title: Kinetics of Nutrient Removal by Nano Zero-Valent Iron under Different Biochemical Environments.
abstract: The effectiveness of nano zero-valent iron (NZVI; an average size of 55 nm at a concentration of 200 mg Fe/L) in nutrient removal was determined under anaerobic, anoxic, and aerobic conditions. Compared to the rate of reduction of nitrate nitrogen (NO3--N) to ammoniacal nitrogen (NH4+-N) by NZVI alone, the presence of activated sludge increased the rate of complete reduction by 300%. About 31% of NO3--N was converted to NH4+-N through NZVI-facilitated dissimilatory nitrate reduction to ammonium, while 56% of NO3--N was removed by heterotrophic denitrification. The presence of sludge reduced the rates of phosphorus removal by NZVI, with the first-order reaction rate constants of 0.06/hour, 0.42/hour, and 0.18/hour under anaerobic, anoxic, and aerobic conditions, respectively. The highest phosphorus removal efficiency (95%) by NZVI was observed under anoxic abiotic conditions, whereas the efficiency dropped to 31% under anaerobic biotic conditions, which was attributed to significant sludge-facilitated NZVI agglomeration.
authors.affiliation: Department of Civil and Environmental Engineering, University of Missouri, E2509 Lafferre Hall, Columbia, MO 65211, USA.
authors.forename: Shengnan
authors.initials: S
authors.lastname: Xu
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Hu
mesh_terms: D000641:Ammonia / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D053768:Metal Nanoparticles / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry*; D010758:Phosphorus / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D009566:Nitrates; D014874:Water Pollutants, Chemical; D014867:Water; D010758:Phosphorus; D000641:Ammonia; D007501:Iron