with nZVI (100 mg) under anaerobic condition in 15 ml glass test tube. After
20 days, PH-07 strain was added in reaction mixture and incubated for 4 days.
The sequential system was found to be effective for degradation of deca-BDE
showing reduction up to 67%. The debrominated products were further treated
with PH-07 strain to study their mineralization. He et al. (2009) also reported
sequential treatment of 2, 2
0 4, 5, 5
0 -pentachlorobiphenyl with an anaerobic nZVI
reaction and successive aerobic transformation with bacterium H1.
4.2 Concurrent/Combined Method
In a microcosm study, Xiu et al. (2010a) investigated the effect of nZVI on
dechlorinating microorganism using trichloroethylene (TCE) as model compound.
For experiments, 100 mg of nZVI (1 g/L) and 4 ml of inoculation culture
(Dehalococcoides spp.) along with mineral salt medium were added simultaneously
in reaction vials containing TCE (20 g/L). The reaction mixture was then put over
shaker at 200 rpm. Two other experiments were also carried out under similar
conditions, one with nZVI alone and another with Dehalococcoides spp. only.
Initially, nZVI was observed to inhibit microbial dechlorination, but later on it was
found to have biostimulatory effect on dechlorinating bacteria which in turn could
enhance the overall rate of contaminant degradation. The reason ascribed to this was
the hydrogen which is evolved from nZVI during cathodic corrosion can be utilized
as electron donor by dechlorinating bacteria. In another combined study, nanoparticle (nFe
0 /Pd) was coated with a polymer (carboxymethyl cellulose, CMC) to avoid
direct contact of nanoparticle with bacterial cells, as their direct contact inhibits the
growth of bacteria cells (Singh et al. 2013). The study demonstrated degradation of
γ-HCH in individual and combined system of CMC-Pd/Fe
0 and Sphingomonas
strain NM05. The results revealed that γ-HCH degradation efficiency in combined
system was 1.7–2.1 times greater as compared to system containing either NM05
strain or CMC-Pd/nFe
0 alone.
5 Conclusion
Integration of nanoremediation with bioremediation either sequentially or concurrently appears to be a feasible alternative to conventional remediation technologies.
More studies and development actions are still needed for bringing down these kinds
of technologies to the marketplace for full-scale implementation. Moreover, the
effect of environmental factors like pH, temperature, ionic strength, presence of
competing or inhibitory substances, etc. on remediation efficacy of nanobioremediation method is also needed.
7 Nano-bioremediation: An Innovative Remediation Technology for Treatment. . .
177
20 days, PH-07 strain was added in reaction mixture and incubated for 4 days.
The sequential system was found to be effective for degradation of deca-BDE
showing reduction up to 67%. The debrominated products were further treated
with PH-07 strain to study their mineralization. He et al. (2009) also reported
sequential treatment of 2, 2
0 4, 5, 5
0 -pentachlorobiphenyl with an anaerobic nZVI
reaction and successive aerobic transformation with bacterium H1.
4.2 Concurrent/Combined Method
In a microcosm study, Xiu et al. (2010a) investigated the effect of nZVI on
dechlorinating microorganism using trichloroethylene (TCE) as model compound.
For experiments, 100 mg of nZVI (1 g/L) and 4 ml of inoculation culture
(Dehalococcoides spp.) along with mineral salt medium were added simultaneously
in reaction vials containing TCE (20 g/L). The reaction mixture was then put over
shaker at 200 rpm. Two other experiments were also carried out under similar
conditions, one with nZVI alone and another with Dehalococcoides spp. only.
Initially, nZVI was observed to inhibit microbial dechlorination, but later on it was
found to have biostimulatory effect on dechlorinating bacteria which in turn could
enhance the overall rate of contaminant degradation. The reason ascribed to this was
the hydrogen which is evolved from nZVI during cathodic corrosion can be utilized
as electron donor by dechlorinating bacteria. In another combined study, nanoparticle (nFe
0 /Pd) was coated with a polymer (carboxymethyl cellulose, CMC) to avoid
direct contact of nanoparticle with bacterial cells, as their direct contact inhibits the
growth of bacteria cells (Singh et al. 2013). The study demonstrated degradation of
γ-HCH in individual and combined system of CMC-Pd/Fe
0 and Sphingomonas
strain NM05. The results revealed that γ-HCH degradation efficiency in combined
system was 1.7–2.1 times greater as compared to system containing either NM05
strain or CMC-Pd/nFe
0 alone.
5 Conclusion
Integration of nanoremediation with bioremediation either sequentially or concurrently appears to be a feasible alternative to conventional remediation technologies.
More studies and development actions are still needed for bringing down these kinds
of technologies to the marketplace for full-scale implementation. Moreover, the
effect of environmental factors like pH, temperature, ionic strength, presence of
competing or inhibitory substances, etc. on remediation efficacy of nanobioremediation method is also needed.
7 Nano-bioremediation: An Innovative Remediation Technology for Treatment. . .
177