title: Effect of magnetic nanoparticles on the performance of activated sludge treatment system.
abstract: Both short-term and long-term exposure experiments were carried out to investigate the influence of magnetic nanoparticles (NPs) on activated sludge. The short-term presence of 50-200 mg/L of NPs decreased total nitrogen (TN) removal efficiencies, resulted from the acute toxicity of a shock load of NPs. However, long-term exposure of 50 mg/L magnetic NPs were observed to significantly improve TN removal efficiency, partially due to the self-repair function of activated sludge and magnetic-induced bio-effect. Sludge properties and extracellular polymer substrates secretion were affected. Additional investigations with enzyme and FISH assays indicated that short-term exposure of 50 mg/L magnetic NPs led to the abatement of nitrifying bacteria. However, the activities of the enzyme nitrite oxidoreductase and key denitrifying enzymes were increased after long-term exposure.
authors.affiliation: School of Environmental Science and Engineering, Shandong University, Jinan 250100, China. sqni@sdu.edu.cn
authors.forename: Shou-Qing
authors.initials: SQ
authors.lastname: Ni
authors.forename: Jianyuan
authors.initials: J
authors.lastname: Ni
authors.forename: Ning
authors.initials: N
authors.lastname: Yang
authors.forename: Juan
authors.initials: J
authors.lastname: Wang
mesh_terms: D002384:Catalysis; D004798:Enzymes / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D008280:Magnetics; D053758:Nanoparticles; D009584:Nitrogen / Q000302:isolation & purification; D012722:Sewage
chemical_list: D004798:Enzymes; D012722:Sewage; D009584:Nitrogen
keywords: Activated sludge; Enzyme; Extracellular polymeric substance; Long-term; Magnetic nanoparticles