Abstract: In order to realize the comprehensive reuse of solid waste,  the iron/sludge-based biochar catalyst  was prepared by using the mixed sludge of activated sludge and Fenton iron sludge from the sewage treatment section of steel plant in Anshan, Liaoning Province as raw materials， and kaolinite as binder by a mixing-extrusion and pyrolysis method. The structure was characterized and the preparation process conditions were optimized. We optimized the process parameters of catalytic ozonation degradation of simulated wastewater containing quinoline as the target pollutant, and studied the stability and catalytic mechanism of catalyst. The experimental results show that the surface of catalyst is rough with a rich porous structures, and the catalyst mainly contains Fe₃O₄，CaCO₃ and ZrO₂ crystals. The optimal preparation conditions for the catalyst are a binder addition of 12.5%, pyrolysis temperature of 800 ℃, and pyrolysis time of 3 h. Under the conditions of initial pH=7, catalyst dosage of 50 g,  and  initial mass concentration of 50 mg/L of quinoline, the removal rate reaches 76.31% after 10 min of reaction. The catalyst has good stability,  and the removal rate of quinoline only decreases by 0.09 percentage points  after continuous  use for five times. There are two types of   hydroxyl radical (^.OH) and superoxide anion radical (O^.-₂), as well as singlet oxygen  (¹O₂) non  free radicals  in the catalytic system, with  O^.-₂   playing a dominant role in the reaction. The change of Fe²⁺/Fe³⁺ ratio before and after the reaction indicates that the redox cycle of Fe²⁺/Fe³⁺ participates in the catalytic degradation reaction. This study provides a new idea and method for the reuse of solid waste and the efficient treatment of coking wastewater.

Key words: Fenton iron sludge, activated sludge,  ,  , iron/sludge-based biochar,  , catalytic ozonation,  , quinoline