pollutants; geography and shift in the diversity of microbes may compromise the
whole process of wastewater treatment (Chandra et al. 2011).
However, there is an increasing ecological issue concerning the discharge of
recalcitrant organic pollutants (ROPs) in industrial wastewaters because they are
resistant to biodegradation during the secondary (biological) treatment at CETP and
thus represent serious challenges to the sustainability of aquatic resources. For
instance, Bharagava et al. (2017b) have reported the presence of a variety of ROPs
such as benzyl chloride, butyl octyl phthalate (BOP), 2,6-dihydroxybenzoic acid
3TMS, dibutyl phthalate, benzyl alcohol, benzyl butyl phthalate (BBP), 4-chloro-3methyl phenol, phthalic acid, 2
0 6
0 -dihydroxyacetophenone, diisobutyl phthalate,
4-biphenyltrimethylsiloxane,
di-(À2ethy
hexyl)phthalate
(DEHP),
1,2-benzenedicarboxylic acid, dibenzyl phthalate (DBP), and nonylphenol (NP) in
TWW after secondary treatment process using gas chromatography-mass spectroscopy data analysis. The US Environmental Protection Agency (USEPA) listed these
chemical compounds as “priority pollutants” and banned their application in leather
production processes because they have been reported to cause endocrine disruption
and toxicity to aquatic organisms (Bharagava et al. 2017a). It has been reported that
the CETP is not working properly and wastewater discharge after secondary treatment does not meet the permissible limits as set by the Environment Protection
Agency. Hence, there is an urgent need to upgrade the existing CETP as per
requirement to adequately treat and detoxify the untreated TWW received from
tannery industries to prevent the pollution as well as safeguard the public health.
Microbes are oftenly used in the degradation and detoxification of TWW. For
instance, Kim et al. (2014) reported the 98.3% of COD and 88.5% of Cr removal
from TWW. Noorjahan (2014) reported 90% of COD, 90% of BOD, and 63.8% of
Cr removal from TWW using E. coli whereas 95.4% of COD and BOD and 73.5% of
Cr removal from TWW using Bacillus sp. Yusuf et al. (2013) reported 87.6% of
COD from TWW using B. subtilis whereas 85.2% of COD from TWW using
P. fragi. El-Bestawy et al. (2013) reported 79.16 of COD, 94.14 of BOD, and
93.66 of Cr from TWW using an optimized bacterial consortium containing
Escherichia coli O7:K1 CE10, Providencia vermicola W9B-11, Bacillus
sp. 58, Pseudomonas stutzeri M15–10-3, Bacillus amyloliquefaciens T004, and
Bacillus sp. PL47. Sivaprakasam et al. (2008) also reported 80% of COD removal
from TWW using a bacterial consortium (B. flexus, P. aeruginosa, S. aureus, and
E. homiense).
Further, the highly saline nature of TWW may create obstacles in the biotreatment
of TWW, which include as follows (Saxena et al. 2016; Sundarapandiyan et al.
2010; Sivaprakasam et al. 2008): (a) a high concentration of salts (>3–5% w/v)
makes the conventional bacterial culture less adaptive during the biotreatment of
TWW and thus a less effective treatment; (b) if adapted to high salt concentration, it
may get easily lost when conventional bacterial culture is grown in salt-free growth
medium, and (c) cellular disruption in the acclimatized bacterial culture due to even
slight changes in the salt concentration (ranging from 0.5 to 2% w/v) thus leads to
system failure. Further, the presence of high concentration of potentially toxic metals
such as Cr and less biodegradable tannins in TWW also inhibit its biotreatment
21 Progresses in Bioremediation Technologies for Industrial Waste. . .
533
whole process of wastewater treatment (Chandra et al. 2011).
However, there is an increasing ecological issue concerning the discharge of
recalcitrant organic pollutants (ROPs) in industrial wastewaters because they are
resistant to biodegradation during the secondary (biological) treatment at CETP and
thus represent serious challenges to the sustainability of aquatic resources. For
instance, Bharagava et al. (2017b) have reported the presence of a variety of ROPs
such as benzyl chloride, butyl octyl phthalate (BOP), 2,6-dihydroxybenzoic acid
3TMS, dibutyl phthalate, benzyl alcohol, benzyl butyl phthalate (BBP), 4-chloro-3methyl phenol, phthalic acid, 2
0 6
0 -dihydroxyacetophenone, diisobutyl phthalate,
4-biphenyltrimethylsiloxane,
di-(À2ethy
hexyl)phthalate
(DEHP),
1,2-benzenedicarboxylic acid, dibenzyl phthalate (DBP), and nonylphenol (NP) in
TWW after secondary treatment process using gas chromatography-mass spectroscopy data analysis. The US Environmental Protection Agency (USEPA) listed these
chemical compounds as “priority pollutants” and banned their application in leather
production processes because they have been reported to cause endocrine disruption
and toxicity to aquatic organisms (Bharagava et al. 2017a). It has been reported that
the CETP is not working properly and wastewater discharge after secondary treatment does not meet the permissible limits as set by the Environment Protection
Agency. Hence, there is an urgent need to upgrade the existing CETP as per
requirement to adequately treat and detoxify the untreated TWW received from
tannery industries to prevent the pollution as well as safeguard the public health.
Microbes are oftenly used in the degradation and detoxification of TWW. For
instance, Kim et al. (2014) reported the 98.3% of COD and 88.5% of Cr removal
from TWW. Noorjahan (2014) reported 90% of COD, 90% of BOD, and 63.8% of
Cr removal from TWW using E. coli whereas 95.4% of COD and BOD and 73.5% of
Cr removal from TWW using Bacillus sp. Yusuf et al. (2013) reported 87.6% of
COD from TWW using B. subtilis whereas 85.2% of COD from TWW using
P. fragi. El-Bestawy et al. (2013) reported 79.16 of COD, 94.14 of BOD, and
93.66 of Cr from TWW using an optimized bacterial consortium containing
Escherichia coli O7:K1 CE10, Providencia vermicola W9B-11, Bacillus
sp. 58, Pseudomonas stutzeri M15–10-3, Bacillus amyloliquefaciens T004, and
Bacillus sp. PL47. Sivaprakasam et al. (2008) also reported 80% of COD removal
from TWW using a bacterial consortium (B. flexus, P. aeruginosa, S. aureus, and
E. homiense).
Further, the highly saline nature of TWW may create obstacles in the biotreatment
of TWW, which include as follows (Saxena et al. 2016; Sundarapandiyan et al.
2010; Sivaprakasam et al. 2008): (a) a high concentration of salts (>3–5% w/v)
makes the conventional bacterial culture less adaptive during the biotreatment of
TWW and thus a less effective treatment; (b) if adapted to high salt concentration, it
may get easily lost when conventional bacterial culture is grown in salt-free growth
medium, and (c) cellular disruption in the acclimatized bacterial culture due to even
slight changes in the salt concentration (ranging from 0.5 to 2% w/v) thus leads to
system failure. Further, the presence of high concentration of potentially toxic metals
such as Cr and less biodegradable tannins in TWW also inhibit its biotreatment
21 Progresses in Bioremediation Technologies for Industrial Waste. . .
533