MICROBIAL REDUCTION OF MANGANESE COUPLED TO TOLUENE OXIDATION

Toluene degradation occurred in anaerobic flow-through sediment column s filled with contaminated sediment and sludge to which either amorpho us or highly crystalline manganese oxide was added. An enrichment cult ure from these sediment columns was able to grow on toluene under stri ctly anaerobic conditions in the presence of manganese oxide. The oxid ation of toluene was coupled to the production of CO2 and to the reduc tion of Mn(IV). Of the different manganese oxides tested, the rate was slowest with crystalline manganese oxide. After several transfers of the enrichment culture, its ability to degrade toluene became less and it was ultimately lost, unless sterilized Rhine river sediment was pr esent in the medium. Direct contact between the bacteria and the manga nese oxide was found to be advantageous for a rapid toluene degradatio n. The degradation rate could be further increased by adding organic l igands such as oxalic acid or nitrilotriacetic acid.