Effect of Environmental Conditions on Sulfate Reduction with Methane as Electron Donor by an Eckernförde Bay Enrichment

Abstract

Sulfate reduction (SR) coupled to anaerobic oxidation of methane (AOM) is meditated by marine microorganisms and forms an important process in the global sulfur and carbon cycle. In this research, the possibility to use this process for the removal and recovery of sulfur and metal compounds from waste streams was investigated. A membrane bioreactor was used to enrich for a community of methane-oxidizing sulfate-reducing microorganisms from Eckernförde Bay sediment The AOM and SR rate of the obtained enrichment were 1.0 mmol gvss(-1) d(-1). The operational window and optimal environmental conditions for SR with methane as electron donor were assessed. The optimum pH, salinity, and temperature were 7.5, 30% per hundred and 20 degrees C, respectively. The enrichment had a good affinity for sulfate (Km < 0.5 mM) and a low affinity for methane (Kn > 0.075 MPa). A0M coupled to SR was completely inhibited at 2.4 (L0.1) mM sulfide. AOM occurred with sulfate, thiosulfate, and sulfite as electron accepters. Sulfate reduction with methane as electron donor can be applied for the removal of sulfate or for the production of sulfide,for metal precipitation. However, the low optimal temperature and the high salt requirement limit the operational window of the process.