Sulfur Reduction and Inhibition in Anaerobic Treatment of Simulated Pulp Mill Wastewater

Summary Bioassay studies were conducted on the anaerobic degradation of a simulated pulping wastewater (evaporator condensate) containing sulfur compouds (sulfate, sulfite, or dithionite). Sulfite and dithionite (1000 mg S/l) totally inhibited methane production while sulfate (1000 mg S/l) had a minor effect. High concentrations of sulfite (1000 mg S/l) appeared to inhibit sulfite reduction. Biochemical reduction of dithionite (100–1000 mg S/l) could not be demonstrated. Methane bacteria outcompeted sulfate-reducing bacteria when methanol was the only substrate available. Methanol was utilized by sulfate reducers in the presence of a specific methanogen inhibitor, BES. Increase of the methanol concentration in an acetate -methanol medium stimulated sulfate reduction.