A novel point-of-use water treatment method by antimicrobial nanosilver textile material

December 10, 2014 · 1 comment

A novel point-of-use water treatment method by antimicrobial nanosilver textile material. J Water Health. 2014 Dec;12(4):670-7. doi: 10.2166/wh.2014.197.

Liu H1, Tang X2, Liu Q3. Author information: 1Key Laboratory of Natural Medicine and Immuno-Engineering of Henan Province, Henan University, Kaifeng, Henan 475004, China E-mail: hjliu@henu.edu.cn; AGplus Technologies Pte Ltd, 10 Jalan Besar #10-06 Sim Lim Tower, Singapore 208787.
2AGplus Technologies Pte Ltd, 10 Jalan Besar #10-06 Sim Lim Tower, Singapore 208787.
3School of Architecture and the Built Environment, Singapore Polytechnic, 500 Dover Road, Singapore 139651.

Pathogenic bacteria are one of the main reasons for worldwide water-borne disease causing a big threat to public health, hence there is an urgent need to develop cost-effective water treatment technologies. Nano-materials in point-of-use systems have recently attracted considerable research and commercial interests as they can overcome the drawbacks of traditional water treatment techniques. We have developed a new point-of-use water disinfection kit with nanosilver textile material. The silver nanoparticles were in-situ generated and immobilized onto cotton textile, followed by fixing to a plastic tube to make a water disinfection kit. By soaking and stirring the kit in water, pathogenic bacteria have been killed within minutes. The silver leaching from the kit was insignificant, with values <100 ppb – the current US EPA and WHO limit for silver level in drinking water. Herein, the nanosilver textile water disinfection kit could be a new, efficient and cost-effective point-of-use water treatment method for rural areas and emergency preparedness.

Assessing point-of-use ultraviolet disinfection for safe water in urban developing communities

December 10, 2014 · 0 comments

Assessing point-of-use ultraviolet disinfection for safe water in urban developing communities. J Water Health. 2014 Dec;12(4):663-9. doi: 10.2166/wh.2014.223.

Barstow CK1, Dotson AD2, Linden KG1. Author information 1Civil, Environmental and Architectural Engineering, University of Colorado, Boulder, CO 80309, USA E-mail: karl.linden@colorado.edu.
2Civil Engineering, University of Alaska, Anchorage, AK 99508, USA.

Residents of urban developing communities often have a tap in their home providing treated and sometimes filtered water but its microbial quality cannot be guaranteed. Point-of-use (POU) disinfection systems can provide safe drinking water to the millions who lack access to clean water in urban communities. While many POU systems exist, there are several concerns that can lead to low user acceptability, including low flow rate, taste and odor issues, high cost, recontamination, and ineffectiveness at treating common pathogens. An ultraviolet (UV) POU system was constructed utilizing developing community-appropriate materials and simple construction techniques based around an inexpensive low-wattage, low pressure UV bulb.

The system was tested at the bench scale to characterize its hydrodynamic properties and microbial disinfection efficacy. Hydraulically the system most closely resembled a plug flow reactor with minor short-circuiting. The system was challenge tested and validated for a UV fluence of 50 mJ/cm(2) and greater, over varying flow rates and UV transmittances, corresponding to a greater than 4 log reduction of most pathogenic bacteria, viruses, and protozoa of public health concern. This study presents the designed system and testing results to demonstrate the potential architecture of a low-cost, open-source UV system for further prototyping and field-testing.

Comparison of Three Household Water Treatment Technologies in San Mateo Ixtatán, Guatemala

December 2, 2014 · 0 comments

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

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.

Fouling in hollow fiber membrane microfilters used for household water treatment

December 2, 2014 · 0 comments

Fouling in hollow fiber membrane microfilters used for household water treatment. Journal of Water, Sanitation and Hygiene for Development, In Press,  2014 | doi:10.2166/washdev.2014.206

Authors: Anna Murray, Mario Goeb, Barbara Stewart, Catherine Hopper, Jamin Peck, Carolyn Meub, Ayse Asatekin and Daniele Lantagne

Department of Civil and Environmental Engineering, Tufts University, 200 College Avenue, Medford, MA 02155, USA E-mail: anna.murray@tufts.edu
Pure Water for the World, Trojes, Honduras
Department of Chemistry, University of Maine, Orono, ME, USA
Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA
Pure Water for the World, Rutland, VT, USA
Department of Chemical and Biological Engineering, Tufts University, Medford, MA, USA

The Sawyer PointOne hollow fiber membrane microfilter is promoted for household water treatment in developing countries. Critical limitations of membrane filtration are reversible and irreversible membrane fouling, managed by backwashing and chemical cleaning, respectively. The PointOne advertised lifespan is 10 years; users are instructed to backwash as maintenance. Owing to reduced turbidity and bacterial removal efficiencies, six PointOnes were removed from Honduran homes after 23 months of use. In the laboratory, we tested sterile water filtrate for turbidity and bacterial presence before and after backwashing and chemical cleaning. Sterile water filtrate from uncleaned filters had turbidity of 144–200 NTU and bacteria counts of 13–200 CFU. Cleaned filter effluent was positive for total coliforms.

On one new and one used, cleaned filter, we imaged membranes with scanning electron microscopy and characterized surface elemental compositions with spectroscopy. Images and spectroscopy of the used, cleaned membrane revealed a dense, cake fouling layer consisting of inorganic metal oxides, organic material, and biofouling. Burst fibers were visually observed. This PointOne was thus irreversibly fouled and non-functional after <2 years of use. Further research is recommended to determine: impacts of source water quality on PointOne performance, a cleaning regimen to manage fouling, and an appropriate filter lifespan.

Porous Ceramic Tablet Embedded with Silver Nanopatches for Low-Cost Point-of-Use Water Purification

December 1, 2014 · 2 comments

Porous Ceramic Tablet Embedded with Silver Nanopatches for Low-Cost Point-of-Use Water Purification. Environ. Sci. Technol., November 11, 2014

Beeta Ehdaie , Carly Krause , and James A. Smith *

Department of Civil and Environmental Engineering, University of Virginia, Charlottesville, Virginia 22904,

Email: *J. A. Smith. E-mail: jas9e@virginia.edu.

This work describes a novel method to embed silver in ceramic porous media in the form of metallic silver nanopatches. This method has been applied to develop a new POU technology, a silver-infused ceramic tablet that provides long-term water disinfection. The tablet is fabricated using clay, water, sawdust, and silver nitrate. When dropped into a household water storage container, the ceramic tablet releases silver ions at a controlled rate that in turn disinfect microbial pathogens. Characterization of the silver-embedded ceramic media was performed using transmission electron microscopy. Spherical-shaped patches of metallic silver were observed at 1–6 nm diameters and confirmed to be silver with energy dispersive spectroscopy. Disinfection experiments in a 10 L water volume demonstrated a 3 log reduction of Escherichia coli within 8 h while silver levels remained below the World Health Organization drinking water standard (0.1 mg/L). Silver release rate varied with clay mineralogy, sawdust particle size, and initial silver mass. Silver release was repeatable for daily 10 L volumes for 154 days. Results suggest the ceramic tablet can be used to treat a range of water volumes. This technology shows great potential to be a low-cost, simple-to-use water treatment method to provide microbiologically safe drinking water at the household level.

Comparing Willingness to Pay for Improved Drinking-Water Quality Using Stated Preference Methods in Rural and Urban Kenya

December 1, 2014 · 0 comments

Comparing Willingness to Pay for Improved Drinking-Water Quality Using Stated Preference Methods in Rural and Urban Kenya. Appl Health Econ Health Policy. 2014 Nov 8.

Brouwer R1, Job FC, van der Kroon B, Johnston R.
Author information
1Department of Environmental Economics, Institute for Environmental Studies, Vrije Universiteit, De Boelelaan 1087, 1081 HV, Amsterdam, The Netherlands, r.brouwer@vu.nl.

BACKGROUND: Access to safe drinking water has been on the global agenda for decades. The key to safe drinking water is found in household water treatment and safe storage systems.
OBJECTIVE: In this study, we assessed rural and urban household demand for a new gravity-driven membrane (GDM) drinking-water filter.
METHODS: A choice experiment (CE) was used to assess the value attached to the characteristics of a new GDM filter before marketing in urban and rural Kenya. The CE was followed by a contingent valuation (CV) question. Differences in willingness to pay (WTP) for the same filter design were tested between methods, as well as urban and rural samples.
RESULTS: The CV follow-up approach produces more conservative and statistically more efficient WTP values than the CE, with only limited indications of anchoring. The effect of the new filter technology on children with diarrhea is among the most important drivers behind choice behavior and WTP in both areas. The urban sample is willing to pay more in absolute terms than the rural sample irrespective of the valuation method. Rural households are more price sensitive, and willing to pay more in relative terms compared with disposable household income.
CONCLUSION: A differentiated marketing strategy across rural and urban areas is expected to increase uptake and diffusion of the new filter technology.

Carbon Financing of Household Water Treatment: Background, Operation and Recommendations to Improve Potential for Health Gains

November 10, 2014 · 0 comments

Carbon Financing of Household Water Treatment: Background, Operation and Recommendations to Improve Potential for Health Gains. Env Sci Tech, Oct 2014.

Authors: James M. Hodge and Thomas F. Clasen. Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia 30322, United States, e-mail: tclasen@emory.edu

Household water treatment (HWT) provides a means for vulnerable populations to take charge of their own drinking water quality as they patiently wait for the pipe to finally reach them. In many low-income countries, however, promoters have not succeeded in scaling up the intervention among the target population or securing its consistent and sustained use. Carbon financing can provide the funding for reaching targeted populations with effective HWT solutions and the incentives to ensure their long-term uptake. Nevertheless, programs have been criticized because they do not actually reduce carbon emissions. We summarize the background and operation of carbon financing of HWT interventions, including the controversial construct of “suppressed demand”.

We agree that these programs have limited potential to reduce greenhouse gas emissions and that their characterization of trading “carbon for water” is misleading. Nevertheless, we show that the Kyoto Protocol expressly encouraged the use of suppressed demand as a means of allowing low-income countries to benefit from carbon financing provided it is used to advance development priorities such as health. We conclude by recommending changes to existing criteria for eligible HWT programs that will help ensure that they meet the conditions of microbiological effectiveness and actual use that will improve their potential for health gains.

Cholera at the Crossroads: The Association Between Endemic Cholera and National Access to Improved Water Sources and Sanitation

November 10, 2014 · 0 comments

Cholera at the Crossroads: The Association Between Endemic Cholera and National Access to Improved Water Sources and Sanitation. Am Jnl Trop Med Hyg, Nov 2014.

Authors: Benjamin L. Nygren*, Anna J. Blackstock and Eric D. Mintz

Address correspondence to Benjamin L. Nygren, Centers for Disease Control and Prevention, 1600 Clifton Road NE, MS-C09, Atlanta, GA 30329. E-mail: bnygren@cdc.gov

We evaluated World Health Organization (WHO) national water and sanitation coverage levels and the infant mortality rate as predictors of endemic cholera in the 5-year period following water and sanitation coverage estimates using logistic regression, receiver operator characteristic curves, and different definitions of endemicity.

Each was a significant predictors of endemic cholera at P < 0.001. Using a value of 250 for annual cases reported in 3 of 5 years, a national water access level of 71% has 65% sensitivity and 65% specificity in predicting endemic cholera, a sanitation access level of 39% has 63% sensitivity and 62% specificity, and an infant mortality rate of 65/1,000 has 67% sensitivity and 69% specificity.

Our findings reveal the tradeoff between sensitivity and specificity for these predictors of endemic cholera and highlight the substantial uncertainty in the data. More accurate global surveillance data will enable more precise characterization of the benefits of improved water and sanitation.

Open-source mobile water quality testing platform

November 10, 2014 · 0 comments

Open-source mobile water quality testing platform. Journal of Water, Sanitation and Hygiene for Development, Vol 4 No 3 pp 532–537 2014.

Authors: Bas Wijnen, G. C. Anzalone and Joshua M. Pearce

Department of Materials Science & Engineering, Michigan Technological University, 601 M&M Building, 1400 Townsend Drive, Houghton, MI 49931-1295, USA E-mail: pearce@mtu.edu
Department of Electrical & Computer Engineering, Michigan Technological University, 601 M&M Building, 1400 Townsend Drive, Houghton, MI 49931-1295, USA

The developing world remains plagued by lack of access to safe drinking water. Although many low-cost methods have been developed to treat contaminated water, low-cost methods for water-quality testing are necessary to determine if these appropriate technologies are needed, effective, and reliable. This paper provides a methodology for the design, development, and technical validation of a low-cost, open-source (OS) water testing platform. A case study is presented where the platform is developed to provide both the colorimetry for biochemical oxygen demand/chemical oxygen demand and nephelometry to measure turbidity using method ISO 7027. This approach resulted in equipment that is as accurate, but costs between 7.5 and 15 times less than current commercially available tools. It is concluded that OS hardware development is a promising solution for the equipment necessary to perform water quality measurements in both developed and developing regions.

Scaling up Multiple Use Water Services: Accountability in the water sector

November 10, 2014 · 0 comments

Scaling up Multiple Use Water Services: Accountability in the water sector, October 2014.

Authors: Barbara van Koppen, Stef Smits, Cristina Rumbaitis del Rio and John B. Thomas. IWMI.

Scaling up Multiple Use Water Services argues that by designing cost-effective multi-purpose infrastructure MUS can have a positive impact on people’s health and livelihoods. It analyses and explains the success factors of MUS, using a framework of accountability for public service delivery, and it also examines why there has been resistance against scaling up MUS. A stronger service delivery approach can overcome this resistance, by rewarding more livelihood outcomes, by fostering discretionary decision-making power of local-level staff and by allowing horizontal coordination. This book should be read by government and aid agency policy makers in the WASH and agriculture sectors, by development field workers, and by academics, researchers and students of international development.

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