Catalytic ozonation in advanced treatment of kitchen wastewater: multi-scale simulation and pilot-scale study

Catalytic ozonation is regarded as a promising technology in the advanced treatment of refractory organic wastewater. Packed-bed reactors are widely used in practical applications due to simple structures, installation and operation. However, mass transfer of packed-bed reactors is relatively restrained and amplified deviations usually occurred in scale-up application. Herein, a multi-scale packed-bed model of catalytic ozonation was established to guide pilot tests. First, a laboratory-scale test was conducted to obtain kinetic parameters needed for modeling. Then, a multi-scale packed-bed model was developed to research the effects of water distribution structure, catalyst particle size, and hydraulic retention time (HRT) on catalytic ozonation. It was found that the performance of packed bed reactor was increased with evenly distributed water inlet, HRT of 60 min, and catalyst diameter of about 3–7 mm. Last, an optimized reactor was manufactured and a pilot-scale test was conducted to treat kitchen wastewater using catalytic ozonation process. In the pilot-scale test with an ozone dosage of 50 mg/L and HRT of 60 min, the packed-bed reactor filled with catalysts I was able to reduce chemical oxygen demand (COD) from 117 to 59 mg/L. The performance of the catalytic ozonation process in the packed-bed reactor for the advanced treatment of actual kitchen wastewater was investigated via both multi-scale simulation and pilot-scale tests in this study, which provided a practical method for optimizing the reactors of treating refractory organic wastewater.