JP2558185B2 - Solid-liquid separation method for microbial culture - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-liquid separation method for a microbial culture solution, and is applied to the fermentation industry and the like.

[0002]

2. Description of the Related Art Since the size of microorganisms is extremely small, 1 to 10 .mu.m, various pretreatment methods have been proposed for efficient separation from a culture solution. For example, Japanese Patent Publication 53-25
JP-A-49-128474 and JP-A-51-128474 disclose a technique of adding a polymer flocculant.
Japanese Patent No. 86584 discloses a technique of adding a metal salt such as an iron salt, an aluminum salt, or a calcium salt. Further, JP-A-49-133584 discloses a combined use technique of an inorganic salt and a polymer flocculant. The technique of adding a porous non-swelling solid such as diatomaceous earth or perlite as a filter aid is widely known.

[0003]

[Problems of the prior art] The method using a filter aid such as diatomaceous earth has many problems in terms of chemical cost and solid waste because the amount of the filter aid added is large. In the method of using a flocculant such as a polymer flocculant or an inorganic salt, the setting of flocculation conditions is delicate, and the water content of the dehydrated cake is high and sticky. Also, it is not a proper shape. An object of the present invention is to obtain a dehydrated cake that is stable and easy to dispose of at a low cost when performing solid-liquid separation of a microorganism culture liquid.

[0004]

[Means for Solving the Problems] The present invention is configured as follows to achieve the above object. The present invention is characterized in that after adding bentonite to a microbial culture solution, a polymer flocculant is added to cause flocculation and a dehydration operation is performed. Further, in the present invention, the pH of the microorganism culture solution at the time of adding the polymer flocculant is 2.0 to 4.0.
It is characterized by Further, the present invention is characterized in that the amount of bentonite added is 5 to 100% by weight based on the solid suspension in the microorganism culture solution.

[0005]

Since the microbial cells are composed of proteins, they are negatively charged at a pH above the isoelectric point and have a pH below the isoelectric point.
At, it is positively charged. Since bentonite is negatively charged, it is electrically coupled to microorganisms in a low pH state. Bentonite loses its swelling property due to an ion exchange action in a low pH state. The suspension thus coagulated easily aggregates with the polymer flocculant to form flocs with good dehydratability. Bentonite is non-toxic and can be used as feed. Compared with filter aids such as diatomaceous earth, it is effective with a small addition amount, and the chemical cost is low.

[0006]

[Examples] A microbial culture solution which is the subject of the present invention is prepared by culturing yeast, mold, bacteria, etc.
It is generated in the process of producing enzymes and antibiotics. For solid-liquid separation of the culture broth, a pressure filter such as a belt press or a filter press, a vacuum filter such as a belt filter or an Oliver filter, or a known dehydrator such as a centrifuge such as a decanter is used. I can do things.

The bentonite used in the present invention is preferably fine particles having a high swelling property, but commercially available bentonite can be used without any trouble. It is most convenient to use the added form as a slurry of 5 to 10%, but it is also possible to directly add the powder, and any adding method can be selected.

As the polymer flocculant used in the present invention, known substances commercially available as water treatment chemicals can be used.
Examples of the anionic polymer include acrylamide / acrylate copolymer, acrylamide / acrylamide 2-methylpropanesulfonate, polyacrylate, and the like.
As the cationic polymer flocculant, a (co) polymer of a cationic monomer such as a salt or quaternary salt of dialkylaminoalkyl (meth) acrylate or a salt or quaternary salt of dialkylaminoalkyl (meth) acrylamide,
Examples thereof include polydimethyldiallylammonium chloride, chitosan, Mannich modified products of polyacrylamide, and polyvinylamine.

When the anionic polymer flocculant and the cationic polymer flocculant are used in combination, the cohesive force increases and the floc strength increases. The addition amount is about 0.1 to 2.0% by weight based on the solid suspension, and is appropriately selected depending on the aggregation state.

By adding a polyvalent metal salt of iron, aluminum, calcium, magnesium or the like before adding the polymer flocculant, it is possible to perform the flocculation treatment even at a pH of 4 or more, but the dehydration In some cases, deterioration or contamination with metals may be a problem, and pH adjustment with an acid is most preferable as a non-swelling means for bentonite. The pH may be adjusted before or after the addition of bentonite. Specific examples will be shown below.

Example 1 Candida utilis was cultivated using a culture solution containing glucose, yeast extract, and nutrient salts, and a suspension containing suspended cells and having a solids concentration of 5.2% at pH 6.6. Got
200 ml of the main culture solution was placed in a glass beaker having a volume of 300 ml, pH was adjusted with sulfuric acid or caustic soda, bentonite was added, and the mixture was stirred at a stirring intensity of 150 rpm for 1 minute. Then, a polymer flocculant was sequentially added to 150 rp.
Stir for 20 seconds at m. The diameter of the flock formed at this time is measured. The bacterial cell culture liquid thus aggregated was placed in a Buchner funnel having a diameter of 7 cm. The filter paper of No. 2 is filtered, and the time required to obtain 100 ml of filtrate under a reduced pressure of 700 mmHg is measured. The bentonite used in this experiment was Kunigel V1 manufactured by Kunimine Sekika Kogyo Co., Ltd.
The dispersion was adjusted. The polymer coagulant is an anionic polymer coagulant Hymolok S manufactured by Kyoritsu Organic Industry Research Institute Co., Ltd.
S-120 and cationic polymer flocculant Hymolok M
P-173H, each of which was dissolved in 0.1% before use. Hymolok SS-120 is a polyacrylamide partial hydrolyzate (anionization rate 40 mol%, intrinsic viscosity 25 dl / g), and Hymolok MP-173H
Is polymethacryloyloxyethyltrimethylammonium chloride (intrinsic viscosity 5.4 dl / g). The experimental results obtained are shown in Table 1. Margins below this page

[0012]

[Table-1] Amount of flocculant added MP-173H 300ppm SS-120 50ppm Note) When no coagulant was added, filtration was impossible regardless of whether bentonite was added.

Example 2 The same coagulation filtration experiment as in Example 1 was carried out using the distillation residue (suspended solids concentration 3.9%) discharged from the barley shochu manufacturing process as a sample. The polymer flocculants used were the cationic polymer flocculant Hymolok MP-173H (described above) and the anionic polymer flocculant Hymolok SS-190 (polyacrylic acid soda) manufactured by Kyoritsu Organic Industry Research Institute Co., Ltd. It has an intrinsic viscosity of 15 dl / g). The dissolved concentration was adjusted to 0.2% and used. Table of the obtained experimental results
It is shown in FIG.

[0014]

[Table-2] Flocculant addition amount MP-173H 150ppm SS-190H 50ppm

[0015]

As is clear from Tables 1 and 2, the floc diameter increases and the filtration time decreases as the amount of bentonite added increases. The aggregation effect is particularly remarkable in the range of pH 2.0 to 4.0. Due to this aggregation effect, solid-liquid separation of the microorganism culture liquid can be performed with a simple device.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area C12R 1:72)

Claims (3)

(57) [Claims] 1. A solid-liquid separation method for a microorganism culture liquid, which comprises adding bentonite to a microorganism culture liquid, then adding a polymer flocculant to cause aggregation, and performing a dehydration operation. 2. The p of the microbial culture solution when the polymer flocculant is added.
H is 2.0-4.0, The solid-liquid separation method of the microorganism culture solution of Claim 1 characterized by the above-mentioned. 3. The method for solid-liquid separation of a microbial culture solution according to claim 1, wherein the amount of bentonite added is 5 to 100% by weight based on the solid suspension in the microbial culture solution.