Advanced oxidation and artificial recharge: a synergistic hybrid system for removal of organic micropollutants

Dunea, the drinking water company for The Hague and surroundings, has as objective the production of drinking water of impeccable quality, particularly with respect to organic micropollutants. As organic micropollutants are only a minor part of the total natural organic matter, a challenge is posed in targeting the removal of a very small, specific part of the DOC, without removing all of the natural organic matter. In addition, organic micropollutants encompass a broad range of physicochemical properties, which make their removal by a single treatment step impossible. Combining AOP with artificial recharge and recovery, two complementary processes are expected to provide a hybrid system for organic micropollutant removal, according to the Dutch multiple barrier approach. Pilot-scale experiments with O₃ and different advanced oxidation processes (UV/H₂O₂, UV/O₃ and O₃/H₂O₂) were carried out in cooperation between Dunea and ITT Wedeco. The pilot installation had a capacity of about 0.5–2.0 m³/h, with a varying LP-UV-dose, ozone dose and peroxide dose. Atrazine, isoproturone, carbamazepine, diclofenac and ibuprofen are well removed by UV/H₂O₂ as well as by O₃/H₂O₂. In general, O₃/H₂O₂ is a more energy efficient process compared to UV/H₂O₂. MTBE is best removed by O₃/H₂O₂, Amidotrizoic acid and iohexol are best removed by UV/H₂O₂.