The inhibitory effect of in situ extracellular polymeric substances on trimethoprim adsorption by activated sludge. (July 2021)

• Record Type: Journal Article
• Authors: Ma, You; Yuan, Pei-Kun; Wu, Yu; Cheng, Xin-Ying; Meng, Han; He, Huan; Wang, Guo-Xiang; Chen, Xue-Ming; Xie, Wen-Ming; Zhang, Li-Min
• Is Part Of: Chemosphere. Volume 274(2021)
• Publication Date: 2021-07
• Subjects: Activated sludge -- Adsorption -- Extracellular polymeric substances (EPS) -- Kinetic models -- Trimethoprim (TMP); Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2021.129798
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The extracellular polymeric substances (EPS) of activated sludge are a mixture of high molecular weight polymers secreted by microorganisms, which are mainly composed of proteins, polysaccharides and humic substances. It is widely accepted that EPS have a good adsorption ability for pollutants with different functional groups. However, recent studies showed the EPS had an inhibitory effect on pollutant sorption, which is contradictory to previous viewpoint. Therefore, in this study, three types of activated sludge with different EPS contents and compositions were used to investigate the role of EPS in an antibiotic-trimethoprim (TMP) sorption process at environmentally relevant concentration. The in situ experiments results showed the adsorption capacity of activated sludge for TMP were increased from 2.98, 5.37 and 28.33 μg/g VSS to 7.87, 12.93 and 150.24 μg/g VSS in nitrifying activated sludge, wastewater treatment plant activated sludge and anaerobic ammonia-oxidized activated sludge, respectively after EPS extracted. The adsorption process can be well described by the pseudo-second-order kinetic model. Results of zeta potential, contact angles and infrared spectrum showed TMP replacing proteins embedded into the cell membrane enhancing the TMP adsorption capacity of activated sludge after EPS extraction. Our results demonstrated that less proteins in EPS of activated sludge is more beneficial for TMP adsorption removal. Graphical abstract: Image 1 Highlights: Three different activated sludge were used for TMP sorption experiment. The adsorption capacity was increased significantly after EPS extraction. The adsorption process can be described by the pseudo-second-order kinetic model. The mechanism of TMP adsorption enhancement after EPS extraction was explored.