1.
[Virus adsorption onto nano-sized iron oxides as affected by different background solutions].
Shen, LL, Zhao, BZ, Zhang, JB, Chen, J, Zheng, H
Huan jing ke xue= Huanjing kexue. 2010;(4):983-9
Abstract
Batch adsorption studies were conducted to investigate virus adsorption onto four commercial nanoparticles of iron oxide as affected by different background solutions, using bacteriophage phiX174 as virus indicator. When artificial ground water was used, the 4 studied nanoparticles showed high virus adsorption capacity, among which alpha-Fe2O3 was the most effective, with the adsorption percent reaching 100% at low initial virus concentration (i.e. 1E + 03 PFU x mL(-1)). Virus adsorption results were described using the Langmuir and Freundlich adsorption isotherms. The estimated adsorption parameters indicated the presence of multilayer adsorption and favorable adsorption. The adsorption percentage by the studied nanoparticles increased with decreasing virus initial concentration. Our results further showed that higher ionic strength of the background solution reduced the virus adsorption, indicating that electrostatic interaction likely dominated the virus adsorption. The presence of anions in the background solution reduced the virus adsorption, probably because of the competitive adsorption between the viruses and anions for sorption sites available, among which HPO4(2-) showed more reduced than HCO3(-). On the other hand, the presence of multivalent cations was favorable for virus adsorption, with bivalent cations (e.g. Ca2+ and Mg2+) showing more favorable than monovalent cations (e.g. Na+ and K+). Results of this study suggest that nanoparticles of iron oxide may be potentially useful for virus removal from infecting water, while other anions or cations in the water should be considered.
2.
Evaluation of the fern Azolla for growth, nitrogen and phosphorus removal from wastewater.
Forni, C, Chen, J, Tancioni, L, Caiola, MG
Water research. 2001;(6):1592-8
Abstract
Water fern (Azolla filiculoides Lam.) has been assessed for nitrogen and phosphorus removal in outdoor experiments comparing sewage water (S) from an experimental aquaculture plant, well water (W) and mineral growth medium Hoagland (H). The experiments were undertaken during the spring and the summer. The yield of fern biomass and nitrogenase activity was higher in H than in W and S waters. The enzyme activity had a decreasing trend with significant differences (p < 0.05) in the three waters. Peroxidase (POD) activity in April decreased with significative differences in W and S waters (p < 0.05). The electrical conductivity and the concentrations of NO3- in the three waters decreased significantly (p < 0.05). The highest removal of nitrate from the media was obtained in July. In S water, NO2- concentration decreased, while it increased in W water. PO(4)3- concentration was very low in W and S waters and decreased in H medium. The results obtained confirm the ability of the fern to grow in sewage water.