Study On The Mechanism Of Enhanced Organic Wastewater Treatment By Cavitation Impinging Streams

Since twenty-first Century, China’s chemical industry has developed rapidly and the development of industry will inevitably lead to water pollution. Organic wastewater of chemical production has a high discharge capacity, strong toxicity, and high content of organic pollutants. The problem of conventional treatment is low efficiency, high cost and complex operation. The use of cleaner and more efficient means to deal with organic wastewater has become a problem to be solved at present. Cavitation impinging stream is a new concept to meet the demand of the mainstream in the field.Cavitation impinging stream is a novel theory that combines the concept of cavitation and impinging stream. Cavitation can provide extreme physical and chemical conditions for the reaction and the flow field characteristics of impinging stream have unique advantages in the aspects of enhancing the macro and micro mixing and increasing the reaction rate. In this paper, single cavitation impinging stream and the cavitation impinging stream-fenton is used to deal with the simulation wastewater of Rhodamine B. The mechanism of the treatment of organic wastewater from the process of cavitation impingement flow enhancement is studied from both theory aspect and experiment aspect.The experiment in this thesis firstly determined the optimal oxidation condition for Fenton’s reagent treating simulation wastewater by changing the dosing ratio of Fe2+ / H2O2 and initial pH values. Then the cavitation impinging stream reactor was applied alone to treat the simulation wastewater. It was found that COD and chroma removal rate got increased with the time( maximum: 19.6% and 34.1%), which proved the coupling between cavitation and impinging stream technique was completely feasible. The cavitation impinging stream can provide energy for the reaction so as to degrade the pollutants in organic wastewater but with low degradation efficiency. Therefore, the cavitation impinging stream and Fenton’s reagent were used in combination to treat the simulation wastewater under the optimal oxidation condition. The COD and color removal rate reached 98.1% and 97.2% maximally, which had increased by 24.3% and 18.4% compared with the single usage of Fenton’s reagent. It proved that the cavitation impinging stream can enhance the organic wastewater treatment process. The cavitation impinging stream-fenton’s removal rate was higher than their separate application in different periods, which reflected their synergistic effect. The time needed by cavitation impinging stream to reach the same removal rate under the same experimental condition was twice shorter than the other cavitation methods. The results showed that the cavitation impinging stream can enhance the molecular collision probability and accelerate the reaction rate. More importantly, the reaction for the cavitation impinging stream-fenton method on treating the Rhodamine B simulation wastewater accords with first-order reaction kinetic.The thesis not only proved the mechanism of cavitation impinging stream on enhancing the organic wastewater treatment process through theory and experimental study, but proved that the combined cavitation impinging stream and Fenton’s reagent can treat the organic wastewater more efficiently, which laid the theoretical foundation for the follow-up relevant researches.