Performance Of PTA Wastewater Treatment And Microbial Community Characteristics In UBF Reactor

As an important raw material，Purified terephthalic acid (or PTA) is widelyused in petrochemical industry to make various synthetic products includingpolyethylene terephthalate bottles, polyester textile fiber, polyester films, pesticide,etc. As it not only varies a lot in properties and amounts, but also contains massivenondegradable pollutions, the treatment of PTA wastewater receives a continuousattention from people around the world.Generally, PTA wastewater are produced under a temperature varies from4560℃. According to references, most researches of PTA wastewater are carried outunder mesophilic condition, only few are conducted under thermophilic environment.The effects of temperature on performance and microbial community structure ofPTA wastewater in anaerobic reactor remain unknown, which is necessary to ourfurther study in achieving a better performance. Based on these, we design a UBFhybrid reactor to treat a synthetical PTA wastewater. The main purpose of this studyis to investigate the performance characteristics in UBF reactor under differenttemperatures. Furthermore, by use of fluorescence in situ hybridization (FISH forshort), cloning and T-RFLP technique, qualitative and quantitative analysis oncomposition of microorganisms in the reactor are also determined.According to our research, among four different temperatures:33℃,37℃,43℃and53℃,37℃is approved to be the optimum temperature in treating PTAwastewater, with a COD removal rate over94%and TA removal rate a little higherthan97%. The effluent COD concentration is below100mg/L while that of TA is1550mg/L. Furthermore, TA removal rate of33℃,43℃and52℃are79.34%,90.80%,70.08%. Within the reactor, sludge particle size distribution under differentoperating temperature were also analyzed, it shows that, temperature change has asignificant influence on the particle size distribution, and sludge flocks collapseeasily when temperature increased to5055℃.The distribution of bacteria andarchaea during stable operation are then analyzed by Fluorescence in situhybridization, the percentage of bacteria and archaea37℃are46.8%and53.2%respectively.Bacteria clone library under different temperature are built, the correspondingphylogenetic trees are then established. From the results，the nine dominant bacteriabelong to Firmicutes, Chloroflexi, Spirochaetes, Actinobacteria, Deinococcus-Thermus, Nitrospirae, Bacteroidetes and Proteobacteria. The contents of Delta-Proteobacteria under37℃and43℃are48.65%and41.38%separately, it is assumed to be the dominant bacterium group degrading TA. Otherwise,Betaproteobacteria are the dominant population under52℃and33℃conditions.Which also occupies a large percent:43.24%and33.33%.With T-RFLP technology, we digest sludge sample with three separaterestriction enzyme: MspI、HhaI and RsaI. Although the consent of a certain bacteriais not in full accord, the three enzymes come to the same conclusion on thedominant bacterium group. That is,-Proteobacteria and β-Proteobacteria aredominant population at37℃and43℃respectively.