Chloramine and MIEX control of disinfection by-products formed from an alluvial aquifer water source

Samples collected during this study show that current DBP formation potential did not notably change from the source waters in the wells through water treatment plant and into the distribution system. Samples also reveal that current DBP concentrations and future DBP formation potential near the compliance locations in the City of Columbia system will remain close (~74 to 85 samples collected during this study show that current DBP formation potential did not risk being out of compliance with the MCL again in the future). The most prominent treatment strategy for reducing DBP concentrations being considered by the City of Columbia is a switch from free chlorine to chloramines. Testing of finished water samples from the water treatment plant suggests that chloramines will stall DBP formation at approximately one-half of the current compliance sample concentrations. Although the City is going forward with the switch to chloramines as the residual disinfectant in their distribution system, the recommendation of the MoWRRC is that the City also consider other MIEX (magnetic ion exchange) as modifications to the operation of the water treatment plant that would also effectively reduce DBP concentrations through removing precursors of DBPs in the distribution system while allowing for the switch back to free chlorine as the residual disinfectant.