Bacterial Degradation of Azo Dye Containing Wastes - Microbial Degradation of Synthetic Dyes in Wastewaters - page 62

degradation by enzymes of bacteria. Immobilized bacterial cells, on furnace char-
coal in down lm bioreactor, were reported to enhance degradation of

dye manufacturing industrial ef

ow xed

uent (Sheth and Dave 2010 ).

2.4 Bacterial Degradation of Azo Dyes by Microbial Fuel
Cells (MFCs)

In recent years, interest in MFCs has increased tremendously, both in terms of
number of researchers as well as the applications of these systems. In a MFC,
microorganisms interact with electrodes using electrons, which are either removed
or supplied through an electrical circuit (Rabaey et al. 2006 ). MFCs are the major
type of bio-electrochemical systems (BESs), which convert biomass spontaneously
into electricity through the metabolic activity of the microorganisms. MFC is
considered to be a promising sustainable technology to meet increasing energy
needs, especially using wastewaters as substrates, which can generate electricity
and accomplish wastewater treatment simultaneously. Thus, it may balance the
operational costs of wastewater treatment plant (Lu et al. 2009 ). The use of bacterial
fuel cells for decolorization of azo dyes is an emerging research area. Bacterial fuel
cells are capable of producing energy and reducing dye color of textile wastewater
simultaneously. A new trend of bacterial fuel cells has emerged for enhancement of
decolorization and at the same time generating electricity from a readily degradable
organic carbon source. Sun et al. ( 2009 ) have studied decolorization of azo dye
Active Brilliant Red X3 using glucose as substrate, in which improvement of
decolorization activity was observed by MFCs along with electricity generation.
Thus, biodegradation of dyes by MFCs has opened new horizons in bioelectricity
and energy research.

3 Decolorization and Degradation of Textile Wastewater

Increasing industrialization and urbanization leads to environmental pollution.
Textile and dye manufacturing industries are major consumers of water and hence
potential sources for water pollution. The main recalcitrant component of textile
and dye industry ef

uent is dye along with a complex mixture of many polluting
substances ranging from organochlorine based waste pesticides to heavy metals.
Removal of dyes from ef uent has been given a top priority, because state and

federal agencies in the USA and all other developed countries all over the world,
have been requiring lower ef

uent color limits (<200 units of American Dye
Manufacturers Institute, ADMI) (Banat et al. 1996 ). Biological treatment of

industrial ef uent is economically viable and cost-effective. But the main problem

encountered is that dyes are highly resistant to bacterial degradation under