Effects of desloratadine on activated sludge: behaviour of EPS and sludge properties

Abstract

Desloratadine (DESL), a second generation of antihistamines, is an important anti-allergic pharmaceutical used to treat allergic rhinitis, hay fever and urticaria. In this study, the overall performance, extracellular polymeric substances (EPS) production, and sludge properties were assessed in a sequencing batch reactor wastewater treatment process with activated sludge during 139 days, under the presence of DESL (1, 5, and 10mgL-1). DESL at 10mgL-1 impacted biomass activity decreasing the chemical oxygen demand removal (78%) and the ammonium removal (71%). The removal of DESL was of 63%. Tightly bound EPS (TB-EPS) was significantly higher (149.5mg gMLVSS-1) at the end of operation. Peaks attributed to protein-like fluorophores clearly predominated along the experimental phases using three-dimensional excitation-emission matrix (3D-EEM) fluorescence. The peak locations and intensities in the EPS fluorescence revealed the difference in the chemical structures of the EPS caused by DESL exposure. Quantitative image analysis results clearly demonstrated the formation of large aggregates. Principal component analysis (PCA) showed a positive relationship between TB-EPS components, and large aggregates. Moreover, the results allowed to distinguish the different operational phases, emphasizing the effect of DESL on EPS and aggregates.