JPH04256405A - Improved method for clarifying suspension - Google Patents

Abstract

PURPOSE:To improve efficiency in liq.-solid separation and to enhance the clarification degree of a soln. by treating a suspension at the high pressure of >=300 MPa before the suspension, especially the suspension of an insoluble salt complex, is clarified by liq.-solid separation. CONSTITUTION:The suspended matter is separated from the suspension of an insoluble salt complex by filtration or precipitation to clarify the suspension. In this case, the suspension is treated under high pressure before or during the separation of the suspended matter. An org. extract such as a polysaccharide extract, fungus extract or their neutralized liq. or a microbe culture soln. are exemplified as the insoluble salt complex. The appropriate range of the pressure in the high-pressure treatment is easily set as desired because its critical condition is essential for the separation efficiency in clarification, and the pressure is preferably set at >=300 MPa (hydrostatic pressure). The high-pressure treating time is appropriately set in conformity to the extractant similarly to the pressure and is preferably controlled to about 10-30 min.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving the efficiency of a method for separating and clarifying suspended matter in a suspension. This technology can be applied to solution clarification operations in the food field, pharmaceutical field, and chemical industry field.

0002

BACKGROUND OF THE INVENTION Separation operations have heretofore been carried out for the purpose of separating products, recovering useful components, removing unnecessary harmful components, etc., and are one of the important operations. Separation operations generally include those involving phase changes such as distillation, but here we will discuss separation between a fluid and a powder.

[0003] Liquid-solid separation can be roughly divided into filtration and sedimentation, the latter of which also includes centrifugation. Conditions such as the type, concentration, particle size, etc. of the powder handled therein are extremely wide-ranging, and the types and structures of the equipment used are also extremely diverse.

[0004] To give specific examples, filtration includes constant pressure filtration, constant speed filtration, variable pressure variable speed filtration, continuous filtration, centrifugal filtration, etc., and sedimentation includes gravity wet classification, centrifugal classification, sedimentation concentration, etc. In either case, particles are separated from a liquid based on their particle size and sedimentation velocity.

[0005]

However, depending on the nature of the suspended matter (particles), separation may be difficult or insufficient even using the above-mentioned means. That is, the separation step is usually employed as one step in a series of operations, and this is the case when the system itself is not a simple system but a complex system. For example, in order to further clarify the extract obtained by extracting the extract from the extract using a solvent, in many cases fine insoluble salts generated by the extractant or neutralizing agent are suspended in the extract. Because of this, conventional clarification methods were insufficient for separation. This is because such insoluble salts are not only fine but also in a hydrated state and have a slow precipitation rate.

[0006] In view of the problems of the prior art described above, the present invention
An improved method of clarification is provided for efficiently separating suspended solids from liquids.

[0007]

[Means for Solving the Problems] The present inventors have conducted extensive research to solve the above problems, and have found that when a liquid in which an insoluble compound is suspended is subjected to high pressure treatment before or during clarification treatment, the insoluble compound becomes The present invention was completed based on the discovery that salt complexes and the like tend to dissociate, recombine, or aggregate to form precipitates, which facilitates liquid-solid separation and makes the solution highly clear.

That is, the present invention provides a suspension clarification process in which a suspended substance is separated from a suspension of an insoluble compound by filtration or sedimentation, in which the suspension is subjected to high pressure before or during the separation of the suspended substance. This is an improved suspension clarification method characterized by improving separation efficiency through processing. According to the present invention, it becomes possible to efficiently separate, recover, or remove fine insoluble compounds that were extremely difficult to separate using conventional techniques. Therefore, recovery, concentration, purification, etc. of solid or liquid useful substances can be effectively carried out.

The present invention will be explained in detail below.

[0010] In the present invention, the "suspension of an insoluble compound" to be treated refers to a suspension in which a fine insoluble compound is suspended in a liquid dispersion medium having suspending properties. This includes both those for the purpose of recovery and those for the purpose of recovering solids. Further, this suspension may be obtained at any stage during the product manufacturing process, and it does not matter what the product manufacturing process is. For example, neutralized liquid after extraction of specific components from animals and plants, neutralized liquid after hydrolysis of proteins, etc., neutralized liquid after alkaline isomerization of sugar, neutralized liquid of milk whey, etc. Other examples include various neutralizing liquids, various wastewaters, various treated liquids that have been subjected to classification and separation treatment, microbial cell disruption liquids, and the like.

The term "insoluble compound" herein refers to one or more solid compounds that are dispersed in a liquid as a suspension. As long as it is a solid compound that exhibits a dispersed state, its shape, size, form, etc. are basically not limited, but considering the purpose of the present invention, it is fine and has a low sedimentation rate, and conventional techniques are sufficient to separate it. Preferably, it is impossible to do so.

[0012] Furthermore, the suspended solids that exhibit an effective separation effect in the present invention have certain structural properties. Although the separation effect of the present invention is brought about by the action of high-pressure treatment, which will be described later, it has been found that the behavior under high pressure differs depending on the type of suspended solids, and that the same effects are not achieved. This seems to be determined by whether or not the suspended solids have a chemical structure that can be activated under high pressure, rather than by the characteristics such as particle size or shape. That is, when particles in suspension exhibit behaviors such as dissociation, recombination, or aggregation under high pressure, the particle size and sedimentation rate change accordingly, which can facilitate subsequent separation. It is not clear what structures are involved. According to the present inventors, the separation effect of high pressure treatment was particularly great for insoluble salt complexes. However, usually
Dispersed systems are often complex systems composed of various components, and the effects of high-pressure treatment and interactions between multiple components cannot be ignored, so the suspended solids are limited to insoluble salt complexes only. It's not a thing. In other words, the present invention can be applied to a suspension containing a group of fine particles that can be dissociated, recombined, or aggregated under high pressure.

Examples of insoluble salts whose solubility changes under high pressure include calcium citrate, calcium lactate, and calcium phosphate. On the other hand, when the system itself is complex, such as when an organic extract is neutralized, the insoluble salts produced by neutralization form a complex, and although their behavior is not uniform, they dissociate under high pressure. It was discovered that it has the property of causing recombination or aggregation. The reason for this is not clear, but it is thought to be due to a change in the structure of water. Since the above-mentioned composite is fine and hydrated, the sedimentation rate is low, and therefore, conventional mechanical separation operations alone are insufficient to separate it.

[0014] The above-mentioned insoluble salt complex broadly means an insoluble compound in which salt formation is mediated. Examples include extracts of organic matter such as polysaccharide extracts, bacterial cell extracts, or neutralized liquids thereof, microbial culture liquids, and the like. More specific examples include extracts of water-soluble fibers such as hemicellulose, pectin, and carrageenan and other water-soluble substances from plants, neutralized solutions thereof, and concentrated and desalted solutions thereof. These contain complexes of neutralized salts, proteins, sugars, other metal ions, etc. as suspended solids. The complexes are bonded to each other and aggregated or dissociated and recombined by high pressure treatment. In this process, other insoluble substances present are taken together, bonded, and aggregated, so that various insoluble substances other than the complex may coexist in the suspension.

[0015] The concentration of suspended solids in the suspension is not particularly limited.

[0016] Furthermore, since the growth of complexes occurs under high pressure, salts, etc., which are to serve as growth nuclei, are newly added to the suspension to form a complex with the substance to be separated in the suspension. , can also promote separation. Therefore, it includes operations such as neutralizing a suspension whose pH is on the acidic or alkaline side, and adding another salt to already existing salts to perform ion exchange.

The pH etc. of the suspension may be appropriately set depending on the insoluble compound to be separated. Next, in the present invention, "filtration or sedimentation separation" refers to known liquid-solid separation methods, including those that physically capture solids with porous materials and those that utilize the sedimentation phenomenon of particles in a gravitational field or centrifugal field. It means all separation operations. Therefore, the present invention can be applied to all liquid-solid separation devices. Specific device names include devices such as a clarifier, separator, press filter, and microfilter. These devices are used as a means for clarifying aqueous solutions etc. in which polysaccharides are extracted from natural plants or microorganisms.

The present invention is characterized in that the suspension is subjected to high pressure treatment before or during the clarification treatment. However, other steps may be incorporated as necessary, such as secondary clarification or intervening other steps before high-pressure treatment, or solid-liquid separation or other treatment after high-pressure treatment. For example, when clarifying a polysaccharide extract extracted from a plant body, if the subject of the present invention is to apply high-pressure treatment during extraction, concentrate and desalinate the obtained liquid, the clarification effect will be further improved. improves.

[0019] "High-pressure treatment" refers to treatment whose main purpose is to apply a predetermined pressure to the object to be treated, but the magnitude of the pressure depends on the dispersion medium, the type of suspended solids, and the intended separation. Since it varies depending on the ingredients, it should be set through prior testing. Since the pressure conditions of high-pressure treatment usually have critical significance for the separation efficiency in clarification treatment, an appropriate range can be easily set depending on the purpose. Usually, a pressure of 300 MPa (hydrostatic pressure) or higher is preferred. More preferably 500MP
That's all a. At a pressure lower than 300 MPa, the dissociation, recombination, and agglomeration of the composite do not occur sufficiently, and separation efficiency cannot be sufficiently improved in the clarification process. On the other hand, although it is not necessary to clearly define the upper limit of the pressure from the viewpoint of effectiveness, it is not very practical to set the pressure to 1000 MPa or more when considering the structure of the apparatus.

[0020] Like the pressure, the high-pressure treatment time is appropriately set depending on the extraction and the like, but it is preferably about 10 to 30 minutes. Here, the processing time refers to the time during which the pressure is maintained after reaching a predetermined pressure. If the time is too short, the effect will not be sufficient, and if the time is too long, no improvement in the effect will be observed. The specific means for performing high-pressure treatment may be any shape or method as long as it can achieve high pressure, but for example,
This can be performed using a cold isostatic pressure device or the like. Further, the temperature of the suspension during high-pressure treatment should be relatively high, but it is usually about 40 to 60°C.

[0021] According to the above-described clarification treatment involving high-pressure treatment, the efficiency of separating suspended solids can be greatly improved compared to conventional methods that do not involve high-pressure treatment. Furthermore,
No loss of physical properties of the target substance is observed. Here, improving means improving in relative evaluation. Furthermore, in the case of solid-liquid separation, separation efficiency is generally defined as the rate at which solids migrate to the sedimentation layer, but in the present invention, since a suspension is treated, it is one of the separation efficiency values. It is possible to display the turbidity of the liquid as an index. According to the present invention, the turbidity of the liquid is reduced to about 1/5 to 1/2, although it varies depending on the specific object to be treated, treatment conditions, etc. In addition, the turbidity of a liquid can be measured, for example, by absorbance at 660 nm in the case of a cloudy liquid. It can also be evaluated by the ash content of the solution after the suspended solids have been separated and removed. This is because insoluble ash is one of the causes of solution turbidity, and effects such as an increase in separation efficiency can be evaluated by its dissolution or dissociation, recombination, and aggregation effects.

[0022]

[Examples] The present invention will be further explained below with reference to Examples. Example 1 A neutralized solution (solid content 3.5%, dry 100 g of ash (16.9% by weight) was stored in a pressure container and placed in a cold isostatic pressurizer (Mitsubishi Heavy Industries, MCT-150S).
When the mixture was subjected to high pressure treatment at 800 MPa for 60 minutes (50°C), a precipitate was formed and separated into a clear solution and two layers. The treated solution was centrifuged at 3000 rpm for 20 minutes to clarify the supernatant, which was collected to obtain 98 g of a clear solution. In addition, as a comparative example, a clarified liquid was obtained that was not subjected to the above-mentioned high-pressure treatment.

Since it is known that the arabinoxylan concentration in the obtained clarified liquid has a high correlation with the Brix degree, for convenience, the Brix degree of the extract was measured and used as an index of arabinoxylan. A Brix degree of 1% corresponds to 0.9% arabinoxylan. The degree of clarification was expressed by absorbance at 660 nm. In addition, the ash content in the product was measured by freeze-drying the clear liquid (based on dry weight). The results of these measurements are shown in Table 1.

[0024]

[Table 1] As is clear from Table 1, the supernatant after centrifugation was clarified by the high-pressure treatment, although the solid content hardly changed, and the ash content in the product was also reduced. That is, insoluble salts that are difficult to remove by centrifugation are dissociated, recombined, and aggregated by high-pressure treatment, making centrifugation easier. On the other hand, those that were not subjected to high pressure treatment were cloudy. Example 2 After culturing kefir grains (mixed bacterial mass of lactic acid bacteria and yeast) that produce polysaccharides in a skim milk medium for 24 hours, the kefir grains were separated, and microbial polysaccharides were extracted and separated with 1% calcium hydroxide. Neutralized with acetic acid to obtain 100 g of neutralized liquid (solid content: 2 g)
). When the aqueous solution was subjected to high pressure treatment at 700 MPa for 30 minutes as in Example 1, the extract was separated into two layers: a precipitate and a clear liquid. When this was centrifuged at 5000 rpm for 10 minutes, the supernatant liquid became clear. . 90 g of supernatant liquid was collected and the turbidity expressed as absorbance at 660 nm was 0.78.

On the other hand, the supernatant obtained without the above high-pressure treatment becomes cloudy due to lactic acid, medium components, complex salts of neutralized salts, etc., and the turbidity is 2.35. is about 1
/3. Example 3 Polysaccharides were extracted from an artificial culture of shiitake mushrooms containing rice bran and bagasse as a medium using 2% calcium hydroxide, the pH was adjusted to 4 with acetic acid, and soluble proteins were acid precipitated. After removing the precipitate, adjust the pH to 7 with sodium hydroxide and make the solution 100%
(solid content: 10 g). When this solution was subjected to high pressure treatment at 800 MPa for 30 minutes in the same manner as in Example 1, the extract was separated into two layers, a precipitate and a clear liquid.
The supernatant was clarified by centrifugation at m for 20 minutes. 85 g of supernatant liquid was collected, and the turbidity expressed as absorbance at 660 nm was 0.88.

On the other hand, the supernatant obtained without the above-mentioned high-pressure treatment becomes cloudy due to complexes of insoluble proteins, medium components, neutralized salts, etc., and this turbidity is 2.83. The turbidity was reduced to about 1/3. Example 4 Approximately 4.5 kg of a 0.5M lactic acid solution was added to 20 kg of skim milk with stirring, and the pH was adjusted to 4.5.
It was left standing at 55°C for 15 minutes. Next, the curd and whey were separated using filter paper (Whatman filter paper No. 41) to obtain about 16 kg of acidic whey. Next, the acidic whey was adjusted to pH 7.0 with a 20% sodium hydroxide solution. Acidic whey neutralization solution consists of insoluble salts (mainly calcium phosphate)
It was cloudy. When 500 g of this neutralized liquid was treated at 500 MPa for 30 minutes in the same manner as in Example 1, the neutralized liquid was separated into two layers: a precipitate and a clear liquid. This is 5000
After centrifugation at rpm for 20 minutes, about 10 g of insoluble salt water was recovered.

On the other hand, when a neutralized solution of acidic whey that had not been subjected to high pressure treatment was similarly centrifuged, the precipitate was approximately 6.
Only g was recovered and the supernatant was cloudy.

[0028]

Effects of the Invention As explained above, by applying high pressure treatment, it is possible to improve the efficiency in clarifying a suspension, particularly a useful substance suspended in an insoluble salt complex. The treatment method of the present invention is particularly used in the clarification process in which polysaccharides are extracted from natural plants and microorganisms, and the crude extract is centrifuged or filtered to dissociate and recycle fine suspended salt substances that are difficult to separate. Since they can be bound or aggregated, separation efficiency can be improved and clarification can be achieved.

Claims (3)

[Claims] Claim 1: In a suspension clarification process in which a suspended substance is separated from a suspension of an insoluble compound by filtration or sedimentation, the suspension is subjected to high pressure treatment before or during suspension separation. An improved suspension clarification method characterized by improving separation efficiency. 2. The improved clarification method according to claim 1, wherein the pressure of the high-pressure treatment is 300 MPa or more. 3. The improved clarification method according to claim 1, wherein the suspension is a polysaccharide extract, a bacterial cell extract, or milk whey.