Abstracts 239

biosorption kinetics, single and multicomponent equilibria in conditions of perfect mixing. The design and scale-up of a biosorption unit requires a thorough understanding of complex mixtures of ions, their interaction with solid material and the mixing pattern involved. To plan for. organize and control the unit operations of modern waste water treatment technology, we must understand the factors which influence the performance of the bioadsorbers. Based on transport phenomena principles and conservation laws suitable mathematical models may be developed and used for process evaluation, simulation and optimization. Our experience in this field will be presented.

Biological Treatment of Waste Water Contaminated by Phenols and Heavy Metals

J. Pacaa and P. Kujan* UDepartment qf Fermentation Chemistry and Bioengineering, Facultr qf Food and Biochemical Technology ICT Prague, Technicka 5, 166 28 Prague 6, Czech Republic and hDepartment of Biogenesis and Biotechnology of Natural Products. Institute of Microbiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic

The inhibitory effect of several selected metals on the rate of phenol degradation under aerobic conditions was tested. The metals used were Cu, Ni, Zn. Cr, Cd and the mixture of Cu. Ni and Zn. The phenol degradation was carried out in a fed batch process under oxistat control. The kinetic of phenol degradation was described using specific rates of phenol and oxygen consumptions. Experiments proved two different levels of the inhibitory effect of heavy metals on the cell metabolism.

Heavy Metal Bioprecipitation by k&genes Eutrophus CH34 Immobilized in a Membrane Bioreactor

L. Diels”, S. Van Roy”, R. Leysen’ and M. Mergeay” “Environmental Technology!, hFunctional Material, Vlaamse Instelling voor Technologisch Onderzoek, VITO, Boeretang 200. B-2400 Mol. Belgium

The heavy metal resistant Alicaligenes eutrophus CH34 makes a supersaturated zone of metals around its cell. This is the result of a plasmid encoded cation/proton chemiosmotic efflux system. Together with the high metal concentration the pH increases due to the proton transport to the cytoplasm. Carbon dioxide produced by the cellular carbon metabolism is transformed in this pH gradient into carbonates which precipitate with the metal cations which are present in local concentrations higher than the solubility product. This crystallization starts at proteins, induced by some metals, and which function as nucleation sites (probably via carboxylic groups). This bioprecipitation process is used in a new membrane bioreactor concept to remove heavy metals from industrial waste waters. Metals like Cd. Zn. Cu, Co, Ni. Pb, Ge, Y, etc. could be removed.

Chromium Removal from Industrial Effluents Using Biopolymer Gel Beads

J. A. Teixeira and M. Manuela Aratijo Departamento de Engenharia Biologica. Universidade do Minho. Campus de Gualtar. 4709 Braga Codex

Biosorption of heavy metals from aqueous effluents is a remediation technology suitable for the treatment of high flow effluents with low metal concentrations. Metal removal from waste waters is made. traditionally using processes as precipitation. adsorption. electrochemical systems, ion

exchange and solvent extraction. Recently, the utilization of biopolymers such as alginates and carrageenans for metal removal has been a matter of great interest.

Liquid effluents with high contents of trivalent chromium are obtained in the tannery industries. due to the utilization of chromium during processing. As a consequence, it is important to develop mechanisms for an efficient removal of chromium from tannery industries effluents. In this work. results describing the removal of trivalent chromium from aqueous solutions using alginate gel beads are presented. Sorption isotherms as well as the effect of temperature and pH on the mechanisms of chromium removal are presented. The kinetics of sorption are also evaluated and a corresponding model is developed. Finally, a methodology for trivalent chromium removal with alginate is proposed. This method includes two steps: in the first one, chromium is removed by using it as an agent for alginate bead formation (for chromium concentrations above 300 mg-’ ); afterwards, the obtained solution is placed in contact with previously formed calcium alginate beads for removal of the remaining chromium.

Heavy Metal Biosorption by the Mycelium of Fusarium Flocciferum A. Delgado”, M. A. Barreirosb and J. M. Novak” “Laboratdrio de Engenharia Bioquimica, hstituto Superior Tecnico Avenida Rovisco Pais, 1096 Lisboa Codex, Portugal, and hInstituto de Tecnologias Ambientais, Institute National de Engenharia e Tecnologia Industrial, Azinhaga dos Lameiros 22, 1699 Lisboa Codes, Portugal

The biosorption capacity of dead biomass of Fusarium flocctferum was studied for Cu, Cd and Ni. It was verified that Langmuir isotherm describes well the biosorption of these metals, although copper had shown a more irregular behaviour. The metal/biomass affinity followed the order Cd > Ni > Cu. based on estimated Qmax. These values. expressed as mg metal/ 100mg biomass, are 20.4 for Cd, 5.2 for Ni and 2.3 for Cu.

The pH was found to be the most important factor: the removal capacity was shown to increase with pH, for ail ions. but the upper limit of working pH was limited by hydroxide precipitation. It was verified that the equilibrium was achieved within a few seconds, revealing the absence of diffusional barriers and the importance of surface components of fungal walls in the phenomenon. Biomass concentration also has a significant effect: biosorption markedly decreases as biomass concentration increases. Several treatments were tried in the preparation of the biomass (acids, bases, detergents and heat). The higher values were obtained with autoclaved and dried powdered mycelia. No significant differences were found for metal affinity in mycelia with incubation periods from 24 h to 4 days, but, older cultures (5-14 days) showed a decrease in the adsorption capacity.

Fusarium jloccijerum dried biomass seems to be adequate for the removal of valuable metals such as cadmium and nickel from industrial effluents. However, as the metal recovery and recycling is an imperious need for its industrial application, elution and biosorbent half-life period studies should be undertaken.

Cadmium Removal from Dilute Aqueous Solution by Beads of Polysaccharide Gels Usable for Microbial Cell Immobilization

P. Harel, L. Mignot and G.-A. Junter Microbial Technology Group, URA 500 CNRS and University of Rouen. bdtiment INSERM, 543, chemin de la Breteque, 76230 Bois-Guillaumr. France