4.7 Biostimulation
Biostimulation and bioaugmentation are very important strategies in executing the
bioremediation process. Biostimulation is the process in which microbial growthstimulating agents such as electron acceptors, nutrients, etc. are added to the
contaminated site to enhance the growth of existing microbial population, whereas
in bioaugmentation microorganisms are added to the contaminated site to enhance
microbial degradation process (Dedyukhina and Eroshin 1991). In biostimulation,
the addition of nutrients such as glucose as carbon and energy source for the removal
of dyes stimulates the production of enzymes for the co-metabolism of glucose and
enhances the dye removal process (Semrany et al. 2012).
5 Issues Related to Bioremediation
In spite of bioremediation is simple, easy, efficient, and economical technique for the
removal of dyes from industrial effluents, it has not been used widely in large-scale
industrial applications. The constraints associated with bioremediation technique in
dye removal need to be addressed for its use in large-scale applications. One of the
main problems restricting the use of bioremediation in large-scale applications is the
use of live microorganisms. Living organisms require nutrients for their continuous
growth and function. Microorganisms need both micro- and macronutrients such as
carbon (C), hydrogen (H), nitrogen (N), sulfur (S), phosphorous (P), potassium (K),
copper, cobalt, zinc, iron, etc. A phototropic alga gets CO 2 directly from the air and
does not require any additional supply of nutrients. Various types of microorganisms, such as bacteria, fungi, and algae, are used in bioremediation, and they require
different nutrients for their growth. The use of large quantities of nutrients and
various types of nutrients restrict the use in large-scale applications due to economic
constraints. Economical and nutrient-rich medium is to be developed for its use in
large-scale applications. Abundantly and cheaply available plant, animal, and waste
medium are a good option for this purpose.
Continuous monitoring and controlling of bioremediation process in large-scale
industrial applications is very difficult and depends on many factors such as soil
type, temperature and pH of the medium, oxygen availability, nutrient availability,
microbial population, electron availability, etc. (Khan et al. 1997). Furthermore,
most of the studies conducted on bioremediation were carried in a laboratory under
sterile conditions. But industrial effluents are highly complex and contain a mixture
of various pollutants like metals, dyes, phenols, etc., and physical conditions
maintained in mixed cultures may not be suitable for all organisms. Hence, highly
resistant microorganisms are needed to be isolated and can be used for bioremediation of industrial effluents. Isolated microorganisms are expected to give better
results compared to mixed cultures. However, using pure cultures for bioremediation
may not be economical; therefore, there is a need to develop and use the indigenous
9 Removal of Dyes From Industrial Effluents Using Bioremediation Technique
187
Biostimulation and bioaugmentation are very important strategies in executing the
bioremediation process. Biostimulation is the process in which microbial growthstimulating agents such as electron acceptors, nutrients, etc. are added to the
contaminated site to enhance the growth of existing microbial population, whereas
in bioaugmentation microorganisms are added to the contaminated site to enhance
microbial degradation process (Dedyukhina and Eroshin 1991). In biostimulation,
the addition of nutrients such as glucose as carbon and energy source for the removal
of dyes stimulates the production of enzymes for the co-metabolism of glucose and
enhances the dye removal process (Semrany et al. 2012).
5 Issues Related to Bioremediation
In spite of bioremediation is simple, easy, efficient, and economical technique for the
removal of dyes from industrial effluents, it has not been used widely in large-scale
industrial applications. The constraints associated with bioremediation technique in
dye removal need to be addressed for its use in large-scale applications. One of the
main problems restricting the use of bioremediation in large-scale applications is the
use of live microorganisms. Living organisms require nutrients for their continuous
growth and function. Microorganisms need both micro- and macronutrients such as
carbon (C), hydrogen (H), nitrogen (N), sulfur (S), phosphorous (P), potassium (K),
copper, cobalt, zinc, iron, etc. A phototropic alga gets CO 2 directly from the air and
does not require any additional supply of nutrients. Various types of microorganisms, such as bacteria, fungi, and algae, are used in bioremediation, and they require
different nutrients for their growth. The use of large quantities of nutrients and
various types of nutrients restrict the use in large-scale applications due to economic
constraints. Economical and nutrient-rich medium is to be developed for its use in
large-scale applications. Abundantly and cheaply available plant, animal, and waste
medium are a good option for this purpose.
Continuous monitoring and controlling of bioremediation process in large-scale
industrial applications is very difficult and depends on many factors such as soil
type, temperature and pH of the medium, oxygen availability, nutrient availability,
microbial population, electron availability, etc. (Khan et al. 1997). Furthermore,
most of the studies conducted on bioremediation were carried in a laboratory under
sterile conditions. But industrial effluents are highly complex and contain a mixture
of various pollutants like metals, dyes, phenols, etc., and physical conditions
maintained in mixed cultures may not be suitable for all organisms. Hence, highly
resistant microorganisms are needed to be isolated and can be used for bioremediation of industrial effluents. Isolated microorganisms are expected to give better
results compared to mixed cultures. However, using pure cultures for bioremediation
may not be economical; therefore, there is a need to develop and use the indigenous
9 Removal of Dyes From Industrial Effluents Using Bioremediation Technique
187