| The streams from petrochemical industry often exhibit some characteristics,such as complex composition and refractory of organic matters.In this study,a commingled petrochemical industrial wastewater was collected from a petrochemical industrial plant in North China.The composition and biodegradation characteristics of organic matters in this industrial wastewater were revealed.According to the removal performance of biological system(anaerobic filter(AF)and pure oxygen aeration biological process)during petrochemical wastewater treatment,the adverse effect of organic matters on biological treatment system was observed and this mechanism of adverse effect was revealed.Furthermore,the operation condition of the system was also optimized.The results was showed as follows:(1)Three kinds of petrochemical industrial stream,namely purified terephthalic acid(PTA),polyethylene terephthalate(PET)and polyether industrial wastewater,exhibited complex composition of organic matters.According to the results of resin and molecular weight fractionation,the hydrophobic and small molecule size organic matters were dominated in the three petrochemical streams.In accordance with spectral analysis,such as UV-vis and FT-IR technology,the complex compounds might exist in the three streams,such as phenyl rings,alkanes,esters,organic acids,phenols and alcohols.The fluorescence spectra of dissolved organic pollutants in wastewater were resolved by EEMs-PARAFAC technology,and the typical pollutants in the streams were identified.PTA wastewater contained phenyl terephthalic acid(TA),benzoic acid(BA)and other aromatic compounds,PET wastewater contained ethylene glycol terephthalate,phenol and other aromatic compounds,polyether wastewater contain petroleum and other pollutants.Moverover,the biotoxicity of three streams was also analyzed,the PTA wastewater exhibited the strongest biotoxicity,while the PET wastewater has the strongest biotoxicity under the unit TOC(2)The anaerobic filter(AF)combined with pure oxygen aeration process was applied to treat the mixed stream from the petrochemical industry.50-70% of COD removal efficiency was obtained during anaerobic treatment.PET and polyether wastewater exhibited adverse effect on the biodegradation of typical pollutants in the PTA wastewater during mixed wastewater treatment in accordance with anaerobic biodegradation process of organic matters in wastewater.However,the COD removal efficiency of aerobic biological system was achieved at 50%-80%.The results of aerobic biodegradation process of wastewater showed that the PTA wastewater represented adverse effect on not only microbial activity but also organic matters removal processes during the mixed wastewater treatment because of high concentration of PTA wastewater.On the contrary,the PET and polyether streams did not affect aerobic biological degradation processes during mixed wastewater treatment.(3)The results of principal component analysis(PCA)showed that DO was weakly correlated with MLSS,while OLR has strong correlation with SS and SV in effluent,indicating that the change of OLR has a great influence on the sedimentation of sludge and SS of the effluents.(4)In order to improve the treatment effect of biological system,it was found that increasing the sediment circulation in the AF system can avoid short cut of influent.The results showed that under the condition of large variation of water quality,sediment cycling could make the anaerobic biological system recover rapidly.According to the results of operation condition optimization of the system,such as HRT and temperature parameters,it was found that prolonging HRT can increase the removal rate of organic matter,and the best operation condition of temperature optimization was 37 ?. |
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