Interaction mechanism between stratified extracellular polymeric substances (EPS) from activated sludge and claforan in domestic wastewater

摘要

Extracellular polymeric substances (EPS) play a crucial role in claforan bio-adsorption using activated sludge, but the interaction mechanism between claforan and EPS remains unclear. Fluorescence spectroscopy technology was employed to illuminate the mechanism in this study. Two protein-like fluorescence peaks (peak A with Ex/Em = 225 nm/337 nm and peak B with Ex/Em = 280/335 nm) and humic acid-like (peak C with Ex/Em = 350/434) were identified in loosely bound extracellular polymeric substances (LB-EPS). Fluorescence of the peaks A and B for LB-EPS were markedly quenched by claforan at all temperatures whereas fluorescence of peak C for LB-EPS was quenched only at 288 K. Peak A and Peak B interaction with Claforan fits Stern-Volmer equation and Hill model. log K-b was 7.17 and 5.05, respectively, and the number of binding sites (n) was 1.56 and 1.19. log K-b and n for peak C were not able to fit the equation at 298 K. The fluorescence quenching of interaction between peak A and peak B and Claforan was governed a static process, whereas the interaction between peak C and Claforan may be both static and dynamic quenching. The molecular binding mechanisms obtained in this study will add fundamental knowledge of understanding the roles of EPS from activated sludge in claforan bio-adsorption in domestic wastewater.