sometimes leads to death (Saha et al. 2010; Ghosh and Das 2014). Lead exposure
may lead to severe kidney failure and nervous system failure and may damage the
reproductive system (Wu et al. 2014).
Synthetic dyes used in the textile industry are highly colored, stable, and designed
to resist the effects of laundering and sunshine. Dye-containing effluents are generally treated using conventional physicochemical methods such as ion exchange,
membrane separation, osmosis, adsorption, coagulation, flocculation, etc. Most of
these methods involve high cost of operation, low efficiency, and limited versatility
and produce large quantities of sludge and create disposal problems (Saibaba and
King 2013a; Priya and Nagan 2015). Thus, the development of efficient, simple,
easy to use, economical, and environmental-friendly technologies for dye removal is
of utmost importance. Over the past few decades, dye removal using bioremediation
has been gaining importance. In bioremediation microorganisms remove the dyes
from effluents through various processes such as biotransformation, biodegradation,
biosorption, etc. Bioremediation methods are relatively inexpensive and efficient
and offer a wide choice in the use of microorganisms. Bioremediation can be used
for complete removal of dyes; these methods produce less sludge, and more importantly, these methods are ecofriendly.
2 Bioremediation
Textile dyes are one of the major pollutants discharged into the water bodies.
These dyes are very harmful to humans and other flora and fauna living on the
earth. The presence of dyes, even in very small concentrations, gives bright color to
the water and makes them unusable (Saibaba and King 2013b). Even as low as
1 ppm concentration of synthetic dye gives a bright color and makes the water
unaesthetic. But the textile industry effluents contain very high concentrations of
dyes ranging 10 ppm to 200 ppm. Industrial dye effluents contain significant
amounts of suspended solids, BOD/COD ratio from 0.2 to 0.5, and high fluctuations
in pH, temperature, and salinity and affect the environment adversely. Hence, these
effluents need to be treated before they are discharged into the environment for
environmental protection and sustainability. Most of the dyes are brightly colored,
soluble in water, reactive, and very difficult to treat by conventional water treatment
methods. However, most of the dyes, metals, and other organic materials can be
degraded by biological methods. Biological methods are ecofriendly and produce
good results for dye removal processes. Large number of bacteria, fungi, and algae
are found to be effective for the removal of dyes by bioremediation methods.
Bioremediation is a process in which organic and inorganic pollutants are
degraded or transformed into less toxic components through biological processes
(Mueller et al. 1996). In bioremediation, toxic components are detoxified or
degraded to less toxic components by intracellular accumulation or by enzymatic
reactions. In bioremediation, both living and nonliving biomass can be used. Bioremediation is very effective for the removal of pollutants from the different
9 Removal of Dyes From Industrial Effluents Using Bioremediation Technique
175
may lead to severe kidney failure and nervous system failure and may damage the
reproductive system (Wu et al. 2014).
Synthetic dyes used in the textile industry are highly colored, stable, and designed
to resist the effects of laundering and sunshine. Dye-containing effluents are generally treated using conventional physicochemical methods such as ion exchange,
membrane separation, osmosis, adsorption, coagulation, flocculation, etc. Most of
these methods involve high cost of operation, low efficiency, and limited versatility
and produce large quantities of sludge and create disposal problems (Saibaba and
King 2013a; Priya and Nagan 2015). Thus, the development of efficient, simple,
easy to use, economical, and environmental-friendly technologies for dye removal is
of utmost importance. Over the past few decades, dye removal using bioremediation
has been gaining importance. In bioremediation microorganisms remove the dyes
from effluents through various processes such as biotransformation, biodegradation,
biosorption, etc. Bioremediation methods are relatively inexpensive and efficient
and offer a wide choice in the use of microorganisms. Bioremediation can be used
for complete removal of dyes; these methods produce less sludge, and more importantly, these methods are ecofriendly.
2 Bioremediation
Textile dyes are one of the major pollutants discharged into the water bodies.
These dyes are very harmful to humans and other flora and fauna living on the
earth. The presence of dyes, even in very small concentrations, gives bright color to
the water and makes them unusable (Saibaba and King 2013b). Even as low as
1 ppm concentration of synthetic dye gives a bright color and makes the water
unaesthetic. But the textile industry effluents contain very high concentrations of
dyes ranging 10 ppm to 200 ppm. Industrial dye effluents contain significant
amounts of suspended solids, BOD/COD ratio from 0.2 to 0.5, and high fluctuations
in pH, temperature, and salinity and affect the environment adversely. Hence, these
effluents need to be treated before they are discharged into the environment for
environmental protection and sustainability. Most of the dyes are brightly colored,
soluble in water, reactive, and very difficult to treat by conventional water treatment
methods. However, most of the dyes, metals, and other organic materials can be
degraded by biological methods. Biological methods are ecofriendly and produce
good results for dye removal processes. Large number of bacteria, fungi, and algae
are found to be effective for the removal of dyes by bioremediation methods.
Bioremediation is a process in which organic and inorganic pollutants are
degraded or transformed into less toxic components through biological processes
(Mueller et al. 1996). In bioremediation, toxic components are detoxified or
degraded to less toxic components by intracellular accumulation or by enzymatic
reactions. In bioremediation, both living and nonliving biomass can be used. Bioremediation is very effective for the removal of pollutants from the different
9 Removal of Dyes From Industrial Effluents Using Bioremediation Technique
175