title: Inactivation and magnetic separation of bacteria from liquid suspensions using electrosprayed and nonelectrosprayed nZVI particles: observations and mechanisms.
abstract: Here, nonelectrosprayed nanoscale zerovalent iron (NE-nZVI), electrosprayed nZVI (E-nZVI) and preoxidized nZVI (O-nZVI) particles were applied to inactivating Bacillus subtilis, Escherichia coli as well as bacteria in various wastewater samples. In addition, magnetic separation was applied to the mixture of 0.2 mL bacterial sample and 1.8 mL E-nZVI or NE-nZVI suspensions. Bacterial concentrations and optical density of the supernatants were analyzed using culturing, optical adsorption and qPCR tests.  In general, for wastewater samples the inactivations were shown to range from 1-log to 3-log. PCR-DGGE analysis indicated that no gene mutation occurred when bacteria were treated with nZVI. Using magnetic separation, significant physical removals, revealed as a function of nZVI type (NE-,E- and O-nZVI) and bacterial concentration, up to 6-log were obtained. E-nZVI and NE-nZVI were shown to react differently with B. subtilis and E. coli, although exhibiting similar inactivation rates. qPCR tests detected higher amount of DNA in the supernatants from mixing E. coli with NE-nZVI, but less for E-nZVI. However, the opposite was observed with B. subtilis. Our data together with optical adsorption analysis suggested that the inactivation and magnetic separation mainly depend on Fe(0)/Fe(3)O(4) shell compositions, the type of bacteria (aerobic and anaerobic) and their concentrations.
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Chen
authors.forename: Min
authors.initials: M
authors.lastname: Gao
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Fangxia
authors.initials: F
authors.lastname: Shen
authors.forename: Yan
authors.initials: Y
authors.lastname: Wu
authors.forename: Zhenqiang
authors.initials: Z
authors.lastname: Xu
authors.forename: Maosheng
authors.initials: M
authors.lastname: Yao
mesh_terms: D001412:Bacillus subtilis / Q000187:drug effects; D004203:Disinfection / Q000379:methods; D004926:Escherichia coli / Q000187:drug effects; D005618:Fresh Water / Q000382:microbiology; D007501:Iron / Q000633:toxicity; D008280:Magnetics; D053768:Metal Nanoparticles / Q000633:toxicity; D012722:Sewage / Q000382:microbiology; D013535:Suspensions; D014865:Waste Disposal, Fluid / Q000379:methods; D014873:Water Pollutants
chemical_list: D012722:Sewage; D013535:Suspensions; D014873:Water Pollutants; D007501:Iron