Study On Disinfection Of MBR Effluent By UV And Hydraulic Characteristics Of UV Disinfector

Hospital wastewater, which contains complex components and various microorganisms, has stronger infectivity and greater threat to public health. Study on hospital wastewater is representative in the disinfection field. Disinfection of the effluent from a hospital membrane bioreactor (MBR) by ultraviolet (UV) was studied in this dissertation. UV disinfection could decrease the disinfection by-products (DPBs) in large extent, and has positive effect on protecting water environment, ensuring public health, decreasing waterborne diseases, and maintaining society stabilization. In addition, the results are universal in the field of disinfection on the effluent from microfiltration membrane, and effective to deal with the possible commonality sanitation incidents. They are also of reference value for disinfection of the effluent from MBR that is for domestic or municipal wastewater treatment.Inactivation of microorganisms in the effluent from MBR by UV and the influence of photoreactivation and dark repair on it were studied in static disinfection experiments. The results show that UV has good effect on inactivation of microorganisms. Three log-unit of inactivation on bacteria could be achieved at UV dose of 16 mJ/cm~2. Different UV intensity has little influence on inactivation of bacteria at the same UV dose. When the effluent turbidity fluctuates within a range (< 3 NTU), it has little impact on inactivation of bacteria. Additionally no dark repair was observed in the samples irradiated by UV after three hours; however, photoreactivation occurred at the exposure of general fluorescent light and sunlight. The photoreactivation rate, potential and saturation time were different from each other.Acoording to the study of static experiments, a full-scale UV disinfector was designed. The influence of the inlet and outlet shapes and positions on hydraulic characteristics of UV disinfector was studied in this paper. The tracer experiment shows that hydraulic characteristic is close to ideal plug flow gradually along with the increase of Reynolds number. Positions of the inlet and combined modes of inlet and outlet have little effect on the hydraulic characteristic of the reactor.The UV disinfector was used for inactivation of microorganisms in MBR effluent in a hospital. The test results show that the residual microorganisms can meet Discharge Standard of Water Pollutants for Medical Organization (GB18466-2005) and the UV disinfector has higher value for application.