Mechanism of Ozone Oxidation of Polycyclic Aromatic Hydrocarbons During the Reduction of Coking Wastewater Sludge

Abstract

Activated coking wastewater sludge is a significant problem, due to the content of adsorbed hydrophobic organic micro‐pollutants which are adsorbed. Here we discuss an O3 fluidized bed reactor (FBR) process able to stabilize and reduce the coking sludge, and also removing 16 target polycyclic aromatic hydrocarbons (PAHs) adsorbed onto the sludge. The degradation efficiencies and influential factors affecting the sludge ozonation, such as the concentration of O3 and of H2O2, UV irradiation, and the initial pH were investigated. The results indicate that the target PAHs present in the activated coking sludge, especially those with high molecular weight can be effectively removed by O3 FBR. However, the concentration of O3 plays an important role in the degradation of the target PAHs because a low concentration can generate an increase in the concentrations of PAHs in the liquid phase of the activated coking sludge. Due to the synergistic effect (S > 0), increasing the concentration of H2O2 and increasing the pH value, can improve the removal of most of the target PAHs. The degradation kinetics of the target PAHs are assigned to a pseudo first‐order model. In this process, the solubilization rate of the activated coking sludge reached about 68.2% and the target PAHs adsorbed on it were removed by >95% at 500 mg O3 g−1 SS.