Long-term effects of increasing acidity on low-pH sulfate-reducing bioprocess and bacterial community

摘要

An ethanol-fed, sulfate-reducing anaerobic baffled reactor was operated over a period of 260 days to assess the effects of sequentially more acidic conditions (pH 4.5-2.5) on sulfate reduction and bacterial community. Results showed that the reactor could reduce sulfate and generate alkalinity at progressively lower pH values of 4.5, 3.5, and 2.5 in a synthetic wastewater containing 2500 mg/L sulfate. About 93.9% of the influent sulfate was removed at a rate of 4691 mg/L/day, and the effluent pH was increased to 6.8 even when challenged with influent pH as low as 2.5. Illumina MiSeq sequencing revealed that a step decrease in influent pH from 4.5 to 2.5 resulted in noticeable decrease in the bio-diversity inside the sulfidogenic reactor. Additionally, complete and incomplete organic oxidizers Desulfobacter and Desulfovibrio were observed to be the most dominant sulfate reducers at pH 2.5, sustaining the low-pH, high-rate sulfate removal and alkalinity generation.