PHOTO AND ELECTROCHEMICAL INTERVENTIONS FOR ORGANIC CONTAMINANT REMOVAL: DEGRADATION, SORPTION AND KINETIC CHARACTERIZATION

While conventional drinking water treatment strategies can help mitigate physical, chemical and biological water quality challenges, the process itself may introduce or fail to adequately remove contaminants, thereby exceeding regulatory guidelines and posing compliance challenges. Disinfection byproducts (DBPs) can be unintentionally formed during pre-oxidation and disinfection, within the treatment plant and throughout the distribution system, when oxidants react with natural organic matter and other organic precursors. Moreover, persistent organic pollutants constitute a contaminant class which survive conventional treatment largely intact. Together, these two contaminant classes create substantial toxicity concerns post treatment. Traditional treatment processes fail to manage either of these contaminant classes adequately, creating the need to develop other targeted treatment strategies. This thesis investigates two complementary independent approaches, namely, photodegradation of DBPs and electrosorption of persistent aromatic organics using activated carbon fiber electrodes, with the objective of advancing the design and operation of post-conventional treatment strategies. DBP photodegradation was investigated by applying ultraviolet C (UV-C) irradiation and understanding the impact of operational parameters such as UV-C wavelength and irradiance on haloacetonitrile (HAN) degradation, as a representative DBP. Degradation kinetics, quantum yield and fluence based degradation rates were characterized for the tested HAN. Organic micropollutant removal was investigated using an electrosorption process employing activated carbon fibers (ACF), with two target aromatic organic compounds, namely phenol and benzotriazole (BTA). The effect of initial concentration, applied electric potential and fiber orientation on the electrosorption process were systemically evaluated using unmodified ACF electrodes. Additionally, electrochemical regeneration performance of BTA laden ACFs was investigated across repeated electrosorption-electrodesorption cycles. Photodegradation achieved substantial HAN removal under UV-C irradiations, with degradation following pseudo-first-order kinetics. ACF electrodes exhibited notable increase in sorption capacity with an applied electric potential, considerably improving contaminant uptake for the two tested target organic compounds, when compared to passive adsorption (i.e., non-electrochemical conditions). Findings demonstrate that ACF orientation/structure are an under explored, but a critical determinant of electrosorption performance, suggesting that the structural characteristics necessitate systemic understanding as a foundation for optimizing sorption capacity and regeneration performance. Together, these findings constitute emerging empirical evidence supporting electrochemical and photochemical strategies as feasible post-conventional treatment approaches and highlight UV-C and unmodified ACF electrosorption processes as promising strategies for DBP and organic micropollutant treatment, respectively.