Modeling, validation, and optimization of a rotating advanced oxidation contactor equipped with TiO2-zeolite composite sheets for sulfamethazine removal

Abstract

The necessity to remove antibiotic residues such as sulfamethazine from veterinary/hospital wastewater is evident due to their widespread existence, challenges in treatment, and potential harm in aquatic ecosystems. This study focused on modeling, validating, and optimizing the removal of sulfamethazine (SMT) using two lab-scale rotating advanced oxidation contactor (RAOC) systems equipped with TiO2-zeolite composite sheets. Four key parameters—temperature, UV intensity, rotation speed, and sheet area by tank volume (A/V)—were investigated to understand their individual effects and interactions using the drum-RAOC system. The adsorption and decomposition processes of the RAOC systems were separately studied. In terms of the adsorption process, A/V was found to be the primary parameter influencing RAOC performance, with significant interaction observed between temperature and A/V. For the decomposition process, A/V and UV intensity were identified as the dominant parameters, with interactions affecting photocatalysis performance. Kinetic fitting was used to explore the underlying mechanisms, and liquid film thickness on the sheet surface was employed to support the explanations. Furthermore, validation experiments conducted using the disk-RAOC system confirmed the accuracy and applicability of these models. Through comprehensive optimization, the optimal parameter set was determined: temperature of 20°C, rotation speed of 5 rpm, UV intensity of 1.5 mW/cm2, and A/V of 200 cm2/L. Additionally, the current findings were compared with previous studies to illustrate the efficiency of RAOC systems. These results provide valuable guidelines for designing and operating RAOC systems and serve as a reference for balancing performance and consumption in immobilized photocatalysis systems.