Microorganism removal from wastewater by rapid mixed media filtration

Reuse of domestic sewage effluents in Arizona requires that certain microbiological standards be met. The purpose of this project was to determine the effectiveness of rapid mixed media filtration in the removal of enteric viruses, fecal coliforms and roundworm eggs from sewage destined for reuse as irrigation water. Two surrogate viruses, the simian rotavirus SA-11, used in place of human rotavirus which is pathogenic to man, and f2 coliphage, known to adsorb poorly to surfaces, were used to evaluate filter performance. No significant removal of coliphages occurred by the filters. Addition of ferric chloride and anionic polymer did not enhance virus removal. When small amounts of alum and polymer were added, removal of colliphage increased to 37-40%. Average removal of rotavirus ranged from 21 to 27% after addition of alum and polymer. Mixed media filtration effectively reduced coliform numbers. The removal of Ascaris ova by filtration was essentially complete.