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S. H. Das et al.
containing 500 mg/ml of resorcinol as sole carbon source for bacteria was prepared.
Then each metal at different concentrations (5 ppm, 25 ppm, and 50 ppm) was
added to separate flasks. Cell growth and resorcinol removal were measured and
the maximum cell growth, maximum specific degradation rate, and percentage of
removal efficiency were calculated for each run.
2.4 Optimization of Process Parameters for Removal
of Resorcinol in Presence of Toxic Heavy Metals
The optimization of the process parameters for removal of resorcinol in presence of
toxic heavy metals was done by Response Surface Methodology by using DesignExpert 11.0 software. The variable experimental parameters chosen were different
concentrations of metals (Cr (VI), Hg, and Pb) and aeration condition. A set of forty
experiments with varied values of process parameters were suggested by the software according to which the experiments were conducted. The resorcinol removal
efficiency was measured for each run. This response was studied and analyzed by the
software to predict the optimum operating conditions. All experiments were carried
out for 24 h at 35 °C.
3 Results and Discussions
3.1 Kinetic Study of Growth of Bacteria in Presence
of Resorcinol and Different Heavy Metals
From Fig. 1a–c, it was observed that the growth rate of bacteria was found to increase
with the concentration of chromium (VI). This was probably because of the presence
of chromium reductase in the bacterial system, which reduced Cr (VI) to less toxic
form of Cr (III) (Anyanwu and Ezaka 2011; Focardi et al. 2013). Bacterial growth
rate was found to increase with the increase of mercury concentration from 5 to
50 ppm due to bioaccumulation of mercury and production of methylated mercury
(MeHg) by the bacterial consortium (Kucharzyk et al. 2015). Growth rate of the
bacteria was found to remain same with the increase of lead concentration (Mishra
and Mishra 2015).
From Fig. 2 it was noted that chromium (VI) and mercury in the media had
enhanced the growth of bacteria while lead had interfered with the above process.
S. H. Das et al.
containing 500 mg/ml of resorcinol as sole carbon source for bacteria was prepared.
Then each metal at different concentrations (5 ppm, 25 ppm, and 50 ppm) was
added to separate flasks. Cell growth and resorcinol removal were measured and
the maximum cell growth, maximum specific degradation rate, and percentage of
removal efficiency were calculated for each run.
2.4 Optimization of Process Parameters for Removal
of Resorcinol in Presence of Toxic Heavy Metals
The optimization of the process parameters for removal of resorcinol in presence of
toxic heavy metals was done by Response Surface Methodology by using DesignExpert 11.0 software. The variable experimental parameters chosen were different
concentrations of metals (Cr (VI), Hg, and Pb) and aeration condition. A set of forty
experiments with varied values of process parameters were suggested by the software according to which the experiments were conducted. The resorcinol removal
efficiency was measured for each run. This response was studied and analyzed by the
software to predict the optimum operating conditions. All experiments were carried
out for 24 h at 35 °C.
3 Results and Discussions
3.1 Kinetic Study of Growth of Bacteria in Presence
of Resorcinol and Different Heavy Metals
From Fig. 1a–c, it was observed that the growth rate of bacteria was found to increase
with the concentration of chromium (VI). This was probably because of the presence
of chromium reductase in the bacterial system, which reduced Cr (VI) to less toxic
form of Cr (III) (Anyanwu and Ezaka 2011; Focardi et al. 2013). Bacterial growth
rate was found to increase with the increase of mercury concentration from 5 to
50 ppm due to bioaccumulation of mercury and production of methylated mercury
(MeHg) by the bacterial consortium (Kucharzyk et al. 2015). Growth rate of the
bacteria was found to remain same with the increase of lead concentration (Mishra
and Mishra 2015).
From Fig. 2 it was noted that chromium (VI) and mercury in the media had
enhanced the growth of bacteria while lead had interfered with the above process.