The Improvement of Rice Straw Anaerobic Co-Digestion with Swine Wastewater by Solar/Fe(II)/PS Pretreatment

Abstract

Rice straw (RS) is among the agricultural waste products with the highest methane production potential in the world, but the refractory complex structure and high carbon-to-nitrogen ratio of RS cause low methane conversion efficiency and limit its widespread application in anaerobic digestion. In this study, Solar/Fe (II)/persulfate (PS) pretreatment of RS was investigated to improve microbial accessibility, and anaerobic co-digestion combined pretreated RS and swine wastewater (SW) were evaluated to improve the efficiency of anaerobic digestion. The results showed that the Solar/Fe (II)/PS pretreatment could disrupt the structure of RS and promote the reduction of sugar content, increasing microbial accessibility to RS. When all the components of the pretreated RS (including the use of the solution remaining from the pretreatment) were anaerobically co-digested with SW, the cumulative biogas production and cumulative methane production reached 252.10 mL/g·VS and 163.71 mL/g·VS, 19.18% and 36.97% higher than the anaerobic co-digestion of untreated RS and SW, respectively. The anaerobic co-digestion of the Solar/Fe (II)/PS-pretreated RS with SW is a promising approach to achieving the utilization of RS components and maximizing methane yields, providing a cost-effective and pollution-free method for the production of high-quality bioenergy from agricultural waste.