Enhancement of high solid anaerobic co-digestion of swine manure with rice straw pretreated by microwave and alkaline

Abstract This study was to evaluate the effect of pretreated rice straw on high solid anaerobic co-digestion with swine manure, focusing on biogas production and kinetics. The rice straw pretreated by microwave, alkaline and alkaline-microwave was co-digested with swine manure under high solid state, and the effect was evaluated in bath reactors. The results indicated that, high solid anaerobic co-digestion of swine manure with rice straw pretreated by alkaline and alkaline-microwave could increase biogas yields by around 25%, with biogas productivities improved by 2.85–5.88% for per unit of total solid (TS). The biogas yields and productivities with rice straw pretreated by alkaline and alkaline-microwave could reach 355–357 L kg −1 TS-loaded and 679–699 L kg −1 TS-reduced, and their co-digestion process fitted the two-stage first order model accurately, discerned from the smaller average relative differences of 5.74% and 6.09% in contrast to 11.56% and 13.81% by using the single-stage first order model.