Integrated production to digestion of a mycelium lignocellulosic biocomposite: Effects of temperature and co-digestion

Abstract

The current study developed a mycelium lignocellulosic biocomposite (MLB) from rice husk and tangerine peel and evaluated its potential for resource recovery through anaerobic digestion (AD) under different temperatures. The MLB was cultivated with G. lucidum without the use of synthetic binders. Several substrate-to-water ratios were examined, with a 1:2 ratio yielding the most favorable material properties. After production, the MLB was subjected to AD at 36 °C and 55 °C using two operational strategies: mono-digestion and co-digestion with sewage sludge (SL). Under mesophilic co-digestion, methane yields reached 284 mL CH4/g∙VSfeed, accompanied by efficient conversion of volatile fatty acids (VFAs) to methane. However, thermophilic operation enriched heat-adapted consortia but led to VFA accumulation and reduced methane production. These results highlight a substrate-dependent temperature effect: thermophilic conditions enhance sludge biodegradation but do not sufficiently overcome the recalcitrance of MLB, whereas mesophilic co-digestion promotes syntrophic interactions and achieves higher conversion to methane.