Operation of iron-based monolithic catalyst packing ozonation for industry wastewater advanced treatment: The importance of gas–liquid flow patterns and wastewater flow regimes.

[Display omitted] • Long-term operation has proved the superiority of this catalytic ozonation process. • The gas–liquid counter-current flow better than co-current for COD removal. • The importance of catalyst packing was proved by setting wastewater short-circuiting. • After 5 years of use, the micro-porous aerator operated well-maintained. In this study, from the feasibility verification of the lab-scale test to the working condition study of the pilot-scale test the large-scale engineering application of the display manufacturing industry wastewater advanced treatment by ozonation with iron (Fe)-based monolithic catalyst packing was finally realized. Different from chemical packings, the catalyst packing has large porosity and specific surface area, while the pore size is small, which meets the requirements of •OH reaction, and these characteristics are necessary for engineering applications. Under the three scales, the reaction procedure and the corresponding reactor structure were introduced in detail. The importance of gas–liquid flow patterns and gas distribution device on treatment effect were proved in pilot-scale test. The treatment effect under gas–liquid counter-current flow was better than that of co-current flow. Through the analysis of the working conditions, the working parameters for high wastewater quantity and high organic loading were obtained. The large-scale test achieved the same excellent treatment effect as the lab/pilot-scale test, after 5 years of operation, the average chemical oxygen demand (COD) removal was about 72.0 %, and the COD concentrations after treatment were all lower than 30 mg/L. The biochemical oxygen demand (BOD 5) decreased from 10.22 to 2.50 mg/L on average. Under the short-circuiting phenomenon, the wastewater through the catalyst area unevenly and the organic pollutants were not effectively oxidized and decomposed. This also proved the importance of Fe-based monolithic catalyst packing in advanced treatment. This work proved the importance of gas–liquid flow patterns and wastewater flow regimes in the reactor, which can provide reference for other catalytic ozonation technology in large-scale engineering applications. [ABSTRACT FROM AUTHOR]