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

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.

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

“…Three doses of chitosan were tested in the 57-day bench-scale treatment study along with a control condition with no chitosan treatment: 0 mg/L, 3 mg/L, 10 mg/L, and 30 mg/L. The choice of these chitosan doses was based on previous studies by our laboratory on the range of effective chitosan doses for microbial and turbidity reductions [ 14 , 15 , 16 , 18 ].…”

“…In previous laboratory studies the positively charged chitin derivative chitosan, a natural and biodegradable polysaccharide byproduct of the crustacean fishing industry and available as well from other natural sources, such as insect exoskeletons, has been proposed as a coagulant–flocculant POU treatment for use in multiple-barrier methods, such as with cloth and ceramic filters [ 14 , 15 , 16 , 17 ]. When chitosan is added to water, suspended colloidal material including viruses, bacteria, and spores are coagulated, allowing the coagulated particles to then flocculate together during slow mixing and then settle out of the water or be remove by subsequent filtration.…”

Bromine and Chlorine Disinfection of Cryptosporidium parvum Oocysts, Bacillus atrophaeus Spores, and MS2 Coliphage in Water

“…MS2 coliphage (ATCC# 15597-B1) stocks were prepared using an E. coli F-amp host as previously described . Volumes of 100 μL of serially diluted samples from disinfection experiments were assayed by the double agar layer (DAL) plaque technique on the host bacterium, E. coli F-amp, using previously described standard procedures .…”

Natural-based coagulants/flocculants as sustainable market-valued products for industrial wastewater treatment: a review of recent developments

“… 63 To utilize these active chemicals in the coagulation–flocculation process to eliminate colloidal organic and inorganic contaminants from wastewater, their contents can be modified. 64 Interparticle bridging, adsorption, charge neutralisation, and hydrophobic flocculation are coagulation-related processes. 33 Gelatin is another frequently used animal-based coagulants/flocculants used for industrial wastewater treatment.…”