The paper studied growth and decline principal microbial species including methanogens, denitribacter and desulfobacter, sludge characteristics, the alternating of dominant methanogens, and the relationship between them and treatment process using the upflow anaerobic sludge blanket (UASB) reactor to treat refined p-phthalic acid(PTA) industrial waste water with and without pretreatment.

To treat high concentration of caprolactam sewage more effectively, up flow type of anaerobic sludge reactor was used to pre-treat before the former A/O system.