Improving anaerobic digestion of piggery wastewater by alleviating stress of ammonia using biochar derived from rice straw

In this study, impact of a rice straw-derived biochar on the anaerobic digestion of piggery wastewater was investigated under different ammonium stress levels. The results showed that the biogas yield was decreased from 1293.27mL to 402.31 mL and the COD removal rate was decreased from 70.68% to 38.13% with the NH4+-N concentration increasing from 900mg/L to 3500 mg/L. At no ammonium stress level, the COD removal rate was increased from 70.68% to 83.75%, and biogas yield was increased from 1293.27mL to 2306mL with the increase of biochar dosage from 0g to 15g. While with the addition of biochar increasing from 0g to 15g, the COD removal rate was increased from 38.13% to 70.38% and the biogas yield was increased from 382 mL to 1878 mL at high ammonium stress level. It indicated that the presence of biochar not only could promote biogas yield but also could release the ammonium inhibition. (c) 2020 Elsevier B.V. All rights reserved.