A Pilot Study On Recycled Water Disinfection With UV

Municipal wastewater recycling is an important way for resolving water pollution and water shortage. As the final step of treatment process, disinfection plays a vital role in recycling water system. In this work, a pilot plant was built in Beishiqiao Wastewater Treatment Centre to disinfect recycled water with UV. The disinfection efficiency, influencing factors and kinetics were studied, to ensure the safety of using recycled water.The result showed that UV disinfection was very effective for killing total bacteria and total coliform bacteria. When irradiation time was 4.5 seconds with dosage of 125mJ/cm2, total bacteria and total coliform bacteria removal rates were both more than 98%; and when irradiation time was more than 30 seconds with more dosage than 800mJ/cm2, total bacteria and total coliform bacteria removal rates more than 99.94% and 99.90% respectively, but the survived total coliform bacteria number rang from 10 to 20 per liter, it was more than 3 per liter, so it was not satisfied the standard of GB/T 18920-2002; by mathematic analysis, got the relationship between irradiation dosage and total coliform bacteria survival rate with -In (N/N₀) = 0.003D+5.1736; the turbidity and chroma could reduced the intensity arrived bacteria's surface, the bacteria removal rates decreased with the increase of turbidity, while the change of chroma not apparently influenced bacteria removal rates; UV irradiation had some impacts on COD, ammonia and turbidity also.