title: Response of anaerobic granular sludge to a shock load of zinc oxide nanoparticles during biological wastewater treatment.
abstract: The increasing use of zinc oxide nanoparticles (ZnO NPs) in consumer and industrial products highlights a need to understand their potential environmental impacts. In this study, the response of anaerobic granular sludge (AGS) to a shock load of ZnO NPs during anaerobic biological wastewater treatment was reported. It was observed that the extracellular polymeric substances (EPS) of AGS and the methane production were not significantly influenced at ZnO NPs of 10 and 50 mg per gram of total suspended solids (mg/g-TSS), but they were decreased when the dosage of ZnO NPs was greater than 100 mg/g-TSS. The visualization of EPS structure with multiple fluorescence labeling and confocal laser scanning microscope revealed that ZnO NPs mainly caused the decrease of proteins by 69.6%. The Fourier transform infrared spectroscopy analysis further indicated that the C-O-C group of polysaccharides and carboxyl group of proteins in EPS were also changed in the presence of ZnO NPs. The decline of EPS induced by ZnO NPs resulted in their deteriorating protective role on the inner microorganisms of AGS, which was in correspondence with the observed lower general physiological activity of AGS and the death of microorganisms. Further investigation showed that the negative influence of ZnO NPs on methane production was due to their severe inhibition on the methanization step.
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Mu
authors.forename: Xiong
authors.initials: X
authors.lastname: Zheng
authors.forename: Yinguang
authors.initials: Y
authors.lastname: Chen
authors.forename: Hong
authors.initials: H
authors.lastname: Chen
authors.forename: Kun
authors.initials: K
authors.lastname: Liu
mesh_terms: D000143:Acids; D000693:Anaerobiosis / Q000187:drug effects; D001673:Biodegradation, Environmental / Q000187:drug effects; D001704:Biopolymers / Q000737:chemistry; D005110:Extracellular Space / Q000737:chemistry; D008697:Methane / Q000032:analysis; D050296:Microbial Viability / Q000187:drug effects; D053758:Nanoparticles / Q000633:toxicity* / Q000648:ultrastructure; D012722:Sewage / Q000382:microbiology*; D013052:Spectrometry, X-Ray Emission; D017550:Spectroscopy, Fourier Transform Infrared; D014865:Waste Disposal, Fluid; D018508:Water Purification / Q000379:methods*; D015032:Zinc / Q000032:analysis; D015034:Zinc Oxide / Q000633:toxicity*
chemical_list: D000143:Acids; D001704:Biopolymers; D012722:Sewage; D015032:Zinc; D008697:Methane; D015034:Zinc Oxide