Kinetics of temperature effects and its significance to the heating strategy for anaerobic digestion of swine wastewater

The effects of temperature on biogas production and the heating strategy for anaerobic digestion of swine wastewater were investigated. Through a kinetic model, the maximum volumetric rate of biogas production (Rpmax) for digestion at 15, 20, 25, 30, and 35 °C were found to be 0.282, 1.189, 1.464, 1.789, and 2.049 L L−1 d−1, respectively. The temperature-activity coefficient of Rpmax was 1.332 at 15-20 °C, 1.043 at 20-25 °C, 1.041 at 25-30 °C, and 1.028 at 30-35 °C. Anaerobic digestion appeared to be more sensitive to temperature variation within 15-20 °C than to variation within 20-35 °C. In terms of energy input-output ratio and total annual cost, the optimal heating strategy is an increase in the fermentation temperature from 15 to 20 °C.