Effect of photochemical advanced oxidation processes on the formation potential of emerging disinfection by-products in groundwater from part of the Pannonian Basin

This study evaluates the effect of photochemical advanced oxidation processes (AOPs) (O₃/UV, H₂O₂/UV and O₃/H₂O₂/UV) on the formation potential (FP) of emerging disinfection by-products including nitrogenous by-products (N-DBPs) and haloketones (HKs) in groundwater from part of the Pannonian Basin (AP Vojvodina, Republic of Serbia). Among the N-DBPs, the haloacetonitrile (HAN) precursor contents were 9.83 ± 0.59 μg/L while precursors of halonitromethanes, particularly trichloronitromethane (TCNM) were not detected. Similarly, precursors of HKs as carbonaceous DBPs were also not detected in raw water. Ozonation alone and the H₂O₂/UV process with a lower UV dose maximally decomposed HAN precursors (about 70%) while during O₃-based AOPs, HANFP varied significantly. Application of UV photolysis and H₂O₂/UV processes with increasing UV dose doubled the HANFP. Ozone alone, O₃/UV and H₂O₂/UV slightly increased HK formation potential, particularly 1,1-dichloro-2-propanone FP (0.93 ± 0.21 to 2.01 ± 0.37 μg/L). None of the investigated treatments influenced the formation of TCNM precursors. The effect of the applied treatments on bromide incorporation was most evident for HANs.