Substrate-Driven Microbial Dynamics and Digestate Traits in Microalgal Co-Digestion

초록

Purpose This study examines the potential of anaerobic co-digestion of microalgal biomass with carbon-rich wastes to improve CH4 yield and support sustainable digestate valorization. Methods The green microalga Desmodesmus intermedius KNUA024 was cultivated under controlled conditions and tested in biochemical methane potential assays, either alone or with waste cooking oil (WCO) as a co-substrate. Microbial communities were profiled by high-throughput sequencing, and digestates were analyzed for nutrients and trace metals. Results Co-digestion with WCO increased CH4 yield by up to 47% compared to microalgae-only digestion and improved process stability. Substrate composition strongly influenced microbial succession, with lipid-rich substrates promoting syntrophic and methanogenic groups. Digestates contained valuable nutrients but also trace metals near regulatory limits, indicating the need for careful monitoring. Conclusion Substrate-driven microbial dynamics play a decisive role in both methane production and digestate quality. Co-digestion with lipid-rich wastes offers a practical strategy to enhance anaerobic digestion efficiency and contribute to sustainable bioenergy systems. Statement of Novelty This study integrates three-domain (bacterial, archaeal, and fungal) microbial profiling with digestate valorization, linking enhanced biogas production to sustainable reuse pathways and offering a novel approach toward a circular bioeconomy in microalgae-based waste management.

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