AWWA WQTC62512

The objective of this study was to develop credible design/operation criteria for granular activated carbon (GAC), magnetized ion exchange (MIEX®) resin, and fixed-bed ion exchange (IX) processes that enabled the Palmdale Water District Water Treatment Plant, CA (PDWTP) to limit total trihalomethanes (TTHMs) and haloacetic acids (total of five species, HAA5) formation up to 60 g/L and 45 g/L, respectively. The process selection conducted by the PWDTP was based on these design criteria and associated cost-analysis evaluation. A six months pilot-scale study was conducted at the PDWTP, during which the different treatment processes were tested at pilot-scale. A total of 90 SDS tests were performed. All processes successfully reduced SDS-TTHH and SDS-HAA5 below the stipulated goals. Combining MIEX® treatment operating with a 5% RR and 15% RR, respectively with 50 and 28 mg/L of ferric chloride, decreased SDS-TTHMs to 47 and 52 g/L. The bromide-specific resin successfully reduced SDS-TTHMs to values below 47 g/L, while the NOM-specific resin averaged SDS-TTHMs around 46-73 g/L, up to a maximum of 100 g/L. After 120 days of operation GAC effluent SDS-HAA5 were <20 g/L. SDS-TTHM concentrations were maintained below 60 g/L up to 60 days and never exceeded 80 g/L. Using a model that assumed the blending of 10 GAC adsorbers' effluents resulted in a average concentration of 60 g/L after 120 days in operation. DBP formation was predicted using a DWR model. Includes 2 references, tables, figures.