JPH0296647A - Apparatus for detecting biomass - Google Patents

Abstract

PURPOSE:To enable non-destructive measurement of the biomass in the state of sediment by providing a permittivity measuring device measuring an electric capacity between electrodes and an arithmetic element converting the electric capacity into the biological concentration while detecting an interface whereon the biological concentration differs. CONSTITUTION:A culture tank 1 is filled up with bacteria 2 and a detecting element 4 moving vertically and provided with a pair of electrodes 3 is fitted thereto. In a state wherein this detecting element 4 is placed at a position being near to the bottom of the culture tank 1, an electric capacity is measured. In this constitution, a signal relating to an electrode position is detected by a potentiometer 6 fitted to a moving device and it is transferred to a computer 9 through a D/A converter 7. Besides, the value of the electric capacity measured by a measuring device 8 is transferred to the computer 9 through an interface, and the biological concentration in each depth in the culture tank 1 is calculated from the relationship between the value of the electric capacity and the biological concentration which is determined beforehand.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for detecting biomass, particularly biomass in a settling state rather than in a stirred or suspended state. The present invention measures the biological concentration in a culture tank or treatment tank when living organisms (bacterial cells, animal cells, plant cells) are in a sedimented state, and also measures the biological concentration in areas where living organisms are present in high concentrations and in low concentrations. This relates to a device that measures the interface with an existing area online. Therefore, the present invention plays a very important role in fields such as bioindustry, food industry, medicine, sewage treatment, and wastewater treatment.

(Conventional technology) Bioreactors and culture equipment that produce useful substances using various microorganisms, animal and plant cells, etc., have an internal biomass that changes from moment to moment. It is very important to measure the biomass in order to understand the internal state.

In bioreactors, etc., when measuring the bacterial cell concentration in a suspended solution of various microorganisms with small cell sizes, it is possible to measure the bacterial cell concentration based on various optical properties of the microorganism in the culture medium. It is possible. (Hakuhi and other 4 volumes r
Chemical Measurement Handbook” Asakura Shoten (1981-6-20
) P, 613).

However, when stirring or the like is not performed, the organisms are usually not in a suspended state but in a sedimented state. In such cases, after making the concentration of organisms in the tank uniform by stirring or other operations, a portion of the suspension is taken out and the wet temperature is determined.
Find the dry weight.

After staining cells and nuclei, methods such as counting the number of cells under a microscope are used, and in addition to determining the concentration of organisms in the sedimented area using these methods, the interface position created by organisms is measured by vibration, ultrasound, visual inspection, etc. It is customary to measure and estimate the biomass of the entire tank. Therefore, regardless of which method is adopted, in order to detect the concentration of organisms, it is necessary to collect organisms from the bioreactor or culture device using a sampling method, and the information on the amount of biomass must be reflected in the online control of the bioreactor, etc. was impossible.

Furthermore, when measuring the interface between an area where living organisms exist at a high concentration and an area where living organisms exist at a low concentration using methods such as the above-mentioned methods using light or ultrasound, suspended solids (SS) other than living organisms may be present. There are problems such as misidentification due to the color of the m-complete solution and increased errors due to air bubbles, and the complexity of the measuring device. Due to the various problems mentioned above, it is impossible to measure biomass in real time and reflect it in online control, and therefore importance has been placed on the development of a method that can measure biomass online.

Regarding the measurement of biological concentration, the present inventors first discovered a method of measuring by using electric capacitance (permittivity), and the method of measuring the concentration of biological organisms was discovered by using capacitance (permittivity).
It has become possible to measure cells as they are without destroying them (Japanese Patent Application No. 22481/1982).

However, if the organisms are homogeneously dispersed in the system, the biomass of the entire tank can be detected by simply measuring the concentration of the organisms as described above; Because there are areas where organisms are present at high density or concentration and areas where organisms are present at low density or concentration, measuring only the concentration of organisms in either area does not indicate that the density of organisms differs depending on the area. Moreover, this measurement cannot represent the biomass of the entire tank. Therefore, it is necessary to define this region, that is, to accurately detect the interface between the region where organisms are present in high concentration and the region where organisms are present in low concentration. In other words, by detecting this interface, the volumes of the high-concentration region and the low-concentration region can be calculated immediately, so if the bioconcentration in each region is measured, the biomass in each region can be detected. By combining these, the biomass of the entire tank can be detected. However, an effective device for detecting the interface between a region with a high concentration of living organisms and a region with a low concentration of living organisms has not yet been developed. Industrially performing the detection of the same with a single device is groundbreaking, not only in terms of the structure of the invention but also in the setting of the objective itself.

(Problems to be Solved by the Invention) As described above, with the conventional techniques, it has been completely impossible to measure the biomass in the sedimentation state online as it is.

(Means for Solving the Problems) The present invention has been made in view of the current state of the technology as described above, and involves inserting an electrode into a culture tank or treatment tank in which living organisms are in a sedimentation state. In addition to measuring the biological concentration by measuring the dielectric constant (permittivity), by moving the measurement electrode vertically up and down, we were able to unexpectedly measure the boundary (interface) between high and low biological concentration areas. As a result, they succeeded in measuring the amount of biomass in culture tanks and treatment tanks.

That is, the present invention requires a capacitance measurement section equipped with at least one pair of electrodes and a drive section for moving the measurement section. Any electrode can be used as long as it can measure capacitance and the influence of biological cells and electrode polarization are unlikely to overlap.

For example, the measurement can be advantageously performed using a platinum black electrode. There is no particular limitation on the number of detection units installed, but if a large number of detection units are installed, biological concentration detection and interface detection can be performed in a short time. The detection unit may be movable only in the vertical direction.

If it is movable in either the left or right direction, measurements can be made more efficiently. The electrodes of the detection part may be facing directly or may be mounted on the same plane. When the detection part is moved, the bio-based SS that has settled into the electric field created by the electrodes enters the electric field. It is better to use electrodes that are directly facing each other when the concentration of organisms inside and outside the electric field is quickly equalized, but if it is difficult to equalize the concentration of organisms inside and outside the electric field due to solidification or high viscosity, electrodes should be used. A coplanar arrangement is advantageous.

Roughly speaking, biological cells are composed of a cytoplasm containing a cell nucleus, a cell membrane surrounding the cytoplasm, and a wall.

Among these, the cell membrane is mainly composed of lipids and has a very high electrical resistance value.Therefore, the measurement target including cells is in an electrolyte solution (the substrate contains ions and can be regarded as an electrolyte solution). In addition, oil particles containing an electrolyte (cell fluid contains ions and can be considered an electrolyte) inside
It can be regarded as an emulsion system in which cells (cells) are present. Regarding such systems, see Hana et al.
24, No. 7, 1986), a theoretical analysis has been carried out. Using floriculture theory, it is possible to regularly analyze the state of emulsion oil (for example, the volume ratio of oil, etc.).

Against this background, the present inventors repeated experiments using various bacterial bodies and cells, and as a result, the measurement of capacitance was
When conducting this study in the frequency band of K&~10 MHz, we found that the capacitance in this band particularly increases with increasing biomass. Therefore, in the present invention,
Although other frequency bands may be used, it is particularly industrially advantageous to measure capacitance within the above range.

Usually, the measured value obtained by a measuring device is the capacitance, and the dielectric constant cannot be directly determined. The reason for this is that the capacitance varies depending on the area, shape, distance between electrodes, etc. of the electrodes for measurement. However, if the cell constant etc. are determined in advance, conversion to the dielectric constant is easy. Next, an example of a method for determining biomass from measured values (electrical capacitance) by vertically moving a detection unit equipped with a pair of electrodes will be described.

Since electrical capacitance is affected by the shape of the electrodes, culture equipment, etc., the frequency characteristics of the electrical capacitance in a state where no living organisms are present in the electric field created by the electrodes are determined in advance, and then subtracted from the frequency characteristics of the measurement target. , determine the change in capacitance caused by the presence of bacterial cells. At this time, due to the presence of living things, the frequency ranges from several kilohertz (Hz) to several megahertz (M
Hz) (This range varies depending on the ion concentration of the environment, the type of measurement target, etc.) An increase in capacitance is observed over a wide frequency range. Therefore, in order to calculate the biological concentration from the capacitance, it is possible to adopt the value at the frequency that shows the most significant change in response to changes in the cell concentration, or to perform appropriate data processing. If the relationship with the biological concentration (dry weight, number of bacterial cells, etc.) is determined, the biological concentration can be easily calculated from the capacitance.

Next, we will discuss an example of a method for detecting interfaces created by living organisms. The capacitance is measured with the concentration detection part (electrode) placed at the position closest to the bottom of the culture tank.

Next, the capacitance is sequentially measured while moving the electrode upward. The measured value shows a large value in a high biological concentration area, but as the electrode moves to a low concentration area, the measured value quickly becomes a small value. The electrode position at which this measured value rapidly decreases corresponds to the height of the interface.

Note that even if the interface is not clear, the biological concentration at each height can be determined.

FIG. 1 shows an example of a measurement system according to the present invention. The culture tank 1 is filled with bacterial cells etc. 2, and a detection unit 4 equipped with a pair of vertically movable electrodes 3 is installed. Measure the capacitance with the device placed close to the bottom. Next, the capacitance is sequentially measured while moving the electrode upward using the moving device 5. The signal regarding the ft pole position is a moving bag! After being detected by a potentiometer 6 or the like attached to a winding drum or the like, it is transferred to a computer 9 via a D/A converter 7. '#S The determined capacitance value is transferred to the computer 9 via the interface, and the bioconcentration at each depth in the culture tank is calculated from the relationship between the capacitance value and the bioconcentration determined in advance. When the electrode section moves to a low concentration area, the measured value quickly begins to show a small value. The height of the interface can be measured from the electrode position when this measured value rapidly decreases.

As the measuring device 8, a device with a fixed frequency can be used, but it is preferable to use a type that can measure capacitance at multiple frequencies.As the measuring device 8, i, cR
An isoelectric constant measuring device such as a meter is used as appropriate. Electrode 3 is 1
Although one unit was installed in this embodiment, a plurality of units may be installed as necessary.

Of course, the measurement target is not limited to microorganisms, but also animal cells and plant cells. In addition, when bacterial cells are immobilized using various fixatives, or when cells grow attached to the surface of plastic beads commonly used for culturing adherent animal cells (for example, Itodex manufactured by Pharmacia), Can be measured freely. next,
Examples of the present invention will be described below, but these are merely illustrative and do not limit the present invention in any way.

Example 1 Regarding a sample in which the solution was filled up to a height of 40 mm and activated sludge was filled until the sedimentation area reached 20 mm.

The biomass was measured using a pair of electrodes equipped with a pair of platinum plates with a surface area of 2d on the same plane at a distance of 2aIN between centers, and the results shown in Figure 2 were obtained.In Figure 1, the horizontal axis is the bottom of the culture tank. The vertical axis is the value obtained by subtracting the measured value in a solution containing no bacterial cells from the capacitance value at a measurement frequency of 300 KHz at each electrode position. When the detection part was in the high concentration area, it showed a nearly constant value, but as the electrode moved to the low concentration area, it decreased, and after the electrode moved completely to the low concentration area, it showed a low constant value. The electrode position showing the average value of the high concentration area and the low concentration area coincided with the interface position between the high concentration area and the low concentration area of bacterial cells, and this measuring device was able to detect the interface. The bacterial cell concentration in the high concentration range was determined from the relationship between the capacitance value and the bacterial cell concentration, and the amount of bacterial cells in the culture device was measured from the interface position measured as described above.

(Effects of the Invention) The present invention simultaneously detects the concentration of organisms and the position of the interface created by the organisms by enabling vertical movement of the detection unit that measures electric capacitance It (permittivity). This is a novel and outstanding effect that has not been possible before, making it possible to measure biomass online and in real time.

Therefore, according to the present invention, biomass in a sedimented state can be measured non-destructively, and the present invention can be widely used in biotechnology, water treatment fields, and various other fields.

According to the present invention, the biomass of the entire tank can be measured not only when the tank is divided into two layers but also when the tank is divided into three or more layers. The biomass of the entire tank can be measured accurately and online in real time.

[Brief explanation of drawings]

FIG. 1 illustrates one embodiment of the detection device of the present invention, and FIG. 2 is a graph illustrating the relationship between the height of the interface and the capacitance. Figure 1 Agent Patent attorney 1) Parent Male

Claims (1)

[Claims] a biological concentration detection unit equipped with at least one pair of electrodes;
A drive section for moving the detection section, a dielectric constant measuring device for measuring the capacitance (permittivity) between the electrodes, and a dielectric constant measuring device for measuring the capacitance (permittivity) between the electrodes.
1. A biomass detection device comprising: a calculation unit that converts dielectric constant (permittivity) into bioconcentration and detects interfaces where bioconcentrations differ.