AWWA ACE95254

The proposed Disinfectants/Disinfection Byproducts Rule provides alternative performance criteria for compliance with the enhanced coagulation requirements. The purpose of these alternate performance criteria is to avoid the addition of excessive amounts of coagulant with little additional removal of TOC. These alternate criteria are particularly applicable to waters with high alkalinities for which large amounts of coagulant may be required to depress the pH to the range where effective coagulation of organic material occurs, and to waters with high proportion of hydrophilic organic carbon which tends to be less amenable to removal by coagulation than hydrophobic organic carbon. The two alternate performance criteria are based on a "point of diminishing returns" and on a "maximum" pH as determined from jar test studies. The "point of diminishing returns" is defined as the alum dose beyond which less than 0.3 mg/L of TOC is removed per 10 mg/L alum addition. Equivalent values are given for other coagulants. The "maximum pH" is defined as the alum dose required to achieve a target pH value which is set based on cost considerations. The objectives of this investigation were: to evaluate the appropriateness of the enhanced coagulation requirements for the removal of total organic carbon (DBP precursors) as specified in the proposed D/DBP Rule; and to evaluate the proposed criteria for achieving compliance with the enhanced coagulation requirements in accordance with the Draft Guidance Manual for Enhanced Coagulation and Enhanced Softening (USEPA, 1993).

Product Details

Published:

01/01/1995

ISBN(s):

089867834X

Number of Pages:

23

File Size:

1 file , 760 KB