Temperature effects on the methanogenesis enhancement and sulfidogenesis suppression in the UASB treatment of sulfate-rich methanol wastewater

This study aims at investigating that the temperature effects on the overall organics removal capability and the reaction kinetic properties of methanogenesis/sulfidogenesis in anaerobic treatment of sulfate-rich methanol wastewater. A lab-scale upflow anaerobic sludge blanket (UASB) reactor was operated for 285 days treating sulfate-rich methanol wastewater at a temperature range of 17.5–50 °C. The COD/SO₄ ²⁻ ratio of synthetic wastewater is 0.5. Experimental results indicate that both methanogens and sulfidogens showed lower metabolic activities at 17.5–25 °C. The average chemical oxygen demand (COD) removal efficiencies were higher than 90% at 40–50 °C. During these experimental periods, larger than 85% of influent COD was confirmed to be utilized for methanogenesis, revealing that methanogens prevailed over sulfidogens and dominated significantly in the COD utilization. In contrast, the sulfidogenesis-based COD utilization was effectively limited under the temperature range of 40–50 °C.