Research On Heterogeneous Ozone Catalytic Oxidation Of Chemical Wastewater And Enhanced Reactor

Heterogeneous ozone catalytic oxidation was one of the advanced oxidation technologies for the treatment of refractory organic wastewater.Because of its advantages of strong oxidizability,no secondary pollution,easy separation and recovery of catalysts,it has attracted extensive attention in the field of chemical wastewater treatment.At present,the research direction of heterogeneous ozone catalytic oxidation technology mainly included the preparation of high performance heterogeneous catalyst and the development of high efficiency enhanced ozone reactor.The reaction efficiency of the reaction system was not only related to the catalyst and reaction conditions,but also directly affected by the mass transfer characteristics of the gas-liquid-solid interface.Therefore,both the catalyst and reactor for the catalytic oxidation of ozone were important.In this paper,the heterogeneous ozone catalytic oxidation of wastewater from the chemical plant was studied.The performance and influencing factors of the catalyst were investigated.Based on this,the performance of the enhanced ozone reactor was investigated.The specific research contents are as follows:?1?The activated carbon/ozone system was used to catalyze the oxidation of wastewater,which the treatment effect was better than the simple addition of ozone oxidation and activated carbon adsorption.The synergistic effect factor was 1.26,indicating that there was a synergistic effect between activated carbon/ozone system,but the effect was not obvious.In acidic environment,activated carbon took adsorption as the leading role,while activated carbon was mainly used for catalysis in an alkaline environment,which promoted the production of ozone to hydroxyl radicals.Under the optimized process conditions,the COD removal rate of activated carbon/ozone treatment wastewater reached 73.4%.However,there were problems such as activity reduction and quality loss of activated carbon during long-term operation.?2?The effect of the?-Al2O3/ozone system which was used to catalyze the oxidation of wastewater was significantly better than the simple addition of ozone oxidation and?-Al2O3 adsorption.It showed that there was a significant synergistic effect between?-Al2O3/ozone system.The synergistic factor was 2.88.The optimum reaction system was listed as:the catalyst dosage 16 g/L,the particle size 1.5³.0 mm,the ozone dosage 46.1 mg/min,and the initial pH 9.Under the above conditions,the removal rate of chemical wastewater with a COD concentration of 201 mg/L was52.9%.The?-Al2O3/ozone system has good catalytic activity,stable performance in the process of treating wastewater.?3?The cold model experimental device was used to study the performance of the enhanced ozone reactor,and further the feasibility of strengthening the ozone reactor was verified by the its pilot and engineering equipment.With the increase of circulating flow rate,the gas entrainment,gas holdup rate and k_Laa increased,while the bubble diameter showed a decreasing trend.As the circulating flow rate increased,the ozone solubility increased continuously within a certain range.Compared with the conventional bubble reactor,the enhanced ozone reactor could significantly enhance the ozone mass transfer performance.The enhanced ozone reactor not only eliminated the amplification effect,but also increased the COD removal rate and shortened the reaction residence time 1/3.