The adsorptive removal of disinfection by-product precursors in a high-SUVA water using iron oxide-coated pumice and volcanic slag particles

The main objective of this work was to study the effectiveness of iron oxide-coated pumice and volcanic slag particles in removing disinfection by-product (DBP) precursors from a raw drinking water source with high specific UV absorbance (SUVA254) value. Iron oxide coating of particles significantly increased dissolved organic carbon (DOC) uptakes and decreased DBP formation after chlorination compared to uncoated particles. pH values close to neutral levels during adsorption and chlorination provided DOC, trihalomethane and haloacetic acid reductions around 60-75% employing 6 g/L coated particle dosage. Higher degree of DOC and DBP reductions (>85%) were obtained with increasing particle dose. The uptake of bromide by iron oxide surfaces was negligible and increasing bromide concentrations (up to 550 μg/L) did not negatively impact the DOC uptake. However, due to competition between natural organic matter (NOM) and bicarbonate for the iron oxide surfaces, increasing bicarbonate alkalinity levels reduced DOC uptakes. Overall, the results indicated that the iron oxide-coated pumice/slag particles are effective adsorbents to remove NOM and control DBP formation in waters with relatively high DOC and SUVA254 levels. However, they may not be effective for waters with alkalinity levels above 250 mg CaCO3/L.