Household water treatment and safe storage – effectiveness and economics. Drink. Water Eng. Sci. Discuss., 8, 143–176, 2015.

• Full text

Authors: S. M. L. Stubbé, A. Pelgrim-Adams, G. L. Szanto, and D. van Halem.

Household Water Treatment and safe Storage (HWTS) systems aim to provide safe drinking water in an affordable manner to users where safe piped water supply is either not feasible or not reliable. In this study the effectiveness, costs and cost drivers 5 of three selected HWTS systems were identified. The selected systems are SODIS, ceramic filter and biosand filter.

These options were selected based on their current usage rate, available scientific data, and future potential. Data was obtained through peer-reviewed literature, reports, web-pages and informal sources. The findings show a wide dispersion for log removal of effectiveness of the HWTS systems.

The reported costs of HWTS systems show a wide range as well. The price per cubic 15 meter water is found to be EUR 0–8 (SODIS), EUR 0.37–6.4 (ceramic) and EUR 0.08– 12.3 (biosand). The retail prices found are: negligible (SODIS), USD 1.9–30 (ceramic) and USD 7–100 (biosand). No relationship was observed between removal efficiency and economics of the three systems.

Biosand water filters for floating villages in Cambodia: safe water does not prevent recontamination. Journal of Water, Sanitation and Hygiene for Development, In Press, Uncorrected Proof © IWA Publishing 2015 | doi:10.2166/washdev.2015.120

• Order info

Authors: K. D. Curry, M. Morgan, S. H. Peang and S. Seang

Bridgewater State University, 131 Summer Street, Bridgewater, MA 02325, USA E-mail: kcurry@bridgew.edu. Water for Cambodia, Siem Reap, Cambodia Mahidol University, Bangkok, Thailand. Kulara Water Co. Ltd., Tbaeng Kaeut Village, Siem Reap Province, Cambodia

Water for Cambodia used biosand filters (BSFs) to provide microbiologically safe drinking water for people in Moat Khla floating village in 2010 and 2011. All 189 families use the lake, which by WHO standards is deemed unsafe for drinking water. Surveys from December 2010 to February 2011 compared 40 families using BSFs and 40 families not using BSFs. Over 92% of BSF households and 90% of non-BSF households were using high-risk lake source water (>100 colonies Escherichia coli/100 mL). Only 2.5% of BSF households had filtered water with bacteria in the high-risk range and only 5% of these 40 households showed recontamination in their storage water.

Forty percent of non-BSF households had high-risk bacteria levels in their stored water, and most used no treatment. Storage water for non-BSF families showed a significant reduction in mean log10 E. coli levels compared to their lake source water. Stored water for non-BSF families showed recontamination even for UV-treated water and boiled river water. Recontamination occurs in both groups but is much less for BSF households highlighting the value of proper storage containers used by BSF households and the need for water and sanitation education for floating villages in Cambodia.

The effect of increasing grain size in biosand water filters in combination with ultraviolet disinfection. Journal of Water, Sanitation and Hygiene for Development, Vol 4 No 2 pp 206–213

• Abstract/order info

This paper is in the public domain: verbatim copying and redistribution of this paper are permitted in all media for any purpose, provided this notice is preserved along with the paper’s original DOI. Anyone using the paper is requested to properly cite and acknowledge the source as Journal of Water, Sanitation and Hygiene for Development 4(2), 206–213. doi:10.2166/washdev.2013.171

Authors: Timothy E. Frank, Matthew L. Scheie, Victoria Cachro and Andrew S. Muñoz
2354 Fairchild Drive Suite 6J-117, USAF Academy, CO 80840, 01-719-660-6903, USA E-mail: tefrank18@gmail.com

With sand less than 0.70 mm often difficult to source in the field, it is of interest to study larger grained sand for use in biosand water filters (BSF). This study examined how sand grain size affects biological sand water filtration and how the combination of biological sand filtration and ultraviolet (UV) disinfection affects drinking water quality. Two BSFs were built: a control with maximum grain size, dmax = 0.70 mm and an experimental with grain sizes ranging from 0.70 mm to dmax = 2.0 mm. Untreated water was passed through each BSF daily. Results show Escherichia coli and turbidity removal characteristics of the control and experimental BSFs were not significantly different from one another. Both BSFs produced water that met World Health Organization (WHO) drinking water guidelines for turbidity, and although E. coli reduction was over 98% for each BSF, a high initial bacteria concentration resulted in effluent levels above WHO guidelines. Subsequently, effluent from each BSF was placed in clear plastic bottles under UV light, after which water from each BSF met E. coli guidelines. The data yielded promising results for using larger sand in BSFs, but longer duration studies with more data points are needed.

Designing Programme Implementation Strategies to Increase the Adoption and Use of Biosand Water Filters in Rural India. Water Alternatives, 7(2) 2014.

• Full text, pdf

Authors: Tommy K.K. Ngai. Centre for Affordable Water and Sanitation Technology (CAWST), Calgary, Alberta, Canada; tngai@cawst.org

Richard A. Fenner. Centre for Sustainable Development, Department of Engineering, University of Cambridge, Cambridge, England; raf37@cam.ac.uk

Abstract: Low-cost household water treatment systems are innovations designed to improve the quality of drinking water at the point of use. This study investigates how an NGO can design appropriate programme strategies in order to increase the adoption and sustained use of household sand filters in rural India. A system dynamics computer model was developed and used to assess 18 potential programme strategies for their effectiveness in increasing filter use at two and ten years into the future, under seven scenarios of how the external context may plausibly evolve. The results showed that the optimal choice of strategy is influenced by the macroeconomic situation, donor funding, presence of alternative options, and the evaluation time frame.

The analysis also revealed some key programme management challenges, including the trade-off between optimising short- or long-term gains, and counter-intuitive results, such as higher subsidy fund allocation leading to fewer filter distribution, and technology advances leading to fewer sales. This study outlines how an NGO can choose effective strategies in consideration of complex system interactions. This study demonstrated that small NGOs can dramatically increase their programme outcomes without necessarily increasing operational budget.

Chapter 42: Global review of the adoption, use, and performance of the biosand filter
Chapter 43: Recent advances in household biosand filter design

Authors: Tommy Ngai and Derek Baker, CAWST.

• The chapters appear in a text book “Progress in Slow Sand and Alternative Biofiltration Processes: Further developments and applications” by the International Water Association Publishing, 2014. London, UK.
• Order info - http://www.iwapublishing.com/template.cfm?name=isbn9781780406374

Biological Sand Filters: Low-Cost Bioremediation Technique for Production of Clean Drinking Water. Current Protocols in Microbiology, May 2014.

• Full text

Michael Lea

The burden of microbiologically contaminated water is borne most heavily by the rural (largest, 80%) and peri-urban (fastest-growing) populations without access to safe water in developing countries—all need microbiologically clean water to sustain their lives and secure their livelihoods.

There is conclusive evidence that biological sand (biosand) filters are capable of dramatically improving the microbiological quality of drinking water. Biosand filters are based on a centuries-old bioremediation concept: water percolates slowly through a layer of filter medium (sand), and microorganisms form a bacteriological purification zone atop and within the sand to efficiently filter harmful pathogens from microbiologically contaminated water. Household-scaled biosand filters are a small adaptation of traditional large, slow sand filters such that they can uniquely be operated intermittently.

To use the simple, yet effective, on-demand biofiltration intervention, a person simply pours contaminated water into the household biosand filter and immediately collects treated water.

The purpose of the following comprehensive protocols is to facilitate knowledge transfer with the goal to empower vulnerable, poorest-of-poor populations in rural and peri-urban communities of developing countries, and to also promote using naturally occurring biology and readily available materials that they already possess as a cost-effective practical approach to combat poverty and inequality and achieve the health benefits of safe water by developing their own household water security solutions.

This paper is in the public domain: verbatim copying and redistribution of this paper are permitted in all media for any purpose, provided this notice is preserved along with the paper’s original DOI. Anyone using the paper is requested to properly cite and acknowledge the source as Journal of Water, Sanitation and Hygiene for Development 4(2), 206–213. doi:10.2166/washdev.2013.171 | (Order info)

The effect of increasing grain size in biosand water filters in combination with ultraviolet disinfection

Timothy E. Frank, Matthew L. Scheie, Victoria Cachro and Andrew S. Muñoz

2354 Fairchild Drive Suite 6J-117, USAF Academy, CO 80840, 01-719-660-6903, USA E-mail: tefrank18@gmail.com

With sand less than 0.70 mm often difficult to source in the field, it is of interest to study larger grained sand for use in biosand water filters (BSF). This study examined how sand grain size affects biological sand water filtration and how the combination of biological sand filtration and ultraviolet (UV) disinfection affects drinking water quality. Two BSFs were built: a control with maximum grain size, dmax = 0.70 mm and an experimental with grain sizes ranging from 0.70 mm to dmax = 2.0 mm. Untreated water was passed through each BSF daily. Results show Escherichia coli and turbidity removal characteristics of the control and experimental BSFs were not significantly different from one another. Both BSFs produced water that met World Health Organization (WHO) drinking water guidelines for turbidity, and although E. coli reduction was over 98% for each BSF, a high initial bacteria concentration resulted in effluent levels above WHO guidelines. Subsequently, effluent from each BSF was placed in clear plastic bottles under UV light, after which water from each BSF met E. coli guidelines. The data yielded promising results for using larger sand in BSFs, but longer duration studies with more data points are needed.

MS2 Bacteriophage Reduction and Microbial Communities in Biosand Filters. Environ Sci Technol. 2014 Jun.

• Order info

Wang H, et al.

This study evaluated the role of physical and biological filter characteristics on the reduction of MS2 bacteriophage in biosand filters (BSFs). Three full-scale concrete Version 10 BSFs, each with a 55 cm sand media depth and a 12 L charge volume, reached 4 log10 reduction of MS2 within 43 days of operation. A consistently high reduction of MS2 between 4 log10 and 7 log10 was demonstrated for up to 294 days. Further examining one of the filters revealed that an average of 2.8 log10 reduction of MS2 was achieved within the first 5 cm of the filter, and cumulative virus reduction reached an average of 5.6 log10 after 240 days. Core sand samples from this filter were taken for protein, carbohydrate, and genomic extraction. Higher reduction of MS2 in the top 5 cm of the sand media (0.56 log10 reduction per cm vs 0.06 log10 reduction per cm for the rest of the filter depth) coincided with greater diversity of microbial communities and increased concentrations of carbohydrates.

In the upper layers, “Candidatus Nitrosopumilus maritimus” and “Ca. Nitrospira defluvii” were found as dominant populations, while significant amounts of Thiobacillus-related OTUs were detected in the lower layers. Proteolytic bacterial populations such as the classes Sphingobacteria and Clostridia were observed over the entire filter depth. Thus, this study provides the first insight into microbial community structures that may play a role in MS2 reduction in BSF ecosystems. Overall, besides media ripening and physical reduction mechanisms such as filter depth and long residence time (45 min vs 24 ± 8.5 h), the establishment of chemolithotrophs and proteolytic bacteria could greatly enhance the reduction of MS2.

Biosand Filter Performance: The Multi-Faceted Aspects of Poverty Observed in Sisit, Kenya, 2014.

• Full text

Authors: E. Davis Lacey, Laura W. Lackey

The purpose of this research endeavor was to examine how various technical, geographical, and socioeconomic parameters affected biosand filter (BSF) performance in Sisit, Kenya. In 2010, Mercer students installed 25 BSFs throughout the village of Sisit. As part of the 2012 Mercer on Mission trip to Sisit, each previously installed filter’s performance parameters (flow rate, % coliform removal, etc.) were compared to respective distances, populations, and levels of affluence. Analysis illustrated that the distance between a household and the community center is highly correlated to various aspects of BSF performance. A relationship was also shown to exist between a BSF’s coliform removal efficiency and the distance between the associated household and water collection point.

Intermittent versus continuous operation of biosand filters. Water Research, Feb 2014.

• Order info/Authors

Candice Young-Rojanschi, et al.

Highlights

• Biosand columns were operated either continuously or intermittently.
• Continuous operation of biosand filters is more effective at removing Escherichia coli and MS2.
• E. coli removal occurs during the pause period throughout the filter, up to 20 h.
• Anoxic conditions can occur within the first 10 cm of filter media in intermittenly operated filters.
• Hydraulic conductivity decreased at all media depths over the experimental period.

The biosand filter is a household-scale point-of-use water filtration system based on slow sand filtration, but modified for intermittent operation. Studies on slow sand filters show that intermittent operation reduces filter effectiveness. However, continuous versus intermittent operation of biosand filters has never been compared. Eight 10-cm diameter columns were constructed to represent field biosand filters. Five were operated intermittently with a 24-h residence period, while the remaining three were operated continuously. Continuous operation of the filters resulted in significantly better reduction of Escherichia coli (3.71 log₁₀versus 1.67 log₁₀), bacteriophage MS2 (2.25 log₁₀ versus 0.85 log₁₀), and turbidity (96% versus 87%). Dissolved oxygen levels at 5 and 10 cm of media depth in intermittent filters reached an average of 0 mg/L by 24 h of residence time on day 60 of the experiment. A simple numerical model was developed to describe E. coli removal during ripening from days 0–58 for continuously operated versus intermittent filters. This research confirms that although biosand filters were developed for intermittent operation, the filters perform significantly better when operated continuously. However, both operational modes resulted in a significant reduction of microbial indicators.