Grantee Research Project Results
Final Report: Community-Level Water Disinfection Technology for Dhaka, Bangladesh
EPA Grant Number: SU835313Title: Community-Level Water Disinfection Technology for Dhaka, Bangladesh
Investigators: Davis, Jennifer , Cooke, Keegan G. , Luby, Stephen P , Crider, Yoshika S. , Pickering, Amy , Marshman, Elizabeth , Mansouri, Nabil
Institution: Stanford University
EPA Project Officer: Hahn, Intaek
Phase: I
Project Period: August 15, 2012 through August 14, 2013
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2012) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Safe and Sustainable Water Resources , P3 Awards , Sustainable and Healthy Communities
Objective:
Around the world, 798 million people lack access to what are considered safe sources of water. However, the criterion for safety uses infrastructure type as a proxy for safety, rather than assessment of actual water quality. In urban areas of the developing world, 80% of the population utilizes piped water (UNICEF, 2012), considered a safe source when measuring progress in the population accessing safe water. In reality, millions of these individuals are accessing water sources that fail to meet World Health Organization (WHO) safe drinking water standards because of contamination in leaky distribution networks, placing them at serious risk for diarrheal illness. To put this growing problem in context, it is estimated that half of the world's population will live in urban settings by 2033. The majority of them will be poor (UN-HABITAT, 2003). Developing-world governments with limited resources will face increasing pressure to provide reliable and safe supplies of water.
Numerous attempts have been made to address this issue of urban water quality, but these actions have focused primarily on two approaches: city-level centralized facilities, which treat water prior to distribution; or on household-level point-of-use (POU) technologies used by consumers prior to consumption. However, evidence strongly suggests that these solutions are inadequate to sufficiently address the problem at hand. Centralized facilities are enormously expensive, not only to build but also to properly maintain central treatment plants and vast distribution networks, and POU technologies face low rates of use due to required changes in behavior. One notable gap in water disinfection approaches comes at the community level. Approximately 2.3 billion people around the world use shared water points, where disinfection could occur after water travels through a distribution network but before it is collected by users. This gap presents a clear opportunity for technology innovation.
As the second fastest growing city in the world with more than 20% of its 15 million residents living in slums, Dhaka, Bangladesh, is emblematic of the challenges that resource-constrained governments face in providing rapidly expanding populations with safe water supplies. While many areas have piped water delivered to community standpipes, the water becomes contaminated as it travels through an unpressurized and permeable distribution network, and residents of low-income areas are not accessing clean water. The majority of these low-income residents utilize shared water points.
Our objective was to develop an innovative community-scale technology to disinfect drinking water in Dhaka, Bangladesh, that is low cost, requires minimal behavior change, and is easily scalable. During Phase I, we designed a new automatic chlorine dispenser and evaluated both performance and acceptance in Dhaka slum compounds through a household pilot study with our partner organization icddr,b (International Center for Diarrheal Disease Research, Bangladesh). Both performance and acceptance results from this pilot study are extremely promising. While Dhaka is our starting point, representing the typical challenges of low-income urban centers around the world, we ultimately hope to scale this technology to reach millions of low-income urban residents throughout the developing world.
Summary/Accomplishments (Outputs/Outcomes):
An automatic chlorination technology was developed and extensively tested both in the lab at Stanford and in the field at handpumps in Dhaka. After field verification, ten devices were installed at shared handpumps in Dhaka slum compounds. Compound households with children under 5 were regularly surveyed for 3 months to assess water quality and user satisfaction of the technology. Compounds were randomly assigned to one of three treatment groups: (1) to receive an automatic chlorine doser installed directly on the compound’s standpipe with fixed chlorine dosing, (2) Aquatab point-of-use water treatment (chlorine tablets) with safe water storage, or (3) control (no intervention). We chose to compare effectiveness of our device to Aquatabs, one of the most popular POU treatments, in order to verify that a community-scale approach could be comparable to or better than POU approaches. Water samples were collected regularly and tested for E.coli and total coliform CFUs per 100 mL using membrane filtration and MI media, to test effectiveness of the device at improving microbial water quality. Survey results indicate that the technology delivered chlorine residuals within a safe and effective range and improved water quality of stored drinking water.
Our preliminary analysis of data collected 3 months post-installations found that 85% of households with access to the automatic-chlorine doser had a free chlorine residual over 0.2 ppm in their stored drinking water, compared to 53% of households receiving Aquatabs, and 0% of control households. Among those water samples with detectable chlorine, the mean free chlorine concentration was 0.7 ppm among automatic chlorination compounds and 1.7 ppm among Aquatab households. These results align with our expectations for the automatic chlorine doser to provide chlorine residuals between 0.5 ppm and 1.5 ppm at the start of storage times. We also found that the presence of E. coli contamination was least likely among households with access to automatic chlorination, as compared to Aquatab and control households. There was a statistically significant higher proportion of households free from E. coli contamination in the auto-chlorination group (85%) compared to the control group (46%), where there was no significant difference in stored water E. coli contamination between Aquatab and control households.
A total of 70% of households accessing automatically chlorinated water reported to be satisfied with their water supply and treatment services, while 83% of Aquatabs households reported that they were satisfied with their water supply and treatment services. We hypothesize that the Aquatabs users may have been more satisfied due to the high quality storage container they received as part of the intervention, a benefit that was not distributed to automatic-chlorine users. Satisfaction with taste was similar across groups, while satisfaction with smell was higher among Aquatabs households. When asked how difficult they perceived the water treatment product was to use, half of automatic- chlorination households reported that the doser was “very easy” to use, while only 3% of Aquatabs households gave this response.
User feedback is being incorporated into an iterative design process in the lab in preparation for a future round of field-testing. Nine first round prototypes are still functioning in the field, with performance being carefully monitored. Significant progress has been made on a second round improved prototype that will be tested in the field in coming months.
Conclusions:
We were able to design, prototype, and field test a new community-scale technology for treating water in Dhaka. Our partnership with icddr,b allowed us to not only establish proof-of concept for this technology, but also to assess user perceptions and impacts of real use in the field. We found that our device was able to deliver a safe chlorine residual and significantly improved water quality, as compared to households with no device and those receiving a point-of-use water intervention. In addition, our devices have been able to function over a period of 4 months and households have expressed high satisfaction. These results indicate both that the technology is significantly improving water quality and that a community-scale approach may be more effective than traditional POU approaches. Our team is now prepared to take the technology to the next phase of development, as well as to begin exploring and testing practical and long-term fee recovery strategies.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
Other project views: | All 2 publications | 2 publications in selected types | All 2 journal articles |
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Crider Y, Sultana S, Unicomb L, Davis J, Luby S, Pickering A. Can you taste it? Taste detection and acceptability thresholds for chlorine residual in drinking water in Dhaka, Bangladesh. SCIENCE OF THE TOTAL ENVIRONMENT 2018;613-614:840-846 |
SU835313 (Final) |
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Pickering A, Crider Y, Amin N, Bauza V, Unicomb L, Davis J, Luby S. Differences in Field Effectiveness and Adoption between a Novel Automated Chlorination System and Household Manual Chlorination of Drinking Water in Dhaka, Bangladesh: A Randomized Controlled Trial. PLOS ONE 2015;10(3):e0118397 |
SU835313 (Final) |
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Supplemental Keywords:
drinking water, disinfection, water purification technologies, Dhaka, Bangladesh, chlorineRelevant Websites:
Stanford Dhaka Water Project | Bangladesh ExitThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.