Production of volatile derivatives of metal(loid)s by microflora involved in anaerobic digestion of sewage sludge

Gases released from anaerobic wastewater treatment facilities contain consi derable amounts of volatile methyl and hydride derivatives of metals and me talloids, such as arsine (AsH3), monomethylarsine, dimethylarsine, trimethy larsine, trimethylbismuth (TMBi), elemental mercury (Hg-0), trimethylstibin e, dimethyltellurium, and tetramethyltin. Most of these compounds could be shown to be produced by pure cultures of microorganisms which are represent atives of the anaerobic sewage sludge microflora, i.e., methanogenic archae a (Methanobacterium formicicum, Methanosarcina barkeri, Methanobacterium th ermoautotrophicum), sulfate-reducing bacteria (Desulfovibrio vulgaris, D. g igas), and a peptolytic bacterium (Clostridium collagenovorans). Additional ly, dimethylselenium and dimethyldiselenium could be detected in the headsp ace of most of the pure cultures. This is the first report of the productio n of TMBi, stibine, monomethylstibine, and dimethylstibine by a pure cultur e of M. formicicum.