Research On UV-H₂O₂ Combined Disinfection Reactor And Its Engineering Application

Ultraviolet-hydrogen peroxide(UV-H2O2)combined disinfection reactor is the research object of the article.The reaction mechanism and reasonable adjustment range of UV-H2O2 composite process were explored through chemical experiments.The fluid flow and optical radiation are coupled by ANSYS-Fluent.The results of the velocity field,motion trajectory,radiation field and ultraviolet dose of the disinfection reactor were analyzed.Details are as follows.(1)The chemical experiment about the UV-H2O2 coupling technique which is applied in conditioning water.The effects of UV light intensity,initial hydrogen peroxide concentration,water salinity,initial solution pH and inlet flow on hydrogen peroxide decomposition efficiency and instantaneous concentration of hydroxyl radical were investigated by static and dynamic experiments.The results showed that the decomposition rate of hydrogen peroxide and the production of hydroxyl radical increased with the increase of UV intensity.The initial concentration of H2O2 had little effect on the rate of H2O2 decomposition under the UV light,but had a greater effect on the absolute decomposition of H2O2.When the concentration of sodium chloride in the solution was lower than 0.61 mol/L,the decomposition efficiency of hydrogen peroxide increased with the increase of sodium chloride concentration.The formation of hydroxyl radical was more favorable in acidic environment,followed by neutral environment and alkaline environment.The hydroxyl radical produced when pH is maintained between 4 and 5 can kill most harmful microorganisms in ballast water.(2)The UV-H2O2 coupling disinfection model based on CFD was established,which is applied to simulate the reaction effect of the sterilizer under different inlet flow and different UV power.The flow field and radiation field inside the disinfection reactor were numerically simulated by ANSYS-Fluent,and its motion trajectory and radiation field were analyzed.The simulation result is processed by Fortran 90,such as the calculation of the UV dose of each particle.The simulation results verified by experiments which show that secondary circulations exist in the reactor and can be developed into vortices,which fully guarantee the mixing and reaction time of water in the reactor.In order to ensure each particle has uniform ultraviolet radiation,the radiation intensity near the light source is the strongest during the process of ultraviolet lamp irradiation,and with the increase of radial distance,the intensity of ultraviolet light shows an exponential decline trend.The fitting coefficient R2 between the intensity of ultraviolet light and distance is 0.9855.Compared with the change of the total dose of the particles in the sterilizer,it is found that the improvement effect of adjusting the inlet flow rate on the reactor performance is better than that of changing the intensity of ultraviolet light.(3)Based on the numerical simulation method,the closed-tube UV-H2O2 combined reactor was transformed and simulated.It was found that increasing the number of UV lamps can increase the efficiency of the sterilizer.However,the disinfection effect is weakened by increasing the number of baffles to change the flow state.Compared with the number of UV lamps,the number of baffles has a greater impact on the internal dose of the sterilizer.