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

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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.

Morphology, composition and performance of a ceramic filter for household water treatment in Indonesia. Water Practice & Technology Vol 10 No 2 pp 361–370 © IWA Publishing 2015 doi:10.2166/wpt.2015.044.

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Authors: K. Matthies, H. Bitter,  et al.

People in rural developing areas often depend on point-of-use water treatment for safe drinking water. A very popular and efficient technology for this is the use of ceramic filters, as promoted by the non-governmental organization Potters for Peace. These filters are already used in many countries worldwide, including Indonesia, where they are manufactured in Bandung, Java by Pelita Indonesia. The filters are made of local clay and combustible material, and coated with silver after firing. However, data available on them are very scarce. The structure, composition, and physico-chemical and microbiological performance of the filter were examined. Pore sizes mostly ranged from 1 to 40 µm and flow rate was about 1.3 L/h. Silver, arsenic and manganese were leaching from the filter in remarkable concentrations. While values for silver were about 0.01–0.02 mg/L, manganese was washed out after a few liters and leaching of arsenic fell below 0.02 mg/L after filtering some liters. With a log reduction of 3–5, efficiency in bacteria reduction was satisfactory in contrast to virus removal which was not sufficient according to the World Health Organization guidelines, with a log reduction below 1.

Silver Dissolution and Release from Ceramic Water Filters. Env Sci Tech, June 2015.

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Authors: Anjuliee M. Mittelman, Daniele S. Lantagne, Justine Rayner, and Kurt D. Pennell

Application of silver nanoparticles (nAg) or silver nitrate (AgNO3) has been shown to improve the microbiological efficacy of ceramic water filters used for household water treatment. Silver release, however, can lead to undesirable health effects and reduced filter effectiveness over time. The objectives of this study were to evaluate the contribution of nanoparticle detachment, dissolution, and cation exchange to silver elution, and to estimate silver retention under different influent water chemistries. Dissolved silver (Ag+) and nAg release from filter disks painted with 0.03 mg/g casein-coated nAg or AgNO3 were measured as a function of pH (5–9), ionic strength (1–50 mM), and cation species (Na+, Ca2+, Mg2+).

Silver elution was controlled by dissolution as Ag+ and subsequent cation exchange reactions regardless of the applied silver form. Effluent silver levels fell below the drinking water standard (0.1 mg/L) after flushing with 30–42 pore volumes of pH 7, 10 mM NaNO3 at pH 7. When the influent water was at pH 5, contained divalent cations or 50 mM NaNO3, silver concentrations were 5–10 times above the standard. Our findings support regular filter replacement and indicate that saline, hard, or acidic waters should be avoided to minimize effluent silver concentrations and preserve silver treatment integrity.

Effect of common rooftop materials as support base for solar disinfection (SODIS) in rural areas under temperate climates. Solar Energy, May 2015.

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Authors: M. Vivaa, M. Fuentes, J. Castro, R. García-Pacheco

Highlights

• Metal roofing and bamboo vegetable cover were studied as support materials for SODIS.
• Metal covers enhance SODIS due to high reflectivity & heat transfer properties.
• Maximum water temperatures differences in the bottles were of about 2.5 °C.
• SODIS processes starting at midday achieved faster inactivation.

Two common rooftop materials easily found in rural areas – zinc-coated metal sheet and bamboo cover – were studied to analyse their possible influence in the solar disinfection process by affecting the received UV radiation and water temperature in SODIS plastic bottles. The objective is to use available local materials to enhance the process while reducing the extra energy usage required for the manufacturing of new ad-hoc systems.

Experiments were conducted at a temperate climate, 40 °N latitude, over different seasons of the year. Escherichia coli and total coliforms disinfection processes were studied. Results show that in most cases the bottles over the zinc-coated metal roofing material reached an inactivation level of 1-log higher than those on the bamboo cover. Maximum water temperatures differences in the bottles over the two materials were of about 2.5 °C in the best case. Higher inactivation in the zinc-coated metal sheet when water temperature is below 40 °C should be attributed to better material reflectivity. At water temperatures around 40 °C, the 2.5 °C difference can be significative and accelerate the disinfection process.

Material heat transfer characteristics have been also found to be essential, especially when the solar disinfection starts at mid-day instead of early in the morning. In this case, as the support materials are already at higher temperatures because of solar irradiance absorption, the water temperature in the bottles increases more rapidly, contributing to the water disinfection process when it rises above 40 °C.

Development of improved low-cost ceramic water filters for viral removal in the Haitian context. Journal of Water, Sanitation and Hygiene for Development Vol 5 No 1 pp 28–38 © IWA Publishing 2015 doi:10.2166/washdev.2014.121.

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Authors: L. Guerrero-Latorre, M. Rusiñol, A. Hundesa, M. Garcia-Valles, S. Martinez, O. Joseph, S. Bofill-Mas and R. Girones

Household-based water treatment (HWT) is increasingly being promoted to improve water quality and, therefore, health status in low-income countries. Ceramic water filters (CWFs) are used in many regions as sustainable HWT and have been proven to meet World Health Organization (WHO) microbiological performance targets for bacterial removal (2–4 log); however, the described viral removal efficiencies are insufficient to significantly reduce the associated risk of viral infection. With the objective of improving the viral removal efficiencies of ceramic water filters, new prototypes with different oxide compositions and firing atmospheres have been developed and evaluated.

For removal efficiencies human adenoviruses, MS2 bacteriophage and Escherichia coli were quantified in all prototypes. A new model of CWF that was fired in a reductive atmosphere presented virus and bacteria removal efficiencies greater than 3.0 log and 2.5 log, respectively, which would fulfill the viral targets that are recommended by the WHO. Ceramic characterization of the selected filters, which were fired in a reductive atmosphere, showed that a larger specific surface area than those of control filters and higher fraction of a positive Z-potential fraction are the most likely explanations for this increase in virus removal.

A Review of Heterogeneous Photocatalysis for Water and Surface Disinfection. Molecules 2015, 20, 5574-5615.

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Authors: John Anthony Byrne, et al.

Photo-excitation of certain semiconductors can lead to the production of reactive oxygen species that can inactivate microorganisms. The mechanisms involved are reviewed, along with two important applications. The first is the use of photocatalysis to enhance the solar disinfection of water. It is estimated that 750 million people do not have accessed to an improved source for drinking and many more rely on sources that are not safe. If one can utilize photocatalysis to enhance the solar disinfection of water and provide an inexpensive, simple method of water disinfection, then it could help reduce the risk of waterborne disease.

Chlorine dispensers in Kenya: scaling for results, 3ie Grantee Final Report, 2015.

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Authors: Amrita Ahuja, et al.

We conducted three studies: one survey experiment and two large-scale randomized evaluations, to investigate how a particular community-level water treatment device, the chlorine dispenser, is valued and allocated by local government officials, and how best it can be financed and managed.

The first study involved 179 elected county councilors in rural Kenya, who chose between different public goods packages in an incentivized survey. The public goods varied with respect to two attributes: how the location of the infrastructure was decided and who controlled the funding associated with maintaining it. We found that on average, councilors valued the opportunity to target the water treatment technology, but not the ability to control funding for maintenance.

The second study, Community Financed Dispensers (CFD) concerned how to finance the chlorine refills required to keep chlorine dispensers functional. The chlorine dispenser is a classic common good in that chlorine is rival in consumption, yet it is not practical to restrict access to it. 104 communities were randomly assigned to a free provision arm or one of four community financing arms. In the community financing arms, water source users were responsible for purchasing chlorine refills. In half of these, an upfront contribution to the cost of the dispenser was required prior to installation (“up-front payment” treatment); cross-cut with this was a “threat of removal” treatment, in which the dispenser was a portable model that could be removed if the community failed to stock it with chlorine. In free provision communities, permanent dispensers were installed and chlorine refills were provided at no cost. We found no effect of up-front payment on household chlorine usage three months after installation, nor on whether the dispenser contained chlorine at unannounced visits over a period of eleven months. In contrast, threat of removal led to a 20 percentage point increase in the probability that a dispenser was stocked relative to permanent community-financed dispensers, which were stocked 41% of the time. Further, we estimate that in communities receiving free refills, enough doses were consumed to consistently treat all households’ drinking water. Households in threat of removal communities consumed 28-30% of the
recommended doses and households in other communities consumed 20% of the recommended doses.

Effectiveness of Chlorine Dispensers in Emergencies: Case Study Results from Haiti, Sierra Leone, DRC, and Senegal. Environ. Sci. Technol., March 2015.

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Authors: Travis Yates , Elise Armitage , Lilian V. Lehmann , Ariel J. Branz , and Daniele S. Lantagne

Dispensers are a source-based water quality intervention with promising uptake results in development contexts. Dispenser programs include a tank of chlorine with a dosing valve that is installed next to a water source, a local Promoter who conducts community education and refills the Dispenser, and chlorine refills. In collaboration with response organizations, we assessed the effectiveness of Dispensers in four emergency situations.

In the three initial and four sustained response phase evaluations, 70 Dispenser sites were visited, 2,057 household surveys were conducted, and 1,676 water samples were analyzed. Across the evaluations, reported Dispenser use ranged from 9-97%, confirmed Dispenser use (as measured by free chlorine residual) ranged from 5-87%, and effective use (as measured by improvement in household water quality to meet international standards) ranged from 0-81%.

More effective Dispenser interventions installed Dispensers at point-sources, maintained a high-quality chlorine solution manufacturing and distribution chain, maintained Dispenser hardware, integrated Dispensers projects within larger water programs, remunerated Promoters, had experienced project staff, worked with local partners to implement the project, conducted ongoing monitoring, and had a project sustainability plan. Our results indicate that Dispensers can be, but are not always, an appropriate strategy to reduce the risk of waterborne diseases in emergencies.

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, March 2015.

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Authors: Amy J. Pickering , Yoshika Crider, Nuhu Amin, Valerie Bauza, Leanne Unicomb, Jennifer Davis, Stephen P. Luby

The number of people served by networked systems that supply intermittent and contaminated drinking water is increasing. In these settings, centralized water treatment is ineffective, while household-level water treatment technologies have not been brought to scale. This study compares a novel low-cost technology designed to passively (automatically) dispense chlorine at shared handpumps with a household-level intervention providing water disinfection tablets (Aquatab), safe water storage containers, and behavior promotion.

Twenty compounds were enrolled in Dhaka, Bangladesh, and randomly assigned to one of three groups: passive chlorinator, Aquatabs, or control. Over a 10-month intervention period, the mean percentage of households whose stored drinking water had detectable total chlorine was 75% in compounds with access to the passive chlorinator, 72% in compounds receiving Aquatabs, and 6% in control compounds. Both interventions also significantly improved microbial water quality. Aquatabs usage fell by 50% after behavioral promotion visits concluded, suggesting intensive promotion is necessary for sustained uptake. The study findings suggest high potential for an automated decentralized water treatment system to increase consistent access to clean water in low-income urban communities.

Microbial Removals by a Novel Biofilter Water Treatment System. Am Jnl Trop Med Hyg, March 2015.

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Authors: Christopher Wendt, Rebecca Ives, Anne L. Hoyt, Ken E. Conrad, Stephanie Longstaff, Roy W.Kuennen, and Joan B. Rose

Two point-of-use drinking water treatment systems designed using a carbon filter and foam material as a possible alternative to traditional biosand systems were evaluated for removal of bacteria, protozoa, and viruses. Two configurations were tested: the foam material was positioned vertically around the carbon filter in the sleeve unit or horizontally in the disk unit. The filtration systems were challenged with Cryptosporidium parvum, Raoultella terrigena, and bacteriophages P22 and MS2 before and after biofilm development to determine ALR for each organism and the role of the biofilm.

There was no significant difference in performance between the two designs,and both designs showed significant levels of removal (at least 4 log10 reduction in viruses, 6 log10 for protozoa, and 8 log10 for bacteria). Removal levels meet or exceeded Environmental Protection Agency (EPA) standards for microbial purifiers. Exploratory test results suggested that mature biofilm formation contributed 1–2 log10 reductions. Future work is recommended to determine field viability.