Oxidation Pretreatment Of Organic Peroxide Production Wastewater

Since the Action Plan for Prevention and Control of Water Pollution put forward in 2015,the national industries vigorously carry out heavy pollution enterprises internal wastewater station upgrading projects,including the implementation of the new requests Emission standard of pollutants for petroleum chemistry industry（GB31571-2015）from July 1,2017will become a new challenge faced by industrial enterprises wastewater stations.Organic peroxide production wastewater had high concentration of organic pollutants,poor biodegradability and strong pungent smell.Conventional biochemical methods are difficult to achieve a good treatment effect,so before biological treatment of such wastewater,necessary pretreatment technology should be taken to improve the biodegradability of wastewater and reduce the concentration of some pollutants.In view of this,iron-carbon microelectrolysis-Fenton combined process and ozone catalytic oxidation process were used to pretreat the wastewater.In the iron-carbon microelectrolysis-Fenton combined process,the influence of iron-carbon microelectrolysis and Fenton oxidation treatment on COD and biodegradability of wastewater was firstly explored.On this basis,the experimental study of combined process was carried out.In the experiment of ozone catalytic oxidation process,the catalyst CeO₂-C was prepared by the loading method,and the catalyst CeO₂-Z was prepared by the ion exchange method.The preparation conditions of the two catalysts were optimized,and the structure and properties of the catalysts were characterized by SEM,EDS and XRD.The effects of CeO₂-C and CeO₂-Z catalysts on the removal efficiency of pollutants were investigated.The degradation mechanisms of pollutants by the two pretreatment methods were investigated by using 3-D fluorescence（3D-EEM）,wavelength scanning and Gas Chromatography-Mass Spectrometry（GC-MS）.The optimal operating parameters obtained by single factor test and response surface optimization method in iron-carbon microelectrolysis test were as follows:the pH was 3.1,the m_（Fe）was 30.5g/L,m_（Fe）/m_（C）was 1.01,and the reaction time was 122.8min.Under these conditions,the COD removal rate of the wastewater was 35.67%,and the process of COD degradation follows the second-order kinetics.The optimal operating parameters obtained by single factor test and orthogonal test in Fenton oxidation test were:the dosage of H₂O₂was0.25mol/L,the dosage ratio of H₂O₂ to Fe²⁺was 7:1,and the reaction time was 45min.Under such conditions,the COD removal rate was 42.16%,and the process of COD degradation follows the second-order kinetics.In the iron-carbon microelectrolysis-Fenton combined process,the maximum COD removal rate was 52.24%when the dosage of H₂O₂was0.1mol/L and added 30min after the reaction starts.The B/C of wastewater was increased from 0.113 to 0.173,0.195 and 0.223 respectively by iron-carbon microelectrolysis,Fenton oxidation and iron-carbon microelectrolysis-Fenton combined process,which significantly improveed the biodegradability of wastewater.CeO₂-C catalyst was prepared by impregnation method with ceramsite as carrier.During the preparation of the catalyst,the effects of CeO₂ loading content,calcination temperature and time on the performance of the catalyst were discussed by single factor test and orthogonal test.The optimal preparation conditions of CeO₂-C were obtained by taking COD removal rate as the index:CeO₂ loading content was 4%,calcination temperature was 450℃and the time was 5h.CeO₂-Z catalyst was prepared by ion exchange method with zeolite as carrier.During the preparation of the catalyst,the effects of ion exchange concentration,exchange temperature,time and times on the performance of the catalyst were discussed by single factor test and response surface optimization method.The optimal preparation conditions were obtained by taking COD removal rate as response.The concentration of ion exchange solution was 0.24mol/L,the exchange time was 16h,and the exchange times were 2.SEM,EDS and XRD characterization of CeO₂-C and CeO₂-Z catalysts showed that the active groups distributed on the support was CeO₂.The catalysts CeO₂-C and CeO₂-Z prepared under the optimal conditions were used in the ozone catalytic oxidation test.When the ozone flow rate was 6L/min,the catalyst dosage was 20g/L,the solution pH was 6,and the reaction time was 60min,The COD removal rates of CeO₂-C and CeO₂-Z ozone catalytic oxidation were 28.11%and 33.42%,respectively,which were 10.17%and 15.48%higher than that of ozone oxidation.After ozone oxidation,CeO₂-C and CeO₂-Z ozone catalytic oxidation treatment,the B/C of wastewater increased to 0.135,0.152 and 0.158,respectively,which significantly improved the biodegradability of wastewater.The results of 3D-EEM analysis of wastewater before and after pretreatment showed that the two oxidation pretreatment technologies had good removal effect on tyrosine,aromatic proteins substanceⅠand humic acid substance in wastewater.The results of wavelength scanning analysis showed that the effluent absorption peaks of the two oxidation pretreatment technologies were significantly reduced compared with the raw water,indicating that they had a good removal effect on the refractory organic compounds such as benzene ring,heterocyclic ring and other unsaturated cyclic aromatic hydrocarbon compounds in the wastewater.The results of GC-MS analysis showed that the two oxidation pretreatment methods could degrade the macromolecules in the wastewater,and could degrade the high boiling point macromolecules such as acids,esters,anilines and benzene rings into small molecules,thus improving the biodegradability of the wastewater.Iron-carbon micro-electrolysis-Fenton combination process and ozone catalytic oxidation for organic peroxide production wastewater had good oxidation pretreatment effect.These two pretreatment technologies had a good degradation effect on refractory organic substances in wastewater,and can improve the biodegradability of wastewater.These two pretreatment technologies had a good engineering application prospect in the oxidation pretreatment of organic peroxide production wastewater.