JPH11113587A - Production of alcohol by alcoholic fermentation and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject method capable of efficiently producing an alcohol by feeding a raw material substrate solution from the upper side of a fermentation tank containing immobilized cell bodies in the tangential direction of the tank wall, providing the raw material substrate solution with a downward moving spiral flow pattern so as to move the immobilized cell bodies. SOLUTION: This method comprises the steps of: putting immobilized cell bodies 3 into a raw material substrate solution 2 in a fermentation tank 1; feeding the raw material substrate solution 2 from a liquid feeding port 4 on the upper side of the fermentation tank 1 in the tangential line of the inner wall of the tank so as to form a downward moving spiral flow pattern in the solution 2; moving the immobilized cell bodies 3 put in the tank 1 along with the spiral flow pattern to the bottom of the tank 1 and raising the cell bodied along the wall surface of a liquid suction pipe 6 to the surface so as to move them along with the spiral flow pattern again notwithstanding using no stirring paddle in the tank 1; and separating an alcohol from the resultant alcohol-containing liquid transferred through the liquid suction pipe 6 by an alcohol separator 18 comprising an alcohol solution filtration film 8, pervaporation film 9, etc., thus affording an alcohol efficiently and continuously by means of an alcoholic fermentation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for continuously producing alcohol by alcoholic fermentation using immobilized cells.

Heretofore, batch fermentation has been widely used for alcohol production from sugars, but the reaction rate is low.
There was a disadvantage that the productivity per volume of the fermenter was low. Therefore, as a method of increasing the reaction rate and increasing the productivity per fermenter, the alcohol concentration in the fermenter solution is increased in order to eliminate the inhibition of the produced alcohol reaction while increasing the sugar concentration and the bacterial cell concentration of the raw material substrate solution. Continuous fermentation methods that reduce the concentration have been developed and are being used.

[0003] As a continuous fermentation method, for example, there is a method in which bacteria immobilized on a carrier are charged into a fermentation tank and an alcohol fermentation reaction is performed in order to maintain a high sugar concentration and a high bacterial cell concentration in a raw material substrate solution. However, in this method, as the alcohol fermentation reaction proceeds, compared to the method of using the cells alone without immobilization, immobilized cells, which are aggregates of cells, are used. The immobilized cells float along with the carbon dioxide gas, and condensed on the liquid surface, causing the carriers to come into contact with each other, resulting in poor stirring efficiency, insufficient alcohol production, and insufficient substrate uptake. Thus, problems such as a reduction in the reaction rate and a risk of damage to the cells are likely to occur.

[0004] For example, Japanese Patent Application Laid-Open No. 58-149686 proposes a method for continuously producing alcohol by immobilized cells using a fluidized-bed fermentation apparatus. Japanese Patent Application Laid-Open No. 61-185180 proposes a continuous alcohol production method using immobilized cells using a horizontal coiled-tube bioreactor.

However, in the method, since the immobilized cells are packed into the fermenter at a high density, drift in the fermenter is likely to occur, and local accumulation of the produced alcohol and carbon dioxide is likely to occur. However, there was a problem that it was easily deactivated. However, there is a problem that the apparatus becomes large and the pressure loss is large because the fermenter is formed into a serpentine tube.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and disperses the immobilized cells in the fermenter without aggregating them. It is an object to provide a method for producing alcohol with high efficiency by easily releasing alcohol and carbon dioxide gas as products.

[0007]

The present applicant has previously proposed in Japanese Patent Application Laid-Open No. Hei 8-252434 a method for continuously producing alcohol by supplying a substrate from the side of a fermenter using an alcohol-producing bacterium. Furthermore, as a result of repeated studies on a continuous method for producing alcohol using immobilized cells, the present invention was reached. That is, according to the present invention, in a method for producing alcohol by alcohol fermentation using immobilized cells, a raw material substrate solution is supplied from above a fermenter in a tangential direction to an inner wall of the fermenter, and a raw material in the fermenter is supplied. A method for producing a fermentation alcohol is provided, wherein a spiral flow from top to bottom is formed in a substrate solution, and the immobilized cells are moved in the tank with the spiral flow.

Further, according to the present invention, in a method for producing alcohol by alcoholic fermentation using immobilized cells, a fermenter for alcoholic fermentation and a raw material substrate solution are placed on the inner wall of the fermenter from above the fermenter. Provided is an alcohol production apparatus including a tangential liquid supply port, an alcohol separation unit for introducing and separating an alcohol-containing liquid from the fermenter, and a sludge separation unit.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The alcohol production process of the present invention will be described below in detail with reference to the schematic process diagram of the method for producing alcohol by fermentation shown in FIG.

[0010] The fermenter preferably has a cylindrical inside, and particularly preferably has a conical bottom so that inactivated or damaged immobilized cells (hereinafter referred to as sludge) can be easily removed. The inner diameter of the fermenter 1 is not particularly limited. On the upper side surface of the fermenter 1, a liquid feed port 4 for supplying the raw material substrate liquid 2 in a tangential direction of the inner wall of the fermenter is provided. Although the liquid supply port 4 is provided in the tangential direction of the inner wall, if the liquid supply port 4 is further provided obliquely downward with respect to the horizontal direction, particularly 3 ° to 15 ° downward with respect to the horizontal direction, an effective spiral flow is generated. Is preferred. Usually, a carbon dioxide outlet 14 is provided in the upper part of the fermenter 1, and carbon dioxide produced from the immobilized cells during alcohol fermentation is released to the outside of the fermenter 1.

At the bottom of the fermenter 1, a sludge separating section 12 is provided.
Is provided. The sludge separating unit 12 is configured by providing a sludge filter 17 made of synthetic resin, metal, or the like at the bottom of the fermenter 1, for example. The hole diameter of the sludge filter 17 used in the sludge separating section 12 may be any size as long as the sludge can pass through, and is preferably 5 mesh to 100 mesh. The sludge separating section 12 is divided into two types of sludge filters 17a and 17b having different hole diameters.
Is preferable because sludge can be efficiently extracted. In particular, the first-stage sludge filter 1
7a is 5 mesh to 30 mesh, the second-stage sludge filter 17b is 10 mesh to 100 mesh, and the hole diameter of the first-stage sludge filter 17a is larger than the hole diameter of the second-stage sludge filter 17b. The hole diameter is appropriately selected so that the sludge filter 17a
And the sludge filter 17b are preferably arranged so as to provide a space in which sludge can be deposited.

Although the sludge filtered by the sludge filter 17 may be discarded as it is, if a sludge filtration membrane 13 is provided at a subsequent stage of the sludge filter 17 through a sludge extraction pipe 15 having a valve 16,
It is preferable to collect the raw material substrate solution contained in the sludge and provide a pipe so as to supply the raw material substrate solution into the fermenter 1 again from the liquid feed port, because the yield of alcohol can be improved, which is preferable.
Further, a sludge extraction pipe 15a having a valve 16a between the first-stage sludge filter 17a and a second-stage sludge filter 17b, and a sludge extraction pipe 15b having a valve 16b after the second-stage sludge filter 17b. When provided, the sludge filtered by two types of sludge filters can be separately introduced into the sludge filtration membrane 13, so that the efficiency of filtration is improved, which is preferable. The sludge filtration membrane 13 may be any membrane capable of solid-liquid separation capable of recovering the raw material substrate solution withdrawn from the sludge extraction pipe 15 accompanying the sludge, and may be a microfiltration membrane, an ultrafiltration membrane, a pervaporation membrane, or the like. It is preferably exemplified, and a microfiltration membrane is particularly preferably used.

The alcohol separating section 18 for introducing and separating the alcohol-containing liquid from the fermenter 1 may be provided with a means for concentrating alcohol. Examples of the alcohol concentration means include a distillation column, an adsorbent, a dehydrating agent, a membrane separation means for performing pervaporation or gas separation, and the like.Aromatic polyimide membranes, especially aromatic polyimide membranes composed of biphenyltetracarboxylic acids and the like A gas separation membrane and a pervaporation membrane are preferable, and the use of the pervaporation membrane 9 is more preferable because the apparatus can be simplified.

The pervaporation membrane 9 includes an alcohol selective permeation type pervaporation membrane and a water selective permeation type pervaporation membrane. Examples of the material of the alcohol selective permeation type pervaporation membrane include polyolefins of hydrophobic porous membranes such as polyethylene, polypropylene, and polybutene and copolymers thereof, and polypropylene is particularly preferably used. Alcohol selective permeation type pervaporation membranes generally have a pore size of 0.01 μm to 1.0 μm.
m and a film thickness of 40 μm to 70 μm are preferable, and in particular, the pore diameter is 0.1 μm.
The thickness is preferably from 05 μm to 0.5 μm, and the film thickness is preferably from 50 μm to 60 μm. Further, the membrane preferably has a separation coefficient α of water of 5 to 100, particularly 10 to 50, since a sufficient permeation amount can be obtained.

The separation coefficient α of alcohol to water is expressed by the following equation.

[0016]

(Equation 1)

C ₁ : Alcohol concentration in feed liquid (% by weight) C ′ ₁ : Water concentration in feed liquid (% by weight) C ₂ : Alcohol concentration in permeate (% by weight) C ′ ₂ : In permeate Water concentration (% by weight)

Further, the alcohol permeation rate of the membrane is preferably 0.5 kg / m ² · hr or more.

Examples of the water selective permeation type pervaporation membrane include an aromatic polyimide membrane, a polyvinyl alcohol membrane,
Chitosan membrane, alginic acid membrane, polyacrylonitrile membrane, cellulose acetate membrane, cellophane membrane, polyamide membrane,
An N-vinylpyrrolidone graft film, a polyvinylpyridine film, a composite film thereof, or the like can be preferably used, and an aromatic polyimide film made of biphenyltetracarboxylic acid is particularly preferable since it has long-term durability. The pervaporation membrane 9 can be used in any of a flat membrane, a spiral membrane, and a hollow fiber membrane. However, when an asymmetric hollow fiber membrane is used, the membrane has excellent mechanical strength and can increase the effective membrane area. It is particularly preferable because it is easy. Note that a condenser 10 and a vacuum pump 11 are preferably connected to the pervaporation membrane 9 for collecting alcohol.

The method of introducing the alcohol-containing liquid into the pervaporation membrane 9 of the alcohol separation section 18 is, for example, as follows.
By providing the sampling tube 6 in the fermenter 1, an alcohol-containing liquid can be introduced. The position of the tip of the sampling pipe 6 is preferably closer to the sludge separation unit 12, and the sludge separation unit 1
It is preferably located 2 to 10 mm above, preferably 2 to 3 mm above 2. Further, it is preferable to provide a filter 5 made of a synthetic resin, metal, or the like at the tip of the collection tube 6 because immobilized bacteria can be prevented from clogging the collection tube 6.
The hole diameter of the filter 5 may be larger than the size of the immobilized cells so that the immobilized cells do not pass therethrough.
00 mesh is preferably exemplified. In addition, in order to collect the alcohol-containing liquid, a liquid feeding pump 7 such as a vacuum pump may be connected to the liquid collecting pipe 6.

Furthermore, if an alcohol solution filtration membrane 8 is provided in front of the pervaporation membrane 9 in the alcohol separation section, fine solids such as detached immobilized bacteria and the like contained in the alcohol-containing liquid can be removed. It is preferable because it can be performed. The alcohol solution filtration membrane 13 may be any membrane capable of solid-liquid separation, such as an ultrafiltration membrane, polyacrylonitrile, polysulfone, polyethylene, polypropylene, polytetrafluoroethylene, cellulose acetate, polycarbonate, polyvinylidene fluoride, ceramic, etc. Any of a filtration membrane and a pervaporation membrane such as polyolefin represented by polyethylene and polypropylene can be used. Among them, a microfiltration membrane is preferable, and a microfiltration membrane made of ceramic is particularly preferably used. It is preferable to provide a pipe so that the substrate solution recovered by the pervaporation membrane 9 or the alcohol solution filtration membrane 8 is again supplied from the liquid feed port into the fermenter 1 because the yield of alcohol can be improved. .

Hereinafter, the alcohol production method of the present invention will be described.
Detailed description will be given in accordance with a schematic explanatory process diagram of the alcohol production process by the fermentation method shown in FIG. In the present invention,
As the cells, yeasts and anaerobic bacteria having an alcohol-producing ability are used, but yeasts are generally preferably used. Yeast and anaerobic bacteria may be used alone or in combination of two or more.

Examples of yeast include Saccharomyces cerevisiae and Saccharomyces
Ubalam (Saccharomyces uvarum), Saccharomyces
Formocensis (Saccharomyces formosensis), Saccharomyces Carlsbergensis (Saccharomyces c
arlsbergensis) and other Saccharomyces
A genus yeast, Zygosaccharomyces japonica (Zygosa
Yeasts belonging to the genus Zygosaccharomyces such as ccharomyces japonicus and Zygosaccharomyces soya, Chizosaccharomyces mellacei, Chizosaccharomyces pombe (Chizosac)
e) Chizosaccharomyces such as
Genus yeast. Zymomonas is an anaerobic bacterium
Mobilis (Zymomonas mobilis), Clostridium
Thermohydrosulfuricam (Clostridium thermohydr
osulfuricum), and Saccharomyces cerevisiae is particularly preferably used.

The method of immobilizing cells is roughly classified into a carrier binding method in which cells are bound to a water-insoluble carrier and immobilized, and a cross-linking method in which cells are cross-linked and immobilized using a crosslinking agent. There are three types of gel encapsulation method of entrapping and immobilizing in a hydrophilic gel, and the immobilized cells may be prepared by any of the immobilization methods. As the carrier used in the carrier binding method,
Activated carbon, zeolite, alumina, aluminum silicate, zirconia, titania, silicon nitride, porous inorganic substances such as silicon carbide, cellulose, agarose, dextran, chitin, collagen, tannin, nylon, amino acid polymer, polyacrylamide, polystyrene, polyvinyl alcohol, Organic polymer substances such as ion exchange resins are exemplified. Examples of the cross-linking agent used in the cross-linking method include glutaraldehyde, hexamethylene diisooctinate, and a maleimide derivative.

The hydrophilic gel of the carrier used in the gel entrapping method includes porous epoxy resin, nylon microcapsules, unsaturated polyester microcapsules, acetic acid.
Cellulose butyrate microcapsules, polyacrylamide gel, sodium alginate gel, calcium alginate gel, low methoxy pectin gel, carrageenan gel,
Examples include agar gel, egg white gel, gelatin, collagen, silica gel and the like. As the carrier for immobilizing the cells, a spherical carrier having a particle size of 0.5 mm to 5 mm, preferably 2 mm to 4 mm is suitably used. If the carrier is too small, the rate of breakage of the cells due to contact between the carriers or the wall in the fermenter increases, while if it is too large, the total surface area cannot be increased and the reaction efficiency deteriorates. It is preferable that the immobilized cells contain 5 to 30% by weight of the cells, especially 10% by weight.
% By weight is preferred. If there are too few cells,
The efficiency of the alcohol production reaction becomes poor, and if it is too much,
Since the distance between the cells is short, the production of alcohol is inhibited. As a raw material substrate, various saccharide raw materials such as molasses, beet molasses, and starch saccharified solution are used.

In carrying out the present invention, the immobilized cells 3 are charged into the raw material substrate solution 2 in the fermenter 1, and the fermenter 1
The raw material substrate solution 2 is supplied in a tangential direction to the inner wall of the fermenter 1 from the liquid feed port 4 at the upper part of the fermenter 1 to generate a spiral flow of the raw material substrate solution 2 from top to bottom. By causing the fermenter 1 to form a spiral flow, the immobilized cells charged in the fermenter 1 ride on the spiral flow without stirring the inside of the fermenter 1 with stirring blades. It goes to one bottom, and when it has a sampling tube 6, it rises above the liquid surface along the wall surface of the sampling tube 6, and rides again on the spiral flow of the raw material substrate solution 2. By generating a spiral flow of the raw material substrate solution 2, the raw material substrate solution 2 is sufficiently taken in while the immobilized bacterial cells 3 disperse without aggregating, and moved in the fermenter 1 to efficiently perform the alcohol fermentation reaction. It can be performed.

The concentration of immobilized cells in the raw material substrate solution in the fermenter 1 is preferably from 6 g / liter to 25 g / liter, particularly preferably from 10 g / liter to 20 g / liter. If the concentration of the immobilized cells is too low, the fermentation efficiency is poor. However, if the concentration is too high, the damage due to the contact between the immobilized cells and the incorporation of the substrate become difficult, so that the fermentation efficiency is reduced. The fermentation reaction is usually performed at a temperature of 10 to 35 ° C,
The reaction time is between 24 and 72 hours. It is appropriate that the pH in the fermenter 1 is maintained at 4 to 6. The supply rate of the raw material substrate solution 2 varies depending on the supply amount, the immobilized cells, the size of the fermenter 1 and the like, but is 1 liter / min. ~ 1
0 l / min, preferably 2 l / min.
~ 5 liters / min. Is mentioned. If the supply rate is too high, the cells may be damaged due to collision between the immobilized cells or the inner wall of the fermenter 1, and if the supply rate is too low, a sufficient spiral flow cannot be formed.

In carrying out the fermentation reaction, it is preferable that the concentration of the raw material substrate in the fermenter 1 is maintained at 5 to 15% by weight. If the raw material substrate concentration exceeds 15% by weight, the substrate concentration is inhibited, such as a decrease in fermentation rate and the life span of the immobilized cells. If the concentration is too low, the fermentation efficiency is reduced. On the other hand, since the cells are also subject to product inhibition, the fermenter 1
It is necessary to keep the alcohol concentration in the inside low. For this reason, it is preferable to continuously withdraw the alcohol solution from the liquid collection tube 5, and the withdrawal speed is particularly preferably 60% to 100% / min. Of the total amount of the alcohol solution in the alcohol production apparatus. The alcohol separation unit 18 separates the alcohol solution into a high-concentration alcohol solution and a low-concentration alcohol solution (hereinafter, referred to as a recovery liquid), and obtains a high-concentration alcohol solution that reaches, for example, 30% by weight to 50% by weight from the condenser 10. . By returning the recovered liquid to the fermenter 1 again, the alcohol concentration in the fermenter 1 can be maintained at a preferable concentration of 3% by weight to 8% by weight, the efficiency of alcohol fermentation can be increased, and the recovery cost can be reduced. Here, the alcohol concentration in the fermenter 1 is 8
When the content is more than 3% by weight, product inhibition such as a decrease in fermentation speed or the life of the immobilized cells occurs.

Since the immobilized bacterial cells 3 inactivated or damaged in the fermenter 1 do not produce carbon dioxide, they settle to the bottom by their own weight and are introduced into the sludge separating section 12 as sludge. The sludge separation unit 12 has two types of filters 1
7, the relatively large sludge settled between the first-stage large-diameter filter 17a and the second-stage small-diameter filter 17b, and passed through the second-stage filter 17b. Fine sludge settles at the bottom. Precipitated sludge is appropriately removed and filtered through a sludge filtration membrane 13. The saccharified liquor of the filtrate is returned to the fermenter 1 as a raw material substrate solution, so that the waste liquid can be reduced and the sludge can be discarded as a solid. It is preferable because the rate can be increased. Two types of filters 1
When using No. 7, the removal of sludge is performed by using the valve 16
It is preferable to separately provide the extraction pipes 15a and 15b having the above, and alternately extract and introduce the filtration into the sludge filtration membrane 13 to perform filtration in a short period of time.

[0030]

【Example】

Example 1 2.3 g of sodium alginate dissolved in 72.5 g of pure water was mixed with dried yeast Saccharomyces cerevisiae (S
accharomyces cerevisiae)
g was mixed with the mixture to prepare a dope solution. 5
A dope solution was dropped from a 3 mm inner diameter tube at a rate of 25 seconds / drop into a 5% by weight calcium chloride aqueous solution adjusted to a temperature of 2 ° C., with a sphere diameter of 2 mm and a cell concentration of 17% by weight in the immobilized cells. Sodium alginate entrapping immobilized cells were prepared. Apparatus similar to the process shown in FIG. 1, inner diameter 200 mm,
Contents 3 liters, cylindrical fermenter 1 with a conical bottom
Raw material substrate solution 2 having a liquid temperature of 30 ° C. and a molasses concentration of 15% by weight
And 4.5 liters of the sodium alginate-incorporated immobilized bacterial cells 3 (equivalent to 37.5 g of dry yeast) were added, the concentration of the immobilized bacterial cells in the raw material substrate solution was set to 13 g / liter, and the temperature was maintained at 30 ° C. From the liquid feed port 4 (inner diameter 15 mm) provided on the liquid surface at the top of the fermenter 1, 3.0 liter / min. The raw material substrate solution 2 is supplied at a flow rate and a temperature of 30.
The alcohol fermentation reaction was continuously performed at ℃. The fermentation liquor was collected at a rate of 3.0 liter / m from a collection tube 6 formed of a stainless steel filter (having a hole diameter of 100 mesh) at the lower part of the fermenter 1.
in. The liquid was sampled and guided to a ceramic multi-tube microfiltration membrane 8 by a liquid sending pump 7 to filter fine solids contained in the collected alcohol-containing liquid. Further, a porous polypropylene hollow fiber membrane module (a pore diameter of 0.1 μm, a film thickness of 55 μm, a membrane area of 0.50 m ² , a permeation speed of 5.0 kg / m ² · hr, a separation coefficient α (EtOH / H ₂ O) = 10)
And the permeate side is 5 to 10 Torr by a vacuum pump 11.
Was sucked. Ethanol vapor obtained from the permeation side is liquefied in the condenser 10, and a 30 wt% ethanol solution 800 ml / 12 hr. I got The raw material substrate solution recovered from the non-permeate side of the alcohol solution filtration membrane 8 and the pervaporation membrane 9 was supplied again to the fermenter 1 from the liquid feed port 4. At the bottom of the fermenter 1, a stainless steel sludge filter 17a (hole diameter 5 mesh) and a stainless steel sludge filter 17b (hole diameter 50 mesh) are provided.
, And two sludge filters 15a and 15b each having a valve. The sludge settled at the bottom of the fermenter 1 is alternately opened every six hours by opening the valve 16a or 16b, and passing through the sludge extraction pipe 15a or 15b, through a sludge filtration membrane 1 made of a ceramic multi-tube microfiltration membrane.
3, the raw material substrate solution recovered from the permeate side was again supplied to the fermenter 1 from the liquid feed port 4, and the sludge having a reduced water content obtained on the non-permeate side was discarded.

Comparative Example 1 An apparatus similar to the one shown in FIG. 2, that is, the fermenter 1 has a spherical shape with a content of 3 liters, the fermenter 1 is provided with a stirrer 19, The same apparatus as in Example 1 was used except that the outlet 14 was not provided. 4 liters of the raw material substrate solution 2 is placed in the fermenter 1 and the stirrer 19 provided in the fermenter 1 is set at 50 r.
p. m, and the alcoholic fermentation reaction was carried out in the same manner as in Example 1 except that the raw material substrate solution 2 was supplied from the upper part of the fermenter 1 at a substantially right angle to the horizontal plane (liquid level). From the permeate side of the pervaporation membrane 9, 500 ml of a 20% by weight ethanol solution / 12 hr. I got During the reaction, the immobilized cells 3 rise to the surface of the liquid,
Was not taken into the liquid even if it rotated.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory process diagram of an alcohol production process by a fermentation method of the present invention.

FIG. 2 is a schematic explanatory process diagram of an alcohol production process by a conventional fermentation method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fermenter 2 Raw material substrate solution 3 Immobilized microbial body 4 Liquid supply port 5 Filter 6 Sampling tube 7 Liquid supply pump 8 Alcohol solution filtration membrane 9 Pervaporation membrane 10 Condenser 11 Vacuum pump 12 Sludge separation part 13 Filtration membrane for sludge 14 Carbon dioxide outlet 15, 15a, 15b Sludge extraction pipe 16, 16a, 16b Valve 17, 17a, 17b Filter for sludge 18 Alcohol separator 19 Stirrer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C12R 1: 865)

Claims (3)

[Claims] In a method for producing alcohol by alcohol fermentation using immobilized cells, a raw material substrate solution is supplied from above the fermenter in a tangential direction to the inner wall of the fermenter, and the raw material substrate solution is supplied to the raw material substrate solution in the fermenter. A method for producing a fermentation alcohol, comprising: forming a spiral flow from top to bottom, and moving the immobilized cells in the tank with the spiral flow. 2. A method for producing alcohol by alcohol fermentation using immobilized cells, comprising: a fermenter for performing alcohol fermentation; and a feeder for supplying a raw material substrate solution from above the fermenter in a direction tangential to the inner wall of the fermenter. An alcohol production apparatus comprising a liquid port, an alcohol separation unit for introducing and separating an alcohol-containing liquid from the fermenter, and a sludge separation unit. 3. The alcohol production apparatus according to claim 2, wherein the sludge separating section comprises two types of filters having different hole diameters.