Ozone Catalysis/electrolytic Oxidation Combined With UASB/SBR Treatment Of Epoxy Resin Wastewater

With the continuous development of China’s industrial scale,the discharge of industrial wastewater is also increasing,and most industrial wastewater was characterized with the complex components,poor biodegradability and toxicity,which makes it difficult to be treated.In this paper,the mixed wastewater from epoxy resin production in a chemical plant in Anhui Province was taken as the research object.Considering the characteristics of epoxy resin mixed wastewater such as the high salinity,high COD concentration and poor biodegradability,.the epoxy resin mixed wastewater was firstly pretreated by the combined technology of catalytic oxidation and electrolytic oxidation to improve the biodegradability,then subsequently was biochemically treated by UASB-SBR.The main resulted were listed as follows:（1）The important influencing factors for the combined technology of catalytic oxidation and electrolytic oxidation process were investigated and the operation parameters were optimized.The results showed that when the initial wastewater was treated by catalytic oxidation,magnetic activated carbon was used as the catalyst and the initial pH was 11,the gas flow rate and the catalyst addition amount were 60 L/h and 6 g/L respectively.The reaction time was 3 h,the removal efficiency of COD_Crr was about 28%,and the BOD₅/COD_Crr was increased to 0.30.Then,the catalytic oxidation effluent was further treated by electrolytic oxidation,without additional electrolyte,the initial pH was adjusted to 11,the current density was 60 mA/cm²,the electrode spacing was 4 cm,the reaction time was 3 h,and the COD_Crr removal efficiency was about 50%.At this time,the COD_Crr of the pretreated effluent was about 2412 mg/L,and the TN was about 44 mg/L,which reduces the load for the subsequent biochemical treatment,and the BOD₅/COD_Crr was increased to 0.42,which greatly improved the biodegradability of the wastewater.（2）The components of the wastewater analyzed by ultraviolet-visible spectrophotometry（UV-vis）and gas chromatography-mass spectrometry（GC-MS）.UV-vis results showed that after pretreatment of epoxy resin wastewater,the conjugated double bond of the component may be converted into a heteroatom-containing saturated hydrocarbon and a heteroatom-containing double bond compound.GC-MS results showed that phenols and esters in wastewater are effectively degraded,so that the COD_Crr value of the wastewater was reduced and the biodegradability of the wastewater was improved.（3）UASB-SBR combined process was used for biochemical treatment of pretreated effluent,and the effects of salinity and hydraulic retention time on each process was investigated.The results showed that when the pretreated effluent was properly diluted,the pH of the influent water was adjusted to about 7,the hydraulic retention time（HRT）was 48 h,the COD_Crr removal efficiency was about 55%in the UASB process.The UASB effluent is further treated by SBR reactor,the COD_Crr removal efficiency in the SBR process was about 50%.Finally,the effluent COD_Crr concentration is approximately 290 mg/L.（4）The epoxy resin mixed wastewater was treated by the combination of catalytic oxidation-electrolytic oxidation-UASB-SBR.The removal efficiency of wastewater COD_Crr could reach more than 95%and the removal efficiency of TN could reach more than 78%.Greatly reduced the difficulty of handling the sewage treatment plant in the chemical industry park,reach the takeover standard of the chemical industry park sewage treatment plant.