Experimental Study On Microwave-assisted Degradation Of Organic Wastewater

Livestock wastewater is one of the more difficult organic wastewater to treat due to its complex composition,high concentration of organic matter,eutrophication,etc.Traditional treatment methods have their limitations in terms of process flow as well as treatment effect.Microwave catalytic oxidation technology is fast and efficient in wastewater treatment,but is more often used in industrial wastewater.In this study,the feasibility of microwave catalytic oxidation technology in livestock wastewater treatment was investigated to provide a theoretical basis for practical engineering.The experiment takes livestock wastewater as the research object,and the COD concentration as the evaluation index,and mainly studies the degradation effect of microwave in combination with catalyst and oxidant on COD in livestock wastewater.In order to study the advantages of microwave heating on COD removal effect,firstly,it was compared with traditional heating,and the synergistic effect between different components was studied and analyzed.The results show that there is a synergistic effect between microwave,catalyst and oxidant,and microwave heating can not only save the treatment time,but also greatly improve the COD removal rate.A microwave catalytic oxidation experimental bench was established to investigate the effect of single factors on COD degradation with granular activated carbon and copper oxide in homogeneous state as catalysts.The results of the single-factor experiments showed the influence of initial p H,microwave time,microwave power,catalyst dosage and hydrogen peroxide dosage on the effect of COD degradation,and obtained a better range of values for the five factors.After the treatment of livestock wastewater by microwave catalytic oxidation technology,the COD concentration can reach the emission standard.In order to study the best experimental conditions for COD degradation by microwave catalytic oxidation process,the strength of the effect of different factors on COD degradation effect and the interaction between different factors,after orthogonal experiments and response surface optimization experiments to verify,the microwave-activated carbon reaction system and microwave-copper oxide reaction system within the order of the effect of each factor on COD and the best experimental conditions were obtained.Two homogeneous catalysts,activated carbon and copper oxide,were found to be effective for COD removal during microwave-induced hydrogen peroxide.To further investigate the effect of catalyst performance on COD removal in microwave catalytic oxidation process,the carbon loaded catalysts in non-homogeneous state were prepared by impregnation calcination,and the loading effect and loaded active components were tested by XRD,BET and other characterization methods.The results showed that the prepared charcoal-loaded catalysts had good loading effect and the active components mainly existed in the form of Cu O;after the optimization of the orthogonal experiment with 5 factors and 4 levels,the order of the effect of each factor on COD in the microwave-charcoal-loaded catalyst reaction system and the best experimental conditions were obtained.It was found that the carbon loaded catalyst was better than activated carbon for COD degradation,and the COD removal rate was increased by 21.3%.However,due to the destruction of the pore structure and the leaching of the active material,the char-loaded catalyst performed poorly in terms of reusability.In order to analyze the changes of temperature field within the reaction system,COMSOL Multiphysics software was used to explore and focus on the hot spot effect in the reaction process.During the simulation,it was found that a local hot spot appeared at the activated carbon location,and the temperature gradually decreased from inside to outside with the activated carbon as the center,showing an obvious temperature gradient.The maximum error between the experimental results and the simulation results of the average temperature within the reaction system under different microwave power was only 5.8%.Meanwhile,with the increase of microwave power,the experimental results are closer to the simulated results.