Impact of enhanced and optimized coagulation on removal of organic matter and its biodegradable fraction in drinking water

The presence of biodegradable organic matter (BOM) can affect drinking wate r quality. A variety of treatment processes can be used to control BOM duri ng drinking water production. Studies of enhanced coagulation (coagulation optimized for removal of dissolved organic material as well as particles) s howed that removal of DOC could be improved from the current average of 29% (plant conditions termed baseline coagulation) to an average of 43% for op timized coagulation at the 10 sites tested. Similarly, removal of biodegrad able dissolved organic carbon (BDOC) could be improved from the current bas eline level of 30% to 38% through the application of optimized coagulation. At lower pH, ferric coagulants generally performed better for removal of o rganic carbon than did alum or polyaluminum chloride. In most of the cases, assimilable organic carbon (AOC) was not affected by coagulation, probably because the AOC fraction was composed of small molecular weight, non-humic compounds that are not amenable to coagulation. (C) 2000 Elsevier Science Ltd. All rights reserved.