Evaluating the photodegradation of Carbamazepine in a sequential batch photoreactor system: Impacts of effluent organic matter and inorganic ions

Abstract

Removal of pharmaceutical Carbamazepine (CBZ) compound from municipal wastewater has become an issue from the human health and environmental risks point of view, due to its latent recalcitrance and toxicity properties. This study investigated the photodegradation performance of a sequential batch annular slurry photoreactor (SB-ASP) system for the removal of CBZ compound from secondary municipal wastewater. Two different immobilised TiO 2 photocatalysts, namely anatase titanate nanofiber and mesoporous TiO 2 impregnated kaolinite catalyst were applied in the SB-ASP system. Various modes of sequential batch reactor (SBR) cycles, presence of effluent organic matter (EOM) and inorganic ions, mainly nitrate and phosphate that could affect the photodegradation performance of the SB-ASP system were evaluated during the removal of CBZ. High performance size exclusion chromatography revealed that the photocatalytic reaction will preferentially compete and attack on high molecular weight EOM prior to the photodegradation of CBZ. The presence of inorganic ions was found to affect the surface fouling of immobilised photocatalysts used to a different extent, without completely retarding their photoactivity. This study also highlighted that the operation of SB-ASP system was useful to enhance the photodegradation of CBZ compound in a semi-continuous operation without constant catalyst replacement. It is foreseeable that the integration of SB-ASP system with biological treatment systems could provide an advanced treatment option for the recycling and reuse of municipal wastewater.