Effects of EBCT and Water Temperature on HAA Removal using BAC

AND YUEFENG F. XIE aloacetic acids (HAAs) are a group of disinfection by-products (DBPs) regulated under the Stage 1 Disinfectants/Disinfection Byproducts Rule (D/DBPR). The maximum contaminant level for five HAAs is 60 μg/L. These five regulated HAAs are monochloroacetic acid (ClAA), dichloroacetic acid (Cl2AA), trichloroacetic acid (Cl3AA), monobromoacetic acid (BrAA), and dibromoacetic acid (Br2AA). The upcoming Stage 2 D/DBPR may require water utilities to comply with this maximum contaminant level by using locational running annual averages instead of running annual averages. This will require water utilities to better control peak DBP levels in their distribution systems. As a result of this requirement, many water utilities are interested in identifying and adopting cost-effective HAA control technologies. Currently, the best available technologies for HAA control include enhanced coagulation/ softening and granular activated carbon (GAC) adsorption for precursor removal and the use of alternative disinfectants.