Polyacrylamide degradation in oil field wastewater by UV/H2O2 and UV/PDS: Rapid experimental measurement and model simulation

Ultraviolet-based advanced oxidation processes (UV-AOPs) are effective for degrading refractory pollutants in wastewaters. However, performing rapid efficiency evaluations represents a significant challenge for process selection and optimization in practical application. This study investigated polyacrylamide (PAM) degradation by UV/hydrogen peroxide (H2O2) and UV/potassium peroxydisulfate (PDS) in pure water and practical oil field wastewater. Based on a previously developed mini-fluidic photoreaction system that is easy to operate and requires low sample volumes, an experimental setup for rapid evaluation of UV-AOP efficiency was constructed that enabled on-line analyses of viscosity, UV absorbance, and pH via specially fabricated flow cell devices together with off-line analyses of PAM, chemical oxygen demand (COD), and acrylamide (AM). The PAM degradation rate constants (k′PAM) in practical oil field wastewater by UV/H2O2 and UV/PDS were 2.4 and 2.1 m2 einstein−1, respectively, which were much higher than those by sole UV process (0.8 m2 einstein−1). Combing with the analyses of viscosity, UV absorbance (220 nm), pH, COD, and AM concentration, the UV/H2O2 and UV/PDS demonstrated the effectiveness in PAM degradation in oil field wastewater. Additionally, the scavenging capacities of HO• and SO4•− of practical oil field wastewater were determined, and the k′PAM values were predicted by model simulation and verified experimentally. This study provides rapid evaluation methods for UV-AOP efficiencies, which is helpful for selecting and optimizing UV-AOPs for industrial wastewater treatments.