Study On Treatment Of High Concentration Phenolic Wastewater By Wet Oxidation In Microchannel Reactor

In recent years,the pollution of water bodies caused by toxic aromatic compounds in industry has become a major problem of national environmental governance.Industrial phenol-containing wastewater is a serious threat to the health and safety of human life.At present,the catalytic wet oxidation technology is a very effective treatment method for high concentration and refractory organic wastewater.But the traditional wet oxidation process needs the severe test conditions,critical equipment and high cost,which greatly limits the development of its application.In recent years,the convergence of wet oxidation and microchemical technology has been attracted people’s attention.In this study,a micro-channel reactor was used as a reaction vessel in the gas-liquid phase wet oxidation process.Because the reaction rate control steps in the process of treating phenol-containing wastewater by oxygen oxidation are determined by reaction kinetics and the mass transfer of oxygen from gas phase to liquid phase.Meanwhile,microchannel reactors have been used as an important tool for enhancing mass transfer in many fields.Therefore,in this study,the newly developed micro-channel reactor with superior mass transfer performance was firstly applied to the field of wet oxidation treatment of industrial organic wastewater.The degradation of high concentration resorcinol wastewater by wet oxidation in microchannel reactor was investigated in order to find an efficient degradation process of industrial high concentration organic wastewater.In this study,the simulated oxidation process of industrial phenolic wastewater was selected as the research object.The research on the removal rate of COD for resorcinol,oxidation reaction kinetics and the degradation path showed the advantages of the microchannel reactor in the gas-liquid phase wet oxidation process.The main research conclusions are as follows:Using wet oxidation technology in the microchannel reactor,the oxidation degradation system of resorcinol were investigated by changing p H of the reaction solution,gas liquid ratio,reaction pressure,total flow rate of reaction gas-liquid,number of reactors,initial concentration and reaction temperature.The results showed that the removal rate of wastewater COD was 90.2%when the initial COD was 20000mg/L,the number of reactors is 10,the pressure P=50 bar,T=240°C,the liquid-gas ratio Q_L:Q_G=1:7,the total flow Q=50 m L/min.In order to improve the wastewater COD removal rate,according to the above technological conditions,the effect of the transition metal salts as catalyst on the degradation of phenolic wastewater was studied.The COD removal rate of phenolic wastewater with the initial COD of 20,000 mg/L can reach 98.9%,when the amount of Cu²⁺was 70 mg/L.The reaction kinetics of wet oxidation and wet catalytic oxidation for the treatment of phenolic wastewater were investigated in experiments.The results showed that the kinetic model of resorcinol oxidation degradation was the first order reaction kinetics and the activation energy of oxidation degradation was 50.63 k J/mol without catalyst and 34.27 k J/mol with copper salt catalyst.It can be seen that the activation energy of wet oxidation degradation reaction is reduced by 32%with the adding of copper salt catalyst.Meanwhile,the reaction path of resorcinol oxidation degradation was deduced by analysis of the resorcinol and intermediates using HPLC.