The Treatment Performance Of PTA Wastewater By Combined UASB And SBR Process

With the rapid development of our country's industrialization technology,a large amount of wastewater has been produced.Among them,PTA wastewater occupie a considerable part of the ratio.PTA is called p-terephthalic acid,which has a very wide range of uses in the industry.It is commonly used as a film,plasticizer,insulating paint,etc,or as a variety of polyester-based materials.Because of the characteristics of PTA wastewater,an UASB and SBR combined unit is used as an experimental reactor.Anaerobic UASB reactor was the initial degradation of wastewater,and then connected to the aerobic SBR.The experimental device is UASB combined with SBR,the initial experiment was firstly connected to the reactor,the activated sludge had been inoculated and domesticated in the reactor.After the reactor was started successfully,the quality of the influent water was changed to the experimental simulation PTA wastewater.In the UASB reactor,the hydraulic retention time(HRT)directly affects the processing efficiency of the reactor The optimal time of hydraulic retention was 18h in the study.At this moment,the COD concentrations of anaerobic and aerobic effluent were 550.8 mg/L and 30.3 mg/L respectively,the removal rates were 89%and 94%;the effluent acetic acid was only 20 mg/L;the methane content of air bag was up to 42%.It can be seen that the proportion of HRT with 18h is 60%when the particle size was over 300 ?m.Dominant bacteria reached more than 5 species,the state of the bacteria is well maintained in SEM image.The experiment was conducted to study the impact test,including the PTA wastewater of high concentration and high salinity.First of all,the HRT of UASB was set as the optimal condition for 18h.After 80 days of reaction operation,the indicators of effluent reached a stable condition.Due to the larger increase of influent COD,the HRT was adjusted to 24h.After 100 days of reaction operation,the removal rate reached stable.At this time,the COD concentrations of anaerobic and aerobic effluent were 793.8 mg/L and 39.7 mg/L respectively.The methane content of air bag was 30%.Salt content increased,the removal rate of various indicators decreased significantly in high salinity.The final COD concentration of UASB and SBR effluent were 1022.1 mg/Land 90.2mg/L,respectively.The methane content is about 16%at steady conditions.The results of SEM and FISH showed that the dominant species were less and the percentage of archaea was decreased from 15%to 10%.In summary,within a certain range of impact test research,UASB combined SBR reactor can achieve the removal of PTA wastewater.It was compared and analyzed the characteristics and diversity of microbial communities in the sludge.The bacteria in the sludge samples were classified into 16 phylum,19 class,14 order and 15 genus.Through the analysis of OUT value and exponent Chao,sludge microbial enrichment before salt is higher than salt.The Proteobacteria?Chloroflexi Nitrospirae and Planctomycetes occupyed a larger proportion for phylum level,the percentage becomes smaller.The Gammaproteobacteria,Deltaproteobacteria,WSP-1 and Synergistia showed obvious changes for class level.The Anaerolineales and Syntrophobacterales played an important role for order level.The Syntrophobacterales were one of the more important species in the anaerobic reaction.In this experiment,the relative abundance of Syntrophobacterales before and after salt addition was 21%and 14%,respectively.Under the genus level,the relative abundance of Syntrophus,Longilinea,Macellibacteroides,Desulfomicrobium,Geobacter and Acetoanaerobium accounted for a larger proportion.In the archaeal communities of sludge microorganisms,there was Methanomicrobia for class.The contents of Methanobacteria was 88%and 69%respectively before and after adding salt.The result of high-throughput sequencing showed that the biological diversity of sludge is inversely proportional to salinity.