Biogas production characteristics of solid-state anaerobic co-digestion of banana stalks and manure

To investigate the characteristics of solid-state anaerobic co-digestion of banana stalks with swine manure or with cow manure, the effect of manure to banana stalks ratio on the biogas production potential was evaluated in a laboratory scale, which operated at mesophilic (35°C±1°C) and solid-state (20% total solids) conditions. The experimental results showed that cumulative biogas from the co-digestion mixture with 75% of manure increased 1.3 to 2.0 times compared with banana stalks alone. Adding manure could enhance the bioconversion of biogas, but the improved efficiency was different for the two kinds of manure. The anaerobic digestibility of the mixture (swine manure with banana stalks) was higher than that of the mixture (cow manure with banana stalks). The highest methane yield of 191 mL/g and the highest cumulative methane of 12.7 L were both achieved by the co-digestion mixture with 50% of swine manure, which respectively increased by 69% and 92% above that obtained from the co-digestion of cow manure with banana stalks. As for the highest biogas yield and the highest cumulative biogas, they were observed in the co-digestion mixture with 75% of swine manure and separately reached 365 mL/g and 23.9 L. These were about 18% and 32% higher than those of the mixture of cow manure with banana stalks, respectively. In addition, it was found that the two kinds of manure could enhance the degradation of cellulose and semi-cellulose in the mixture, and that their maximum degradation ratios could increase by 1.2 times and by 3.6 times respectively as compared with the digestion of banana stalks alone. The results of this paper will provide a reference for biogas projects of solid-state anaerobic co-digestion of banana stalks with manure.