Performance and mechanism of a novel hydrolytic bacteria pretreatment to boost waste activated sludge disintegration and volatile fatty acids production during acidogenic fermentation

Abstract

In this study, an innovative mixed hydrolytic bacteria culture (HB) (the main dominant bacterial species: Lactobacillus acetotolerans), as an environmentally friendly pretreatment technique, was developed to enhance the volatile fatty acids (VFAs) production from waste-activated sludge (WAS). The highest VFAs production of 517 and 518 mg/g VSS were achieved with HB 8% and HB 8%-35 °C pretreatments, which were almost 3.6 folds compared to the control (143 mg/g VSS), respectively. The mechanism analysis revealed that HB boosted the bioavailability of organics released from WAS and significantly accelerated sludge solubilization. Protease and α-glucosidase enzymatic activity were improved and associated with hydrolysis and acidogenesis. Furthermore, the microbial community analysis showed that HB pretreatment significantly increased the hydrolytic and acidifying bacteria proportions (e.g., Veillonella, Macellibacteroides sp., Clostridium_sensu_stricto_1 and Bacteroides sp., etc.). This study provides a promising, low-cost, and eco-friendly approach for recovering resources from WAS and transforming them into high-value products.