Abstract
Effects of sulfate and sulfide on methanogenesis were examined in a sulfate-poor anaerobic sludge that had been acclimated with glucose as a carbon source for more than 3 years. Bacterial sulfide production occurred immediately when sulfate was added into the sludge. High density of sulfidogens (1010-1011 cells per g VSS) should inhabit in the sludge. At the same time methanogenesis was inhibited and the maximum inhibition was 53% of the initial methanogenesis at 0.6mM of sulfate. Up to 3mM of sulfide stimulated the methanogenesis, but more than 5mM of sulfide inhibited markedly the methanogenesis. These results show that high density of sulfidogens maintained by their fermentation from substrates under sulfate-poor environments and inhibited partially methanogenesis under sulfate-rich environment because of sulfidogens's predominant utilization of competitive substrates between sulfidogens and methanogens.
