UV-based advanced oxidation processes in photoreactors with reflective sleeves

Abstract

UV-based advanced oxidation processes (UV-based AOPs) via photolysis of radical precursor chemicals (RPCs) are among the most effective technologies for eliminating trace organic contaminants in water treatment facilities. However, mathematical discussions on the kinetics and energy consumption for the engineering photoreactor set-up of UV-based AOPs, especially the newly proposed UV-based AOPs (e.g., UV/persulfate, UV/chlorine and UV/chloramine), are scarce. In this study, a photoreactor with reflective sleeves was mathematically characterized and validated using clean and complex water matrices, and approaches for measuring effective light absorbance by RPC (IRPC) and the reflectance of the photoreactor wall (η) were proposed. By applying IRPC and η, and employing geosmin as a model compound, energy optimization of the UV-based AOPs was conducted based on an updated kinetic model. A new equation was derived for UV/H2O2 to obtain the most cost-effective RPC dose regarding EE/O (electric energy required for one order of contaminant removal) (Copt-EE/O). This equation was then successfully extended to other UV-based AOPs (including UV/persulfate, UV/chlorine, and UV/chloramine). The balance between the treatment goals and operational costs was also discussed. Overall, the new concepts and approaches proposed in this study may aid in the energy optimization and reduce RPC consumption of various UV-based AOPs for engineering applications.