Performance and mechanism of sodium percarbonate (SPC) enhancing short-chain fatty acids production from anaerobic waste activated sludge fermentation

A novel pretreatment technique (i.e., using Sodium percarbonate, SPC) to improve the short-chain fatty acids (SCFA) production waste activated sludge (WAS) was proposed in this study. Results indicated that the maximum SCFA production of 1605.7 mg COD/L and acetic acid of 52.9% were attained at 0.2 g SPC/g TSS, being 8.4 and 2.8 times of the control (191.3 mg COD/L and 19%), respectively. Meanwhile, the optimal time for SCFA accumulation was decreased from 6d (control) to 4d (0.2 g/g TSS). Mechanism explorations unraveled that SPC largely accelerated WAS solubilization and enhanced the bioavailability of organics released from WAS. It improved enzymatic activities related to hydrolysis and acidogenesis, while suppressed the Coenzyme F420 responsible for SCFA consumption. Illumina MiSeq sequencing analysis showed that SPC substantially enhanced the relative abundances of hydrolytic and/or acid-forming microbes. Furthermore, CO3- and O2− were the key factors to production enhancement in SPC-involved sludge fermentation. [Display omitted] •SPC pretreatment enhanced SCFA production from anaerobic WAS fermentation.•SPC pretreatment facilitated WAS disintegration and the biodegradability of organics.•SPC pretreatment accelerated hydrolysis/acidogenesis while suppressed methanogenesis.•SPC pretreatment enhanced the abundances of hydrolytic and/or acid-forming microbes.•CO3- and O2− were main contributors to sludge solubilization and SCFA production.