AWWA ACE54303

Standards for the quality of filtered drinking water have become increasingly more stringent, in part because of increased concerns about the possible passage of disinfectant resistant pathogens, such as Cryptosporidium, through filters. This has caused increased attention to many aspects of operational practices, including the recycle of spent filter backwash within the treatment plant. In the USA, the 1996 Safe Drinking Water Act Amendments required the US Environmental Protection Agency (USEPA) to create a regulation governing the practice of backwash recycle. In developing the draft Filter Backwash Recycle Rule, proposed in April 2000 (US EPA, 2000), it was found that there were relatively few systematic studies of the actual impact of backwash recycle on treatment, despite use of this practice by 50 to 60% of US treatment plants. BHC Company and UMass, through an AWWARF Tailored Collaboration Project, have studied full-scale recycling practices and conducted extensive pilot-scale studies of pathogen removal by clarification and filtration and the impacts of filter backwash recycle. The purpose of this paper is to present results of pilot-scale investigations of the impacts of variations in backwash recycle loading rate and quality on subsequent clarification and filtration performance. This portion of the work is focused on measures of particle removal such as turbidity, particle counts and suspended solids, as well as on organic matter removal and coagulation conditions. Includes 7 references, table, figures.

Product Details

Edition:

Vol. - No.

Published:

06/01/2001

Number of Pages:

14

File Size:

1 file , 510 KB