Microbial Community Analysis of Purified Terephthalic Acid Wastewater Treatment Process Using 16S rDNA-based Method

Abstract

PTA (purified terephthalic acid) wastewater contains various aromatic compounds such as phthalate isomers, p-toluic acid benzoic acid and acetic acid, which can be converted into valuable biogas under methanogenic condition. Although many full-scale PTA wastewater treatment processes are currently being operated in the world, the involved microbial reactions have not yet fully elucidated especially for the p-toluic acid degradation. In this study, a lab-scale PTA wastewater treatment process consisting of two sequentially-connected UASB (upflow anaerobic sludge blanket) reactors was operated and the microbial community at each stage was investigated by comparing the T-RFLP (terminal restriction fragment length polymorphism) patterns together with the 16S rDNA gene clone libraries complementarily. In the first stage reactor, where most contaminants except p-toluic acid were completely degraded, both Syntrophus and Syntrophobacter species known to have a higher substrate affinity for benzoate were identified to be most predominant. In the second stage reactor, on the other hand, a species belonging to the family of Bacteroidales was most predominant with Syntrophus and Syntrophobacter species diminished. As time goes by, in the second stage reactor mainly treating p-toluic acid, it was further revealed that Pelotomaculum-related group was remarkably increased compared to the result of D100. Considering the substrate availability at each stage, this result strongly suggests that the Pelotomaculum-related groups are closely related to the p-toluic acid degradation.