Role of temperature on microbial community profiles in an anaerobic bioreactor for treating PTA wastewater

Thermophilic digestion usually has higher specific gas output and faster reaction rate, the temperature fluctuations of purified terephthalate (PTA) manufacturing wastewater from 45 °C to 90 °C makes PTA wastewater very suitable and favorable for thermophilic treatment. However, the startup way of thermophilic digester is very critical as unsuitable startup ways may lead to inefficiency of the system. In this study, the experimental temperatures were set at 37 °C, 43 °C and 52 °C respectively by step increase strategy in order to culture thermophilic microbial organisms involved in anaerobic TA degradation. The performance and microbial community profiles of PTA wastewater treatment system were investigated under different operational temperatures using 454-pyrosequencing approach. During the step temperature increase process, 37 °C was proved to be the most favorable operational temperature with a highest COD removal of 96.10(±1.58)%, but with undergoing 43 °C, COD removal decreased to 90.42(±2.65)%, and 52 °C seemed to be the worst as it achieved only 70.08(±5.46)% COD reduction. Step-wise temperature increase is tested not very appropriate to culture thermophilic microorganism for TA degradation as prospective. Furthermore, during startup stage, the predominant bacteria family shifted from Syntrophorhabdaceae (belonging to δ-proteobacteria) at 37 °C to Comamonadaceae (belonging to β-proteobacteria) at 43 °C and OPB95 (belonging to OP8) at 52 °C. For archaeal community, hydrogenotrophic methanogen Methanobacteriaceae was predominant at all three temperatures, and it was proved to be most abundant at 37 °C compared with the other two temperatures.