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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.

Advanced Oxidation Processes (AOP) are known as an effective treatment barrier for micropollutants. Well known AOP combinations are UV/H2O2 and O3/H2O2. This paper will present a more detailed view on how to use the different options combining UV; ozone and H2O2. The focus of this investigation is on treatment effects (reduction of specific contaminats), water matrix, energy consumption and cost calculation (CAPEX, OPEX). The presented data are extracted from extended pilot trials carried out at DUNEA in 2009 and 2010. Dunea (The Netherlands,The Hague) produces drinking water from the Meuse River, which contains a variety of organic micropollutants as a result from upstream activity. Dunea is performing research to extend the current multiple barrier treatment (e.g. pre-treatment, artificial recharge and recovery (ARR), post-treatment) with an advanced oxidation processes (AOP), situated at the pre-treatment location in Bergambacht, before ARR. The degradation of organic micropollutants as a result of advanced oxidation using different combinations of hydrogen peroxide, ozone, low pressure (LP) UV lamps has been assessed by means of pilot-scale (5 m3/h) experiments. The influent was pre-treated river water, with an yearly average UV-transmission of 80% and a DOC concentration of 4 mg/L.The peroxide doses were varied as 0, 5 and 10 ppm, the ozone doses were varied as 1, 2 and 3 g ozone/m3. The UV doses were varied between 300 and 650 mJ/cm2. The installed power for the LP reactor was 0.26 kWh/m3. Atrazine, bromacil, ibuprofen and NDMA were spiked (10-20 µg/L) and used as model compounds. Bromacil was completely (>99%) removed by ozone/peroxide. Atrazine and ibuprofen were good (58% and 85% respectively) removed by O3/H2O2 and NDMA was not (9%) removed by this technique, whereas NDMA showed good (82%) removal by UV/H2O2. Atrazine, bromacil and ibuprofen were degraded by UV/H2O2 at 53, 46 and 59 %, respectively. In addition also combined AOP was tested; spiked water was treated by O3/H2O2 first and let over the LP-UV reactor directly afterwards. All four compounds showed highest degradation during combined AOP treatment. With this combined AOP, lower ozone dose and lower UV dose result in comparable degradation compared to single AOP treatment. For all these techniques a detailed capital expenditure operational expenditure (CAPEX / OPEX) evaluation was carried out based on a daily water flow of 240,000 m3/d. This evaluation resulted in the finding, that the combined AOP is the most economical solution with the best treatment result. Other advantages of the combined AOP are limited by-product formation, especially bromate, and a future barrier against OMPs encompassing a broad spectrum of properties.

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). The efficiency of DOC removal was studied by applying O, HO/O, HO/UV and O/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 O and HO dosages up to 2 and 4mgL, respectively, and UV dosage up to 300mJcm, HC enhanced DOC removal by 5-15% in all combinations, except for O/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 HO/UV AOPs and combinations with HC.