REMOVAL OF FECAL COLIFORM BACTERIA BY ZEBRA MUSSELS: AN ALTERNATIVE TO DISINFECTION IN MUNICIPAL WASTEWATER TREATMENT

摘要

The use of zebra mussel (Dreissena polymorpha) filtering capability to remove fecalcoliform bacteria in municipal wastewater effluent was investigated. The purpose of thisstudy was to explore the zebra mussel's efficiency in fecal coliform removal from thetertiary effluent and to evaluate their feasibility as biofilters in the final treatment ofwastewater. The bench-scale study was conducted at the Ann Arbor WastewaterTreatment Plant, Ann Arbor Michigan, from summer 1998 to winter 1999. Variouszebra mussel densities (mussels/L) and system contact time (hours) were evaluated.Fecal coliform removal efficiencies were positively related to the zebra mussel densitiesand contact time. Results showed that a zebra mussel density of 28 mussel/L and acontact time of 1.5 hours were optimal for producing a good quality effluent. Thisoptimal condition was later employed in evaluating the seasonal effects (i.e., coolertemperatures and survival rates of the mussels) in the removal efficiencies of variouscomponents. In the cooler effluent zebra mussels in the system survived longer, buttheir removal rates of fecal coliform were lower. Overall, the data tend to show thatzebra mussels utilized as 'biofilters' produced a better quality effluent as compared to the disinfected effluent.