Process Enhancement Study Of Organic Wastewater Oxidation By Ozone Based On Micro-Nano Bubble Technology

Ozone oxidation technology is a well-known advanced oxidation process,which has been widely used in wastewater treatment.However,due to its low mass transfer efficiency and poor solubility,its further wide application is limited.Therefore,in this paper,the micro-nano bubble technology was used to strengthen the ozone oxidation process.At the same time,the micro-nano bubble coupled with packing internals was carried out by adding packing internals into the bubble column reactor to further strengthen the ozone oxidation process.To explore whether the micro-nano bubble coupled with packing internals can enhance the ozone oxidation process better,the method of experiment combined with simulation was adopted in this paper.The results of the hydrodynamic performance experiment,mass transfer experiment,and wastewater degradation experiment showed that the micro-nano bubble technology significantly improved the gas holdup,mass transfer efficiency,and decolorization efficiency during the ozone oxidation process,which was 6.83 times,3.01 times,and 2.52 times,respectively.Based on these results,the gas holdup,mass transfer efficiency,and decolorization efficiency were further increased by 12.15%,23.22%,and10.17% after adding packing internals.This indicated that the micro-nano bubble coupled with packing internals can effectively enhance the ozone oxidation process.The effect of packing type on the enhanced ozone oxidation process by the micro-nano bubble coupled with packing internals was also analyzed.The results showed that within a certain porosity range,the type of packing had little effect on the enhanced ozone oxidation process by the micro-nano bubble.A single factor experiment was carried out to evaluate the enhanced ozone oxidation process by the micro-nano bubble coupled with packing internals using methyl orange simulated wastewater,and the experimental results showed that within a certain time,the decolorization rate of methyl orange solution decreased with the increase of initial p H value and initial concentration of dye,increased with the increase of ozone dosage,and presented a trend of increasing first and then decreasing with the increase of circulating liquid flow.The optimal process conditions are that the initial p H value was 3,the dosage of ozone was 0.56 mg/L,the initial concentration of methyl orange was 30 mg/L,and the circulating liquid flow was 75 L/h.After 120 min of treatment,the decolorization rate was99.28%,which provided certain guidance for future industrial applications.A preliminary numerical simulation of the enhanced ozone oxidation process by the micro-nano bubble coupled with packing internals was conducted using Fluent software to explore the gas-liquid two-phase flow law inside the reactor.The simulation results showed that the micro-nano bubbles were very stable during their rising process,the probability of coalescence and fragmentation was very small,and the gas-liquid surface renewal rate was low.After the addition of the packing internals,the bubbles constantly underwent deformation,collision,coalescence,and fragmentation during the rising process,which greatly promoted the renewal of the liquid membrane inside this system and then improved the liquid membrane mass transfer coefficient.At the same time,the residence time of bubbles inside the liquid phase became longer and the gas-liquid interface area decreased,but overall,the reduction of the gas-liquid interface area had less effect on the ozone mass transfer efficiency,so the addition of the packing internals promoted the mass transfer and reaction process.The simulation found that too large or too small circulating liquid flow was not conducive to the mass transfer and reaction progress.A preliminary simulation of the reaction process of Methyl Orange degradation by ozone was conducted,and the simulation results can provide guidance for future research and industrial design.