Hydrodynamic cavitation in combination with the ozone, hydrogen peroxide and the UV-based advanced oxidation processes for the removal of natural organic matter from drinking water

Abstract

Natural organic matter in drinking water is causing concern especially due to the formation of disinfection by-products (DBPs) by chlorine, as these are proven to have adverse health effects on consumers. In this research, humic acid was used as a source of dissolved organic carbon (DOC) in drinking water (up to 3mgL^-1). The efficiency of DOC removal was studied by applying O₃, H₂O₂/O₃, H₂O₂/UV and O₃/UV advanced oxidation processes (AOPs) alone and combined with hybrid hydrodynamic cavitation (HC), generated by an orifice plate, as this technology recently shows promising potential for the treatment of water, containing recalcitrant organic substances. It was observed that the combined treatment by HC could significantly affect the performance of the applied AOPs, with as little as 3-9 passes through the cavitation generators. For O₃ and H₂O₂ dosages up to 2 and 4mgL^-1, respectively, and UV dosage up to 300mJcm^-2, HC enhanced DOC removal by 5-15% in all combinations, except for O₃/UV AOPs. Overall, the potential benefits of HC for DOC removal were emphasized for low ratio between applied oxidants to DOC and high UV absorbance of the sample. Investigated DBPs formation potentials require special attention for H₂O₂/UV AOPs and combinations with HC.

Keywords: Advanced oxidation; Disinfection by-products; Hydrodynamic cavitation; Hydrogen peroxide; Ozone; Ultraviolet.