Impacts of Turbidity and Algal Content of Unfiltered Drinking Water Supplies on the Ultraviolet Disinfection Process

摘要

Ultraviolet (UV) disinfection is gaining popularity as a primary disinfectant in the United States, especially for groundwater sources and conventionally treated surface waters. However, it is still unknown whether it is a feasible option for disinfection of unfiltered drinking water supplies. Some of the concerns for the use of UV in unfiltered supplies are that they are allowed turbidity levels up to 5 NTU (USEPA, 1979) and also may have seasonally high algal counts. This paper presents the results of continuing studies at the University of New Hampshire (UNH) funded by the American Water Works Association Research Foundation and the United States Environmental Protection Agency through UNH's Water Treatment Technology Assistance Center on the effects of particles on UV disinfection. The research was conducted in two phases of medium pressure UV collimated tests. In Phase I, laboratory waters with varying turbidity and algal levels were prepared and tested. Phase II examined reservoir samples from unfiltered drinking water supplies. Results from the collimated beam tests indicate that UV performance is not affected by turbidity up to 12 NTU and algal content up to 42 μg/L as chlorophyll-a (approximately 4.2 × 10~7 cells/L).