Effects of Vanillin on Characteristics of Extracellular Polymeric Substances and Treatment Performance in a Conventional Activated Sludge Process

摘要

Quorum sensing is biological activity of cell-to-cell communication in which bacteria produces signaling molecules to trigger group behaviors. Quorum sensing is reported to contribute to production of extracellular polymeric substances (EPS) in wastewater treatment processes. Vanillin, a main constituent of vanilla extract, has not only been widely used in food and beverage application, but also reported to be an effective inhibitor of bioactivity including quorum sensing. This study investigated effects of vanillin on treatment performance of organic removal and sludge settlability, EPS and microbial community in a lab-scale sequential batch reactor of conventional activated sludge process. The result showed that addition of vanillin at 25mg/L caused change in EPS characteristics and microbial community, although it did not have effect on treatment performance and sludge settlability. The observed change in EPS after vanillin addition was (i) EPS content in sludge decreased; (ii) protein and polysaccharide of loosely-bound EPS and polysaccharide of tightly-bound EPS significantly decreased; (iii) EEM fluorescence intensity of protein-like substances, hydrophobic-acid fraction and fulvic-acid like substances in soluble EPS and tightly bound EPS were decreased. Consequently, it was implied that vanillin can inhibit quorum sensing to affect sludge characteristics through reduction of EPS and its polysaccharide and protein content.