Effect of Biochar in Modulating Anaerobic Digestion Performance and Microbial Structure Community of Different Inoculum Sources

The use of biochar materials to regulate anaerobic digestion (AD) processes has attracted interest, but the regulation of microbial mechanisms in AD by biochar is unclear. To investigate how bio-char modulate the process of AD, different inoculum sources including cellulose-peptone-swine inoculum (CPSI) and swine manure inoculum (SMI) were designed to determine the effect of bio-char on the performance and microbial communities of anaerobic digestion of the feedstock con-centration from 1 to 6%. The results shown that the methane yields of CPSI seeds were higher 20.3-38.7% than these of SMI seeds without biochar addition. Whereas the biochar addition re-duced 5.3 and 23.1% of the corresponding methane yield of CPSI and SMI, respectively. The bio-char was weakening the potential ammonia inhibition by adsorption, and it can improve the deg-radation rate of organic contend of soluble COD for different inoculum sources. Microbial com-munity analyses showed that the biochar addition could facilitate the growth of proteolytic bacte-ria Bacteroidetes and Clostridiales, and it enriched the relative abundance of hydrogenotrophic methanogens Methanobrevibacter and Methanobacterium. Overall, although the modulation of bio-char possessed different effects for the anaerobic digestion performance, it contributed to the sta-bility and degradation efficiency of digestion system. The recycling implication of biochar is criti-cal to realize a low-carbon and renewable treatment system for organic wastes.