scholarly journals Inactivation of bacteria from contaminated streams in Limpopo, South Africa by silver- or copper-nanoparticle paper filters

2016 ◽  
Vol 2 (1) ◽  
pp. 85-96 ◽  
Author(s):  
Theresa A. Dankovich ◽  
Jonathan S. Levine ◽  
Natasha Potgieter ◽  
Rebecca Dillingham ◽  
James A. Smith

There is an urgent need for inexpensive point-of-use methods to purify drinking water in developing countries to reduce the incidence of illnesses caused by waterborne pathogens.

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Deepa Dixit ◽  
Virupakshi Soppina ◽  
Chinmay Ghoroi

AbstractAccess to safe drinking water is still a distant dream to millions of people around the world. Especially, people from the low-income group in the developing countries remain deprived of this fundamental right and causes millions of death. There is an urgent need to develop affordable and easy to handle water filter which can provide desired drinking water quality without any electricity. In the present work, a simple and low-cost surface engineered particle (SEP) based filter is developed via alkali treatment of soda-lime-silica particle. The SEP based filter can be used as a portable, non-electric, gravity-driven Point-of-Use (POU) water disinfection system. The developed SEP-based filter is capable to arrest the 99.48% (~2 to 2.5 log10 reduction) of gram-negative bacteria Escherichia coli (E. coli OP50) on its surface from the water containing 3 × 108 cells/ml. No bacterial regrowth is observed in the purified water for 12 h. The performance of SEP bed filter is implicated to the nano-scale surface roughness, its distribution along with the surface charge and surface hydrophobicity which are favorable to attract and adhere the bacteria in the flowing water. The observation is consistent over multiple filtration cycles indicating the suitability of SEP based bed filter for POU water disinfection. The SEP surface with 0.05 mM Ag+ loading (SEP+) completely inactivated (>99.99999%) bacteria and protects any bacteria recontamination in the purified water for its long term usage. The strong and effective silver binding property of SEP surface enables very minimal silver loading and eliminates any health hazard due to low silver leaching (~50 ppb) which is well below the drinking water equivalent level (DWEL ≤ 100 ppb). In rural and urban slum areas of developing countries where no water purification system exists prior to consumption, the easy-to-implement and affordable SEP-based gravity-driven non-electric point-of-use water purifier (materials cost ~ 0.25 USD) can be used to protect millions of lives from water borne diseases.


2006 ◽  
Vol 1 (2) ◽  
Author(s):  
Stephen W. Gundry ◽  
James A. Wright ◽  
Ronan Conroy ◽  
Martella Du Preez ◽  
Bettina Genthe ◽  
...  

Aims: To assess contamination of drinking water in rural Zimbabwe and South Africa Methods: We conducted a cohort study of 254 children aged 12-24 months in rural South Africa and Zimbabwe. In dry and wet seasons, we measured water quality, using the indicator organism E. coli, at improved and unimproved sources, in household storage and drinking cups. We also recorded hygiene and socio-economic factors for each household. Results: For improved sources, samples with E. coli counts less than 10 cfu/100ml were as follows: at source: 165 (88%); in household storage 137 (59%); in drinking cups 91 (49%). The corresponding values for unimproved sources were: source 47 (29%); household storage 32 (19%); drinking cups 21 (18%). This significant deterioration in microbial quality of water from improved sources was seen in both countries and both survey rounds. Conclusion: Although improved sources generally delivered ‘safe’ water at the point-of-supply, 12% of source samples were contaminated and as such were ‘unsafe’. Furthermore, in household storage, more than 40% of samples were ‘unsafe’. For monitoring the Millennium Development Goal for water, UNICEF-WHO are assuming an equivalence between ‘improved’ sources and ‘safe’ water. Our findings suggest that this equivalence may be unsound.


2003 ◽  
Vol 1 (2) ◽  
pp. 73-84 ◽  
Author(s):  
Philip F. Souter ◽  
Graeme D. Cruickshank ◽  
Melanie Z. Tankerville ◽  
Bruce H. Keswick ◽  
Brian D. Ellis ◽  
...  

Contamination of drinking water by microorganisms and arsenic represents a major human health hazard in many parts of the world. An estimated 3.4 million deaths a year are attributable to waterborne diseases. Arsenic poisoning from contaminated water sources is causing a major health emergency in some countries such as Bangladesh where 35 to 77 million people are at risk.The World Health Organization (WHO) has recently recognized point-of-use water treatment as an effective means of reducing illness in developing country households. A new point-of-use water treatment system that is based on flocculation, sedimentation and disinfection was evaluated for the removal of bacterial, viral and parasitic pathogens as well as arsenic from drinking water to estimate its potential for use in developing countries.Tests were conducted with United States Environmental Protection Agency (EPA)-model and field- sample waters from developing countries. Samples were seeded with known numbers of organisms, treated with the combined flocculation/disinfection product, and assayed for survivors using standard assay techniques appropriate for the organism.Results indicated that this treatment system reduced the levels from 108/l to undetectable (<1) of 14 types of representative waterborne bacterial pathogens including Salmonella typhi and Vibrio cholerae. No Escherichia coli were detected post-treatment in 320 field water samples collected from five developing countries. In addition, the water treatment system reduced polio and rotavirus titres by greater than 4-log values. Cyrptosporidium parvum and Giardia lamblia inocula were reduced by greater than 3-log values following use of this water treatment system. Arsenic, added to laboratory test waters, was reduced by 99.8%, and naturally occurring arsenic in field samples from highly contaminated Bangladeshi wells was reduced by 99.5% to mean levels of 1.2 µg/l.This water treatment system has demonstrated the potential to provide improved drinking water to households in developing countries by removing microbial and arsenic contaminants.


2020 ◽  
Vol 18 (6) ◽  
pp. 968-982
Author(s):  
Marc Verhougstraete ◽  
Kelly A. Reynolds ◽  
Jennifer Pearce-Walker ◽  
Charles Gerba

Abstract Microbial contamination of drinking water post-municipal treatment is difficult to predict as a risk factor for human health. One method to reduce morbidity or mortality from unpredictable exposures is through point-of-use (POU) treatment devices. The goal of this project was to assess the cost-benefit of POU water treatment at the tap in terms of protection from microbes in drinking water. This project estimated: (1) incidence of acute illness (AI), sequela, and mortality associated with waterborne pathogens; (2) illness reduction rates from using POU devices; and (3) healthcare cost reductions associated with POU devices. Infection rates and costs associated with 10 of the most common waterborne pathogens were identified and used to calculate national annual costs. We estimated 9M AI, 0.6M sequela, and 1,400 mortality cases that occur annually in the USA from these pathogens. The greatest cost-benefit was seen when considering the totality of disease burden reduction (AI, sequela, and mortality) including all pathogens at a national level and applying a 35% infection reduction, resulting in a total cost per averted disease case of $1,815. This study suggests that it is cost-beneficial to prevent water-related illness using POU devices.


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