Download 1 - hydroprotech

Enhancement of Phenol Biodegradation
by South Magnetic Field Exposure
Jongtai Jung
(Professor/Ph. D)
Major of Environmental Engineering
Division of Urban and Environmental Engineering
University of Incheon
Objectives
To determine
- if acclimation in the presence of south pole
magnetic field enhanced degradation,
- and if this enhancement varied at different
magnetic field strengths.
Due to the large size of a 0.49 tesla magnet,
the region between zero and 0.49 is examined
in this study
Microorganism
• Activated sludge(Mixed microbial population)
from Waste water treatment plant
• 100 g alginate-immobilized activated sludge
• How to immobilize
- Distilled water
- Concentrated sludge(50 mg dry biomass/ g of pallet)
- 0.5% sodium chloride
- 1% sodium alginate
- 0.1 mol/liter CaCl2
- Distilled water and Conc. Pellets in a ratio 5:2 mixed
with NaCl and Sodium Alginate in a blender
- The homogeneous cell suspension was then extruded
using a syringe pump into CaCl2 solution to obtain the
immobilized bacterial beads
Experiments to be performed
Immobilized cells
Run
Acclimation of free cells
exposed to south magnetic
Series
with south magnetic fields
field during runs
A
No
No
B
Yes
No
C
Yes
Yes(0.35 tesla)
D
Yes
Yes(0.15 tesla)
TABLE 1. Summary of Experiments Performed (series A and B were designed
to investigate the effects of acclimation, while B,C and D were
designed to test further exposure to preacclimated bacteria).
Acclimation
-
Physiological adjustment by an organism
to environmental change
- Acclimating microorganisms to a given toxic
chemical can have positive effect on the treatment
of that chemical
Parameters to be monitored
1) Rate of oxygen consumption
(nmol/min∙ml)
2) Secreted protein concentration (㎍/ml)
3) Rate of phenol biodegradation(ppm/hr)
Analytical Methods
1) Oxygen consumption :
- Clark-type dissolved oxygen probe
- Chart recorder
2) Phenol Concentration :
- Varian 3300 Gas Chromatograph,
- Detector : FID
3) Protein concentration :
- Standard Lowry test(color response measurement)
- Bovine serum albumin (Sigma Chemicals)
as a protein standard
Results and Discussions
- Figure 2,3 and 4 summarize the data obtained from analysis
of phenol, DO and extracellular enzyme concentration
during biodegradation experiments.
- Curve "A" represents experiments conducted with bacteria
not acclimated with the south pole magnetic field, and
not exposed during the runs in the course of the experiment.
This is the control experiment.
- Curve "B" represents magnetically acclimated bacteria which
were not exposed to magnetic fields during subsequent runs.
- Curve "C" and curve "D" represent experiments conducted
with magnetically acclimated bacteria in the presence of a
south pole magnetic field, and further exposed during runs,
curve "C" with 0.35 tesla and curve "D" with 0.15 tesla.
Fig 2. Effect of magnetic field exposure on biodegradation rate. Biodegradation
of phenol is enhanced by exposure during acclimation (B,C,D), and
further increased(C,D) by additional magnetic exposure during runs.
Runs A-D are further described in Table 1.
Effect on rate of biodegradation
- Biodegradation rates in all cases gradually increased as the system stabilized
after 2 or 3 days. The degradation rates for phenol were in the range of 2.5 to
4.25 ppm/hr with microbes not acclimated and not exposed to magnetic
fields(A).
- With magnetically preacclimated bacteria without exposure to magnetic field
after immobilization the rates were in the range 2.8 to 8.96 ppm/hr (Fig2.)
This suggests that the preacclimation step enhanced the maximum rate
approximately twofold.
- Further enhancement of oxidation rates was achieved when magnetically
preacclimated bacteria were used to degrade phenol in the presence of
additional magnetic irradiation after the beads had been immobilized.
- With a field strength of 0.35 tesla(curve “C”), the maximum rates ranged
from 3.96 to 14.4ppm/hr with an enhancement of four-fold over the control
experiment
- With a field strength of 0.15 tesla(curve "D“) the rates ranged from 2.7 to
25.6ppm/hr with an enhancement of 7.5 times the rates observed in the
control experiment
Effect on rate of oxygen consumption
- Figure 3 shows results from the analysis of oxygen consumption rates.
Curve A,B,C and D follow the same trend as was in the analysis of phenol
consumption.
-Oxygen consumption rates of microbes not pre-acclimated with the magnetic
field, and without exposure to magnetic field during biodegradation
experiments were the lowest, in the range of 1.35 to 2.0 nmol/min/ml
(curve "A").
- Oxygen uptake rate for microbes pre-acclimated with south pole magnetic
field were a little higher than control experiments. They ranged from 2.5 to
4.23 nmol/min/ml(curve"B").
The oxygen uptake rates for pre-acclimated microbes with further exposure to
magnetic field during biodegradation are significantly high.
- Curve "C" shows oxygen consumption rates in the presence of 0.35 tesla of
magnetic field. The rates ranged from 5.87 to 16.04 nmol/min/ml, a maximum
enhancement of eight times over the control.
- Curve "D" shows rates in the presence of 0.15 tesla of magnetic field.
The rates ranged from 3.03 to 27.48 nmol/min/ml, a maximum enhancement of
13.5 times over the control experiment.
Fig 3. Effect of magnetic field exposure on rate of consumption.
Acclimation (B,C,D) increases oxidation rate, which is further
enhanced by subsequent exposure (C,D) during runs.
Effect on release of extracellular proteins
- Figure 4 shows results from analysis of extracellular protein
concentration.
- The observed trend followed an identical pattern to that seen in
the analysis of oxygen consumption and phenol disappearance.
- With essentially no extracellular protein present at the start,
protein concentration increased as the microbes were challenged
with phenol.
- Maximum concentration of extracellular protein observed in
the control was 205㎍/ml.
- Where acclimated microbes were exposed to the magnetic field
during biodegradation the maximum extracellular protein
concentration was 465㎍/ml with 0.35 tesla field strength and
2250㎍/ml with 0.15 tesla field strength, and increase by one
order of magnitude from the control experiment.
Fig 4. Effect of magnetic field exposure on extracellular protein production.
Acclimation (B,C,D) increases protein production, which is further
enhanced by subsequent exposure (C,D) to magnetic fields during runs.
Effect of field strength and time(1)
- Results from the analysis of phenol, oxygen and extracellular
protein concentrations all show that south pole magnetic filed
increased biological activity among microorganisms from
activated sludge.
- This increase in activity can be obtained by pre-acclimating
the microbes in the magnetic filed, and also by continuous
exposure of the microbes to the field during biodegradation
experiments.
- Table 2 summarizes the results. Acclimation with, as well as
subsequent continuous application of, south magnetic fields
enhanced biodegradation as measured by phenol disappearance,
oxidation rate, and protein synthesis.
- For reference, all three phenol degradation rates were higher
than reported previously for 0.49 tesla, unacclimated(5.9ppm/hr)
Effect of field strength and time(2)
- Two observations can be made from this analysis.
- First, biological activity in the control and in the pre-acclimated
microbes not exposed to the magnetic field increased gradually
as the system stabilized, and then the activity stabilized.
- When the pre-acclimated microbes were exposed to the magnetic
south field(0.15 and 0.35 tesla) the biological activity increased
significantly and reached a maximum(10days) after which it
decreased. This could be due to inhibition from extended
exposure to the magnetic field.
- Secondly, the enhancement of biological activity changed as the
strength of the magnetic field varied. As shown in Table 2,
biological activity against phenol was most enhanced in the
presence of 0.15 tesla, indicating that the higher intensities may
not have been as productive and that there appeared to be an
optimum value of field strength.
TABLE 2. Summary of Data, acclimation (B versus A)demonstrated general
stimulation, as did subsequent exposure (C and D) to south magnetic
fields during runs).
Phenol
Rate of oxygen
Secreted extracellular
biodegradation
consumption
enzyme concentration
(ppm/hr)
(nmol/min∙ml)
(μg/ml)
Max. value
4.25
2.0
205
Day
7
8
7
Max. value
8.96
4.23
310
Day
8
7
8
Max. Value
25.6
27.48
2250
Day
11
10
11
Max. Value
14.4
16.04
465
Day
4
5
4
Run A
Run B
Run C
Run D
Conclusions
- For treating many waste streams, biological treatment methods
have often been described as offering a complete and cost
effective solution. Biological treatment may be enhanced by
use of immobilized cell bioreactors.
- Acclimation of free cells to a south pole magnetic field prior to
immobilization increases bio-oxidaton and phenol destruction
in the order of 100%.
- Optimum strength and exposure time are important
since higher magnetic irradiation decreases the rate of
biodegradaton.
- The maximum observed enhancement with twice irradiated
cells is 750% higher than control runs.
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