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Bioprocess Engineering

, Volume 23, Issue 2, pp 135–141 | Cite as

pH effects on the removal of Cu2+, Cd2+ and Pb2+ from aqueous solution by waste brewery biomass

  • P. A. S. S. Marques
  • M. F. Rosa
  • H. M. Pinheiro

Abstract

An industrial strain of Saccharomyces cerevisiae collected from the waste of a brewing industry was used to remove lead, cadmium and copper from aqueous solutions (1 mm).

Metal removal efficiency by using either biomass suspension directly diluted into the metal solutions or biomass previously incubated and washed in distilled water was compared. In all experiments with unwashed biomass a shift in the medium pH from 4.5 to a final value in the 7.0–8.0 range occurred. This pH increase was responsible for a metal precipitation effect associated to the metal biosorption. A very different pH profile was observed when washed biomass was used leading to different removal profiles for Cd2+ and Pb2+ and a similar one for Cu2+. In the absence of biomass, medium components and/or the excreted intracellular products proved to interfere in the metal removal and to be responsible for 80% Pb2+ precipitation, in the pH 4.5–5.0 range.

To initial metal solution pH, leading to the lowest residual ion concentrations, after 96 h of contact with unwashed biomass and in the absence of pH adjustment, was 4.5–5.0. Continuous or stepwise adjustment of medium pH to this range during the process was unfavourable for metal removal, being the continuous adjustment the worst procedure. In this case, Cd2+ was not biosorbed and Cu2+ removal decreased from 76 to 33%. However, Pb2+ was always extensively removed (89%) and only slightly affected by pH control.

The global results suggest different removal mechanisms for each cation. Cu2+ was removed by both metal sorption and precipitation, due to the pH shift that occurred during the process, while Cd2+ removal showed to be completely dependent of this pH shift. Pb2+ was totally and quickly removed, by precipitation, in the presence of the biomass suspension and at pH 4.5.

Moreover, the biosorbent changes occurring during the process played an important role in the metal removal when non-viable microbial biomass is used.

Keywords

Biomass Microbial Biomass Biosorption Metal Removal Metal Solution 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • P. A. S. S. Marques
    • 1
  • M. F. Rosa
    • 1
  • H. M. Pinheiro
    • 2
  1. 1.Departamento de Energias Renováveis – Instituto Nacional de Engenharia e Tecnologia Industrial, Estrada do Paço do Lumiar, 1649-038 Lisboa, PortugalPT
  2. 2.Centro de Engenharia Biológica e Química – Instituto Superior Técnico, Av. Rovisco Pais, 1000 Lisboa, PortugalPT

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