MICROBIAL FE(III) REDUCTION IN ACTIVATED-SLUDGE

This study examined the concentration of iron, the rate of Fe(III) red uction and the numbers of Fe(III)reducing bacteria present in activate d sludge from 10 different wastewater treatment plants throughout Denm ark. The temporal variation in Fe(III) reduction rates and the effect of temperature and various electron donors on the Fe(III) reduction ra te in activated sludge within a selected treatment plant in Aalborg, D enmark were also examined. A Fe(III)-reducing bacterium that can grow using the Fe(III) bound within activated sludge as a sole electron acc eptor was isolated from the sludge. These studies demonstrate that Fe( III)-reducing bacteria are present in the activated sludge of Danish w astewater treatment plants as normal members of the microbial communit y and that Fe(III) is a significant electron acceptor in this environm ent.