Abstract
Viruses are major contributors to the annual 1.3 million deaths associated with the global burden of diarrheal disease morbidity and mortality. While household-level water treatment technologies reduce diarrheal illness, the majority of filtration technologies are ineffective in removing viruses due to their small size relative to filter pore size. In order to meet the WHO health-based tolerable risk target of 10−6 Disability Adjusted Life Years per person per year, a drinking water filter must achieve a 5 Log10 virus reduction. Ceramic pot water filters manufactured in developing countries typically achieve less than 1 Log10 virus reductions. In order to overcome the shortfall in virus removal efficiency in household water treatment filtration, we (1) evaluated the capacity of chitosan acetate and chitosan lactate, as a cationic coagulant pretreatment combined with ceramic water filtration to remove lab cultured and sewage derived viruses and bacteria in drinking waters, (2) optimized treatment conditions in waters of varying quality and (3) evaluated long-term continuous treatment over a 10-week experiment in surface waters. For each test condition, bacteria and virus concentrations were enumerated by culture methods for influent, controls, and treated effluent after chitosan pretreatment and ceramic water filtration. A > 5 Log10 reduction was achieved in treated effluent for E.coli, C. perfringens, sewage derived E. coli and total coliforms, MS2 coliphage, Qβ coliphage, ΦX174 coliphage, and sewage derived F+ and somatic coliphages.
Highlights
Lack of access to potable water and reliance on surface water contaminated by fecal pollutants as a source of drinking water contributes to high rates of episodic or chronic diarrheal morbidity and mortality
The aim of this study is to examine the use of chitosan, a non-toxic polysaccharide of repeating N-acetyl-D-glucosamine (GlcNAc) and D-glucosamine (GlcN) monomers, as a cationic coagulant pretreatment to aid in the removal of microbial contamination from drinking waters when combined with ceramic filtration
In summary: it was found that coagulation and flocculation of water with either chitosan lactate or chitosan acetate prior to ceramic filtration significantly increased virus and bacteria reductions from surface waters with and without added wastewater, as compared to waters treated by ceramic filtration only
Summary
Lack of access to potable water and reliance on surface water contaminated by fecal pollutants as a source of drinking water contributes to high rates of episodic or chronic diarrheal morbidity and mortality. In 2015 it was estimated that 1.3 million deaths annually are associated with diarrheal diseases which disproportionately impact children under. Viruses have been identified as major contributors to the global burden of diarrheal disease morbidity and mortality with rotavirus alone accounting for 199,000 deaths in 2015 [1,5]. Rotavirus is the leading cause of moderate-to-severe diarrhea in infants and children under age 5 and norovirus is most common among adult populations [6,7]. Vaccines exist for rotavirus and have decreased diarrhea-associated morbidity and mortality, but for many waterborne diarrheal pathogens such as noroviruses, shigella spp., campylobacter spp., Giardia, and Cryptosporidium there either are no vaccines or their use is not widespread in low and middle income countries [8,9]
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