Document Type

Report

Publication Date

January 1979

Abstract

The purposes of this study were to evaluate virus removal in treatment of water supplies by an in-line direct filtration pilot plant system and to suggest a system design to enhance virus removal. Isotherm and jar tests were conducted to evaluate the effects of pH, sodium ion concentration, and coagulants (alum and cationic polyelectrolytes Cat-Floc T, Nalco 8102, and 8103) on the bacteriophage MS2 contained in water. Isotherm studies were also conducted to assess the kinetic adsorption of MS2 to sand, anthracite, and garnet. Rapid sand, dual-media, and multi-media filters were tested in continuous in-line direct filtration operations. Approximately 95 percent reduction in virus concentration was observed at pH 9. Zero to 0.5 mg/1 of sodium ion present in water had no significant effect on the virus. Alum dosages below 20 mg/1 did not remove the bacteriophase MS2 from water, whereas 50 mg/1 of alum removed 98 percent of the virus. Two mg/1 of Nalco 8101 (the most efficient cationic polyelectrolyte with respect to virus removal) aggregated 96 percent of the virus. Sand and garnet were not foind effective in virus removal from water by the isotherm tests. Anthracite, however, removed approximately 93 percent of the virus in 2 hours. Based on the continuous filtration experiment, it was concluded that in-line direct filtration cannot be counted on to remove virus from water. In-line direct filtration, however, met the effluent turbidity standard of less than 1 NTU. No correlation existed between turbidity breakthrough and birus breakthrough in the effluent. Furthermore, these experiments showed that the effluent quality with respect to both turbidity and virus did not change when hydraulic loading rate was increased from 7.3 to 12.2 m^3/hour/m^2. On a more promising note, addition of 2 mg/1 of Nalco 8101 to the rapid mix basin was suggested as a potential means of virus removal in a water treatment system.