Study On Sound Field Characteristic In Abnormal Canular Ultrasonic Equipment And Its Application In Printing And Dyeing Industry Wastewater Treatment

Using ultrasonic technology to degrade refractory organic pollutants of wastewater has caught the worldwide attention. Nevertheless, up to now, most of the work have dealed with the degradation of single organic pollutant in initially dilute concentration wastewater, and lacking of the knowledge of rules of ultrasonic reactors properly designing, most researches remain their study in laboratories. By contrast, as for the treatment of the refractory dyeing wastewater, coupling ultrasonic cavitation with other degrading technology has been studied. Meanwhile, the degradation efficiency, mechanism, and reaction kinetics of the compounds such as analogue dyeing wastewater and organic compounds (COD_Cr) in printing and dyeing industry wastewater have been investigated in this thesis. Some factors which can influence the efficiency of degradation of acid red FGS wastewater significantly, such as ultrasonic frequency, aeration or non-aeration, input power density, ultrasonic irradiation time, initial concentration of wastewater were investigated. The degradation dynamics of acid red FGS was also discussed. The sound field characteristic and cavitational yield in abnormal canular ultrasonic equipment which designed ourself were studied. Particularly, the influencing factors, mechanism, and reaction kinetics of ultrasonic degradation of organic compounds (COD_Cr) in denim sizing wastewater were in-depth studied. An advanced technology of ultrasound coupling biology degradation of printing and dyeing industry wastewater was developed. Results are showed as following:(1) Acid red FGS can be degradation effectively when ultrasonic frequency is 100 kHz. The degradation rate of acid red FGS in the combination of ultrasound/Fenton treatment is greater than that in the individual use of ultrasound or Fenton reagent. Aeration and acidic conditions are favourable for ultrasonic degradation of acid red FGS. The degradation rate of acid red FGS is proportional to input ultrasonic power density, and inversely proportional to the initial concentration. There is an optimum time of ultrasonic treatment and the best dosage of Fe²⁺ and H₂O₂. The degradation process follows pseudo first-order kinetics.(2) The distributions of sound intensity under cross irradiation, orthogonal irradiation, and combination irradiation are more uniform than that under parallel irradiation. In particular, the distribution of sound intensity under orthogonal irradiation would show better uniformity in different ultrasonic frequency combinations. The maximum average sound intensity and uniform distribution was measured under combination irradiation due to reducing cavitation dead zone, which is beneficial to the occurrence of more intensive cavitation. In the same irradiation time and volume of solution, the more frequency combine, the more uniform distribution of sound intensity is and the greater average sound intensity could be obtained, and thus greater formic acid degradation efficiency and capacity yield.(3) Denim sizing wastewater can be effective degradated in abnormal canular ultrasonic equipment, and the treatment effect with reactorâ…¡with high frequency is better. Neutral conditions are conducive to ultrasonic degradation of COD_Cr, acidic condition or basic condition is unfavorable for this process. The degradation rate of COD_Cr is proportional to ultrasonic time, and inversely proportional to the initial concentration of wastewater. The mechanism was dominated by the reactions of COD_Cr with·OH radicals of the bulk solution. The decomposition process is in line with the equation of pseudo first-order kinetics.(4) The effects of printing and dyeing industry wastewater treatment by various technologies have been analyzed and compared to. The results show that the technology of combination of ultrasound and a small amount of activated carbon, and then biological processes which fully utilizes the merits of individual treatment has a significant effect in removal of COD_Cr and chroma. After ultrasonic pretreatment for 2 hours, then activated carbon treatment for 1 hour, and last for 6 hours'biological treatment, chroma and COD_Cr of outlet water can meet the national discharge standard of Classâ… , COD_Cr removal rate is 92%, and chroma removal rate is above 95%.In summation, ultrasound has great advantage in treating toxic and refractory organics. The technology of wastewater treatment by ultrasound has broad application prospect and promising market.