Improved Anaerobic Digestion Activity of Poultry Dung With Pumice-Supported Trace Elements: Focus on the Statistical Optimization Approach

Abstract

In the present study, two types of pumice (TP) supporting Ni (Ni/TP) and Mo (Mo/TP) as trace element additives for anaerobic digestion (AD) of poultry dung (PD) were synthesized using the NaBH4 reduction method. Multiple effects of operating parameters on the AD system were investigated for each material and optimized by using response surface methodology (RSM). Results showed that the operating parameters have important effects on the selected responses (cumulative biogas production (mL), removal yield for chemical oxygen demand (COD% removal), and methane percentage in biogas (CH4% content)). ANOVA results indicated that the obtained quadratic models for each response were statistically significant (p < 0.05). Moreover, the experimental data was in harmony with the predicted data obtained by the models for the responses selected for each material (R-2 > 0.90). The numerical analysis results showed that at the optimum points, the maximum cumulative biogas production, COD% removal, and CH4% content were 7862.75 mL, 60.43%, and 63.49% for Ni/TP and 7372.79 mL, 55.15%, and 62.67% for Mo/TP, respectively. In addition, the impact of bimetallic material on AD was examined, and the results indicated that Ni and Mo have a synergistic effect on the AD process.