Two-stage anaerobic treatment of purified terephthalic acid production wastewaters

A full-scale two-stage anaerobic treatment plant has been treating the wastewaters from a purified terephthalic acid (PTA) production facility in South Korea for over 4 years. A study was conducted to evaluate the performance characteristics of this system over a 17-month period of operation. The system has provided stable operation with COD removals consistently averaging over 90%. The removal of specific phthalic acid isomers and related chemicals has been essentially 100% except for terephthalic acid which has averaged about 90% and paratoluic acid which had only about 30% removal. About 80% of the removal occurred in the first stage of the two-stage hybrid process. A companion single-stage anaerobic contact process removed only 80 to 85% of the COD and only 35 to 67% of the phthalic acids.