References

63

application of double-layered immobilized enzymes in a vertical bioreactor system

[40]. Despite the unusual degradation properties of peroxidases, the commercial-

ization of enzyme treatment for industrial wastewater treatment is often hindered

by the lack of long-term stability in service and storage, as well as the inability to

recover and reuse enzymes. Recent years have centered attention on the immobiliza-

tion of peroxidases in order to solve the free enzyme disadvantages. Immobilization

enhances the enzyme’s stability toward high temperature and high pH and renders

the enzyme less susceptible to inhibitors. This justifies the widespread deployment

of immobilized peroxidases in applications for wastewater treatment.

4.5

Conclusion

Since ages and until today, no single, environmentally benign, and economically

feasible process has been established that can effectively treat dye-rich wastewater

for reuse, and it has been a major challenge. Different physical and chemical

approaches have been used, and these approaches typically have several drawbacks,

such as secondary waste generation, high costs, poor performance, and insufficient

resources. On the other hand, for dye effluent treatment, bioremediation is an

eco-friendly, effective, inexpensive, and biologically benign technique. The use of

bacteria, fungi, algae, yeast, and plants has shown that they are capable of detoxi-

fying different dyes. In addition, because of its fast growth rate and high hydraulic

retention time, microbial degradation does not create a significant amount of sludge

and may be very successful in the treatment of high-strength organic wastewater. In

this respect, it may be of added benefit to the use of genetically modified organisms

to increase the process efficiency of degradation. Another significant factor is

the convergence of innovations, which may bring future benefits. Integration of

different degradation methods is yet another significant aspect, which may bring

potential benefits. In order to disclose the desirable mechanism of dye degradation,

more information on the biochemistry of degradation is needed. Attempts should be

made to develop and apply these methods of treatment for bacterial decolorization

in real industrial discharges, based on favorable laboratory conclusions. The com-

bination of biochemistry and molecular biology, together with recent proteomics

and genomics studies, has the potential to increase the bacterial degradation of

wastewater containing azo dye.

References

1 Gomes, R., Bras, M., Ferra, M. et al. (2000). Biological treatment of effluent

containing textile dyes. Coloration Technology 116 (12): 393–397.

2 Rai, H., Bhattacharya, M., and Singh, J. (2005). Removal of dyes from the

effluent of textile and dyestuff manufacturing industry: a review of emerging

techniques with reference to biological treatment. Critical Reviews in Environ-

mental Science and Technology 35 (3): 219.