Anaerobic digestion of lipid-rich swine slaughterhouse waste: Methane production performance, long-chain fatty acids profile and predominant microorganisms.

Highlights • Swine slaughterhouse waste produced a maximum methane yield of 999.2 mL/g VS. • Lipid hydrolysis led to serious accumulation of linoleic, oleic and palmitic acids. • Increase of palmitic acid produced by degradation of oleic acid was observed. • Predominant microorganisms were Clostridium , Syntrophomonas and Methanospirillum. Abstract This study investigated methane production, long-chain fatty acids (LCFAs) profile, and predominant microorganisms in anaerobic digestion (AD) of lipid-rich swine slaughterhouse waste (SSW). The maximum methane yield was 999.2 mL/g VS. LCFAs, as inhibitory hydrolysis products, accumulated first to 1165 mg/L on day 3, and then decreased sharply to 125.7 mg/L on day 9, and finally were degraded to 20 mg/L on day 27. Linoleic acid (C18:2), oleic acid (C18:1) and palmitic acid (C16:0) were the dominant LCFAs. The easy conversion of C18:1 to C16:0 compared with difficult degradation of C16:0 resulted in an increase of C16:0 on day 4–6. Predominant microorganisms were Clostridium , Syntrophomonas and Methanospirillum. This study proved the high methane potential of lipid-rich SSW and gained insights into the degradation process by analysis of intermediates of LCFAs and predominant microorganisms. The results can provide valuable guidance for efficient utilization of this waste to produce methane in future. [ABSTRACT FROM AUTHOR]