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causing compounds, algal toxins, pharmaceuticals and personal care products, endocrine disrupting compounds, NDMA and 1,4-Dioxane. Numerous systems, including Tucson’s 5,800 gpm airport remediation project utilizing the TrojanUV Phox D72AL75 installation, the 100 MGD Groundwater Replenishment System in Orange County California and the 50 MGD UV oxidation system in Aurora, Colorado are designed for low-pressure UV oxidation of various contaminants. 6.1 DESIGN CRITERIA The full-scale design criteria together with measured water quality are summarized in Table 3. Table 3: City of St. Anthony Water Village Treatment System Design Specifications UV SYSTEM DESIGN SPECIFICATIONS Design Flow 3000 gpm Average Flow 1250 gpm Target 1,4-dioxane Log Reduction 2.0-Log Measured UV Transmittance 96% The model output for the projected water quality at the peak flow conditions (i.e., 3000 gpm at 96% UVT) provides an electrical energy per order (E EO ) value of 0.41 kWh/kgal/order for 1,4-dioxane when 18 ppm of H 2 O 2 is present. This value is associated with the UV output at the end-of-lamp-life (EOLL) condition as well as an appropriate level of conservatism. Trojan has proposed to reduce 1,4- dioxane by 2.0-log (i.e., 99.0%) in this stream with 2 parallel trains of 2 TrojanUVPhox™ D72AL75 reactors plus one redundant train. This system is described in a separate proposal. While Trojan’s preferred approach to sizing UV-AOP systems is to rely upon our proven mechanistic sizing model, as described above, there are several aspects of the empirical scale-up approach that should be discussed. Full-scale UV reactors typically have superior treatment efficiency compared with pilot-scale reactors for the following reasons. In UV-based AOP systems, most UV photons that are transmitted through the water and reach the wall of the reactor are absorbed by the wall material and do not contribute to the contaminant treatment process. This loss of photons at the reactor wall and other surfaces within the UV reactor represents an inefficiency of the reactor. Conversely, if a large fraction of photons that are emitted by the lamps are absorbed by constituents in the water, a desired result, then the reactor is said to have high absorption efficiency. This reactor absorption efficiency can be increased by providing a longer pathlength for the photons to travel before they reach a surface. Similarly, reactors typically have higher efficiencies when operated at higher flow rates. This is a result of better hydraulic performance (i.e., mixing) that better approaches the ideal plug flow behaviour. The result of these phenomena is that the relatively small pilot reactors operated at relatively low flows generally have a lower efficiency (i.e., higher E EO ) than larger full-scale reactors. It is therefore, not recommended to assume that a full-scale system will have the same E EO as a pilot-scale system when operated with the same water quality and H 2 O 2 dose. 18