Methane enhancement through co-digestion of chicken manure and oxidative cleaved wheat straw: Stability performance and kinetic modeling perspectives

Abstract

Abstract The current study investigated the co-digestion of chicken manure and oxidative cleaved wheat straw in semi continuous stirring tank reactor (CSTR). To elucidate the kinetics of the experimental methane production results, the modified Gompertz model was applied to evaluate the cumulative methane production curves for each experimental Phase. Two CSTRs, named as reactor A and B, have C/N ratio of 25 and 20 respectively, and three different organic loading rates (OLRs) of (1.5 g VS/L.d), (3.0 g VS/L.d) and (4.5 g VS/L.d), termed as Phase-I, Phase-II and Phase-III, were applied to anaerobic digestion experiments under mesophilic conditions. The results indicate that oxidative cleavage pretreatment of wheat straw is effective to reduce the lignin contents and carbon to nitrogen ratio up to 57% and 30% respectively. The modified Gompertz model is well fitted for the experimental data, and the Phase-II and III are concluded as optimum experimental Phases to enhance the methane production capability from the co-digestion of the chicken manure and pretreated wheat straw. Reactor-B at 3.0 g VS/L.d (C/N = 20) is proved optimum with methane production capability of 296.90 mL/g VS, 68.19% volatile solids removal efficiency.