Biological decolourisation of wastewater from molasses fermentation by Trametes versicolor in an airlift reactor

Abstract

Continuous decolourisation of wastewater from molasses fermentation using mycelium of Trametes versicolor in pellets shape was performed in an airlift bioreactor (semi-pilot scale) with the aim of operating steadily for a long period, maintaining the colour removal activity. The influences of influent flow and glucose feed rate were tested. Induction of peroxidases secretion by Mn^{2 +} addition was also studied. The efficiency of the decolourisation process was followed by monitoring colour and enzymatic activities. The experimental results showed that continuous decolourisation in an airlift bioreactor can be considered a suitable alternative for treating molasses fermentation wastewater. A colour removal yield around 60% remained practically constant during 23 days under continuous operation. Laccase was found to be the main enzyme secreted by the strain, being responsible for the decolourisation process. Mn^{2 +} addition was not likely to induct manganese-dependent peroxidase secretion.

Keywords:

• Airlift bioreactors
• enzyme biocatalysis
• molasses
• submerged culture
• wastewater treatment
• white-rot fungi

Acknowledgments

This work has been supported by Ministerio de Ciencia y Tecnología of the Spanish government (CICYT project AMB99-0940) and the sugar company Azucarera Ebro S.L. Soc. Unipersonal.