Enhanced bioproduction of volatile fatty acids from excess sludge by sodium alcohol ether sulphate

• The maximum VFA production was 516 ± 6.0 mg COD/g VSS through AES pretreatment. • Sludge solubilization and hydrolysis were dramatically enhanced. • AES had a positive effect on municipal ES acidification process. • AES pretreatment severely inhibited microbial communities related to methanogenesis. • AES was highly biodegradable but not a substrate for VFA production. The conventional approach of anaerobic fermentation of excess sludge (ES) to produce volatile fatty acids (VFA) is limited by its poor efficiency and secondary pollution. Herein, a new strategy was developed for improving VFA production from the ES by sodium alcohol ether sulphate (AES) pretreatment. A maximum VFA yield of 516 ± 6.0 mg COD/g VSS was obtained with 0.28 g AES/g SS. It was proved that AES pretreatment had a synergistic effect on the enhancement of ES flocs solubilization, as well as hydrolysis and acidification of organic compounds in the ES. Meanwhile, the hydrolytic and acid-producing bacteria (i.e., Actinobacteria and Firmicutes ) were enriched, while the VFA consumers (i.e., Halobacterota ) were reduced by AES pretreatment, which resulted in the improved efficiency of VFA accumulation. Thereby, the AES had a positive effect on the conversion of organic matters in the ES to VFAs. Additionally, up to 97% of added AES could be degraded naturally during the treatment process, relieving the secondary pollution to environment. The strategy of AES pretreatment proposed in this work may provide a viable approach for ES treatment and relatively low-cost recovery of waste biomass.