earticle

영어

PTA (purified terephthalic acid) wastewater contains various aromatic compounds such as phthalate isomers, p-toluate and benzoate, 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-toluate 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-toluate 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. In the second stage reactor mainly treating p-toluate, it was further revealed that an uncultured species belonging to α-proteobacteria was newly present and the relative amounts of Syntrophorhabdaceae and Syntrophomonas species were also remarkably increased compared to the first stage reactor. Considering the substrate availability at each stage, this result strongly suggests that the last three microbial groups are closely related to the p-toluate degradation.