360
S. H. Das et al.
Keywords Resorcinol · Heavy metals · Biodegradation · Response surface
methodology
1 Introduction
Aromatic compounds are abundant in nature and have profound effect on environment. Among various aromatic compounds, phenolic compounds like phenol, cresol,
resorcinol, etc. are present in the effluents of various industries including petrochemicals, coal coking, coal gasification, tanneries, etc. (Nasr et al. 2007). To maintain
ecological balance, it is essential to reduce the concentrations of the above-mentioned
pollutants to acceptable level. Industrial effluent consists not only of resorcinol but
also significant quantity of toxic heavy metals (Tüfekci et al. 2007). Hence, it is
necessary to check the removal of resorcinol by mixed bacterial culture in presence
of heavy metals. Present study deals with the removal of resorcinol in the presence of
different toxic heavy metals such as Mercury (Hg), Lead (Pb), and Chromium (VI)
in concentrations of 5 ppm, 25 ppm, and 50 ppm by a mixed bacterial culture isolated
from the soil of the outer limit of a tannery effluent discharge. Biodegradation usually
involves the complete mineralization of the starting compound to simpler ones like
CO 2 , H 2 O, NO 3
− , and other inorganic compounds. Moreover, it has the advantages of
being economic, eco-friendly and can be easily operated and scaled up (Chakraborty
2016). Chemical methods include stripping, solvent extraction, chemical oxidation,
and coagulation. Though these methods are quite effective in removing pollutants
from industrial effluent but are expensive and often cause disposal problem of toxic
sludge generated. The chemicals used in the process may also cause secondary pollution problem. Physical method such as adsorption by activated charcoal could yield
various toxic intermediates (Laura et al. 2016). While biodegradation does not suffer
from the above-mentioned restrictions of the physicochemical methods, literature
review shows that there are a limited number of microorganisms, especially bacteria,
with the capability of aerobic degradation of resorcinol.
It has been observed that bacteria consortium is always more effective in removing
various organic pollutants as compared to a pure strain. In a mixed culture, one
microorganism may produce needed growth factors beneficial to a second microorganism. It may alter the pH of the medium, thereby improving the activity of one or
more enzymes needed for biodegradation of the pollutant. Mixed cultures are able to
bring about multistep transformations that would be impossible for a single microorganism. If the environmental conditions are maintained, it is easy to grow a mixed
culture indefinitely and carry out repeated subculturing (Das and Chandran 2011).
S. H. Das et al.
Keywords Resorcinol · Heavy metals · Biodegradation · Response surface
methodology
1 Introduction
Aromatic compounds are abundant in nature and have profound effect on environment. Among various aromatic compounds, phenolic compounds like phenol, cresol,
resorcinol, etc. are present in the effluents of various industries including petrochemicals, coal coking, coal gasification, tanneries, etc. (Nasr et al. 2007). To maintain
ecological balance, it is essential to reduce the concentrations of the above-mentioned
pollutants to acceptable level. Industrial effluent consists not only of resorcinol but
also significant quantity of toxic heavy metals (Tüfekci et al. 2007). Hence, it is
necessary to check the removal of resorcinol by mixed bacterial culture in presence
of heavy metals. Present study deals with the removal of resorcinol in the presence of
different toxic heavy metals such as Mercury (Hg), Lead (Pb), and Chromium (VI)
in concentrations of 5 ppm, 25 ppm, and 50 ppm by a mixed bacterial culture isolated
from the soil of the outer limit of a tannery effluent discharge. Biodegradation usually
involves the complete mineralization of the starting compound to simpler ones like
CO 2 , H 2 O, NO 3
− , and other inorganic compounds. Moreover, it has the advantages of
being economic, eco-friendly and can be easily operated and scaled up (Chakraborty
2016). Chemical methods include stripping, solvent extraction, chemical oxidation,
and coagulation. Though these methods are quite effective in removing pollutants
from industrial effluent but are expensive and often cause disposal problem of toxic
sludge generated. The chemicals used in the process may also cause secondary pollution problem. Physical method such as adsorption by activated charcoal could yield
various toxic intermediates (Laura et al. 2016). While biodegradation does not suffer
from the above-mentioned restrictions of the physicochemical methods, literature
review shows that there are a limited number of microorganisms, especially bacteria,
with the capability of aerobic degradation of resorcinol.
It has been observed that bacteria consortium is always more effective in removing
various organic pollutants as compared to a pure strain. In a mixed culture, one
microorganism may produce needed growth factors beneficial to a second microorganism. It may alter the pH of the medium, thereby improving the activity of one or
more enzymes needed for biodegradation of the pollutant. Mixed cultures are able to
bring about multistep transformations that would be impossible for a single microorganism. If the environmental conditions are maintained, it is easy to grow a mixed
culture indefinitely and carry out repeated subculturing (Das and Chandran 2011).