Chromium uptake from aqueous effluents by immobilized Baker's yeast

Utilização de leveduras de panificação na remoção de cromo em meio aquoso

Abstracts

Baker’s yeast immobilized in alginate was used to take up chromium from effluents. Chromium in aqueous solutions were used in different concentrations. To evaluate the viability and efficiency the baker’s yeast for chromium uptake from effluents three experiments done in two differents reactor systems: first in system 1 at 17.5 ml/s and with 10, 20, 25 and 30 mg/l Cr; second in system 2 at 38.7 ml/s with 20 mg/l Cr; third in system 2.1 at 6.65 ml/s and with 20, 30 and 40 mg/l Cr. The efficiency of chromium uptake varied between 86 and 100 %.

Baker’s yeast; chromium; uptake

CHROMIUM UPTAKE FROM AQUEOUS EFFLUENTS BY IMMOBILIZED BAKER’S YEAST

Lucia Beckmann C. Menezes^* , Vera Nobre Braz, Carlos Alberto M. Cordeiro

Departamento de Engenharia Química, Centro Tecnológico, Universidade Federal do Pará, Campus Universitário, Belém, PA, Brasil. Submitted: April 21, 1997; Returned to authors for corrections: May 05, 1997;

Approved: September 19, 1998 SHORT COMMUNICATION

Key words: Baker’s yeast, chromium, uptake

Commercial pressed baker’s yeast (Itaiquara) was immobilized in spherical globules of sodium alginate (15 mg/l) containing glucose, according to the conventional methodology (2). Chromium solutions were prepared by using chromium chlorine in different concentrations from 10 to 40 mg/l of water. These different reactor systems were used: in system 1 a glass tubular reactor (h = 100 cm; d = 4 cm) and layer size of 35 cm were used, with a flow rate of 17.55 ml/s; in system 2, the tubular reactor was modified (h = 102 cm ; d = 11 cm), with a layer size of 25 cm and flow rate of 38.7 ml/s. In system 2.1, a flow rate of 6.65 ml/s was used. The process consisted of repassing 5 liters of chromium chlorine solution in different concentrations through the reactor system, collecting samples at 30 min intervals for posterior analysis. Experiments 1 to 4 were done in system 1 (10, 20, 25 and 30 mg/l Cr), experiment 5 in system 2 (20 mg/l Cr) and experiment 6, 7 and 8 in system 2.1 (20, 30 anf 40 mg/l). The collected samples were preserved adjusting pH to < 2 with nitric acid and were analyzed by atomic absorption spectroscopy (1).

In most of the experiments, modifications in color and odor of the recycled solutions and of the immobilized cells were noted. There were also viscosity and pH increases in the recycled solutions and these changes may have occurred when the immobilized yeasts began to decompose.

In all experiments, the reduction of the metal concentration in solution occurred with larger intensity in the initial stages. In experiment 4 (system 1, 30 mg/l Cr), an increase occurred in the metal concentration at the end of the process, probably because microbial adsorption capacity had been exhausted and the metal was released back into the medium. Results in system 2 were similar to system 1. In experiments 6, 7 and 8 (system 2.1), lower flow rates (6.65 ml/s) were used and resulted in better efficiency.

In experiment 1 (system 1), most of the reduction occurred in the first hour, from 10 mg/l to 1 mg/l, going to zero in 2 hours. In experiment 2, during 30 min, reduction occurred from 20 mg/l to 7.38 mg/l, attaining 2.76 mg/l in 2.5 hours. The efficiencies were 100% and 86.73% respectively. In experiment 3, after 5.5 hours, a reduction from 25 mg/l to 2.0 mg/l, occurred with efficiency of 92%. In experiment 4, a reduction from 30 mg/l to 2.51 mg/l in 7.5 hours, with an efficiency of 91.6% was observed (Fig. 1).

Figure 1
- Uptake of chromium from effluents by baker’s yeast immobilized in alginate in a 4 cm diameter by 100 cm tubular glass reactor, layer size of 35 cm and flow rate of 17.55 ml/s.

Fig. 2 shows that in experiment 5 (system 2), reduction of chromium content from 20 mg/l to 2.1 mg/l in 5 hours, with efficiency of 88.65% was observed. The experiments conducted with 6.65 ml/s flow rate (system 2.1) had 100% in chromium removal efficiency and the experiment 7 (initial concentration = 30 mg/l), showed no reduction of chromium content in some cases, as showed in Fig. 2.

Figure 2
- Uptake of chromium from effluents by baker’s yeast immobilized in alginate in a 11 cm diameter by 102 cm tubular glass reactor, layer size of 25 cm and flow rate of 6.65 ml/s. Experiments 6 to 8 in system 2.1.

In this kind of process, there are many interfering variables and on these we have studied changes metal solution circulation flow, reactor size, immobilized cells layer size and metal solution concentration.

The removal efficiency obtained was from 86.73 to 100%. System 2.1 presented the most efficiency and the shortest process time, 100% in 1.5 hour, but system 1, starting with 10 mg/l chromium concentration, also showed 100% of retention efficiency within 2 hours. It is possible to remove heavy metals from aqueous solutions using immobilized cells of baker’s yeast in a fixed layer reactor.

RESUMO

Utilização de leveduras de panificação na remoção de cromo em meio aquoso

Leveduras de panificação imobilizadas em alginato, foram utilizadas com o objetivo de promover a remoção de cromo presente em efluentes. Trabalhou-se com soluções de cromo de diferentes concentrações. A fim de avaliar a viabilidade e eficiência do uso de leveduras de panificação na remoção de cromo, três experimentos foram realizados em dois diferentes sistemas de reatores: o primeiro no sistema 1 com 17,5 ml/s e 10, 20, 25 e 30 mg/l Cr; o segundo no sistema 2 com 38,7 ml/s e 20 mg/l Cr; o terceiro no sistema 2.1 com 6,65 ml/s e 20, 30 e 40 mg/l Cr. A média das eficiências de retenção do cromo variaram entre 86 e 100%.

Palavras-chave: leveduras de panificação, cromo, remoção

REFERENCES

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4. Costa, A.C.A.; Teles, E.M.; Leite, S.G.F. Accumulation of cadmium from moderately concentrated cadmium solutions by Chlorella and Scenedesmus strains. Rev. Microbiol., 25: 1, 42-45, 1994.

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7. Ibbotson, P.G.; Speding, P.L.; Otterburn, M. Effects of metal ion concentration on a biological reactor. Biotechnol. Bioeng., 36: 685-69, 1990.

8. Jang, L.K. Lopez, S.L.; Eastman, S.L. ; Pryfogie, P.; Recovery of Cooper and Cobalt biopolymer gels. Biotechnol. Bioeng., 37: 3, 266 - 273, 1991.

9. Luef, E.; Prey, T.; Kubicek, C.P. Biosorption of zinc by fungal micelial wastes. Appl. Microbiol. Biotechnol., 14: 688-692, 1991.

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12. .Pelczar Jr., M.R.; Chan, E.C.S.; Krieg, N.R. Microbiology concepts and applications. New York:: Mc Graw-Hill Inc., 1993. 988 p.

13. Spinti, M.; Zhuang, H.; Trujillo, E.M. Evaluation of immobilized biomass beads for removing heavy metals from wastewaters. Water Environ. Research, 67: 6, 943-952, 1995

14. Ting, Y.P.; Lawson, F.; Prince, I.G. Uptake of Cadmium and Zinc by the alga Chlorella vulgaris. Biotechnol. Bioeng., 37: 5, 445-455, 1991.

• ¹
  American Public Health Association. Standard methods for the examination of water and wastewater. 18 edition. Washington: APHA, 1990. 1100 p.
• ²
  Borzani, W. Métodos analíticos para o acompanhamento da fermentação alcoólica São Caetano do Sul: Instituto Mauá de Tecnologia, 1989. 42 p.
• ³
  Chen, C.; Dale, M.C.; Okos, M.R. Minimal nutritional requirements for immobilized yeast. Biotechnol. Bioeng., 36: 993-1001, 1990.
• ⁴
  Costa, A.C.A.; Teles, E.M.; Leite, S.G.F. Accumulation of cadmium from moderately concentrated cadmium solutions by Chlorella and Scenedesmus strains. Rev. Microbiol., 25: 1, 42-45, 1994.
• ⁵
  Gaudy Jr., A.F.; Gaudy, E.T. Elements of bioenvironmental engineering. California: Eng. Press, 1988. 592 p.
• ⁶
  Gourdon, R.; Rus, E. ; Shubhangi, B. ; Sofer, S.S. Mechanism of cadmium uptake by activated sludge. Appl. Microbiol Biotechnol.., 34: 274-278, 1990.
• ⁷
  Ibbotson, P.G.; Speding, P.L.; Otterburn, M. Effects of metal ion concentration on a biological reactor. Biotechnol. Bioeng., 36: 685-69, 1990.
• ⁸
  Jang, L.K. Lopez, S.L.; Eastman, S.L. ; Pryfogie, P.; Recovery of Cooper and Cobalt biopolymer gels. Biotechnol. Bioeng, 37: 3, 266 - 273, 1991.
• ⁹
  Luef, E.; Prey, T.; Kubicek, C.P. Biosorption of zinc by fungal micelial wastes. Appl. Microbiol. Biotechnol., 14: 688-692, 1991.
• ¹⁰
  Macaskie, L.E. An immobilized cell bioprocess for the removal of heavy metals aqueous flow. J. Chem. Technol. Biotechnol., 49: 4, 357 - 377, 1990.
• ¹¹
  Nakajima, A.; Sakaguchi, T. Selective accumulation of heavy metals by microorganisms. Appl. Microbiol. Biotechnol, 24: 59-64, 1986.
• ¹²
  .Pelczar Jr., M.R.; Chan, E.C.S.; Krieg, N.R. Microbiology concepts and applications. New York:: Mc Graw-Hill Inc., 1993. 988 p.
• ¹³
  Spinti, M.; Zhuang, H.; Trujillo, E.M. Evaluation of immobilized biomass beads for removing heavy metals from wastewaters. Water Environ. Research, 67: 6, 943-952, 1995
• ¹⁴
  Ting, Y.P.; Lawson, F.; Prince, I.G. Uptake of Cadmium and Zinc by the alga Chlorella vulgaris Biotechnol. Bioeng., 37: 5, 445-455, 1991.

Publication Dates

• Publication in this collection
  27 May 1999
• Date of issue
  Oct 1998

History

• Accepted
  19 Sept 1998
• Reviewed
  05 May 1997
• Received
  21 Apr 1997