The Efficacy And Mechanism Of Photocatalytic Oxidation On Pseudomonas Aeruginosa In Drinking Water

With wider the application scope of the advanced oxidation technology, the photocatalysis oxidation method, as an important part of the advanced oxidation technologies, is vigorous development. While the introduction of drinking water disinfection by photocatalysis oxidation method also becomes a research hotspot. Photocatalytic disinfection is a kind of efficient, safe, environmental protection, and economic technology, which can inactivate pathogenic virus, bacteria and protozoa effectively. The environmental factors, such as temperature, p H value of water, have small effects on this technology. Therefore, in the treatment of drinking water, water reuse, industrial water and wastewater disinfection, photocatalysis is gradually used, and shows good market potential. Ti O2, the most widely used photocatalyst at present, is facing some problems in the practical water treatment, including unstable preparation, no residual sterilization ability, and difficult to suppress the resurrection and dark repair phenomenon. Seeking more efficient and stable light catalyst to reduce costs, improve the efficiency of reaction, and explore the mechanism of photocatalytic disinfection in drinking water are of great significance.The lab uses the P25 Ti O2, Ag / Ag Cl, a variety of structural materials, nano- Fe2O3, as disinfectants, of which the efficiency and mechanisms in the Pseudomonas aeruginosa disinfection progress were studied.Ag/Ag Cl showed better photocatalytic property compared with P25 Ti O2,the common photocatalyst, in this experiments.When the concentration of Ag/Ag Cl is 0.1g/l, the removal rate of Pseudomonas aeruginosa reaches about 100% in 15 min. Even at low concentrations, 5mg/l, the Ag/Ag Cl can also kill bacteria efficiently, and keep the concentrations of bacterial in water few for a long time after closing the light, which overcomes the dark repair phenomenon of bacterial in P25 Ti O2 disinfection. The structure of bacterial destruction, inorganic ions, and superoxide ion(·OH, ·O 2-) concentration were monitored at the same time. The result illustrates that the ·OH and ·O2- play a important role in photocatalytic disinfection.The experimental results will provide a reference for the mechanism of photocatalysis drinking water disinfection study and dark repair phenomenon.In order to reduce the production cost of the catalyst, the subject has chosen three nano-Fe2O3 material to replace Ag/Ag Cl, including cubes, flake and needle-like morphology. Orthogonal experiment is utilized to determine the value of p H(p H=7), 30%H2O2 dosage(0.015%), and the Fe2O3(nano-needle) for the UV/H2O2/Fe2O3 method to kill Pseudomonas aeruginosa. Then the relationship between the disinfection effect and topography of the nano-Fe2O3 was analyzed. The above method was used to treat the water from Ganjiang River, whose initial p H was 6.2, the bacterial concentration was 6×103CFU/ml. After 1h experiment, the bacterial concentration reduced to 600CFU/ml, while the value of CODcr was from 68.1mg/l down to 17.9mg/l. The experiment provides a theoretical basis for UV/H2O2/Fe2O3 method practicing in drinking water disinfection.