Nitrate-Controlled Anaerobic Oxidation of Pyrite byThiobacillusCultures

Nitrate-dependent pyrite oxidation is an important process as it may prevent pollution by nitrate from agriculture. Anaerobic oxidation of pyrite with nitrate as an electron acceptor was studied in cultures of Thiobacillus denitrificans and Thiobacillus thioparus. Both strains reduced nitrate, with pyrite added as sole electron donor, but T. thioparus reduced nitrate to nitrite only. Accumulation of nitrite, however, was prevented in co-cultures of T. denitrificans and T. thioparus. Furthermore, pyrite oxidation rates were dependent on pyrite pretreatment, which results in different specific surface areas of pyrite. Initial nitrate concentration or pyrite origin did not affect the pyrite oxidation rate.