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 water quality. A variety of treatment processes can be used to control BOM during drinking water production. Studies of enhanced coagulation (coagulation optimized for removal of dissolved organic material as well as particles) showed that removal of DOC could be improved from the current average of 29% (plant conditions termed baseline coagulation) to an average of 43% for optimized coagulation at the 10 sites tested. Similarly, removal of biodegradable dissolved organic carbon (BDOC) could be improved from the current baseline level of 30% to 38% through the application of optimized coagulation. At lower pH, ferric coagulants generally performed better for removal of organic 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.