Evaluation of Chitosans as Coagulants—Flocculants to Improve Sand Filtration for Drinking Water Treatment

The World Health Organization (WHO) reports that two billion people worldwide lack access to safely managed water sources, including 1.2 billion who already have access to improved water sources. In many countries, household point-of-use (POU) water-treatment options are used to remove or deactivate...

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Main Authors: Eleanor B. Holmes, Hemali H. Oza, Emily S. Bailey, Mark D. Sobsey
Format: Article
Language:English
Published: MDPI AG 2023-01-01
Series:International Journal of Molecular Sciences
Subjects:
Online Access:https://www.mdpi.com/1422-0067/24/2/1295
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author Eleanor B. Holmes
Hemali H. Oza
Emily S. Bailey
Mark D. Sobsey
author_facet Eleanor B. Holmes
Hemali H. Oza
Emily S. Bailey
Mark D. Sobsey
author_sort Eleanor B. Holmes
collection DOAJ
description The World Health Organization (WHO) reports that two billion people worldwide lack access to safely managed water sources, including 1.2 billion who already have access to improved water sources. In many countries, household point-of-use (POU) water-treatment options are used to remove or deactivate microorganisms in water, but not all POU technologies meet WHO performance requirements to achieve safe drinking water. To improve the effectiveness of POU technologies, the use of multiple treatment barriers should be used as a way to increase overall treatment performance. The focus of this research is to evaluate multiple barrier treatment using chitosan, an organic coagulant–flocculant, to improve microbial and turbidity reductions in combination with sand filtration. Bench-scale intermittently operated sand filters with 16 cm layers of sands of two different grain sizes representing slow and rapid sand filters were dosed daily over 57 days with microbially spiked surface water volumes corresponding to household use. <i>E. coli</i> bacteria and MS2 coliphage virus reductions were quantified biweekly (N = 17) using culture methods. Bacteria and virus removals were significantly improved over sand filtration without chitosan pretreatment (Wilcoxon Rank-Sum, <i>p</i> < 0.05). When water was pretreated at an optimal chitosan dose of 10 mg/L followed by sand filtration, log<sub>10</sub> reductions in bacteria and viruses met the two-star WHO performance level of effectiveness. Microbial and turbidity reductions generally improved over the filter operating period but showed no trends with filtration rates.
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spelling doaj.art-e5bbad2421224e019b5d8bd0945b8be72023-11-30T22:38:14ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672023-01-01242129510.3390/ijms24021295Evaluation of Chitosans as Coagulants—Flocculants to Improve Sand Filtration for Drinking Water TreatmentEleanor B. Holmes0Hemali H. Oza1Emily S. Bailey2Mark D. Sobsey3Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USADepartment of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USADepartment of Public Health, College of Pharmacy & Health Sciences, Campbell University, Buies Creek, NC 27506, USADepartment of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USAThe World Health Organization (WHO) reports that two billion people worldwide lack access to safely managed water sources, including 1.2 billion who already have access to improved water sources. In many countries, household point-of-use (POU) water-treatment options are used to remove or deactivate microorganisms in water, but not all POU technologies meet WHO performance requirements to achieve safe drinking water. To improve the effectiveness of POU technologies, the use of multiple treatment barriers should be used as a way to increase overall treatment performance. The focus of this research is to evaluate multiple barrier treatment using chitosan, an organic coagulant–flocculant, to improve microbial and turbidity reductions in combination with sand filtration. Bench-scale intermittently operated sand filters with 16 cm layers of sands of two different grain sizes representing slow and rapid sand filters were dosed daily over 57 days with microbially spiked surface water volumes corresponding to household use. <i>E. coli</i> bacteria and MS2 coliphage virus reductions were quantified biweekly (N = 17) using culture methods. Bacteria and virus removals were significantly improved over sand filtration without chitosan pretreatment (Wilcoxon Rank-Sum, <i>p</i> < 0.05). When water was pretreated at an optimal chitosan dose of 10 mg/L followed by sand filtration, log<sub>10</sub> reductions in bacteria and viruses met the two-star WHO performance level of effectiveness. Microbial and turbidity reductions generally improved over the filter operating period but showed no trends with filtration rates.https://www.mdpi.com/1422-0067/24/2/1295HWTSPOUchitosancoagulationsand filtrationbacterial reduction
spellingShingle Eleanor B. Holmes
Hemali H. Oza
Emily S. Bailey
Mark D. Sobsey
Evaluation of Chitosans as Coagulants—Flocculants to Improve Sand Filtration for Drinking Water Treatment
International Journal of Molecular Sciences
HWTS
POU
chitosan
coagulation
sand filtration
bacterial reduction
title Evaluation of Chitosans as Coagulants—Flocculants to Improve Sand Filtration for Drinking Water Treatment
title_full Evaluation of Chitosans as Coagulants—Flocculants to Improve Sand Filtration for Drinking Water Treatment
title_fullStr Evaluation of Chitosans as Coagulants—Flocculants to Improve Sand Filtration for Drinking Water Treatment
title_full_unstemmed Evaluation of Chitosans as Coagulants—Flocculants to Improve Sand Filtration for Drinking Water Treatment
title_short Evaluation of Chitosans as Coagulants—Flocculants to Improve Sand Filtration for Drinking Water Treatment
title_sort evaluation of chitosans as coagulants flocculants to improve sand filtration for drinking water treatment
topic HWTS
POU
chitosan
coagulation
sand filtration
bacterial reduction
url https://www.mdpi.com/1422-0067/24/2/1295
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AT hemalihoza evaluationofchitosansascoagulantsflocculantstoimprovesandfiltrationfordrinkingwatertreatment
AT emilysbailey evaluationofchitosansascoagulantsflocculantstoimprovesandfiltrationfordrinkingwatertreatment
AT markdsobsey evaluationofchitosansascoagulantsflocculantstoimprovesandfiltrationfordrinkingwatertreatment