Freezing/thawing pretreatment coupled with biological process of thermophilic Geobacillus sp. G1: Acceleration on waste activated sludge hydrolysis and acidification.

A novel pretreatment method combining freezing/thawing with Geobacillus sp. G1 was employed to pretreat waste activated sludge (WAS) for enhancing the WAS hydrolysis and subsequent short-chain fatty acids (SCFAs) production. Results showed that freezing/thawing combined with Geobacillus sp. G1 pretreatment achieved the maximal concentrations of soluble protein from 40 ± 6 mg COD/L (non-pretreated) to 1226 ± 24 mg COD/L (pretreated), and accumulated SCFAs concentration increased from 248 ± 81 mg COD/L to 3032 ± 53 mg COD/L. Excitation emission matrix (EEM) fluorescence spectroscopy revealed the highest fluorescence intensity (FI) of protein-like substances, which was the dominant fluorescent organic matters, indicating the synergistic effect of freezing/thawing and Geobacillus sp. G1 pretreatment on organics hydrolysis. High-throughput pyrosequencing analysis investigated that the abundance of bacteria responsible for WAS hydrolysis (such as Clostridium and Caloramator ) and SCFAs production (such as Parabacteroides and Bacterodies ) was greatly enhanced due to the novel pretreatment method used. [ABSTRACT FROM AUTHOR]