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.

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.

Critical parameters in the production of ceramic pot filters for household water treatment in developing countries. Journal of Water and Health, In Press, Uncorrected Proof © IWA Publishing 2014 | doi:10.2166/wh.2014.090

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A. I. A. Soppe, S. G. J. Heijman, I. Gensburger, A. Shantz, D. van Halem, J. Kroesbergen, G. H. Wubbels and P. W. M. H. Smeets

Aqua for All Foundation, Koningskade 40, The Hague 2596 AA, the Netherlands E-mail: gsoppe@planet.nl
Department of Water Management, Delft University of Technology, Stevinweg 1, Delft 2628 CN, the Netherlands
Engineers Without Borders Australia, 99 Howard Street, North Melbourne, VIC, Australia and Downer Ltd., 133 Main South Road, PO Box 13031, Dunedin 9052, New Zealand
Resource Development International Cambodia, No. 50A, Phum Prek Thom Sangkat Kbal Koh, Khan Mean Chey, Phnom Penh, Kingdom of Cambodia
Het Waterlaboratorium, J.W. Lucasweg 2, Haarlem 2031 BE, the Netherlands
Waterlaboratorium Noord, Rijksstraatweg 85, Glimmen 9756 AD, the Netherlands
KWR Watercycle Research Institute, Groningenhaven 7, Nieuwegein 3433 PE, the Netherlands

The need to improve the access to safe water is generally recognized for the benefit of public health in developing countries. This study’s objective was to identify critical parameters which are essential for improving the performance of ceramic pot filters (CPFs) as a point-of-use water treatment system. Defining critical production parameters was also relevant to confirm that CPFs with high-flow rates may have the same disinfection capacity as pots with normal flow rates. A pilot unit was built in Cambodia to produce CPFs under controlled and constant conditions.

Pots were manufactured from a mixture of clay, laterite and rice husk in a small-scale, gas-fired, temperature-controlled kiln and tested for flow rate, removal efficiency of bacteria and material strength. Flow rate can be increased by increasing pore sizes and by increasing porosity. Pore sizes were increased by using larger rice husk particles and porosity was increased with larger proportions of rice husk in the clay mixture.

The main conclusions are larger pore size decreases the removal efficiency of bacteria; higher porosity does not affect the removal efficiency of bacteria, but does influence the strength of pots; flow rates of CPFs can be raised to 10–20 L/hour without a significant decrease in bacterial removal efficiency.

Comparison of Three Household Water Treatment Technologies in San Mateo Ixtatán, Guatemala. J. Environ. Eng. , 2014,  10.1061/(ASCE)EE.1943-7870.0000914 , 04014085.

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Mellor, J., Kallman, E., Oyanedel-Craver, V., and Smith, J.

Silver-impregnated ceramic water filters (CWFs) are a simple and sustainable low-cost technology that has shown promise in improving household drinking water quality and reducing incidences of early childhood diarrhea in a variety of settings. Despite this promise, lower reservoir contamination is thought to be a contributing factor to the decline in the effectiveness being seen over time. A novel silver-impregnated ceramic torus that can be placed in the lower reservoir was designed to minimize this contamination.

This study uses a one-year randomized trial to compare the relative effectiveness of the CWF+torus design with a standard CWF and point-of-use chlorination. The effectiveness of each technology was measured at project inception and subsequently after six and 12 months. Results indicate that the toruses, as designed, are not able to consistently maintain lower-reservoir silver concentrations above those of the simple CWF design and are hence unable to prevent contamination. Furthermore, after six months, only 65% of households that used point-of-use chlorination maintained sufficient chlorine levels above the 0.2  mg/L needed to be effective.

All three technologies showed statistically equivalent log removal efficiencies for total coliform bacteria and all three declined in effectiveness over the first six months. Combined average log removal efficiencies for all three technologies ranged from 2.22±0.21 initially but declined to 1.45±0.35 after six months and to 1.42±0.29 after one year.

Journal of Water, Sanitation and Hygiene for Development Vol 4 No 2 pp 214–222, 2014 doi:10.2166/washdev.2014.114 | (Order info)

Removal of As(III) and As(V) in surface modified ceramic filters

Emily C. Robbins, Jing Guo and Craig D. Adams

Department of Civil, Environmental, and Architectural Engineering, University of Kansas, Lawrence, KS 66045, USA
Department of Civil and Environmental Engineering, Utah State University, Logan, UT 84322, USA E-mail: craig.adams@usu.edu

A new point-of-use (POU) technology using porous ceramic filters with a ferric-iron coating was used to achieve simultaneous arsenic (III) and (V) removal along with filtrative disinfection. The surface modified ceramic filters (SMCF) were produced using standard ceramic filter methods with combustible materials to create a porous ceramic during firing, followed by coating with a ferric oxide surface coating. A majority of the testing was conducted using 2.0-cm thick, 1.3-cm diameter ceramic plugs to simulate full-scale filters in column studies. The SMCF was capable of filtering arsenic for long periods of time with essentially no As breakthrough. As in source water was reduced from 250 μg/L to less than the 10 μg/L WHO guideline for arsenic for 875 and 1,618 bed volumes (or 360 and 666 effective filter runs) with 0.51 and 2 M iron-coated filters, respectively. There was no significant difference in As(V) or As(III) removal performance over a pH range of 6 to 9. Filtration of lake water containing natural organic matter at 5 mg/L as C reduced performance of As(III) and As(V) removal approximately 34 to 38%, respectively. Other metals including cadmium, copper and chromate were also readily adsorbed by the SMCF while selenate was not.

Ceramic water filters impregnated with silver nanoparticles as a point-of-use water-treatment intervention for HIV-positive individuals in Limpopo Province, South Africa: a pilot study of technological performance and human health benefits. J Water Health. 2014 Jun.

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Abebe LS, et al.

Waterborne pathogens present a significant threat to people living with the human immunodeficiency virus (PLWH). This study presents a randomized, controlled trial that evaluates whether a household-level ceramic water filter (CWF) intervention can improve drinking water quality and decrease days of diarrhea in PLWH in rural South Africa. Seventy-four participants were randomized in an intervention group with CWFs and a control group without filters. Participants in the CWF arm received CWFs impregnated with silver nanoparticles and associated safe-storage containers. Water and stool samples were collected at baseline and 12 months. Diarrhea incidence was self-reported weekly for 12 months.

The average diarrhea rate in the control group was 0.064 days/week compared to 0.015 days/week in the intervention group (p < 0.001, Mann-Whitney). Median reduction of total coliform bacteria was 100% at enrollment and final collection. CWFs are an acceptable technology that can significantly improve the quality of household water and decrease days of diarrhea for PLWH in rural South Africa.

Filters for the World: POU filters provide clean water for developing nations | Source/complete article: by Lieselotte Heederik, March 2014 |

This article provides an overview on Point-of Use water filters and gives information on the Nazava water filter. The Nazava filter is new product has recently been introduced on the market in Indonesia. Nazava water filters use a simple ceramic filter shaped like a soda can. The ceramic is impregnated with silver and filled with activated carbon, which helps improve the water’s taste. The filter’s small size makes it easy to transport, and, as its costs per liter are three times cheaper than boiling water and nine times cheaper than bottled water, the economic benefits are high.  

Nazava filters have 99.99% effective bacterial removal. They have been tested in 16 laboratories in Indonesia and overseas. They comply with Indonesian standards for safe drinking water and WHO guidelines for bacteria removal.9 To address the preferences of every household, the filters come in different sizes and colors.

Nazava filters can make well, rain and tap water drinkable without boiling it first. As no fuel wood is needed, they reduce the labor burden on women. Using them also can result in significant savings in gas and kerosene. They purify turbid water as well, as long as the water is fresh.

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Modeling the sustainability of a ceramic water filter intervention. Water Res. 2014 Feb 1;49:286-99. doi: 10.1016/j.watres.2013.11.035.

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Mellor J, et al.

Ceramic water filters (CWFs) are a point-of-use water treatment technology that has shown promise in preventing early childhood diarrhea (ECD) in resource-limited settings. Despite this promise, some researchers have questioned their ability to reduce ECD incidences over the long term since most effectiveness trials conducted to date are less than one year in duration limiting their ability to assess long-term sustainability factors. Most trials also suffer from lack of blinding making them potentially biased.

This study uses an agent-based model (ABM) to explore factors related to the long-term sustainability of CWFs in preventing ECD and was based on a three year longitudinal field study. Factors such as filter user compliance, microbial removal effectiveness, filter cleaning and compliance declines were explored. Modeled results indicate that broadly defined human behaviors like compliance and declining microbial effectiveness due to improper maintenance are primary drivers of the outcome metrics of household drinking water quality and ECD rates.

The model predicts that a ceramic filter intervention can reduce ECD incidence amongst under two year old children by 41.3%. However, after three years, the average filter is almost entirely ineffective at reducing ECD incidence due to declining filter microbial removal effectiveness resulting from improper maintenance. The model predicts very low ECD rates are possible if compliance rates are 80-90%, filter log reduction efficiency is 3 or greater and there are minimal long-term compliance declines. Cleaning filters at least once every 4 months makes it more likely to achieve very low ECD rates as does the availability of replacement filters for purchase. These results help to understand the heterogeneity seen in previous intervention-control trials and reemphasize the need for researchers to accurately measure confounding variables and ensure that field trials are at least 2-3 years in duration. In summary, the CWF can be a highly effective tool in the fight against ECD, but every effort should be made by implementing agencies to ensure consistent use and maintenance.