MIEX? treatment of an effluent-impacted stream

摘要

A case study was conducted to examine the effectiveness of the magnetic ion exchange (MIEX?) process in treating wastewater treatment plant (WWTP) effluent-impacted water and removing disinfection by-product (DBP) precursors. The WWTP effluent increased dissolved organic carbon (DOC), ultraviolet absorbance at 254 nm (UV_(254)), anions, and DBP precursors at the discharge and downstream locations. During this study, the MIEX1 process reduced DOC by 42-47%, UV_(254) absorbance by 61-68%, and trihalomethane (THM) and haloacetic acid (HAA) formation potential (FP) by 50-70% at different downstream locations. On the other hand, only 10-15% halonitromethane (HNM) FP was reduced, and N-nitrosodimethylamine (NDMA) FP increased as a result of chloramination after MIEX treatment. Uniform formation condition (UFC) experiments showed that NDMA concentrations remained below 10 ng/L when chlorine or prechlorination was used for postdisinfection. However, the use of preformed chloramine resulted in 36 ng/L of NDMA formation. Because MIEX is capable of removing a substantial amount of THM and HAA precursors, it may allow the use of more chlorine for longer contact time, which can result in less NDMA formation.