State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, CHINA
Microbial cells have been successfully used as biosorbents to remove heavy metals from wastewater. In some cases, dead cells appear to offer more advantages than living cells in the removal and recovery of heavy metal ions from industrial wastewater. Maintaining higher biosorption capability and understanding the biosorption properties of dead cells are the keys to heavy metal removal and recovery from wastewater using dead cells as biosorbents. The present experiment showed that the dead Pseudomonas putida 5-x cells killed by dilute HCl had a higher Ni2+ biosorption capacity due to the retention of a complete cell structure during the acid treatment process. The biosorption process of the dead cells was faster than that of the living cells. Metabolic-independent physical adsorption played a major role in the Ni2+ sorption by the dead cells.The pH obviously affected the biosorption capacity of the dead cells, because of the variation of the hydrogen ion concentration and cell surface property, as well as occurrence of micro-precipitation along with the change of solution pH. Considering both biosorption capacity and desorption efficiency, pH 6.5-7.0 is a suitable condition for Ni2+ biosorption by dead P. putida 5-x cells killed with dilute HCl.
 Gadd G.M., White C., Removal of Thorium from Simulated Acid Process Stream by Fungal Biomass: Potential for Thorium Desorption and Reuse of Biomass and Desorbent, J. Chem. Technol. Biotechnol., 55, p. 39 (1992).
 Matheickal J.T., Yu Q., Biosorption of Lead(II) and Copper(II) from Aqueous Solutions by Pre-Treated Biomass of Australian Marine Algae, Bioresource Technology,69, p. 223 (1999).
 Schiewer S., Volesky B., Biosorption Process for Heavy Metal Removal, "In: Environmental Microbe-Metal Interactions",Derek R. L., (Ed.), ASM Press Inc., Washington DC, pp. 329-362(2000).
 Wong P.K., So C.M., Cu2+ Accumulation by a Strain of Pseudomonas putida, Microbiology, 73, p. 113 (1993).
 Sze K.F., Lu Y.J., Wong P.K., Removal and Recovery of Copper ion (Cu2+) from Electroplating Effluent by a Bioreactor Containing Magnetite-Immobilized Cells of Pseudomonas putida, Resources, Conservation and Recycling, 18, p. 175 (1996).
 Wang L., Li F.T., Zhou Q., Contribution of Cell Surface Components to Cu2+ Adsorption by P. putida 5-x, Applied Biochemistry and Biotechnology,128, p. 33 (2006).
 Environmental Management Division. Guidebook on the Treatment of Wastewater for the Hong KongElectroplating Industry. Hong Kong Productivity Council: Hong Kong, (1986).
 Taylor M.C., Demayo A., Reeder S.W., Inorganic Chemical Substances-Nickle. In Guidelines for Surface Water Quality; Environment Canada: Ottaw
 Codina J.C., Perez-Garcia A., Vicente A.D., Detection of Heavy Metal Toxicity and Genotoxicity in Wastewater by Microbial Assay, Water Science & Technology, 30, p. 145 (1994).
 Wang L., Chua H., Sin S.N., Zhou Q., Ren D.M., Li Z.L., A Combined Bioprocess for Integrated Removal of Copper and Organic Pollutant from Copper-zontaining Municipal Wastewater, J. Environ. Sci. Heal. Part (A),39, p. 223 (2004).
 Hu Z.C., Norman J.M., Faison B.D., ReeresM.E., Biosorption of Uranium by P. Aeruginosa Strain CSO: Characterization and Comparison Studies, Biotech. Bioeng., 51, p. 237 (1996).
 Townsley C.C., Ross L.S., Atkins A.S., Copper Removal from a Simulated Leach Effluent Using the Filamentous Fungus Trichoderma viride, "In: Immobilisation of Ions by Bio-sorption", Eccles H., Hunt, S. S., (Eds.), Ellis Horwood,Chichester, pp.159-170 (1988).
 Komori K., Rivas A., Toda K., Ohtake H., Biological Removal of Toxic Chromium Using an Enterobacter cloacae Strain that Reduces Chromate Under Anaerobic Conditions, Biotechnology and Bioengineering, 35, p. 951 (1990).
 Ishibashi Y., Cervantes C., Silver S., Chromium reduction by Pseudomonas putida, Applied and Environmental Microbiology,56, p. 2268 (1990).
 Kuyucak N., Volesky B., Biosorbents for Recovery of Metals from Industrial Solutions, Biotechnol. Lett., 10, p. 137 (1988).