Evaluation of the efficiency of polysulfone ultrafiltration membrane-based water purifiers for microbiological decontamination
02 Apr 2009-International Journal of Nuclear Desalination (Inderscience Publishers)-Vol. 3, Iss: 3, pp 260-272
TL;DR: The technique involving the estimation of MWCO, coupled with the rejection characteristics of E. coli and P1 phage, provides an excellent tool to evaluate the efficiency of water purifiers based on UF membrane technology.
Abstract: Indigenously developed polysulfone Ultrafiltration (UF) membrane-based domestic and industrial water purification units were evaluated for their ability to filter bacteria and viruses from water. Escherichia coli (105 cfu/ml) and P1 phage (106 pfu/ml) were filtered through a Domestic Water Purifier (DWP) (dead-end UF unit) and a large-scale spiral water purifier (cross-flow UF unit) and the filtrates were analysed for bacterial and phage counts. Both units were found to be efficient in the complete removal of E. coli and a 99.99% removal of the P1 phage was observed. Both the domestic and industrial water purifiers are highly efficient in the removal of bacteria and viruses. UF membranes were also characterised for Molecular Weight Cut-Off (MWCO) by the polyethylene glycol and polyethylene oxide methods, which showed that MWCO was 60–65 kDa. These MWCO results were further validated using the Bovine Serum Albumin (BSA) rejection behaviour of these membranes, which showed about 90% rejection. The technique involving the estimation of MWCO, coupled with the rejection characteristics of E. coli and P1 phage, provides an excellent tool to evaluate the efficiency of water purifiers based on UF membrane technology.
References
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TL;DR: Comparison with other practical candidate fecal indicators shows that E. coli is far superior overall, and under most circumstances it is possible to design a monitoring program that permits public health protection at a modest cost.
Abstract: Public health protection requires an indicator of fecal pollution. It is not necessary to analyse drinking water for all pathogens. Escherichia coli is found in all mammal faeces at concentrations of 10 log 9(-1), but it does not multiply appreciably in the environment. In the 1890s, it was chosen as the biological indicator of water treatment safety. Because of method deficiencies, E. coli surrogates such as the 'fecal coliform' and total coliforms tests were developed and became part of drinking water regulations. With the advent of the Defined Substrate Technology in the late 1980s, it became possible to analyse drinking water directly for E. coli (and, simultaneously, total coliforms) inexpensively and simply. Accordingly, E. coli was re-inserted in the drinking water regulations. E. coli survives in drinking water for between 4 and 12 weeks, depending on environmental conditions (temperature, microflora, etc.). Bacteria and viruses are approximately equally oxidant-sensitive, but parasites are less so. Under the conditions in distribution systems, E. coli will be much more long-lived. Therefore, under most circumstances it is possible to design a monitoring program that permits public health protection at a modest cost. Drinking water regulations currently require infrequent monitoring which may not adequately detect intermittent contamination events; however, it is cost-effective to markedly increase testing with E. coli to better protect the public's health. Comparison with other practical candidate fecal indicators shows that E. coli is far superior overall.
861 citations
Additional excerpts
...Paratyphi) (Edberg et al., 2000; Enriquez et al., 2001)....
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TL;DR: In this paper, the molecular weight cut-off (MWCO) of the nanofiltration membranes studied were found to be between 3500 and 98,000 Daltons, and the mean pore size (μp) and the geometric standard deviation (σp) around mean ranged from 0.7 to 11.12 µm and 1.68 to 3.31 µm.
760 citations
TL;DR: To perform a risk analysis for the pathogens in drinking water, it is necessary to understand the ecology of these organisms, including newly-recognized pathogens from fecal sources and pathogens that are able to grow in water distribution systems.
Abstract: Emerging pathogens in drinking water have become increasingly important during the decade. These include newly-recognized pathogens from fecal sources such as Cryptosporidium parvum, Campylobacter spp., and rotavirus, as well as pathogens that are able to grow in water distribution systems, like Legionella spp., mycobacteria, and aeromonads. To perform a risk analysis for the pathogens in drinking water, it is necessary to understand the ecology of these organisms. The ecology of the drinking-water distribution system has to be evaluated in detail, especially the diversity and physiological properties of water bacteria. The interactions between water bacteria and (potential) pathogens in such diverse habitats as free water and biofilms are essential for the survival or growth of hygienically relevant organisms in drinking water. Results of epidemiological studies together with ecological data are the basis for effective resource protection, water treatment, and risk assessment.
597 citations
"Evaluation of the efficiency of pol..." refers background in this paper
...coli (EHEC), Yersinia enterocolitica, Campylobacter jejuni, Calciviruses and Microsporidia (Szewzyk et al., 2000)....
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01 Jan 2001
TL;DR: This chapter looks at the history and examines some of the methods used to assess the microbiological quality of water, highlighting the current limitations and also possible future developments.
Abstract: Current guidelines in the three water-related areas (drinking water, wastewater and recreational water) assess quality, in microbiological terms, by measuring indicator organisms. This chapter looks at the history and examines some of the methods used to assess the microbiological quality of water, highlighting the current limitations and also possible future developments. Traditionally, indicator microorganisms have been used to suggest the presence of pathogens (Berg 1978). Today, however, we understand a myriad of possible reasons for indicator presence and pathogen absence, or vice versa. In short, there is no direct correlation between numbers of any indicator and enteric pathogens (Grabow 1996). To eliminate the ambiguity in the term 'microbial indicator', the following three groups (outlined in Table 13.1) are now recognised:
477 citations
TL;DR: Self-sustaining, decentralized approaches to making drinking water safe, including point-of-use chemical and solar disinfection, safe water storage, and behavioral change, have been widely field-tested and merit far greater priority for rapid implementation.
Abstract: Since 1990, the number of people without access to safe water sources has remained constant at approximately 1.1 billion, of whom approximately 2.2 million die of waterborne disease each year. In developing countries, population growth and migrations strain existing water and sanitary infrastructure and complicate planning and construction of new infrastructure. Providing safe water for all is a long-term goal; however, relying only on time- and resource-intensive centralized solutions such as piped, treated water will leave hundreds of millions of people without safe water far into the future. Self-sustaining, decentralized approaches to making drinking water safe, including point-of-use chemical and solar disinfection, safe water storage, and behavioral change, have been widely field-tested. These options target the most affected, enhance health, contribute to development and productivity, and merit far greater priority for rapid implementation.
296 citations
"Evaluation of the efficiency of pol..." refers background in this paper
...Therefore, it is necessary to develop methods to make drinking water free from pathogens (Mintz et al., 2001)....
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