Kazuhiro Takamizawa*, Hiroshi Shamoto*, Hiroyuki Horitsu*, Keiichi Kawai*, Tohru Suzuki*, Tomoko Mori**, Isao Fukunaga*** and Hiroshi Iida****

Abstract

To clarify the role of sulfate-reducing bacteria (SRB) in the insolubilization of heavy metal ions in a waste reclamation site, distribution of SRB in leachate and reduction of heavy metal ion by SRB were studied. SRB were commonly observed in leachate. Cadmium and copper, and iron and zinc, in synthetic medium, were insolubilized within 24hr, and 48hr, respectively, by SRB. But reducing the ratio of hexavalent chromium reached only 16.1% after 48hr treatment by SRB. When cadmium ion was used in the experiment, the precipitate produced was cadmium sulfide as determined by SEM and EDX analyses. These results suggest that SRB play an important role on insolubilization of heavy metals at waste disposal sites.

Key words: sea-based solid waste disposal site, leachate, heavy metal, sulfate-reducing bacteria