The role of mineral bentonite and biochar in improving the performance of anaerobic Co-digestion under mesophilic conditions

Mineral and bio-based accelerants can effectively enhance the performance of anaerobic digestion (AD). In this study, low-cost bentonite (BT) and biochar (BC) were used as accelerants to evaluate the co-digestion performance of cow manure (CM) and vegetable residue (VR). Moreover, individual BT and BC performance as accelerants was benchmarked with combined effect of BT and BC (BT + BC). Three different concentrations of BT (0.5, 1.0, and 2.0 g/L), BC (0.12, 0.16, 0.20 g/L) and BT + BC (0.25 g/L BT+0.06 g/L BC, 0.5 g/L BT+ 0.08 g/L BC and 1.0 g/L BT+ 0.10 g/L BC) were introduced into batch AcoD systems under a mesophilic conditions (36 ± 1 °C). The optimal AD performance was achieved through BT concentration of 2.0 g/L with biogas yield of 580 mL/g VS; TS (42 %), VS (47 %), COD (48 %) reduction rates and NPK fertility content of 4.14 %. Moreover, an enhanced DIET mechanism was described through BT and BC. This study suggests that a low-cost-mineral (BT) could develop a circular bio-economy by improving biogas yield and soil fertility through NPK content by applying digestate produced through AD process in agricultural land.