LAUSR

Anaerobic batch digestion of five different feed reactors was performed under mesophilic temperature at 35 ± 2 °C for a period of 45 days. All the reactors were filled with different combinations of substrates with cow dung and cotton seed hull based on the concentrations of volatile solid with them. The kinetics of biogas production from these feed reactors was studied using different models such as Gompertz model, cone model, Fitzhugh model and logistic kinetic equation. The resulting cumulative biogas production from anaerobic digestion was observed to be 193 ml/g VS and 33 ml/g VS, respectively, with the reactors composed of 100% cow dung (CD) (R1) and 100% cotton seed hull (CSH) (R2). For the reactors composed of mixture of 50% each CD and CSH (R3), mixture of 75% CD and 25% of CSH (R4) and mixture of 25% CD and 75% of CSH (R5), the cumulative biogas productions were 37, 86 and 23 ml/g VS, respectively. Based on the co-efficient of determination (R2) and root mean square error (RMSE), all kinetic models are validated to the best with experimental biogas yield. The cone model showed the good fit for R1, R2 and R4 whereas the logistic kinetic equation showed the good fit for R3 and R5. A new equation is proposed to predict the biogas yield on anaerobic digestion of substrates and its mixture where the digestion period and ratio of mixtures are considered as the input parameters.