Long-term effectiveness of bioaugmentation with rumen culture in continuous anaerobic digestion of food and vegetable wastes under feed composition fluctuations

Abstract

Biogas plants treating food waste (FW) often experience feed load and composition fluctuations. In Korea, vegetable waste from the preparation of kimchi comprises over 20% of the total FW production during the Kimjang season. The large production of Kimjang waste (KW) can cause mechanical and operational problems in FW digesters. This study investigated the long-term effectiveness of bioaugmentation with rumen culture (38 months) in an anaerobic reactor co-digesting FW with varying amounts of KW. The bioaugmented reactor maintained better and stabler performance under recurrent fluctuations in feed characteristics than a nonbioaugmented control reactor, particularly under high ammonia conditions. Bioaugmentation increased microbial diversity, thereby improving the resilience of the microbial community. Some augmented microorganisms, especially Methanosarcina, likely played an important role in it. The results suggest that the proposed bioaugmentation strategy may provide a means to effectively treat and valorize KW-and potentially other seasonal lignocellulosic wastes-by co-digestion with FW.