Synergistic co-digestion of waste commercial yeast and chicken manure: Kinetic simulation, DOM variation and microbial community assessment

Co-digestion of waste commercial yeast (Saccharomyces cerevisiae) and chicken manure was investigated in batch tests. The objective was to explore potential synergistic effects of the combination substrates. The biogas production rate and biomethane yield, batch kinetic simulation, metabolic dynamic and microbial community comparison were evaluated, respectively. The maximum biomethane yield of 364.79 mL/gVS was obtained at the optimum co-digestion feedstock (S.cerevisiae of 0.69 g/gVS) with a significant reaction rate increased of hydrolysis, acidogenesis, acetogenesis and methanogenesis. Person's correlation analysis resulted that the dissolved organic matter (DOM) variation had a close correlation with indexes of NADH, NH₄⁺-N, COD, VFAs and F₄₂₀. The high-throughput sequencing showed that higher diversity was obtained both bacteria and archaea in the optimized condition with more abundant of synergistic bacteria. Moreover, community dynamic reflected that the abundances of hydrogentrophic Methanobacterium and Methanolinea raised from 11.74%, 0.23%–14.49%, 60.78%, respectively. While the proportion of the acetoclastic Methanosaeta was decreased from 88.04% to 24.72% with the increasing of S.cerevisiae dosages from 0.48 g/gVS to1.07 g/gVS.