EPS and aggregates changes on activated sludge under atrazine exposure

Abstract

Extracellular polymeric substances (EPS) play a vital role in biological wastewater treatment systems, affecting their performance in aggregates settling, structure and arrangement, and interacting with micropollutants present in wastewater. In this study, the effects of herbicide atrazine (ATZ) on the EPS yield and composition and aggregates structure were investigated on activated sludge (AS) in a sequencing batch reactor (SBR). The results demonstrated that TB-EPS and LB-EPS increased under ATZ exposure, indicating that microorganisms release EPS as a self-mechanism of defense against environmental changes. Above 5.5 mg L-1 of ATZ aggregates become larger. Principal component analysis (PCA) was useful in highlighting biomass changes during the experimental phases, and Pearson correlation revealed that TB-EPS content correlate well with large aggregates (0.996).