Stabilization of microbial network by co-digestion of swine manure and organic wastes

The production of biogas from organic waste has attracted considerable interest as a solution to current energy and waste management challenges. This study explored the methane (CH₄) production potential of swine manure (SM), food waste (FW), and tomato waste (TW) and the changes in the microbial community involved in the anaerobic digestion process. The results revealed that the CH₄ production potentials of the four kinds of SM samples were influenced by the characteristics of SM (e.g., age and storage period). Among the four kinds of SM samples, the CH₄ yield from the manure directly sampled from primiparous sows (SM3) was the highest. The CH₄ yield was significantly improved when SM3 was co-digested with FW, but not with TW. The addition of SM fostered a stable CH₄ production community by enhancing the interaction between methanogens and syntrophic bacteria. Furthermore, the addition of FW as a co-substrate may improve the functional redundancy structure of the methanogenesis-associated network. Overall, the characteristics of SM must be considered to achieve consistent CH₄ yield efficiency from anaerobic digestion since CH₄ production potentials of SM can be different. Also, the contribution of co-substrate to the synergistic relationship between methanogens and syntrophic bacteria can be considered when a co-substrate is selected in order to enhace CH₄ yield from SM.