title: Toxicity assessment of 4-chlorophenol to aerobic granular sludge and its interaction with extracellular polymeric substances.
abstract: The main objective of this study was to evaluate the toxicity of 4-chlorophenol (4-CP) to aerobic granular sludge in the process of treating ammonia rich wastewater. In the short-term exposure of 4-CP of 5 and 10 mg/L, ammonia nitrogen removal efficiencies in the batch reactors decreased to 87.18±2.81 and 41.16±3.55%, which were remarkably lower than that of control experiment (99.83±0.54%). Correspondingly, the respirometric activities of heterotrophic and autotrophic bacteria of aerobic granular sludge were significantly inhibited in the presence of 4-CP. Moreover, the main components of extracellular polymeric substances (EPS) including polysaccharides and proteins increased from 18.74±0.29 and 22.57±0.34 mg/g SS to 27.79±0.51 and 24.69±0.38 mg/g SS, respectively, indicating that the presence of 4-CP played an important role on the EPS production. Three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy further showed that the intensities of EPS samples were obviously quenched with the increased of 4-CP concentrations. To be more detailed, synchronous fluorescence spectra indicated that the interaction between EPS and 4-CP was mainly caused by tryptophan residues. The mechanism of fluorescence quenching belongs to static quenching with a formation constant (KA) of 0.07×10(4) L/mol, implying the strong formation of EPS and 4-CP complex. The results could provide reliable and accurate information to determine the potential toxicity of 4-CP on the performance of aerobic granular sludge system.
authors.affiliation: School of Resources and Environmental Sciences, University of Jinan, Jinan 250022, PR China.
authors.forename: Dong
authors.initials: D
authors.lastname: Wei
authors.affiliation: School of Resources and Environmental Sciences, University of Jinan, Jinan 250022, PR China.
authors.forename: Yifan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: School of Resources and Environmental Sciences, University of Jinan, Jinan 250022, PR China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Wang
authors.affiliation: School of Resources and Environmental Sciences, University of Jinan, Jinan 250022, PR China.
authors.forename: Mengting
authors.initials: M
authors.lastname: Li
authors.affiliation: School of Resources and Environmental Sciences, University of Jinan, Jinan 250022, PR China.
authors.forename: Fei
authors.initials: F
authors.lastname: Han
authors.affiliation: School of Resources and Environmental Sciences, University of Jinan, Jinan 250022, PR China.
authors.forename: Luyu
authors.initials: L
authors.lastname: Ju
authors.affiliation: School of Resources and Environmental Sciences, University of Jinan, Jinan 250022, PR China.
authors.forename: Ge
authors.initials: G
authors.lastname: Zhang
authors.affiliation: School of Resources and Environmental Sciences, University of Jinan, Jinan 250022, PR China.
authors.forename: Li
authors.initials: L
authors.lastname: Shi
authors.affiliation: School of Resources and Environmental Sciences, University of Jinan, Jinan 250022, PR China.
authors.forename: Kai
authors.initials: K
authors.lastname: Li
authors.affiliation: School of Resources and Environmental Sciences, University of Jinan, Jinan 250022, PR China.
authors.forename: Bingfeng
authors.initials: B
authors.lastname: Wang
authors.affiliation: School of Resources and Environmental Sciences, University of Jinan, Jinan 250022, PR China; Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China. Electronic address: dubin61@gmail.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Du
authors.affiliation: Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Wei
mesh_terms: D000332:Aerobiosis; D000641:Ammonia / Q000032:analysis; D002733:Chlorophenols / Q000633:toxicity*; D009584:Nitrogen / Q000032:analysis; D011108:Polymers / Q000378:metabolism*; D011134:Polysaccharides / Q000032:analysis; D012722:Sewage / Q000382:microbiology*; D013050:Spectrometry, Fluorescence; D014364:Tryptophan / Q000032:analysis; D014865:Waste Disposal, Fluid
chemical_list: D002733:Chlorophenols; D011108:Polymers; D011134:Polysaccharides; D012722:Sewage; C029107:4-chlorophenol; D000641:Ammonia; D014364:Tryptophan; D009584:Nitrogen
keywords: 4-Chlorophenol; Aerobic granular sludge; Excitation-emission matrix (EEM); Extracellular polymeric substances (EPS); Toxicity