Abstract: In order to improve the methane production efficiency of the mixed anaerobic fermentation with rice straw and pig manure in the field, this research carried out an experiment of activated carbon on methane production by simulating the field anaerobic fermentation conditions at medium temperature （35±1） ℃ in the laboratory. Six treatments were used whose activated carbon content account for 0%, 1%, 2%, 3%, 6%, 8% of fermentation substrate, respectively. The variation of gas production and straw degradation of each treatment was determined. The results showed that the activated carbon promoted the mixed anaerobic fermentation process by shortening lag time and increasing the peak value of methane production; the addition of activated carbon significantly influenced the biological methane production of the mixed anaerobic fermentation with straw and pig manure. The biological methane production increased firstly and then decreased with the increasing activated carbon amount, and reached the highest value at 2% and 3% treatments, increasing by 29.29% and 28.04% contrasting to the control, respectively; the addition of activated carbon also promoted the degradation of cellulose and hemicellulose of rice straw in the mixed anaerobic fermentation system. At the treatment of 3% activated carbon, the degradation rate of total lignocellulose, cellulose and hemicellulose reached 29.57%, 45.35% and 34.09%, respectively, increasing by 125.73%, 122.00% and 128.33% contrasting to the control. The results indicated that the addition of activated carbon can accelerate the process of mixed anaerobic fermentation with rice straw and pig manure, and increase the methane production and straw degradation in the anaerobic fermentation system.

Key words: mixed anaerobic fermentation, methane, activated carbon, straw degradation