BioSand Filters: Appropriate Household Water Treatment for Floating Villages in Cambodia

1. BSF NonBSF BioSand Filters: Appropriate Household Water Treatment for Floating Villages in Cambodia BSF Filter Water Lake Water Stored Water Lake Water Stored Water Lake December February February Lake Lake Curry, K.D.1, M. Morgan2, S. H. Peang2, S. Seang2 1: Bridgewater State University, Bridgewater, MA, USA 02325 2. Water for Cambodia, Siem Reap, Cambodia. December Lake BSF SW BSF BSF SW SW SW BSF Background and Overview Number (percent) of 40 BSF and 40 Non-BSF homes in Moat Khlain February 2011 assessed by WHO microbial risk categories for E. coli • Recent work done in Cambodia by Brown et al. (2007) and Liang et al. (2010) have documented ceramic water filters and biosand filters as cost effective point of use (POU) treatment systems capable of removing over 95% E. coli bacteria when properly used and maintained. • Water for Cambodia (WfC) constructs, installs and tests BSF’s in Siem Reap Province as part of their WASH outreach program and explored using BioSand filters (BSF) to provide microbiologically safe drinking water for people in the Moat Khla floating village community on the Tonle Sap Great Lake. • Moat Khla is a floating village in Siem Reap Province , where all 189 families use the natural lake/ river for their water source which by WHO standards is deemed unsafe. • *10 BSF’s installed January 2010; village members requested more. • WfC evaluated BSF’s in December 2010 and February 2011 comparing 40 families using BSF’s and 40 families not using BSF’s. • Turbidity in lake source water decreased in December, and mean bacterial levels increased from 550 CFU’s to over 1100 in February. • >90 % of both households types were using high risk lake source water (>100 CFU’s of E. coli bacteria per 100 ml) using WHO standard. • 5 % of BSF and 40% of Non-BSF household storage water had bacteria levels in the high risk range (> 100 E.coli per 100ml) indicating some source of recontamination . • Non-BSF households untreated storage water showed significant reduction in mean Log10E.coli levels compared to the lake source water. • Surveys revealed Non-BSF families use a wide range of treated and untreated sources for their drinking water showing wide variation in bacteria levels and the occurrence of diarrhea. • Recontamination occurred no matter the source or treatment. • Demand for BSF’s increased to over 80 by February 2011 even though a floating U.V. filtration system was available. • Removal effectiveness of BSF’s ranged 2.2 to 2.4 Log Reduction however recontamination of treated water illustrates that WASH education is essential no matter what water treatment and storage method is used for remote floating villages in Cambodia. E. coli levels in lake source water increased downstream in sample zones closer to the mouth of Moat Khla Location of Moat Khla Village Zones of Floating Houses in Moat Khla Lake Source E. coli and Turbidity Increase as Lake Level Drops from December to February More BSF homes Moved from High Risk to Low Risk than Non-BSF homes E. coli levels were significantly greater in lake water for homes in Zone 1 than Zone 4 Both BSF and Non-BSF homes had large variation in E.coli levels in their stored drinking water = Recontamination Objectives Non BSF Households used many types of source water for drinking all of which showed wide variability in E.coli levels even UV treated and filtered water , Boiled water, and filtered water = Recontamination Evaluate BSF’s as an effective treatment system to provide microbiologically safe drinking water for floating village communities on the Tonle Sap Great Lake. Compare bacteria levels in lake source and household storage water for families with and without BSF’s as a treatment for their drinking water. Confirm the removal efficiency of BSF’s where source water quality varies between the wet and dry season Compare E. colilevels in lake source water used by participating households between geographic zones in a 1 to 1.5 km area of Moat Khla Non BSF Lake & other BSF Lake BSF’s provide Low Risk Drinking Water ≥ 2.2 Log Reduction of E. coli by BSF in both periods BSF FW BSF HS nonBSF HS Non BSF Households suffered diarrhea even when water was boiled or filtered = Recontamination Methods Samples of source water, filtered water, and household storage water for BSF and Non-BSF households obtained during user surveys in December 2010 and February 2011 Processed E. coli samples by membrane filtration and incubation at 44.5 °C on modified m-Tech media for 22-24 hours using a HACH portable incubator on site. Turbidity levels evaluated using a HACH 2100P Turbidimeter. Means compared using independent t-tests or Mann-Whitney U depending on Kolmogorov-Smirnof test of normality within SPSS. Acknowledgements This study was made possible by the generous support of Bridgewater State University and the Middletown Rhode Island Rotary Club but most of all the tireless commitment of all the staff at Water for Cambodia.