JP2644524B2 - Plankton concentration apparatus and concentration method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a highly useful plankton concentrator such as chlorella, for example, and more particularly to a concentrator characterized by utilizing a separation membrane for concentrating. It concerns the device. The plankton that is the subject of the present invention is
It may be of any plant or animal nature, but diatoms, protozoa, etc., whose size is less than or equal to the so-called small plaqueton, are representative of chlorella, which has been recognized as having particularly high utility. Target.

(Prior art) Phytoplankton or zooplankton such as chlorella are planktonic organisms defined as marine (or freshwater) planktonic communities and in some cases contribute to the pollution of lakes and marshes. Although it is a problem, useful plankton such as chlorella is actually playing an important role in the food and fisheries industries as bait, food material, feed, etc. in aquaculture and fisheries, and will be used in the future. The importance is increasing.

By the way, when plankton such as chlorella is used at an industrial level, it is generally necessary to concentrate plankton grown in a breeding pond or the like from the viewpoint of preservation and transportation. This is because plankton has the property that only a limited amount of solids (cells) grow in a certain volume of liquid to maintain its ecosystem. Because there is no reality.

However, it is known that enrichment of plankton involves difficulty due to its inherent difficulty in settling. Such difficulties occur because, for example, chlorella floats by blowing bubbles by photosynthesis, or its specific gravity in water is close to 1, and the size of a solid is as small as 1 μm to several tens of μm.

Conventionally, as one of means for concentrating such plankton, a method of adding an inorganic or polymer flocculant to lake water to purify plankton for purification of lakes and the like, and performing solid-liquid separation by pressure flotation separation is known. Are known.

However, this method can be applied for the purpose of purifying lakes and marshes because the collected plankton contains a flocculant, but cannot be applied for the purpose of using the recovered plankton such as chlorella as bait for aquaculture and fishery. Things.

Therefore, a method using a centrifugal separator has been proposed and actually used as a concentrating means for applying the purpose of using the recovered plankton.

FIG. 7 is a diagram showing a schematic configuration of a plankton concentrating apparatus using this centrifugal separator.
Is a plankton culture tank, and the liquid sent to the stock solution tank 32 by the liquid sending pump 35 is further sent to the centrifugal separator 33 by the liquid sending pump 36 to perform solid-liquid separation by centrifugal force. The plankton discharged and concentrated is collected in a recovery tank
Recovered at 34.

(Problems to be Solved by the Invention) However, according to the study of the present inventors, the following problems are pointed out in the plankton concentration using the centrifuge.

For example, as described above, plankton has a small difference between its specific gravity and liquid specific gravity as represented by chlorella and the like.Therefore, as a centrifuge, it is usual to use a machine with high speed and large centrifugal force, For this reason, problems such as an increase in the size of the device, a large consumption of power, a noise, and a heavy burden on maintenance and management are caused.

In view of the above-mentioned present state of plankton concentration technology, the present inventor has developed a novel plankton concentration suitable for use in the fields of foods, fisheries, etc., in which concentrated plankton can be concentrated without mixing other substances. It is an object of the present invention to provide a plankton concentration apparatus.

Another object of the present invention is to provide an apparatus capable of performing an enrichment scan designed so as not to adversely affect the survival of the plankton in view of the fact that the enrichment target is an organism. There.

Another object of the present invention is to improve the problem that the concentration rate decreases with time, and to provide a concentration apparatus capable of efficiently performing a concentration treatment of a large amount of plankton.

Still another object of the present invention is to provide an apparatus capable of easily monitoring the concentration state and thus efficiently operating the apparatus, an apparatus suitable for the type of target plankton, and an operation method thereof. Where you do it.

(Means for Solving the Problems) A feature of the plankton concentrating device according to the present invention made to realize the above-mentioned object is that a pore-size separation membrane that does not allow plankton to permeate and allows nutrient sources to permeate. A membrane separation unit for passing the liquid to be treated containing the plankton and nutrient substance in a cross-flow manner,
A circulation system for circulating the liquid to be treated through the membrane separation unit, wherein plankton is concentrated and recovered on the non-permeate liquid side.

By the above concentrating device, the useful plankton is separated into water and solid by the separation membrane, and the concentration of the useful plankton is gradually concentrated in the liquid on the non-permeate side including the useful plankton by discharging the water out of the system. If the operation of the apparatus is stopped in the state where the concentration reaches the concentration, useful plankton having a predetermined concentration can be recovered.

The separation membrane used for such concentration enables the plankton to be concentrated on the non-permeate side without allowing permeation of plankton, and a nutrient source substance (necessary for plankton survival) contained in the liquid to be treated. The substance having a pore size that satisfies the condition of permeation is used. As such a membrane, a so-called ultra-membranous membrane is generally used. For example, when specifically targeting chlorella, marine chlorella has a thickness of 1 to 3 μm and freshwater chlorella has a thickness of 5 to 10 μm. For this reason, an ultramembrane of an extent capable of blocking 1 μm or more is preferably used.

The reason for selecting a pore size that allows a nutrient substance to permeate in the separation membrane such as the ultrafiltration membrane is to prevent the growth conditions of plankton such as chlorella from deteriorating.

The liquid is flowed to the membrane separation unit in a cross-flow system because the liquid to be treated is always flowed in parallel to the membrane surface to prevent clogging due to plankton deposition on the membrane surface. To do that.

(Operation) The plankton concentrating device of the present invention having the above-described configuration can concentrate a dilute plankton in a culture solution to a high concentration state by circulating the liquid.

(Examples) The present invention will be described below based on examples shown in the drawings.

Example 1 FIG. 1 shows a system diagram of the apparatus of Example 1 of the present invention, in which 1 is a plankton culture tank, and a raw material liquid (liquid to be treated) in the culture tank 1 is Then, the raw material pump 5 is used to insert a predetermined amount into the stock solution tank 2.

The stock solution tank 2 is sent to the membrane separation unit 3 by the circulation pump 6 through a forward pipe 9 connected to the lower part thereof, and returned from the upper part of the stock solution tank 2 to the stock solution tank 2 through a return pipe 10. These form a circulatory system.

As a structure of the membrane separation unit 3, generally, a structure in which a large number of flat membrane type membranes are stacked together with an excess base and a liquid recovery board is preferably used. It is not limited.

An open / close switching valve 7 is interposed in the middle of the forward pipe 9 of the circulation system, and the forward pipe 9 connected to the lower part of the stock solution tank 2 is branched and passed through the open / close switching valve 8 to concentrate the plankton recovery tank 4.
It is connected to the. Therefore, the above two open / close switching valves 7,
By switching 8, the open / close switching valve 7 is opened and the open / close switching valve 8 is closed, and the liquid in the stock solution tank 2 is circulated to the stock solution tank 2 through the forward pipe 9, the membrane separation unit 3, and the return pipe 10. (Hereinafter referred to as a circulation state) and a state in which the open / close switching valve 7 is closed and the opening / closing switching valve 8 is opened to transfer the liquid in the stock solution tank 2 to the concentrated plankton recovery tank 4 (hereinafter referred to as a recovery operation state). ).

The operation of the plankton concentrating device having the above configuration will be described. First, the stock solution containing plankton cultured in the plankton culture tank 1 has a concentration of about 20 million cells / ml in chlorella, for example. A predetermined amount is transferred into the stock solution tank 2 by 5.

Next, the two switching valves 7, 8 are set so as to be in the above-mentioned circulation state, and the circulation of the stock solution by the circulation pump 6 is started.

With the start of the liquid circulation, plankton in the circulated liquid passes through the membrane separation unit 3 and returns to the stock solution tank 2 through the return path 10, but a considerable amount of liquid passes through the membrane and exits the system as permeated water. Is discharged. As a result, the stock solution is concentrated by the reduced amount of the permeated water. At this time, the degree of concentration in a single circulation cycle is at a low level, but in this example, the circulation pump 6 is operated continuously, and therefore, the liquid in the stock solution tank 2 is continuously and many times. Since the above-described circulation is repeated, the plankton concentration of the liquid in the stock solution tank 2 gradually increases.

Such a decrease in the amount of liquid due to permeation and an increase in the concentration of plankton in the liquid generally indicate the relationship shown in FIG.

When the plankton concentration in the liquid reaches the target predetermined concentration, the operation of the circulation pump 6 is stopped, and the open / close switching valves 7, 8 are switched to the state of the recovery operation to remove the liquid in the stock solution tank 2. It can be transferred to the concentrated plankton recovery tank 4 and recovered.

In the implementation of the apparatus of the present example, when the undiluted solution that first ran into the apparatus was reduced to a predetermined amount by circulation, the undiluted solution was added to the undiluted solution tank 2 without collecting the concentrated solution in the concentrated plankton recovery tank 4. The device can also be operated to replenish. In this way, there is an advantage that a sufficient amount of the concentrated liquid can be secured in one final recovery.

Using the apparatus shown in FIG. 1, concentration operation was performed using 20 containing chlorella at a concentration of 20 million cells / ml as a stock solution.
The membrane separation unit 3 used was a flat membrane type ultrafiltration membrane (membrane area 200 cm ² ) having a molecular weight cut off of 100,000, circulating flow rate 2.5 / min, operating pressure 1-2 kg / cm ² , and 12 hours. I drove.

By this operation, the operation can be continued without a decrease in the permeated water amount with the passage of time, and without causing a problem of performance deterioration due to clogging of the membrane, and the chlorella concentration of the finally obtained liquid can be maintained. Was 1 billion cells / ml (thus enrichment was 50 times).

Embodiment 2 In the embodiment 2 shown in FIG. 3, a bypass 11 is provided in the middle of the outgoing pipe 9 constituting the circulation penalty.
This example shows that the turbidity meter can measure the absorbance of the circulating fluid by using a transparent tube. Other configurations are the same as those of the first embodiment, and the description of each unit is omitted.

In the present embodiment, the turbidity based on the absorbance of the circulating fluid is measured for the following reason. That is, it is not only uneconomical to perform plankton concentration indefinitely, but also from the viewpoint of industrial utilization, concentration above a certain level is practically unnecessary, so the concentration operation of the above-mentioned concentration device is stopped at a predetermined stage. Is performed in the actual driving operation. The operation stoppage does not require such a high degree of density, but it is not desirable from the viewpoint of product management that the concentration of the plankton concentrate obtained at each concentration operation varies greatly. Therefore, it is conceivable to monitor the number of plankton solids (cells) in the concentrated liquid by counting the number of liquids sampled in batches as appropriate using a microscope. There is a problem that the system lacks responsiveness and that it is necessary to arrange work personnel in the device.

Therefore, in this example, by providing a monitor section using a turbidity meter in a part of the circulation system as described above, the circulating fluid concentration can be measured immediately. Also,
By utilizing such turbidity, automatic device operation stop control using a computer can also be made possible.

The measurement of the concentration of the circulating fluid using the turbidimeter in this example can be configured using a combination of a light emitting source 12 such as an ordinary LED and a light receiving cell 13. FIG. 4 shows the concentration of chlorella in the circulating fluid containing chlorella using the turbidity meter.
FIG. 4 is a diagram showing a relationship with absorbance (−logT) when measured with light having a wavelength of 690 nm. Therefore, if the absorbance of the circulating fluid actually concentrated is measured and compared with the characteristic curve shown in FIG. 4 as a reference, the concentration state of the circulating fluid at that time can be confirmed.

The measurement of the concentration of the circulating liquid is not limited to the above method.For example, the liquid is periodically or continuously sampled from the circulating line, and if necessary, after diluting the liquid by a predetermined factor, the concentration is measured using a turbidimeter. The measurement may be performed, and in this case, the use of the turbidity meter can also automate the measurement operation and the control operation for stopping the apparatus based on the measurement result.

When the concentration measurement section is disposed at the end of the circulator, that is, at the end of the return pipe 10 connected to the stock solution tank, plankton remaining in the system (inside of the forward path, return path, membrane separation unit, etc.) When the contained liquid is washed out with seawater or the like, a feature can be obtained that can be used for detecting the end point of the washing.

Embodiment 3 The feature of Embodiment 3 shown in FIG. 5 is that a heat exchanger 15 is provided in the middle of the outward pipe 9 constituting the circulation system. Other configurations are the same as those of the first embodiment, and the description of each unit is omitted.

The reason for adopting such a configuration in this example is that the viscosity of the circulating liquid varies depending on the liquid temperature and the degree of concentration. In industrial concentration processing, the viscosity is reduced as much as possible to reduce the concentration rate. It is desirable that the concentration of the plankton be high, and in addition, since the plankton to be enriched is a living organism, operation of the device outside the conditions for its survival may cause the plankton to die, which is appropriate. This is because the circulating fluid is maintained at an appropriate temperature.

For example, since the circulation pump 6 generates heat due to the operation of the pump, the temperature of the circulating fluid generally tends to increase. Therefore, by providing a heat exchanger at a stage subsequent to the circulation pump 6, the temperature of the circulating liquid can be kept constant. When the temperature of the liquid is too low due to other climatic conditions or geographical conditions, it is preferable to heat the circulating liquid to lower the viscosity of the liquid. Needless to say, the maintenance of chlorella activity is a condition in these liquid temperature controls.

The heat exchanger is not particularly limited, and a known suitable one such as a plate heat exchanger can be used, and the position of the heat exchanger is not particularly limited even if it is located at any position in the circulation system. Not something.

Embodiment 4 The embodiment 4 shown in FIG. 6 is the same as the stock solution tank shown in FIG.
2, a circulation system consisting of the outgoing pipe 9, the circulation pump 6, the membrane separation unit 3, the outgoing pipe 10, and the on-off switching valves 7, 8 is provided as one set, and as shown in FIG. Features.

That is, the concentrated liquid that has been subjected to the first-stage concentration in the first circulating system transfers the plankton concentrated solution from the first-stage circulating system on-off switching valve 8 to the concentrated plankton receiving tank 202 of the second circulating system. It is provided to transport. The second circulation system has the same configuration as that of the first circulation system except that the concentrated plankton receiving tank 202 is used as a stock solution tank as compared with the first circulation system. The second stage of concentration is performed in the second circulation system including the membrane separation unit 203, the return line 210, and the on-off switching valves 207 and 208. The plankton concentrate is further transferred to the plankton receiving tank 302 of the third circulation system from the open / close switching valve 208 of the second circulation system, and has a configuration similar to that of the second circulation system. Third circulation system, that is, concentrated plankton receiving tank 302, outgoing pipe 309, circulation pump 306, membrane separation unit 30
3, the circulatory system consisting of the return pipe 310 and the open / close switching valves 307 and 308
The second stage of concentration is performed.

The first-stage circulation system, the second-stage circulation system, and the third-stage circulation system in this example are sequentially arranged so that the internal capacity thereof becomes, for example, about one-tenth to several tenths. The volume is reduced, so that when the concentration is increased, the amount of the solution decreases, so that an efficient concentration operation can be performed with an apparatus having a size commensurate with the decrease in the amount of the processing solution. -ing

According to such a multi-stage apparatus, although a plurality of circulation systems are required as an apparatus configuration, when a concentration of several tens to hundreds of times is to be processed by a single apparatus. In comparison with the difficulty in designing the apparatus, since a plurality of apparatuses for concentrating at most several to several tens of times are combined, for example, the selectivity of the circulating pump becomes easy, and the operation thereof is performed under unreasonable conditions. An effect such as no longer being performed can be obtained.

The results obtained when the apparatus of FIG. 6 was configured as follows and the plankton concentration operation was performed are shown in the following table. The culture solution used (chlorella stock solution) was 10 m ³ at 20 million cells / ml, and the operating conditions were the same as in Example 1.

According to this embodiment, a plurality of circulation systems can be operated in parallel, and the apparatus can be operated in a relatively narrow range of concentration ratio as compared with the example of the first embodiment. There is an advantage that the design of the circulating pump, for example, is easily prepared.

In addition, the time taken to pass through the plankton device is averaged, and the load on each cell of the plankton is considered to be uniform. Therefore, the design and operation control of this type of device that targets living organisms such as changing the operating conditions of the device There is also an advantage that can be simplified.

(Effect of the Invention) According to the plankton concentrating device of the present invention described above,
The following effects can be obtained in the process of concentrating the rare plankton in the culture solution to a high concentration state.

By circulating the target liquid with a low-pressure pump, useful plankton can be concentrated at low cost.

Since the nutrient source of plankton, which is COD in the liquid to be treated, flows out through the separation membrane into the permeated water, concentration of the substance on the side where plankton is collected does not occur,
The plankton survival condition can be maintained in the same state as the culture solution.

Since the apparatus does not have a high-speed rotating body like a conventional centrifugal separator, there is almost no generation of noise and the working environment is good.

By measuring the concentration of the liquid in the circulatory system continuously or periodically using a turbidity system, it is possible to immediately determine when to stop the operation of the device. It can be obtained in a certain state.
Further, by measuring the plankton concentration in the liquid using a turbidity meter, it is possible to automatically control the stop of the apparatus, thereby facilitating the operation management of the apparatus and reducing the number of workers.

By controlling the temperature of the circulating liquid, it is possible to maintain the viscosity of the liquid in an appropriate state without killing plankton and to operate the apparatus efficiently.

When a plurality of circulation systems are provided in multiple stages, the plurality of circulation systems can be operated in parallel, and the apparatus can be operated in a relatively narrow range of concentration ratio, so that efficient operation can be performed. The design of the device, for example, the design of the circulation pump is facilitated.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a schematic configuration example of a plankton concentrating apparatus according to a first embodiment of the present invention, and FIG. 2 is a view for explaining a relationship between a decrease in a treatment liquid amount and an increase in plankton concentration in a liquid. FIG. 3 is a diagram showing a schematic configuration example of a plankton concentrating device of Example 2, FIG. 4 is a diagram showing a relationship between absorbance and chlorella concentration, and FIG. 5 is a schematic configuration example of a plankton concentrating device of Example 3. FIG. 6 is a diagram showing a schematic configuration example of a plankton concentrator according to a fourth embodiment, and FIG. 7 is a diagram for explaining a configuration example of a conventional plankton concentrator using a centrifuge. It is. DESCRIPTION OF SYMBOLS 1 ... Plankton culture tank 2 ... Stock solution tank 3 ... Membrane separation unit 4 ... Concentrated plankton collection tank 5 ... Stock solution pump 6 Circulating pump 7,8 Open / close switching valve 9 Outbound pipe 10 ... return pipe 11 ... bypass path, 12 ... light emission source 13 ... light receiving cell, 15 ... heat exchanger 31 ... plankton culture tank 32 ... stock solution tank 33 ... centrifuge 34 ... concentration Plankton collection tank 35 Liquid pump, 36 Pump

Claims (6)

(57) [Claims] 1. A membrane separation unit for passing a treatment liquid containing plankton and a nutrient substance through a pore-size separation membrane that does not allow plankton to permeate and allows nutrient substances to permeate, in a cross-flow manner. A plankton concentrating device, comprising: a circulating system for circulating and circulating the plankton through the membrane separation unit; 2. The plankton concentrator according to claim 1, wherein the plankton is chlorella. 3. The plankton concentrator according to claim 1, wherein a heat exchanger is provided in the middle of the circulation system. 4. The plankton concentrator according to claim 1, further comprising a section for measuring the concentration of circulating liquid using a turbidity meter in the middle of the circulation system. 5. The plankton according to claim 1, wherein a plurality of sets of the membrane separation unit and the circulating system are provided in multiple stages with the volume of the processing solution reduced sequentially. Concentrator. 6. The concentrator according to claim 1, wherein the liquid to be treated is added to the circulating system when the amount of liquid on the non-permeating liquid side of the circulating system decreases to a predetermined amount. A plankton enrichment method, characterized by additionally replenishing water.