Rice straw pretreatment using cow breeding wastewater for methane production.

The aim of this study was to investigate the pretreatment of rice straw using cow breeding wastewater. The effects of filtering cow breeding wastewater through rice straw and microaerobic treatment on the pretreatment characteristics and methane production of rice straw were investigated. Generally, the filtration improved the pretreatment effect by adsorbing ammonium nitrogen and achieved higher solids loading for pretreatment. Although airtight treatment was optimal, the lignin removal and methane production of semi-sealed rice straw were only slightly lower than those of sealed rice straw. However, the results of open treatment were similar to those of the control. The maximum lignin removal and methane production reached 68.08% and 292.62 L/kg volatile solids (VS), respectively, for the filtered rice straw soaked in cow breeding wastewater again during pretreatment, and 61.26% and 274.18 L/kg VS, respectively, for the filtered rice straw pretreated directly without soaking.