Bioaugmentation with methanogenic culture to improve methane production from chicken manure in batch anaerobic digestion

This study sought to investigate the effect of bioaugmentation on batch anaerobic digestion of chicken manure. The digestion performance with and without bioaugmentation and bioaugmented efficiency under different dosages were compared. The results demonstrated that bioaugmentation increased the methane yield and shortened the methane production time in batch reactors. Compared to the un-bioaugmented control, the methane yield of bioaugmented digesters was increased by 1.2-, 1.7-, 2.2-, 3.4-, and 3.6-fold at addition ratios of 0.07, 0.14, 0.21, 0.27, and 0.34 g VS bioaugmentation seed (BS)/g VSCM, respectively. However, higher bioaugmentation doses (0.34 g VSBS/g VSCM) did not exhibit significantly improved bioaugmentation efficiency, thus, the recommended dose is 0.27 g VSBS/g VSCM for biomethane conversion of CM. Moreover, whole genome pyrosequencing revealed that Methanoculleus and Methanobrevibacter predominated the non-bioaugmentation digesters, whereas Methanothrix, Methanobacterium, and Methanomassiliicoccus were the dominant methanogens in bioaugmentation digesters. The increased methane may be explained by an increase in the Methanothrix population, which accelerated acetic acid degradation. With bioaugmentation the mainly methanogenic pathways have become more diverse. From gene function perspective, bioaugmentation enhanced metabolic activities in digestor which function better in metabolism.