title: Efficiency and energy requirements for the transformation of organic micropollutants by ozone, O3/H2O2 and UV/H2O2.
abstract: The energy consumptions of conventional ozonation and the AOPs O(3)/H(2)O(2) and UV/H(2)O(2) for transformation of organic micropollutants, namely atrazine (ATR), sulfamethoxazole (SMX) and N-nitrosodimethylamine (NDMA) were compared. Three lake waters and a wastewater were assessed. With p-chlorobenzoic acid (pCBA) as a hydroxyl radical ((•)OH) probe compound, we experimentally determined the rate constants of organic matter of the selected waters for their reaction with (•)OH (k(OH,DOM)), which varied from 2.0 × 10(4) to 3.5 × 10(4) L mgC(-1) s(-1). Based on these data we calculated (•)OH scavenging rates of the various water matrices, which were in the range 6.1-20 × 10(4) s(-1). The varying scavenging rates influenced the required oxidant dose for the same degree of micropollutant transformation. In ozonation, for 90% pCBA transformation in the water with the lowest scavenging rate (lake Zürich water) the required O(3) dose was roughly 2.3 mg/L, and in the water with the highest scavenging rate (Dübendorf wastewater) it was 13.2 mg/L, corresponding to an energy consumption of 0.035 and 0.2 kWh/m(3), respectively. The use of O(3)/H(2)O(2) increased the rate of micropollutant transformation and reduced bromate formation by 70%, but the H(2)O(2) production increased the energy requirements by 20-25%. UV/H(2)O(2) efficiently oxidized all examined micropollutants but energy requirements were substantially higher (For 90% pCBA conversion in lake Zürich water, 0.17-0.75 kWh/m(3) were required, depending on the optical path length). Energy requirements between ozonation and UV/H(2)O(2) were similar only in the case of NDMA, a compound that reacts slowly with ozone and (•)OH but is transformed efficiently by direct photolysis.
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and Drinking Water, Ueberlandstrasse 133, 8600 Dübendorf, Switzerland.
authors.forename: Ioannis A
authors.initials: IA
authors.lastname: Katsoyiannis
authors.forename: Silvio
authors.initials: S
authors.lastname: Canonica
authors.forename: Urs
authors.initials: U
authors.lastname: von Gunten
mesh_terms: D001280:Atrazine / Q000737:chemistry; D002723:Chlorobenzoates / Q000737:chemistry; D004128:Dimethylnitrosamine / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007700:Kinetics; D010084:Oxidation-Reduction; D010126:Ozone / Q000737:chemistry*; D013420:Sulfamethoxazole / Q000737:chemistry; D014466:Ultraviolet Rays; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D002723:Chlorobenzoates; D014874:Water Pollutants, Chemical; D010126:Ozone; D006861:Hydrogen Peroxide; D013420:Sulfamethoxazole; D004128:Dimethylnitrosamine; D001280:Atrazine