Abstract:Evaluation of high-solids anaerobic co-fermentation of carbohydrate, protein and lipid at various mixing ratios was conducted at mesophilic (35℃ ± 1℃) and high-solids (12% total solids) condition. The effects of mixing ratios on methane conversion and degradation efficiency of organic substance were investigated. Results showed that the maximum values of specific methane production potential (Ps), specific methane production rate (Rs) and methane yield were all achieved at mixing ratio of 55:36:9, and they increased to 404.1mL/gVS, 11.2mL/(gVS·d), and 326.7mL/gVS, respectively. Compared with other mixing ratios, the degradation process of oragnic substance was also more effective and more stable at the ratio of 55:36:9. Adding appropriate carbohydrate could not only enchance the degradation itself, but also improve the degradation efficiency of protein and lipid. Moreover, it was found that when carbohydrate in the substrate accounted for more than 65%, the high concentration of total volatile fatty acid (VFA), some single VFA and total undissociated acid became the primary factors resulting in methane production inhibition. Increasing the proportion of protein could lead to the prolonged star-up period as well as fermentation time. When protein increased up to 48%, a switch to the inhibition of methane production by total ammonia (TNH3-N) and free ammonia (NH3-N) occurred.