Removal of Coxsackie and Bacterial Viruses in Water by Flocculation

Abstract

Re-movals of added Coxsackie and bacterial viruses, Escherichia coli, and native bacteria from Ohio River water were studied under varying conditions in a 2-stage flocculation process similar to those employed in water-treatment plants. First-stage treatment using aluminum sulfate at dosages of 25 and 15 ppm (44 and 26 ppm filter alum) reduced the Coxsackie virus by 99-95%. Slightly higher and slightly lower percentage removals of bacteria and bacterial virus, respectively, were noted under the same conditions. In the second stage of treatment, the FeCl3 showed a virus-removal efficiency comparable to Al2(SO4)3 but was poorer with respect to bacterial removal. Removal of Coxsackie virus by combined stages was 99.6% at 5[degree] and 15[degree]C and 99.9% at 25[degree]C by 25 ppm coagulant in each stage. With 15 ppm coagulant Coxsackie removal was 99.8% at 25[degree]C. Removal of native bacteria was 98-99% and 99.99% by 15- and 25-ppm dosages, respectively, at 25[degree]C, and about 99.99% by the 25-ppm dosage at 5[degree]C and 15[degree]C. Evidence of interference effects of Ca++ and Mg++ and critical time relationships on the virus-floc complex formation is also presented.