Enhanced coagulation: a preliminary evaluation

Enhanced coagulation, proposed as a best available technology in Stage 1 of the Disinfectants/Disinfection By‐products (D/DBP) Rule, is capable of controlling DBPs at a large California utility but will add to the cost of treatment. Researchers conducted preliminary enhanced coagulation tests at the Metropolitan Water District of Southern California's (MWDSC's) 5.5‐mgd demonstration plant from August to October 1992. California State Project water and Colorado River water were tested. The first goal was to determine whether this mode of operation is an effective strategy for controlling disinfection by‐products (DBPs) and DBP precursors at MWDSC facilities. If this strategy proved to be successful, the second objective was to estimate the additional operational costs of complying with the proposed Disinfectants/DBP Rule and to identify the coagulation conditions that minimize these costs. Although the results show that enhanced coagulation can meet the criteria being considered for the rule, this process will increase MWDSC's cost of treatment.