JP2009018008A - Selective liquid treatment method by high-voltage pulse control - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a selective liquid treatment method by high-voltage pulse control for selectively sterilizing only microorganisms which are the target for sterilization without damaging effective substances and components in a treatment liquid medium. <P>SOLUTION: In the selective liquid treatment method for sterilizing the microorganism v, which is a bacterium and is mixed in the treatment liquid medium 11 containing a digestive enzyme that is the effective substance, by high-voltage pulse control, the treatment liquid medium 11 is filled in or is repeatedly circulated in a treatment container 10 to which a high-voltage pulse is applied, and the high-voltage pulse having electrical field intensity of 10 kV/cm or greater, a pulse half width of 100-200 ns, and a pulse repetition rate of 2 pps or greater is applied to the treatment liquid medium 11 for sterilizing the microorganisms v. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a selective liquid by high-voltage pulse control that can selectively sterilize only an object to be sterilized in a liquid with a high-voltage pulse without decomposing or deactivating active ingredients such as enzymes in the liquid or deactivating the substance. It relates to a processing method.

  Conventionally, various methods have been proposed for liquid sterilization using high-voltage pulses.

  In these sterilization methods, as shown in Patent Documents 1 to 5, a high voltage pulse is applied between electrodes installed in a medium to be sterilized, and a shock wave generated with a high electric field or various discharges is microbial. It is the method of sterilizing by giving to.

  This high voltage pulse generates a streamer discharge in the liquid, and ozone, OH radicals, shock waves, etc. are generated by the streamer discharge, thereby sterilizing the target microorganism.

JP 2004-248866 A JP 2003-34314 A JP 2001-252665 A JP 2000-166523 A JP 2000-262261 A

  However, if a high electric field or various discharges are generated in the medium to be sterilized, various substances other than microorganisms in the medium are also affected.

  For example, in the production of a digestive enzyme as a pharmaceutical product, when the produced digestive enzyme is concentrated into a powder, microorganisms as miscellaneous bacteria are mixed in the production plant, so that the digestive enzyme that is an active substance is not inactivated. In addition, it is necessary to selectively treat microorganisms that are miscellaneous bacteria. Currently, the treatment of microorganisms by filter filtration is common, but periodic filter replacement is necessary due to filter clogging. In addition, when an active substance having a size larger than that of a microorganism is contained, the microorganism treatment by filter filtration cannot be applied. On the other hand, when a high voltage pulse is applied to the treatment liquid, unnecessary effects such as decomposition and deactivation of enzymes, which are effective substances, are given together with sterilization of microorganisms.

  Therefore, the object of the present invention is to select the high voltage pulse control that solves the above-mentioned problems and can selectively sterilize only the microorganisms to be sterilized without damaging the effective substances and components in the treatment liquid medium. It is to provide a method for treating liquid.

  In order to achieve the above object, the invention of claim 1 is directed to a selective liquid by high voltage pulse control for selectively sterilizing microorganisms as germs mixed in a treatment liquid medium containing an active substance such as an enzyme. A processing method, in which a processing liquid medium is filled or repeatedly circulated in a processing container to which a high voltage pulse is applied, and an input electric energy within a predetermined range that does not damage an effective substance in the processing liquid medium, and A selective liquid processing method by high voltage pulse control characterized in that a high voltage pulse condition for damaging microorganisms is set, and a high voltage pulse is applied to the treatment liquid medium under the high voltage pulse condition to sterilize.

  According to a second aspect of the present invention, there is provided the selective liquid processing method by high voltage pulse control according to the first aspect of the present invention, wherein the range of electric energy input to the processing liquid medium is 50 to 500 J / ml.

  The invention according to claim 3 is the selective liquid processing method by high voltage pulse control according to claim 1 or 2, wherein the microorganism is sterilized by applying a high voltage pulse having a pulse repetition rate of 2 pps or more, preferably 5 pps or more.

  According to a fourth aspect of the present invention, the electric energy input to the treatment liquid medium is 100 J / ml or less, the electric field strength is 10 kV / cm or more, preferably 25 kV / cm or more, and the pulse half-value width is 100 to 200 ns. Or a selective liquid processing method by high voltage pulse control according to any one of the above.

  According to the present invention, the condition of the high voltage pulse that damages only the microorganisms to be sterilized is obtained, and by applying the high voltage pulse under the condition, it can be selectively sterilized without damaging the active substance. It exhibits an excellent effect.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a high voltage pulse sterilization apparatus used in the present invention.

  In FIG. 1, reference numeral 10 denotes a processing container formed in a cylindrical shape with an insulator. A supply port 12 for a processing liquid medium 11 to be sterilized is provided at the bottom of the processing container 10, and a discharge port 13 for the processing liquid medium 11 is provided at the top. It is done.

  In the treatment liquid medium 11, v is a microorganism to be sterilized, the size is about 1 to 5 μm, and the size of the digestive enzyme that is an active substance is on the order of nanometers and is not shown.

  On one side of the processing vessel 10, an anode electrode 14 as a needle electrode is provided so as to be located at the center of the processing vessel 10, and a cathode electrode 15 as a ring-shaped ground electrode is provided on the anode electrode 14. .

  The anode electrode 14 is provided so that the pointed portion 14a protrudes from a protector 18 formed in a semicircular shape with ceramic or the like in order to prevent creeping discharge.

  The supply port 12 and the discharge port 13 are provided so as to sandwich the cathode electrode 15, and the treatment liquid medium 11 from the supply port 12 flows to the discharge port 13 through the electrodes 14 and 15.

  A high voltage pulse generator 16 is connected between the electrodes 14 and 15, and the high voltage pulse generator 16 is connected between the anode electrode 14 and the cathode electrode 15, that is, into the processing liquid medium 11 by the pulse controller 17. The condition of the high voltage pulse to be applied is controlled.

  The pulse control device 17 performs processing by controlling conditions such as the pulse voltage, pulse width, pulse shape, and pulse repetition number in the high-voltage pulse generator 16 using a pulse control circuit such as a pulse shaping circuit or a switching circuit. The high voltage pulse applied to the liquid medium 11 can be controlled to selectively give an effect to the components in the processing liquid medium 11.

  The basic specifications of the high-voltage pulse sterilizer are shown below.

Electrode Anode (dot) Cathode (ring 40mmφ) Copper gap length 20mm
Applied voltage 50-120kV
Discharge current 50-200A
Pulse width 100-160ns (half width)
Pulse repetition rate 2-10pps
Processing container capacity 50ml or 80ml
The circulation flow rate was 200 to 600 ml / min.

  However, pps is an abbreviation of pulse per second, which is the number of pulses applied per second. With the above specifications, the treatment liquid medium 11 was sterilized by appropriately changing the number of pulse repetitions.

  FIG. 2 shows the residual activity of the enzyme with respect to the electric energy [J / ml] input to the treatment liquid medium, and remains when the input electric energy exceeds 100 J / ml regardless of the number of pulse repetitions. It was confirmed that the residual activity was 80% or less when the activity was 90% or less and 500 J / ml or more.

  Fig. 3 shows the experimental results of the survival rate and sterilization rate of microorganisms with respect to the input electrical energy input to the treatment liquid medium. A black circle mark is a circulation type and 6 pps, and B black square is a circulation type. In the case of 2 pps, the black triangle mark of C is the case of 2 pps in the batch formula shown for comparison.

  In the circulation type 2 pps group B, if the input electric energy is increased, the sterilization rate increases accordingly.

  On the other hand, in the 6 pps circulating group A, the sterilization rate improves when the input electric energy is increased as in the case of group B, but due to the difference in the number of repeated pulses, that is, the input electric energy is 200 J / ml. At 2 pps, the sterilization rate is 97% (survival rate 3%), whereas at 6 pps, the sterilization rate is 99.9% (survival rate 0.1%), which can significantly improve the sterilization efficiency. .

  Moreover, in the batch type of C, the sterilization rate was lower than that of the circulation type having the same number of repetitions.

  In the case of the batch type, the treatment liquid medium remains sealed in the container, and if the input electric energy is increased, charges are stored in the treatment liquid medium. It is thought to go down. On the other hand, in the circulation type of groups A and B, since the processing liquid medium circulates inside and outside the container, the high voltage pulse applied to the processing liquid medium is discharged out of the container without being accumulated as a charge, and the batch type Compared to the batch type, since the correlation with the input electric energy is reduced, the survival rate of the enzyme is higher than that of the batch type. However, if the number of pulses is increased, the sterilization rate of the cells can be increased. Here, when the group A is 2 pps, the survival rate of the enzyme is higher, and when the group B is 6 pps, the sterilization rate is increased. Therefore, by selecting the number of repeated pulses according to the sterilization target, optimal sterilization can be performed while ensuring the survival rate of the enzyme.

  Therefore, when the input electric energy is 500 J / ml or less, preferably 100 J / ml or less and the number of repeated pulses is appropriately selected, microorganisms can be sterilized well without damaging the enzyme.

  In addition, it is preferable to circulate the processing liquid medium in the processing container 10 with an average electric field strength of 25 kV / cm and a pulse half width of 100 to 200 ns so that the processing liquid medium is replaced several times in one minute.

  Next, the lower limit of the proper applied voltage will be described.

  The lower limit of the applied voltage is determined by the size of the germ cells and the fact that the cell membrane of the germs is destroyed at a voltage of 1V.

  This cell membrane destruction phenomenon is called “Electroporation”. When a pulse electric field is applied to a cell, the electric field concentrates on the cell membrane (insulating) covering the cytoplasm (conductivity), and the voltage applied to the cell membrane becomes about 1V. Electroporation (electroporation) begins to form pores in the cell membrane, which causes the cells to die.

Here, if the size of various bacteria is about 1 μm,
1 (V) / 1 × 10 ⁻⁶ (m) = 10 kV / cm
Thus, in order to kill cells by applying a voltage of 1 V, the lower limit value of the required electric field strength is 10 kV / cm. If the applied electric field strength is higher than this, germs can be killed.

  Here, a method of calculating input electric energy will be described. Typical experimental conditions for the circulation type are shown below.

Applied voltage V: 58 kV
Effective treatment time τ: 4 minutes (total discharge treatment time t: 10 minutes)
Discharge current I: 310A
Pulse width ΔT: 120 ns
Pulse repetition rate f: 6pps
Solution volume A: 200 ml
Container capacity B: 80ml
Circulation flow rate υ: 200 ml / min Here, the effective discharge treatment time τ is obtained by multiplying the total discharge time t by the ratio B / A of the container volume to the solution volume.

  The input electric energy W is calculated by the following equation.

W = I ・ V ・ f ・ τ ・ ΔT
In addition, the input electric energy w per unit volume is
w = W / B
It is represented by With the above,
Input electric energy W: 3107J (1036J for 2pps)
The input electric energy per unit volume is w: 6238.8 J / ml.

  In the case of 2 pps, it is 12.9 J / ml.

  As described above, in the present invention, by controlling the high voltage pulse condition applied to various processing liquid media, it is unnecessary without affecting useful components and necessary components in the processing liquid media. It is possible to perform treatments such as decomposition and sterilization with selective effects on components and microorganisms. That is, it is possible to sterilize microorganisms mixed in the medium and decompose unnecessary components while maintaining the effects of the necessary components in the treatment liquid medium.

It is a figure which shows the outline of the high voltage pulse sterilization processing apparatus used for the method of this invention. In this invention, it is a figure which shows the residual activity of the effective substance (enzyme) with respect to input electrical energy. In this invention, it is the figure which showed the survival rate and sterilization rate of the microorganisms with respect to input electric energy when changing the number of repetition pulses.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Processing container 11 Processing liquid medium 14 Anode electrode 15 Cathode electrode 16 Pulse generator 17 Pulse control apparatus

Claims (4)

  A selective liquid treatment method by high voltage pulse control that selectively sterilizes microorganisms as germs mixed in a treatment liquid medium containing an active substance such as an enzyme, and a treatment to which a high voltage pulse is applied Set a high voltage pulse condition that fills or repeatedly circulates the processing liquid medium in the container and has a predetermined range of input electric energy that does not damage the active substance in the processing liquid medium and that damages the microorganism. A selective liquid processing method by high voltage pulse control, wherein a high voltage pulse is applied to a processing liquid medium under high voltage pulse conditions to sterilize.   The selective liquid processing method by high voltage pulse control according to claim 1, wherein the range of electric energy input to the processing liquid medium is 50 to 500 J / ml.   3. The selective liquid processing method by high voltage pulse control according to claim 1, wherein the microorganism is sterilized by applying a high voltage pulse having a pulse repetition rate of 2 pps or more, preferably 5 pps or more.   The electric energy input to the treatment liquid medium is 100 J / ml or less, the electric field strength is 10 kV / cm or more, preferably 25 kV / cm or more, and the pulse half-value width is 100 to 200 ns. A selective liquid processing method by voltage pulse control.

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