Chitosan Coagulation Pretreatment to Enhance Ceramic Water Filtration for Household Water Treatment

• Main Authors: Collin Knox Coleman, Eric Mai, Megan Miller, Shalini Sharma, Clark Williamson, Hemali Oza, Eleanor Holmes, Marie Lamer, Christopher Ly, Jill Stewart, Mark D. Sobsey, Lydia S. Abebe
• Format: Article
• Language: English
• Published: MDPI AG 2021-09-01
• Series: International Journal of Molecular Sciences
• Subjects: chitosan; coagulation; flocculation; ceramic filter; filtration; drinking water
• Online Access: https://www.mdpi.com/1422-0067/22/18/9736
• ISSN: 1661-6596; 1422-0067

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 <i>E.coli</i>, <i>C. perfringens,</i> sewage derived <i>E. coli</i> and total coliforms, MS2 coliphage, Qβ coliphage, ΦX174 coliphage, and sewage derived F+ and somatic coliphages.