Simultaneous recovery of short-chain fatty acids and phosphorus during lipid-rich anaerobic fermentation with sodium hydroxide conditioning.

Anaerobic fermentation (AF) could achieve simultaneous recovery of short-chain fatty acids (SCFAs) and phosphorus (P) when waste activated sludge (WAS) and meat processing waste (MPW) act as co-substrate. However, long-chain fatty acids, the degradation intermediates of lipids, always inhibit anaerobic microbial activity. Therefore, sodium hydroxide (NaOH) conditioning was applied to improve the lipid-rich AF performance in this study. The results demonstrated that 96% WAS (v/v) with NaOH addition that remaining at pH 7.5 could achieve the maximum SCFAs yield (1180.05 mg/g VS fed) at 12 d, and ortho-P content in the AF liquor (AFL) was much more than that of without NaOH addition. Anaerovibrio and Aminobacterium , one kind of lipolytic and proteolytic bacteria, respectively, became the major genus in the lipid-rich AF system. 86% of P in the AFL from 96% WAS + pH 7.5 reactor was recovered through vivianite crystallization method, with 91% of SCFAs remaining in the post-AFL. Meanwhile, analysis results verified vivianite formation in the P precipitate products. Overall, this study provided a new idea to achieve SCFAs and P simultaneous recovery from WAS and MPW through AF with NaOH conditioning and vivianite crystallization. [Display omitted] • Meat processing waste and activated sludge were treated by anaerobic fermentation. • NaOH conditioning enhanced SCFAs yield and P release from lipid-rich AF. • Maximal SCFAs yield (1180.05 mg/g VS fed) occurred at pH 7.5 with NaOH addition. • Anaerovibrio , one kind of lipolytic bacteria, was stimulated during lipid-rich AF. • Ortho-P release from the fermentation system was favorable for vivianite recovery. [ABSTRACT FROM AUTHOR]