Enhancement of Phenol Biodegrada-tion

by South Magnetic Field Exposure

Jongtai Jung (Professor/Ph. D)

Major of Environmental EngineeringDivision of Urban and Environmental

EngineeringUniversity of Incheon

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  

Objectives

• 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

Microorganism

Run

Series

Acclimation of free cells

with south magnetic fields

Immobilized cells

exposed to south magnetic

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).

Experiments to be performed

- 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

Acclimation

1) Rate of oxygen consumption (nmol/min∙ml)

2) Secreted protein concentration (㎍ /ml)

3) Rate of phenol biodegradation(ppm/hr)

Parameters to be monitored

1) Oxygen consumption : - Clark-type dissolved oxygen probe - Chart recorder2) Phenol Concentration : - Varian 3300 Gas Chromatograph, - Detector : FID3) Protein concentration : - Standard Lowry test(color response measurement) - Bovine serum albumin (Sigma Chemicals) as a protein standard

Analytical Methods

- 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.

Results and Discussions

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

- 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.

Effect on rate of oxygen consumption

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.

- 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.

Effect on release of extracellular proteins

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.

- 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(1)

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. 

Phenol

biodegradation

(ppm/hr)

Rate of oxygen

consumption

(nmol/min∙ml)

Secreted extracellular

enzyme concentration

(μg/ml)

Run AMax. value 4.25 2.0 205

Day 7 8 7

Run BMax. value 8.96 4.23 310

Day 8 7 8

Run CMax. Value 25.6 27.48 2250

Day 11 10 11

Run DMax. Value 14.4 16.04 465

Day 4 5 4

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).

- 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.

Conclusions

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