Removal of surrogate viruses from water using chitosan coagulation

Chitosan polymers can serve as effective coagulants for removal of turbidity and particles in drinking water. Research suggests chitosan coagulation can remove viruses, but the effects of polymer characteristics on virus reduction and the mechanisms of reduction are unclear. The purpose of this study was to determine the effect of dose, molecular weight (MW), degree of deacetylation (DD), and the addition of functional groups on the efficacy of chitosan coagulation-flocculation for the reduction of bacteriophage MS2, a surrogate non-enveloped virus, in artificial surface water used as a model for household drinking water. MW and dose had significant effects on virus reduction; higher MW gave higher reduction, and virus reduction within each MW was significantly higher at doses 3, 10, and 30 mg/L than 1 mg/L. 85% and 95% DD had the highest virus reductions, occurring at a dose of 10 mg/L. Overall, MW between 100,000 and 1,000,000 Da, DD from 85%-95%, and doses of 3 and 10 mg/L gave the highest viral reductions. Under these conditions, chitosan coagulation can produce ≥ 2 log10 and up to 5 log10 virus reduction. Combined with their ability to remove turbidity, chitosan polymers are an effective option to improve poor water quality for drinking water applications.