Application of UVC-LED/H2O2 in wastewater treatments: treatment efficacy on disinfection byproduct precursors and micropollutants

The applications of advanced oxidation processes (AOPs) for controlling microcontaminants are essential to meet the water quality criteria for potable or nonpotable water reuses. The objective of this study is to demonstrate the application of light emitting diode (LED) as a possible light source to substitute traditional low-pressure mercury lamp (LPUV) in UV/H2O2 processes in treating precursors of disinfection byproducts (DBPs) and pharmaceutical and personals care products (PPCPs) in wastewater. The results of this study revealed that UV fluence plays the most crucial role in the efficiency of UV/H2O2. At the same time, the initial concentration of H2O2, dissolved organic carbon (DOC), and turbidity had minimal effects, except that poor efficiency result of UV/H2O2 was observed at a solution with low DOC concentration (2.4 mg L-1). Although the concentrations of organic matter decreased after UV/H2O2 treatment, the concentration of precursors of DBPs increased in the early stage of the photolysis process and decreased after that; moreover, the profiles of precursors for trihalomethanes and haloacetic acids were different. A comparison between LPUV and UVC-LED as light sources revealed that, at a fixed UV fluence input into the UV/H2O2 process, the trends and efficiencies in the degradation of organic matter and DBP precursors were similar. Meanwhile, the photoelectric conversion efficiency of UVC-LED should be improved for future applications in water treatment. Based on the UV/H2O2 treatment results on synthetic PPCPs wastewater solution, this study showed the effectiveness of UV/H2O2 to degrade micro organic contaminants.