 Field measurement/ Sample collection:- Containment systems Accessing containment systems Physical measurement of the containment systems.. Inspection of the tanks interior for position of pipes, tank design and condition assessment Samples collected: Effluent content or Supernatant & Faecal sludge from the bottom On-site measurements (ph and temperature) (Hanna HI98127) Samples collected were analysis for: Pathogens [E.coli; Helminth eggs (USEPA 2003)] Enteric viruses (Rotavirus, Norovirus, etc.) using Molecular Analysis -TAC method (For future Analysis) Physical parameters (Total solids, Suspended solids, Total Volatile solids (APHA-AWWA-WEF. 2005) Flow measurements

12 Preliminary findings Key Informant interviews: Decanting stations frequently overflow due to power outages or maintenance shutdowns of downstream sewer lines. Sewer blockages and overflow are common, and may be attributable to people flushing trash or other non-biological wastes Community Transect walks: More pathogen and faecal hazards were identified along the transect walks in Trichy than in Coimbatore. Observational surveys: Wrong emptying practices especially for community toilets containment systems Of the systems equipped with overflows, most discharged directly into an open drain, open ground and streams. Fresh faecal matter was observed in the effluent from containment systems of community toilets.

13 Preliminary Findings Cont d 95% of observed systems had straight inlet and outlet pipes Configuration of inlet and outlet pipes was often not as expected for instance, inlet and outlet pipes on the same wall of the tank or close to each other. high risk of short-circuiting No properly designed septic tank was encountered in the study area.. they are simply fully-lined tanks Significant spills occur during discharging /unloading of faecal sludge at the decanting station Sanitation technology User s Survey:- In the rainy season, tanks with overflow pipes to open drains easily get flooded with storm water 90% of the containment systems of the community toilets are emptied weekly 80% of Household containment systems are emptied 8 months - 2 years

14 Preliminary results:- Pathogen load in the Effluent/ Supernatant of Sanitation technologies Highest E.coli pathogens.. In black pipes content and effluent from the community toilets containment systems Content sampled from sewerage system overflow points or points frequently associated with blockages contained lowest E.coli pathogens compared to other sanitation technologies. Due to the dilution effect,. sewerage systems receives both the grey water and black water Households connected to the sewerage system use considerable high volumes of water for flushing. The low E.coli pathogens in the sewer system can also be attributed to the time of sampling Helminth eggs results and other Microbiological Data:- Coming out Soon!!!

15 Conclusions/ Takeaways The range of sanitation technologies encountered in the field is broader than the conventional understanding might suggest,...and it is likely that microbiological performance will vary in kind. Septic tanks are not septic tanks, but are diverse forms of fully-lined tanks, of uncertain "performance Shit flow is not equivalent to Pathogen flow nor does it fully capture faecal hazard flow... because of binary nature of shit flow, which is not quantitative. Faecal sludge characteristics reported as liquidish. with about 2-3%TS.are often wrong because of the wrong emptying practices especially for community toilets containment systems Trichy (TCC) authorities are interested in our results and pathogen flow approach if sanitation is about public health we need to follow the pathogens------where do they leak to environment, in what magnitudes?

16 Bill & Melinda Gates Foundation (sponsor) JW Rosenboom UNC Team Professor Jill Stewart (PI) Professor Pete Kolsky (Former PI) Dr Musa Manga (Lead Researcher) Professor Jamie Bartram (Co. PI) Lisa Fleming, David Holcomb, Beverly Medina (Graduate Assistant) Leeds (collaborator, indep t contractor) Professor Barbara Evans/Andy Peal team developed and published on SFD. Andy advised WHO on SFD fit into MDG monitoring IIHS (collaborator) Urban planning education/training group involved in sanitation planning in Tamil Nadu. Local partner IIHS tremendous facilitation /support/ engagement Very practical, open. PSG (lab resources) Acknowledgments Run a microbial reference lab in Tamil Nadu (. Strong Cooperation from RTI)

17 Thank you for listening!!!

18 Modelling fecal pathogen flows and health risks in urban environments to inform sanitation planning UNC Water & Health Conference 2018 Freya Mills Prof. Juliet Willetts Institute for Sustainable Futures isf.uts.edu.au

19 Key messages 1. Public health risks need to be better taken into account in deciding between sanitation improvement options 2. Using a source-pathway-receptor conceptual approach, it is possible to estimate the pathogen flows across a city, exposure to these pathogens and related health risks 3. Comparing options on the basis of relative health risk may point us to different sanitation solutions as compared with commonly assumed solutions UTS:ISF

20 Why pathogen flows in matter for developing country cities Poor management of sanitation Failures across the service chain release untreated faecal waste into the environment High number of infectious pathogens Pathogens excreted in high numbers Numerous and varied types Persist in the environment Unsafely discharged Safely managed SFD Promotion Initiative 2017 Household Community City Downstream Connected but unclear exactly how Shigella Campylobacter Salmonela V. cholerae Gardia E.Coli - EPEC E.Coli - ETEC Hookworm Ascaris Schistosoma Cryptosporidium Norovirus Sapovirus Entamoeba Adenovirus Rotavirus Trichuris UTS:ISF

21 However, investments rarely consider pathogen flows Current decisions often based on: Capital cost Assumed benefits of individual technologies or practices Environmental discharge standards Protection of downstream environment Rather than an understanding of: Where the most significant public health risks lie? What failures in sanitation systems or services are the source of pathogens? Which improvement options will best address these? UTS:ISF

22 Urban sanitation planning raises many questions about how we protect public health Which option: Will a regular desludging program reduce health risks? Or do we need to also improved containment? Which exposures to pathogens are most significant in terms of the health risks (in waterways, groundwater, food, etc.)? Which of the unsafe flow paths or which faecal waste discharges are of most concern? With limited resources, what data should be collected if we want to find out how to best improve health outcomes? UTS:ISF

23 Aim: to build on existing data, tools and knowledge to develop an approach to inform sanitation options Sanitation tools: Various mapping and assessment tools exist which assess the status of the sanitation service chain or unsafe discharge of faecal waste. Health and exposure: GWPP compilation of pathogen data and knowledge plus various tools to inform exposure and health risk assessments. Sanitation options: Increased consideration of the need to consider a range of sanitation solutions across the service chain and the multiple objectives or cross cutting benefits of sanitation investments. UTS:ISF

24 1. Developed a conceptual approach to bring together sanitation and health assessments to inform decision making 1. Set up the system, assess the faecal waste pathways and identify exposure points Input Data - Pathogen load - Local Data: - Sanitation types - Wastewater flows - Service chain status - Drainage/flooding - Soil/groundwater - Prevalence of disease 2. Calculate pathogen load and flows along the service chain Input pathogen log reduction for system and flow paths, consider type and performance. Add dilution based on local conditions 3. Calculate pathogen concentrations from various flows at each exposure point House Environment Groundwater/well Local drain/canal Receiving waterway Agriculture Reuse Empty fields Validate with literature or local data to adjust model Findings from most significant exposure pathways can inform initial sanitation improvement options to be assessed 4. Calculate the relative heath risk for each exposure point Input exposure quantity, frequency and population exposed suitable to local context. Apply dose-response models, illness/infection and DALY ratios from literature. 5. Develop and test improvement options considering the service chain and compare with base case Model new scenarios by changing setup or inputs and compare the change in health risks with base case UTS:ISF

25 2. Applied the approach to a hypothetical example Toilet to sewer/drain HOUSEHOLD Ie. 1 household Closed Sewer LOCAL AREA Ie. 10 households NEIGHBOURHOOD Ie. 50 households Wastewater Treatment Plant CITY/DOWNSTREAM Ie. 500 households Toilet to septic tank Emptied Sludge Not emptied (Stored) Open Drain Drinking, washing Local Drain Children playing Leaking Drinking, washing Flooding Large Drain/River Hands, fomite Dump in river Washing, bathing, recreation Not treated Receiving waterway Untreated sludge reuse Agriculture Reuse Manual emptying Taken away Image - Mills et al 2018 Dump on site Hands, fomite, flies Other sanitation types, flow paths and exposures can be included Sludge Treatment Plant Untreated sludge to field Empty fields UTS:ISF

26 Household Environment Groundwater Local Drain Community Drain Downstream Waterway Fresh Produce Downstream Environment TOTAL 3. Developed and tested improvement options Sanitation improvement option 1a. Reduce leakage from sewer and drain into groundwater (as 25% population assumed to use groundwater daily for drinking) 1b. Reduce groundwater use for drinking by half by providing an alternative water supply 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 2. Cover local drains 0% 0% 0% 0% 0% 0% 3a. Toilet and septic tank effluent to sewer (not drain) 0% 0% 0% 3b. Improve conveyance (reduce flooding and leakage) 0% 0% 3c. Increase sewer discharge that reaches treatment plant 0% 0% 0% 0% 0% 3d. Improve wastewater conveyance (3a, 3b and 3c) 0% Improvement Small change from base case High change Worsen health risk 4a. Increase sludge emptying 0% 0% 4b. Increase sludge emptying and its delivery to sludge treatment plant 0% 0% 5. Improve faecal sludge treatment and wastewater treatment 0% 0% 0% 0% 0% 6. Cover drains, reduce groundwater use, discontinue reuse of untreated sludge and wastewater for food production 0% 0% UTS:ISF

27 Key limitations and uncertainties remain Preliminary model phase only Preliminary stage for demonstrating use of the conceptual approach Validation and sensitivity testing needed Trade offs complexities vs ease of use for practitioners. Does not yet include time and spatial considerations Research data gaps and uncertainties Empirical research on the impact of sanitation improvements on pathogen discharge Fate of different pathogens in urban environments and treatment technologies Further application of emerging methods to monitor multiple pathogens in the environment (e.g. qpcr) particularly in developing country contexts Develop improved decision making frameworks to support multiple objectives: economic, health, environment UTS:ISF

28 What was achieved and where to next Modelling provides a way forward in the face of data constraints that are typical in developing country urban contexts. Highlights the need to widen our consideration of health risks and exposure and to consider how to prevent pathogen entry to the environment. Further empirical research in specific locations is now required to refine the approach and address data gaps UTS:ISF

29 Thank you Freya Mills Prof. Juliet Willetts Paper: Mills, F., Willetts, J., Petterson, S., Mitchell, C., & Norman, G. (2018). Faecal Pathogen Flows and Their Public Health Risks in Urban Environments: A Proposed Approach to Inform Sanitation Planning. International journal of environmental research and public health, 15(2), 181. Institute for Sustainable Futures isf.uts.edu.au