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

Abstract

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.