| Dyeing wastewater has become second largest industrial source of water pollution in China. With the development of textile industry, a variety of new dyes, PVA slurry, new additives and other more complex and poor biodegradable organic substance enter into the wastewater, bringing greater challenges to the conventional biochemical methods. The discharge of dyeing wastewater has caused serious water pollution, pushing great pressure on the state and local governments to issue stricter standards of discharge. It is essential to search for a high-performance physico-chemical treatment method for dyeing wastewater.Photo-catalytic oxidation method is an effective advanced oxidation technology for treatment of refractory organics. It has been studied for 40 years, and its application in the treatment of dyeing wastewater has accumulated a large of experimental data and provided experience for people to understand the photo-catalytic degradation mechanism of dyes and its kinetics. However, its application in industry still has many problems such as inefficiency of TiO2 photocatalysis light quantum and loss of suspended catalyst. Many researchers have made great efforts to improve the light quantum efficiencies of catalyst and its high load. A major focus has been on TiO2 to solve the problem. However, the research of light source, as the important component in catalytic oxidation method, is extremely limited.This thesis reports our effort to improve advanced treatment of dyeing wastewater. In order to solve the problems of the industrial application of the photochemical catalytic oxidation method, the new types of light source was the focus for our research work. Efforts were made to solve the efficient separation of catalyst suspended photo-catalyst by photo-catalytic coupled with membrane separation, as a new approach for the application of photo-catalytic oxidation in dyeing wastewater treatment.In this paper, different wavelengths from UV light source were studied for the degradation of reactive brilliant red X-3B. It revealed the function of wavelengths in photo-catalytic oxidation.The results showed that there were simultaneous photo-oxidation and photo-catalytic oxidation reactions for reactive brilliant red X-3B under ultraviolet light irradiation (254nm), while under ultraviolet light irradiation (365nm), there were only photo-catalytic reactions. The decay of X-3B followed apparent first-order kinetics under ultraviolet light irradiation (365nm), it also is depicted by more precise formulation of L-H model, while under ultraviolet light irradiation (254nm), it followed apparent second-order kinetics. Compared with the decay half-life of 365nm light, the decay half-life of 254nm in light decreased from 37.263min to 0.855min, indicating that the light quantum efficiency of short-wave UV was higher than that of the long-wave UV.Based on the influence of wavelengths to photo-catalytic efficiency, the thesis investigated the problems of light sources in the application of photochemical reactions, and proposed the possibility and advantage of the microwave electrodeless UV lamp' application to photo-catalytic reaction. The optimal conditions of light were obtained by primary factors which was the pressure and volume of Ar, the dosage of Hg and so on. A new structure of microwave electrodeless UV light source was designed, considering its application in the treatment of many problems. The aspects of light's starting, spectral characteristics were analyzed. Compared with high-pressure mercury, the difference of spectral intensity, spectral uniformity, ozone production and hydroxyl free yields were investigated. The results showed that the highest proportion of short-wave UV output and intensity maximum were attained at temperature of 40℃, Ar pressure of 20Torr, Hg volume of 5mg, diameter of 1.7cm. The the spectral intensity, the proportion of short-wave UV irradiation, spectral uniformity, and other aspects of performance of microwave electrodeless UV source were better than high-pressure mercury lamp. Under the conditions of high-power, microwave electrodeless UV light source achieved to output high-intensity short-wave UV.The direct photo-oxidation and photo-catalytic oxidation of typical azo and anthraquinone dyes were attained by new lamps. The differences of direct photo-oxidation of reactive brilliant red X-3B and reactive brilliant blue KN-R were investigated between new lamps and high-pressure mercury lamps. The result showed that microwave electrodeless UV had an obvious effect of direct photo-oxidation, while high-pressure mercury lamps had no effect of direct photo-oxidation, which also confirmed the results of former experiments. The photo-oxidation mechanism of X-3B was preliminary studied by TOC, HPLC, and ion chromatography. The controlling factors such as type of catalyst, concentration of catalyst, concentration of dye, pH, aeration conditions, and salt ions were discussed in order to provide a basis for the design of industrial application of the catalytic oxidation technology.The method of membrane separation was adopted to solve the problems of separation of TiO2 suspended and its recycling. In order to couple microwave photo-catalytic oxidation with membrane separation, the form of submerged membrane modules was adopted to make microwave photo-oxidation and membrane separation coupled in the same reactor. The appropriate conditions of membrane separation were determined by critical pressure and critical flux of membrane, form of membrane modules, particle size and concentration of catalyst, operating mode of membrane, methods of cleaning and other factors. According to comparison of the degradation in the process of direct photo-oxidation, photo-catalytic oxidation, with the addition of oxidizer, the appropriate conditions of microwave photocatalytic oxidation were determined. The experiment of microwave photo-oxidation coupled with membrane separation process was also carried out to determine the optimal conditions for actual dyeing wastewater, providing a reference for its industrial application.The innovative points of the thesis pare as follows. (1) Comparing the difference between short-wave UV light and long-wave UV light in the degradation of X-3B, it was found that two reactions of direct photo oxidation and photocatalytic oxidation exist under short-wave UV light irradiation. Besides, short-wave UV light has higher catalytic light quantum efficiency than long-wave UV light. (2) The optimal conditions were obtained by the experiments of inert gases, dosage of Hg and the volume.A new type of high-power short-wavelength microwave electrodeless UV source was designed to treat wastewater and investigated the function of direct photo-oxidation and photocatalytic oxidation on typical dyestuff. (3)The problem related to the loss of suspended catalyst was solved by coupling microwave electrodeless UV light with membrane separation method. The application of microwave-photo oxidation technology to treatment of actual dyeing wastewater provides a reference for its industrial application.
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