Simultaneous pretreatment and acidogenesis of solid food wastes by a rotational drum fermentation system with methanogenic leachate recirculation and andesite porphyry addition

A simultaneous pretreatment and acidogenesis process was developed by recirculating methanogenic leachate and adding andesite porphyry (WRS) powder to a rotational drum fermentation system to enhance the anaerobic digestion of solid food wastes. In the continuous operations, methanogenic leachate recirculation significantly increased hydrolysis rates and volatile solids (VS) degradation. The VS degradation ratio and the hydrolysis rate constant at a higher leachate recirculation ratio (2:1 weight ratio of methanogenic leachate to substrate) were increased by 2.1- and 1.4-fold, respectively, compared to those of the lower ratio (1:1 leachate recirculation ratio). A 10% (weight ratio of WRS to substrate solid content) WRS addition assisted the biochemical reactions in the process at the higher leachate recirculation ratio was employed. The hydrolysis rate constant and VS degradation were elevated by 54.7% and 63.9%, respectively, with the WRS addition. Besides, the WRS addition enhanced the VA formation and its conversion to biogas.