Selection of combined additives for enhancing biogas production in anaerobic digestion

In China, the problem of low biogas production exists in many digesters. But some additives could enhance the biogas production by accelerating the process of hydrolysis or methanogenesis in anaerobic digestion. In this research, different kinds of these additives were selected, and then the selected additives were combined optimally to gain a positive impact on the gas production. Swine manure and methanogenic medium were used as the selective substrates, respectively. The results showed that, beer lees could activate the hydrolysis and the gas production rate was 23.17% higher than the control in the first four days, furthermore, in methanogenic medium experiment, both substrate M and trace elements two could promote the metabolism of methanogenic bacteria, which increased by 51.02% and 13.37% in biogas production over the control in 23 days digestion, respectively. Last, the the optimal combinations obtained in orthogonal experiment were trace elements two 10 mL/L, beer lees 2.5 g/L and substrate M 0.05 g/L, which led to 28.46% increase in biogas production in the household digester experiment. This research has provided a useful reference for developing a new type of biogas accelerator.