Degradation And Removal Of Sediment Pcbs Using Microbially Generated Iron Sulfide

This paper describes a method of decontaminating anaerobic sediments from organic micropollutants (polychlorobiphenyls, PCBs) using the controlled growth of the sulfate-reducing bacteria consortia present in the sediment. If iron sulfate is introduced into the sediment, under controlled anaerobic conditions, the sulfate-reducing bacterial consortia will build up over a period of time and produce large quanitities of FeS, which has been shown to be an excellent adsorbent for halogenated hydrocarbons and heavy metals. Evidence is presented that PCBs are first adsorbed, and then electron transfer leads to their breakdown in situ. As the FeS adsorbent is strongly magnetic, it an be removed from the sediment using high-gradient magnetic separation (HGMS) together with the remaining halogenated hydrocarbons and heavy metals which have been adsorbed. HGMS can be done cheaply and on a large scale. The goal of this research is to reduce the polluted sediment disposal and to investigate treatment methods suitable for in situ and in-plant remediation.