Many bacteria such as Staphylococcus arlettae (Elisangela et al. 2009); fungi
such as Trametes pubescens, Pleurotus ostreatus (Casieri et al. 2008), Aspergillus
niger, Fusarium oxysporum, and Fusarium oxysporum (Shahid et al. 2013); and
algae such as Chlorella vulgaris, Elkatothrix viridis, and Volvox aureus (El-Sheekh
et al. 2009) were isolated and studied by many researchers for their potential in the
bioremediation of dyes. These studies reinforced the potential of microorganisms as
efficient and ecofriendly organisms for the removal of dyes from industrial effluents.
3.1 Bacteria
Bioremediation of industrial dye effluents is carried out using various microorganisms such as bacteria, fungi, and algae. Different organisms follow different mechanisms in dye removal. Bacteria are found to be very efficient in the removal of dyes
from industrial effluents due to their size and their ability to grow in different
environmental conditions. The bacterial surface is made up of various functional
groups such as carboxyl, phosphate, amine, hydroxyl, etc. These groups facilitate the
biosorption of metal complex dyes from the industrial effluents. For example,
the negative charge of carboxyl groups present on the bacterial cell wall can bind
positive dye ions through electrostatic interactions. In general increasing the pH
increases the negative charge on the cell wall due to deprotonation and favors the
adsorption of positive metals and other dye complexes. Similarly decreasing pH
below 7 protonates the cell wall surface and increases the positive charge on the cell
wall and favors the adsorption of negative metals and other dye complexes. Solution
pH may also alter the dyes, and hydrolysis reactions can take place.
Biological techniques are simple to design and economical to operate; thus, they
have become one of the highly focused technologies for dye removal. Bioremediation using microorganisms involves the microbial degradation and enzymatic
removal of dyes. Many bacteria were identified as potential and economic dye
removal components. Some of the important bacteria used in the bioremediation
of textile dyes are tabulated in Table 9.1.
3.2 Fungi
Fungi are available in high quantities due to its ability to adapt to any type of
ecosystem and grow easily under various environments. It is recognized as potential
microorganism for dye removal from industrial effluents. Both naturally occurring
fungi and genetically modified fungi are reported to be efficient in bioremediation
process. Fungi contain various extracellular proteins, organic acids, and other
metabolites. Fungal surface primarily consists of carboxyl, amino, phosphate,
hydroxyl, and sulfhydryl groups on the cell wall surface. These functional groups
are responsible for the binding of various dyes on the cell wall through electrostatic
9 Removal of Dyes From Industrial Effluents Using Bioremediation Technique
177
such as Trametes pubescens, Pleurotus ostreatus (Casieri et al. 2008), Aspergillus
niger, Fusarium oxysporum, and Fusarium oxysporum (Shahid et al. 2013); and
algae such as Chlorella vulgaris, Elkatothrix viridis, and Volvox aureus (El-Sheekh
et al. 2009) were isolated and studied by many researchers for their potential in the
bioremediation of dyes. These studies reinforced the potential of microorganisms as
efficient and ecofriendly organisms for the removal of dyes from industrial effluents.
3.1 Bacteria
Bioremediation of industrial dye effluents is carried out using various microorganisms such as bacteria, fungi, and algae. Different organisms follow different mechanisms in dye removal. Bacteria are found to be very efficient in the removal of dyes
from industrial effluents due to their size and their ability to grow in different
environmental conditions. The bacterial surface is made up of various functional
groups such as carboxyl, phosphate, amine, hydroxyl, etc. These groups facilitate the
biosorption of metal complex dyes from the industrial effluents. For example,
the negative charge of carboxyl groups present on the bacterial cell wall can bind
positive dye ions through electrostatic interactions. In general increasing the pH
increases the negative charge on the cell wall due to deprotonation and favors the
adsorption of positive metals and other dye complexes. Similarly decreasing pH
below 7 protonates the cell wall surface and increases the positive charge on the cell
wall and favors the adsorption of negative metals and other dye complexes. Solution
pH may also alter the dyes, and hydrolysis reactions can take place.
Biological techniques are simple to design and economical to operate; thus, they
have become one of the highly focused technologies for dye removal. Bioremediation using microorganisms involves the microbial degradation and enzymatic
removal of dyes. Many bacteria were identified as potential and economic dye
removal components. Some of the important bacteria used in the bioremediation
of textile dyes are tabulated in Table 9.1.
3.2 Fungi
Fungi are available in high quantities due to its ability to adapt to any type of
ecosystem and grow easily under various environments. It is recognized as potential
microorganism for dye removal from industrial effluents. Both naturally occurring
fungi and genetically modified fungi are reported to be efficient in bioremediation
process. Fungi contain various extracellular proteins, organic acids, and other
metabolites. Fungal surface primarily consists of carboxyl, amino, phosphate,
hydroxyl, and sulfhydryl groups on the cell wall surface. These functional groups
are responsible for the binding of various dyes on the cell wall through electrostatic
9 Removal of Dyes From Industrial Effluents Using Bioremediation Technique
177