AWWA ACE94196

The definition of enhanced coagulation in the D/DBP Rule includes TOC removal targets based upon raw water TOC and alkalinity. These target TOC removals are termed as "Step 1" requirement. Alternatively, the Rule will permit lower levels of TOC removal if these target TOC removals could not be achieved as reasonable expenses. These alternative TOC removals are defined as the "Step 2" requirements. A summary of the Step 1 requirements of the enhanced coagulation treatment technique are presented. Step 2 requirements, on the other hand, are defined as "diminishing returns" for TOC removal. The magnitude for the diminishing returns criteria was arbitrarily set at 0.3 mg/L of TOC reduction per 10 mg/L of incremental alum (Al2(SO4)3, 18,H2O) dose. On an equivalent basis, this translates to 0.3 mg/L TOC reduction per 5.5 mg/L of additional ferric chloride (FeCl3) dosage. Further, USEPA does not expect a utility to reduce the coagulation pH as a result of coagulant addition, alone, below the levels indicated, even if the incremental TOC removal criterion is not satisfied. If the incremental TOC removal criterion cannot be satisfied at these pH values, then the utility need not pursue enhanced coagulation beyond this point.

Product Details

Published:

01/01/1994

ISBN(s):

0898677750

Number of Pages:

23

File Size:

1 file , 790 KB