Reduction of dissolved organic matter and trihalomethane formation potential during laboratory‐scale soil‐aquifer treatment

Dissolved organic matter (DOM) in recovered groundwater from soil‐aquifer treatment (SAT) has the potential to generate harmful disinfection by‐products. This study investigated the reduction of mass and trihalomethane formation potential (THMFP) of DOM fractions from secondary effluent during laboratory‐scale SAT. Using XAD‐8 and XAD‐4 resins, DOM was fractionated into three fractions: hydrophobic acid (HPO‐A), transphilic acid (TPI‐A) and hydrophilic fraction (HPI). HPO‐A was removed by 61.1%, TPI‐A by 54.9% and HPI by 75.0% as dissolved organic carbon (DOC) during the laboratory‐scale SAT, respectively. The reduction of THMFP from HPO‐A, TPI‐A and HPI was 27.24, 26.24 and 36.08%, respectively. Specific THMFP for each DOM fraction increased across the soil columns. HPO‐A was found to be the major precursor of THMs. THMFP was strongly correlated to ultraviolet light at 254 nm (UV‐254) for HPO‐A and HPI, while the relationship between THMFP and UV‐254 for TPI‐A was significantly poor.