Process And Application Of Wastewater Treatment For Epoxy Resin Production

Epoxy resin has excellent physical mechanical and electrical insulation properties,bonding properties with various materials,and flexibility in its use process,which are not possessed by other thermosetting plastics.Therefore,it can be made into coatings,composite materials,adhesives,molding materials and injection molding materials,in various fields of national economy has been widely used.However,in the process of epoxy resin production,organic wastewater with high salt and difficult degradation will be produced,which is recognized as a difficulty in epoxy resin industry,and also one of the bottlenecks in inhibiting the development of epoxy resin industry.In this paper,the combined process of coagulation-Fenton-A/O is used to treat the mixed wastewater from epoxy resin production.The optimal process parameters are determined through the pilot experiment to form a complete set of combined processes.The production and treatment effects of the wastewater from epoxy resin production are investigated to provide support for the optimization of design parameters for the sewage treatment plant.The actual debugging operation of the treatment project was analyzed to make the treated effluent index conform to the take-over standard of the sewage treatment plant.The specific research results are as follows:（1）In the coagulation experiment stage,the influence of coagulant type,dosage,p H and compound agent on COD removal was analyzed by single factor.The optimal process parameters were determined as follows:dosage of PAC was 120mg/L,p H was 9.5,dosage of PAM was 2.0 mg/L,and reaction time was 30min.Under this condition,COD removal rate was 28.0%.（2）Through Fenton orthogonal experiment,the order of influence of various factors is as follows:H₂O₂dosage>n（H₂O₂）/n(Fe²⁺)>reaction time>initial p H.The optimal combination parameters are as follows:n（H₂O₂）/n(Fe²⁺)is 40:1,the dosage of H₂O₂is 14m L/L,the initial p H is 3,and the reaction time is 60min.Under these conditions,the COD removal efficiency is the best,reaching 48.1%.The biodegradability of wastewater was increased to above 0.35,which met the requirements of entering the biochemical treatment system.（3）At the starting stage of A/O process,the wastewater pre-treated by the dilution-Fenton combined process takes COD and ammonia nitrogen as removal indexes.With the continuous operation of the system,the removal efficiency of COD and ammonia nitrogen gradually increases and tends to be stable.At this time,the COD removal rate reaches about 95.0%,and the ammonia nitrogen removal rate reaches about 89.0%.After the start-up stage,the A/O process carries on the salt-tolerant acclimation stage.Through the salt-tolerant acclimation in each stage,the average removal rates of COD and ammonia nitrogen reach 89.2%and 81.0%respectively.After the completion of salt-resistant acclimation stage,the influences of two important process parameters,namely nitrifying liquid reflux ratio and hydraulic retention time,on the operation effect of A/O process were studied.The results showed that:Under the condition that the reflux ratio of nitrifying liquid is 300%and HRT is 24h,the operation effect of the system is stable,and the effluent concentrations of COD and ammonia nitrogen are below 300mg/L and 50mg/L,respectively,meeting the requirements of subsequent pipe network pipe connection.（4）After the optimization of the process parameters design and debugging of the reference experiment of the sewage treatment plant in the park,it was officially put into operation.The operation effect of each unit was stable,but there was still insufficient operation.It was analyzed and pointed out that the debugging operation continued after improvement.The main process of the actual project adopts the combined process of coagulation-Fenton-A/O-coagulation to treat the wastewater from epoxy resin production.Through continuous testing,the actual wastewater treatment effect of the combined process is good.The average concentrations of influent COD,BOD₅,ammonia nitrogen and SS are 2606mg/L,554mg/L,112mg/L and 244mg/L,respectively.After process treatment,the average effluent concentrations are 184mg/L,68mg/L,28mg/L and 22mg/L,respectively.The average removal rates of COD,BOD₅,ammonia nitrogen and SS reached 92.9%,87.7%,80.3%and 91.0%,respectively.After the improvement and debugging,the operation effect is stable,the failure rate is greatly reduced,and it can better adapt to the high salt environment,and all the indicators of outlet water can meet the management standards.