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.

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.

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.

Influence of solar water disinfection on immunity against cholera – a review. Journal of Water and Health Vol 12 No 3 pp 393–398 2014.

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Authors: Cornelius Cano Ssemakalu, Eunice Ubomba-Jaswa, Keolebogile Shirley Motaung and Michael Pillay.
Faculty of Applied and Computer Sciences, Vaal University of Technology, Vanderbijlpark 1900, South Africa E-mail: mpillay@vut.ac.za. Council for Scientific and Industrial Research, Natural Resource and the Environment, P.O. Box 395, Pretoria 0001, South Africa. Department of Biomedical Sciences, Tshwane University of Technology, 175 Nelson Mandela Drive, Arcadia Campus, Pretoria 0001, South Africa

Cholera remains a problem in developing countries. This is attributed to the unavailability of proper water treatment, sanitary infrastructure and poor hygiene. As a consequence, countries facing cholera outbreaks rely on interventions such as the use of oral rehydration therapy and antibiotics to save lives. In addition to vaccination, the provision of chlorine tablets and hygiene sensitization drives have been used to prevent new cholera infections. The implementation of these interventions remains a challenge due to constraints associated with the cost, ease of use and technical knowhow. These challenges have been reduced through the use of solar water disinfection (SODIS). The success of SODIS in mitigating the risk associated with the consumption of waterborne pathogens has been associated with solar irradiation. This has prompted a lot of focus on the solar component for enhanced disinfection. However, the role played by the host immune system following the consumption of solar-irradiated water pathogens has not received any significant attention. The mode of inactivation resulting from the exposure of microbiologically contaminated water results in immunologically important microbial states as well as components. In this review, the possible influence that solar water disinfection may have on the immunity against cholera is discussed.

Factors involved in sustained use of point-of-use water disinfection methods: A field study from Flores Island, Indonesia. Journal of Water and Health, In Press, Uncorrected Proof © IWA Publishing 2014 | doi:10.2166/wh.2014.109

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E. Roma, T. Bond and P. Jeffrey
Cranfield University, Water Science Institute, Cranfield, MK430AL, UK E-mail: elisa.roma@lshtm.ac.uk
Environmental Health Group, London School of Hygiene and Tropical Medicine, WC17HT, London, UK
Civil and Environmental Engineering, Skempton Building, Imperial College, London, UK

Many scientific studies have suggested that point-of-use water treatment can improve water quality and reduce the risk of infectious diseases. Despite the ease of use and relatively low cost of such methods, experience shows the potential benefits derived from provision of such systems depend on recipients’ acceptance of the technology and its sustained use. To date, few contributions have addressed the problem of user experience in the post-implementation phase.

This can diagnose challenges, which undermine system longevity and its sustained use. A qualitative evaluation of two household water treatment systems, solar disinfection (SODIS) and chlorine tablets (Aquatabs), in three villages was conducted by using a diagnostic tool focusing on technology performance and experience. Cross-sectional surveys and in-depth interviews were used to investigate perceptions of involved stakeholders (users, implementers and local government).

Results prove that economic and functional factors were significant in using SODIS, whilst perceptions of economic, taste and odour components were important in Aquatabs use. Conclusions relate to closing the gap between factors that technology implementers and users perceive as key to the sustained deployment of point-of-use disinfection technologies.

A Solar Disinfection Water Treatment System for Remote Communities. Procedia Engineering, 2014.

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Peter Kalt, et al.

Worldwide, approximately 780 million people do not have access to safe and clean water for drinking, cooking or washing.
Consumption of untreated water exposes humans to a range of contaminants including faecal-borne pathogens and chemical pollutants. As a consequence, it is estimated that 1.5 million people die each year as a result of the consumption of untreated or contaminated water. These deaths are preventable with access to clean and safe water, but capital costs and maintenance requirements for large-scale treatment systems are prohibitive and challenging to implement in remote or distributed communities. Such remote communities typically suffer from faecal contamination of transient water sources, rather than chemical or radiological contaminants. To address this problem a low-cost continuous-feed water treatment facility has been designed and developed. The facility utilises solar (UVA) radiation to treat pathogens. Additionally, the facility is designed such that it can be manufactured in-situ from limited or improvised resources at low capital and maintenance costs. The system is modular so that multiple systems can be used to increase water treatment capacity as required. Testing indicates that 3 modules of the design can treat 34L of water in 4 hours producing a 4-log reduction in E. Coli (from 8 × 105 CFU/ml) with a residence time of less than 30 minutes. This is based on an average solar-based UVA flux of ranging from 24 to 36 W/m2 (time average of 28 W/m2).

Solar Disinfection of Pseudomonas aeruginosa in Harvested Rainwater: A Step towards Potability of Rainwater. PLoS One, Mar 2014.

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Authors: Muhammad T. Amin, Mohsin Nawaz, Muhammad N. Amin, and Mooyoung Han

Efficiency of solar based disinfection of Pseudomonas aeruginosa (P. aeruginosa) in rooftop harvested rainwater was evaluated aiming the potability of rainwater. The rainwater samples were exposed to direct sunlight for about 8–9 hours and the effects of water temperature (°C), sunlight irradiance (W/m2), different rear surfaces of polyethylene terephthalate bottles, variable microbial concentrations, pH and turbidity were observed on P. aeruginosa inactivation at different weathers. In simple solar disinfection (SODIS), the complete inactivation of P. aeruginosa was obtained only under sunny weather conditions (>50°C and >700 W/m2) with absorptive rear surface. Solar collector disinfection (SOCODIS) system, used to improve the efficiency of simple SODIS under mild and weak weather, completely inactivated the P. aeruginosa by enhancing the disinfection efficiency of about 20% only at mild weather.

Both SODIS and SOCODIS systems, however, were found inefficient at weak weather. Different initial concentrations of P. aeruginosa and/or Escherichia coli had little effects on the disinfection efficiency except for the SODIS with highest initial concentrations. The inactivation of P. aeruginosa increased by about 10–15% by lowering the initial pH values from 10 to 3. A high initial turbidity, adjusted by adding kaolin, adversely affected the efficiency of both systems and a decrease, about 15–25%; in inactivation of P. aeruginosa was observed. The kinetics of this study was investigated by Geeraerd Model for highlighting the best disinfection system based on reaction rate constant. The unique detailed investigation of P. aeruginosa disinfection with sunlight based disinfection systems under different weather conditions and variable parameters will help researchers to understand and further improve the newly invented SOCODIS system.

Cien Saude Colet. 2013 Jul;18(7):2119-27.

[Economic evaluation of social technologies applied to health promotion: water supply by the SODIS System in riverside communities of the Brazilian Amazon]. [Article in Portuguese]

Lobo MA, Lima DM, Souza CM, Nascimento WA, Araújo LC, Santos NB.

The so-called social technologies have been widely used in many places around the world as a viable alternative for low-income populations to gain access to opportunities for employment and income and other aspects related to quality of life, including basic sanitation. This paper conducts a cost-benefit analysis of using a low cost technology for drinking water used in several countries, namely the SODIS system. The study was conducted in riverside communities living in the island area of Belem municipality, located in the Brazilian Amazon. Data were collected through questionnaires answered by families living on three islands: Jutuba, Nova and Urubuoca. The results were positive, considering the cost-benefit analysis of the project, which demonstrates the economic viability of using the SODIS system in the situation investigated.

A Stepped Wedge, Cluster-Randomized Trial of a Household UV-Disinfection and Safe Storage Drinking Water Intervention in Rural Baja California Sur, Mexico. Am J Trop Med Hyg. 2013 Jun 3.

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Gruber JS, et al.

Abstract - In collaboration with a local non-profit organization, this study evaluated the expansion of a program that promoted and installed Mesita Azul, an ultraviolet-disinfection system designed to treat household drinking water in rural Mexico. We conducted a 15-month, cluster-randomized stepped wedge trial by randomizing the order in which 24 communities (444 households) received the intervention. We measured primary outcomes (water contamination and diarrhea) during seven household visits.

The intervention increased the percentage of households with access to treated and safely stored drinking water (23-62%), and reduced the percentage of households with Escherichia coli contaminated drinking water (risk difference (RD): -19% [95% CI: -27%, -14%]). No significant reduction in diarrhea was observed (RD: -0.1% [95% CI: -1.1%, 0.9%]). We conclude that household water quality improvements measured in this study justify future promotion of the Mesita Azul, and that future studies to measure its health impact would be valuable if conducted in populations with higher diarrhea prevalence.

J Water Health. 2013 Mar;11(1):135-45. doi: 10.2166/wh.2012.119.

Application of solar disinfection for treatment of contaminated public water supply in a developing country: field observations.

Mustafa A, Scholz M, Khan S, Ghaffar A.
Department of Environmental Engineering, NED University of Engineering and Technology, Karachi 75270, Sindh, Pakistan E-mail: atifm@neduet.edu.pk.

A sustainable and low-cost point-of-use household drinking water solar disinfection (SODIS) technology was successfully applied to treat microbiologically contaminated water. Field experiments were conducted to determine the efficiency of SODIS and evaluate the potential benefits and limitations of SODIS under local climatic conditions in Karachi, Pakistan. In order to enhance the efficiency of SODIS, the application of physical interventions were also investigated.

Twenty per cent of the total samples met drinking water guidelines under strong sunlight weather conditions, showing that SODIS is effective for complete disinfection under specific conditions. Physical interventions, including black-backed and reflecting rear surfaces in the batch reactors, enhanced SODIS performance. Microbial regrowth was also investigated and found to be more controlled in reactors with reflective and black-backed surfaces. The transfer of plasticizer di(2-ethylhexyl)phthalate (DEHP) released from the bottle material polyethylene terephthalate (PET) under SODIS conditions was also investigated.

The maximum DEHP concentration in SODIS-treated water was 0.38 μg/L less than the value of 0.71 μg/L reported in a previous study and well below the WHO drinking-quality guideline value. Thus SODIS-treated water can successfully be used by the people living in squatter settlements of mega-cities, such as Karachi, with some limitations.