Study on COD removal mechanism and reaction kinetics of oilfield wastewater

The chemical oxygen demand (COD) removal mechanism and reaction kinetics were mainly studied in the treatment of oilfield oily sewage containing polymer by three-dimensional electrode reactor. The results proved that the residual active oxides O₃, H₂O₂, •OH and active chlorine in the system of electrochemical reaction could be effectively detected, and the COD removal mechanism was co-oxidation of active oxides; Under these experimental conditions: the electrolysis current of 6 A, surface/volume ratio of 6/25(cm²·L^-1), the reaction time of 50 min, the COD_cr of treated sewage was no more than 50 mg·L^-1; the removal reaction of COD conformed to apparent second-order reaction kinetic model, the correlation coefficient R² was 0.9728, and the apparent reaction rate constant was k = 3.58 × 10^-4 (L·min^-1·mg^-1·m^-2). To reach the goal, the COD_cr was no more than 50 mg·L^-1 in treated sewage, and the theory minimum processing time was 45.73 min. The verification of experimental results was consistent with kinetic equations.