Treatment Of Polyether Chemical Wastewater By Advanced Oxidation - MBBR Combination Process

The polyether wastewater contained a lot of unreacted raw materials,intermediates and products,which was characterized complex as well as high concentration.The major pollutants are not only small molecule chemicals such as ethanol and hydrocarbon compounds,but also a large amount of toxic and harmful organic pollutants such as polycyclic aromatic hydrocarbons,surfactants,polyethers and amines,which are difficult to be degraded.Without suitable treatment,it will pose a great threat to the ecological environment and human health.However,the conventional treatment processes are difficult to achieve effective treatment of polyether wastewater.In recent years,with the rapid development of the polyether industry,the production of polyether wastewater was increased obviously.Therefore,it is urgent to develop high-efficiency polyether wastewater treatment technologies.In view of the low efficiency of wastewater treatment facility in the polyether production enterprise in Wuxi,a UV-Fenton+mobile bed biofilm reactor（MBBR）combination process was carried out to upgrade the original treatment process.The main research contents are as follows:In this paper,the effect factors of Fenton,UV-H₂O₂ and UV-Fenton on polyether wastewater treatment were compared.The results showed that the UV-Fenton method was more suitable than Fenton and UV-H₂O₂.The operating parameters of the UV-Fenton process were optimized by single factor experiment and response surface method.The optimal conditions were H₂O₂/COD=1.49,FeSO₄·7H₂O/H₂O₂=0.83,t=71 min,pH=3.0.Under this condition,the COD removal rate was 62.3%and the B/C in effluent was increased to 0.48.At the same time,the organic nitrogen was converted into inorganic nitrogen which was favorable for subsequent denitrification.Gas chromatography-mass spectrometry（GC-MS）was employed to analyze the contaminants in polyether wastewater before and after UV-Fenton treatment.The results showed that the influent contained five main types of organic pollutants,of which ethers accounted for approximate 52.6%of total peak area.By means of UV-Fenton method,the total organic pollutant abundance decreased by 93.4%.The proportion of ethers decreased significantly to 6.3%.At this time,the main substances were small molecular hydrocarbons of 61.4%.UV-Fenton effluent was treated by MBBR.The biofilm accumulation and microbial acclimation were completed at the beginning of the experiment.The influence of key parameters,alkalinity,hydraulic retention time（HRT）,dissolved oxygen（DO）and filler filling rate were investigated with a view to guiding the construction and operation of the industrial scale reactor.The experiment obtained a set of optimal operating parameters of alkalinity=300⁴00 mg/L,HRT=12 h,DO=2⁴ mg/L,filler filling rate=40%.Under this operating condition,the COD,NH₄⁺-N and TN removal rate were 92.1%,92.7%and 42.1%,respectively.Meanwhile,alkalinity and DO had the most significant effect on the nitrification and the COD removal effect was mainly affected by DO and HRT.According to the laboratory scale results,UV-Fenton and MBBR treatment system was designed and constructed in industrial scale,which used to upgrade the original Up-flow anaerobic sludge bed（UASB）+aerobic tank process.After three months operation,the feasibility of the UV-Fenton-MBBR combination process in treating real polyether wastewater was verified.The combination process presented a stable treatment effect,the effluent COD,TN and NH₄⁺-N concentration could reach 31.1±5.3,21.8±2.8 and 1.5±0.35mg/L,the corresponding removal efficiencies were improved by 70%,27%and 85%,respectively.