JP2002336818A - Method for treating processing residue of mollusk food, treatment process and treatment device used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for removing harmful metals in a food processing residue of mollusk such as guts of scallops with high efficiency without requiring a large-scale facility to such a degree that the residue can be used not only as animal feed but as nutritional supplements and foods. SOLUTION: The food processing residue of mollusk containing harmful metal ions is immersed in a diluted acid aqueous solution. The immersion liquid flowing and separating from the food processing residue of mollusk is brought into contact with water-resistant chelate fibers so as to adsorb the harmful metal ions in the immersion liquid to remove.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to cadmium, marine wastes produced during processing of fish and shellfish such as scallop offal and squid offal, and the like.
How to remove and detoxify harmful metals such as zinc and mercury,
The present invention relates to a treatment process and an apparatus used for the treatment process.

[0002]

2. Description of the Related Art In the Aomori region of Hokkaido, a large amount of scallop is cultivated for use as food, but only scallop is used for scallop in scallop, and other portions are Disposed as marine waste.

[0003] However, since the visceral part of the scallops, the so-called uro, contains the harmful metal cadmium, it cannot be dumped as it is due to environmental pollution. In addition, since this part contains a lot of nutrients, it has been attempted to use it as a suitable raw material for nutrients, foods, feeds, etc.
Not yet realized.

[0004] For this reason, scallop shells generated in large quantities every year are discarded by the incineration method and the carbonization method.
These methods require large-scale equipment and large amounts of energy, and have the problem of causing crop damage due to dioxin and metal vapor in the combustion gas. Was desired.

In order to solve such a problem, uro has been immersed in dilute sulfuric acid to elute heavy metals therein, and then the eluate is brought into contact with a strongly acidic cation exchange resin and adsorbed thereon. Removal method (Japanese Unexamined Patent Publication No. 9-21713)
No. 1) and a method of extracting uro with an electrolyte solution and then performing electrolysis (Japanese Patent Application Laid-Open No. 8-99001). However, the method using a strongly acidic cation exchange resin has low efficiency and is not practical, and the method using electrolysis requires a large-scale facility for treating urethane discharged in large quantities, and requires a large amount. However, this method is not always satisfactory.

[0006]

SUMMARY OF THE INVENTION Under such circumstances, the present invention overcomes the drawbacks of the conventional method, does not require large-scale equipment, and is efficient, like a scallop shell. It is an object of the present invention to provide a method capable of removing harmful metals in processed mollusc food residues to the extent that they can be used as nutrients and foods as well as animal feed.

[0007]

Means for Solving the Problems The present inventor efficiently and
In addition, intensive studies have been made on methods for removing harmful metals from mollusc tissues at low cost.The mollusc tissues are first pressed with a press roll, and the treated product is eluted with a dilute acid aqueous solution. By contacting a strongly cationic ion exchange fiber with
A method for removing heavy metals with a 0-fold efficiency has been proposed (Japanese Patent Application Laid-Open No. 2001-54783).

However, as a result of further research,
The scallop uro has a cadmium ion of 7 to 30 ppm and a zinc ion of 20
Besides ~ 100ppm, 400 ~ of cadmium ion
It contains an alkali metal ion (K ⁺ + Na ⁺ ) in an amount of 600 times and 80 to 200 times the zinc ion. In both the electrolytic method and the ion exchange method, the alkali metal ion is
Along with the cadmium ion and zinc ion, they are deposited on the electrode or adsorbed on the ion exchanger, so that the efficiency of removing cadmium and zinc is remarkably reduced.Therefore, the presence of monovalent ions such as alkali metal ions Even below, it has been found that the use of a chelating fiber that can preferentially adsorb only divalent ions such as cadmium ions and zinc ions as an adsorbent material can improve the removal effect and reduce the number of column replacements. The present invention has been accomplished based on this finding.

That is, according to the present invention, a mollusc food processing residue containing harmful metal ions is immersed in a dilute acid aqueous solution, and then an immersion liquid flowing out and separated from the mollusk food processing residue is brought into contact with a water-resistant chelate fiber, A processing method for removing harmful metals from mollusc food processing residues, characterized in that harmful metal ions in the adsorbed and removed therefrom,
(1) A first step of immersing mollusc food processing residues containing harmful metal ions in a dilute acid aqueous solution to elute harmful metal ions, and (2) a second step of flowing out the immersion liquid while leaving soft solids.
Step (3) Third step of adjusting the immersion liquid discharged in (2) to pH 5.5 to 9.0 with alkali, (4) pH
The adjusted immersion liquid is brought into contact with the water-resistant chelate fiber,
A fourth step of adsorbing and removing harmful metal ions and discharging the detoxified treated water; (5) a fifth step of cutting the membrane structure of the soft solids left in the second step, (6) A sixth step of squeezing the soft solid cut in the fifth step to squeeze the liquid component, (7) a seventh step of removing the solid content from the squeezed liquid of the sixth step and adjusting the pH, (8) Eighth step in which the pH-adjusted extract is brought into contact with the water-resistant chelate fiber to adsorb and remove harmful metal ions therein, (9) The extract from which the harmful metal ions have been removed is evaporated and concentrated to be harmless. A harmful metal-containing mollusc food processing residue treatment process comprising a ninth step of obtaining a useful concentrate, a dip tank having a liquid drain hole and a mollusk food processing residue outlet at the bottom, PH control tank and water resistant chelate fiber filling A ram is arranged in series, and a membrane cutting machine, a pressing machine, a filter, a pH adjustment tank, a water-resistant chelate fiber packed column, and an evaporator are arranged in series by being connected to the mollusk food processing residue outlet. It is an object of the present invention to provide an apparatus for treating mollusk food processing residues.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is used for removing harmful metals from various fish and shellfish tissues, and is particularly useful for mollusc tissues containing harmful metal ions, such as scallop and squid visceral parts. Suitable to remove and detoxify harmful metal ions contained in what is treated as marine waste

[0011] Scallop cultivation is carried out, for example, in Hokkaido at an annual production of about 500,000 tons, and accompanying this, 100,000 to 170,000 tons of marine waste mainly containing organs such as sea urchin per year. Is discharged. In the method of the present invention,
In addition to uro discharged in such a large amount, squid viscera, which is discarded without being used, so-called goro, can be used as a raw material.

FIG. 1 is a schematic anatomical view of a scallop. The visceral parts, ie, the mid-mesentery, heart, gonads, and mantle (commonly referred to as “strings”), vary depending on the place of production and the time of collection.
Cadmium ion of 7 to 30 ppm, 20 to 100 pp
m of zinc ions and trace amounts of mercury. In the present invention, the whole visceral portion including the string can be used as a raw material.

Most of these metal ions are usually bound to proteins constituting living tissues and cannot be removed by adsorption treatment as they are. Upon immersion, metal ions bound to the protein are released from the protein and eluted through the membrane tissue into the dilute aqueous acid solution.

Therefore, in the method of the present invention, it is necessary to first immerse the mollusc food processing residue containing harmful metal ions in a dilute acid aqueous solution. As the dilute acid aqueous solution, a dilute aqueous solution of an inorganic acid such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid is preferable.If desired, a dilute aqueous solution of an organic acid such as oxalic acid, chloroacetic acid, lactic acid, citric acid, and succinic acid is used. It can also be used. As the concentration of this diluted acid aqueous solution,
A range of 0.05 to 0.5 molar is appropriate. If the concentration is lower than this, sufficient immersion treatment is not performed, and if the concentration is higher than this, the remaining acid interferes with the subsequent treatment.

The immersion treatment with the dilute acid aqueous solution is performed by immersing the as-collected or steamed mollusk food processing residue in a dilute acid aqueous solution for 3 to 24 hours. At this time, if the amount of the dilute acid aqueous solution is too small, the elution of harmful metal ions becomes insufficient, and if the amount is too large, the handling of the eluate in the subsequent step becomes complicated, so the amount of the dilute acid aqueous solution used is About 1 to 5 times is appropriate based on the On the other hand, if the immersion time is shorter than 3 hours, the harmful metal ions bound to the protein will not be sufficiently eliminated, so that the final harmful metal ion concentration cannot be sufficiently reduced. Further, even if it is longer than 24 hours, the elution amount of the harmful metal ion hardly changes, and only the extraction efficiency decreases. In this case, if desired, the time can be reduced by vibration, stirring, or the like.

Next, solid-liquid separation is carried out to flow out and separate the immersion liquid, leaving the immersion-processed mollusk food processing residue. This may be done through a coarse-grained filter if desired, but can usually be done simply by simply decanting.

In the method of the present invention, the immersion liquid that has flowed out and separated from the mollusc food processing residue in this manner is subjected to pH adjustment.
After being adjusted to 5.5 to 9.0, for example, by passing through a column filled with water-resistant chelate fibers, the column is brought into contact with the water-resistant chelate fibers, and the harmful metal ions therein are adsorbed, thereby causing a cause of environmental pollution. Remove and drain. The chelate fiber used at this time is a synthetic fiber having a chelate-forming group, and in the method of the present invention, it is necessary to use a water-resistant fiber. The following chelating groups are known.

(1) aliphatic diol compound residue;

Embedded image (2) 1,3-dicarbonyl compound residue;

Embedded image A residue represented by the formula: (3) a polycarbonyl residue;

Embedded image A residue represented by the formula: (4) an aromatic hydrocarbonyl residue;

Embedded image A residue represented by the formula: (5) an aliphatic amine residue;

Embedded image A residue represented by: (6) a dioxime compound residue;

Embedded image (7) a pyrrole compound residue;

Embedded image A residue represented by the formula: (8) a peptide residue; for example, a residue such as a glutamyl group, an asparagyl group, a histidyl group, a tyrosyl group; (9) an aminophenol residue;

Embedded image (10) oxygen and nitrogen-containing heterocyclic compound residues;

Embedded image A residue represented by the formula: (11) an azo compound residue;

Embedded image A residue represented by the formula: (12) an iminoacetic acid residue;

Embedded image A residue represented by the formula: (13) a thioalcohol residue;

Embedded image A residue represented by the formula: (14) a thiophenol residue;

Embedded image A residue represented by the formula: (15) a thiourea residue;

Embedded image A residue represented by the formula: (16) a phosphate residue;

Embedded image The residue represented by

Of these, residues which form a chelate bond with Cd and Zn but which do not form a chelate bond with an alkali metal, for example, the above-mentioned residues (4), (5) and (1)
0), (12) and (13) are preferred. These chelate-forming groups are used in a free form (H ⁺ form), but a salt with a monovalent metal ion (eg, Na ⁺ form) becomes free form in the presence of an acid and binds to a divalent metal ion. Can be.

The chelate fiber used in the method of the present invention may be prepared by introducing a chelate-forming group into a hydrolyzate of polyvinyl acetate or a copolymer of alkylene and vinyl acetate via a ketal bond or an ester bond. Styrene or divinylbenzene is copolymerized with a styrene derivative having a chelate-forming group to produce a polymer compound having a chelate-forming group, which is then spun according to a conventional method.

The fiber obtained by spinning in this manner is
Used alone or as desired, mixed with fibers of a polymer compound having no chelate-forming group such as polyester, for example, polyethylene terephthalate, polyamide, for example, nylon, or recycled fiber, for example, rayon, or molded into a knitted or woven or nonwoven fabric Used as The mixing ratio with the polymer compound having no chelate forming group is preferably in the range of 3:10 to 10: 3 by mass ratio.

This fiber has a diameter of 20 to 60 μm,
It is used as a continuous system or cut to a length of about 2 to 50 mm. The chelate fiber varies depending on the type and content of the chelate-forming group, but can usually adsorb 100 to 200 meq of cadmium ions per gram thereof.

In the method of the present invention, a chelate fiber is processed into a long non-woven fabric and rolled and formed into a cylindrical unit, or a plurality of circularly cut non-woven fabrics are laminated to form a unit. It is advantageous to use, as the adsorbent, one that is exchangeably mounted in the adsorption column.

The conditions for passing the immersion liquid through the adsorbent are preferably in the range of pH 5.5 to 9.0, liquid temperature of 10 to 30 ° C., and liquid flow rate (SV value) of 5 to 30. At this time, it is preferable that the passage of the liquid is promoted by applying pressure from above the liquid holding portion or suctioning from below the adsorbent layer, and the flow rate is adjusted using a flow meter.

On the other hand, as described above, the mollusc food processing residue from which the immersion liquid has been removed by solid-liquid separation still contains harmful metal ions bonded to proteins in living tissues and harmful metal ions attached to tissues. It needs to be removed. For this reason, if necessary, after cutting the tissue membrane covering the built-in surface of the mesenteric glands, gonads and the like into appropriate dimensions, for example, squeezing with a screw press or pressing roll, attrition mill Trituration, micronization with a homogenizer, and the like are performed to separate the body fluid in the tissue and the fluid attached to the tissue contained in the mollusc food processing residue from the tissue.

Next, the separated liquid thus treated and a tissue such as a membrane component are subjected to solid-liquid separation to remove solids which hinder contact with the water-resistant chelate fiber adsorbent. This solid-liquid separation can be performed, for example, by filtration or centrifugation. In addition, if oxygen is present during the process of removing the harmful metal ion-containing liquid from the mollusc food processing residue or the solid-liquid separation process, the tissue is altered, so that oxygen is not present as much as possible, such as nitrogen. It is preferably performed in an atmosphere of an inert gas.

The separated liquid from which solid content has been removed in this manner is brought into contact with the water-resistant chelate fiber to adsorb and remove harmful metal ions. Since this separation liquid does not contain alkali metal ions, strong cation exchange fibers can be used instead of water-resistant chelate fibers for the adsorption and removal of the harmful metal ions. Next, the separated liquid thus treated is concentrated by evaporation to obtain a pale brown paste containing important nutrients such as proteins, amino acids and polyunsaturated fatty acids. The Cd content of this paste is 0.1 ppm, and it can be used not only as animal feed and fertilizer but also as a food material and a nutrient material. Also, when the steam generated during the above evaporation and concentration is cooled and condensed,
Pure water containing no impurities is obtained.

In the method of the present invention, the processed raw material of mollusks, which is a raw material, may be washed with a large amount of water in advance to remove alkali metal ions contained therein. Since amino acids and other water-soluble useful components contained in raw materials are eluted and cannot be recovered, they should be avoided when aiming for their effective use.

When the chelate fiber used to adsorb harmful metal ions in the method of the present invention reaches a saturated state, it is eluted with an aqueous acid solution having a pH of 3.5 or less, preferably 2.0 to 3.5. Can be played back and used repeatedly. As the aqueous acid solution for elution at this time, for example, an aqueous solution of sulfuric acid having a concentration of 0.5 to 2 mol is suitable, and in addition, an aqueous solution of hydrochloric acid, nitric acid, phosphoric acid, oxalic acid, chloroacetic acid, citric acid or the like may be used. it can.

Next, an example of a series of processes for processing mollusk food processing residues using the method of the present invention will be described with reference to the accompanying drawings. FIG. 2 is a block diagram of this treatment process. For example, in the first step, the raw material and the dilute raw material are placed in a dip tank provided with a liquid drainage hole and an outlet for a dipped mollusk food processing residue at the bottom. A mixture with an acid aqueous solution is accommodated to release and elute harmful metal ions in raw materials. The liquid temperature at this time is 10 to 30 ° C.
The immersion time is about 10 to 40 hours. In this case, elution of harmful metal ions can be promoted by heating, stirring, or adding vibration.

Next, in the second step, the immersion liquid is separated from the soft solids, that is, the processing residue of the mollusk food, by decantation or coarse filtration, and treated according to different steps. That is, the immersion liquid is sent to the third step, and is adjusted to pH 5.5 to 9.0 with an alkali such as sodium hydroxide or potassium hydroxide.
In the process, harmful metal ions are adsorbed and removed by contact with the water-resistant chelate fiber. The contact with the water-resistant chelate fiber is advantageously performed by passing an immersion liquid through a column packed with the water-resistant chelate fiber. The liquid passing conditions at this time are a liquid temperature of 10 to 30 ° C., a liquid passing speed (SV value) of 5 ° C.
The range of ~ 30 is preferred. By contact with this water-resistant chelate fiber, 97% by mass or more of Cd and Zn in the immersion liquid is removed, and their contents become 1 ppm or less. Therefore, the liquid treated in this way is not regulated at all. Can be drained.

On the other hand, the mollusk food processing residue from which the immersion liquid has been removed in the second step is sent to the fifth step, where the membrane tissue is cut into appropriate dimensions. This cleavage releases harmful metal ions bound to proteins in the tissue and facilitates passage through membrane tissue, and during subsequent squeezing,
This is for facilitating biting into the roll.

The processed mollusk food residue thus cut is then squeezed in a sixth step to sufficiently squeeze out the body fluid in the living tissue and the fluid attached to the tissue.
Separated from cell membrane tissue. Grinding treatment or homogenizing treatment can be performed instead of the pressing treatment in the sixth step. The liquid content of the processed product in the sixth step is separated from the solid content by filtration or centrifugation, and in the seventh step and the eighth step, the same pH adjustment with alkali and water resistance as in the third step and the fourth step are performed. The treatment with the chelating fiber is performed, and in the ninth step, the mixture is concentrated to 1/5 to 1/20 based on the volume by an evaporator to obtain a detoxified concentrate. Since the mollusc food processing residue from which the immersion liquid has been removed in the second step has most of the alkali metal ions removed by the immersion treatment in the first step, the water-resistant chelate fiber treatment in the eighth step is eliminated. Alternatively, strong cation exchange fibers can be used.

Next, an apparatus for suitably carrying out the method of the present invention includes, for example, a drain hole at the bottom for containing a mixture of mollusc food processing residue and a dilute acid aqueous solution, and a mollusk food processing residue. An immersion tank provided with an outlet, a drainage treatment system connected to a water-resistant chelate fiber packed column through a pH adjustment tank from a liquid drainage hole, a membrane cutting machine, a squeezing machine, a filter, There is a mollusk food processing residue treatment system in which a conditioning tank and a water-resistant chelate fiber packed column are connected in series.

In this apparatus, a plurality of immersion tanks are arranged in parallel, and while operating using one immersion tank, the raw material is immersed in another immersion tank with a dilute acid aqueous solution. In addition, once the contents of the first immersion tank have been consumed, it is advantageous to switch to the next immersion tank at any time to operate continuously. It is also preferable to prepare a plurality of columns packed with water-resistant chelate fibers in the same manner, so that the column can be replaced with a new one at any time when the adsorption capacity reaches a saturated state.

In this water-resistant chelate fiber packed column, a main body composed of a cylindrical container opened up and down and a water-resistant chelate fiber packed cartridge fitted thereto are provided separately, and only the water-resistant chelate fiber packed cartridge is replaced when necessary. It is convenient to make the structure.

FIG. 3 is a partially cutaway perspective view showing an example of the structure of the cartridge, FIG. 4 is a partially cutaway perspective view showing a different example of the structure, and FIG. FIG. 4 shows a structure in which a water-resistant chelate fiber web 2 is rolled and filled, and FIG. 4 shows a plurality of water-resistant chelate fiber cloths 3, cut into the cylindrical support 1 according to the bottom shape thereof.
Are stacked and filled. As this cartridge, a filament obtained by cutting a filament in a fibrous state into an appropriate length can be filled in a cotton form and used.

In these cartridges, if the water-resistant chelate fiber is filled too softly, it will pass faster when the liquid component is passed, resulting in inadequate contact. Since the treatment time is difficult and the treatment time is long, it is preferable that the water-resistant chelate fiber before filling is pressed down to an extent of 3/4 to 2/3 of the volume.

[0039]

Next, the present invention will be described in more detail by way of examples.

In each of the examples, the water-resistant chelate fiber is

Embedded image (Wherein n is an integer of 2 to 100 and m is an integer of 2 to 100), which has the following properties (hereinafter referred to as H ⁺ type) and A Na-substituted product (hereinafter referred to as Na ⁺ type) was used. Size: Cross-sectional major axis: about 60 μm Cross-sectional minor axis: about 20 μm Ion exchange capacity: Cation exchange capacity: 2.7 meq / g Kind of functional group: Iminoacetic acid group, secondary and tertiary amino group True specific gravity: 1.27 The measurement of metal ions was carried out using a product name “ICAP-757” manufactured by Nippon Jarrell Ash Co., Ltd.
The measurement was performed at 14.438 nm.

Reference Example 1 Strong cationic ion exchange fiber (trade name "I" manufactured by Nichibi Co., Ltd.)
EF-SC ", a cation exchange capacity of 2.5 meq / g) cut into a disk shape having a diameter of 100 mm and a thickness of 8 mm, laminated in a stainless steel cylinder, and compressed to a height of 5/8. As a result, an ion-exchange fiber column of 100 cm was manufactured, and the volume of the ion-exchange fiber was about 7.85.
Liters. Next, Uro (Na 4720 ppm, C
d12.12 ppm, Zn70 ppm) with an equivalent amount of 0.1
The extract obtained by immersing in an aqueous solution of sulfuric acid having a molar concentration at 15 ° C. for 24 hours was adjusted to pH 5.6, and then passed through the above-mentioned ion exchange fiber column to adsorb metals. After the metal ions have been sufficiently adsorbed in this manner, the entire amount of the ion-exchange fibers is taken out to a stainless steel bucket, and 1
200 liters of molar sulfuric acid aqueous solution (bath ratio 1:25.
48) and eluted at 25 ° C. for 1 hour. Next, the eluate was subjected to high frequency inductively coupled plasma analysis (IC
When analyzed by P), the elution amount of each metal was Na268
2 ppm, Cd 49 ppm, Zn 118 ppm,
It was found that about 55 times of Cd and about 23 times of Zn were adsorbed on Na.

Example 1 A scallop urine (Cd 7.27 ppm, Zn 24.1 ppm, Mg6
(15 ppm, Ca664 ppm, moisture 88.3 mass%)
The same volume of a 0.1 molar aqueous sulfuric acid solution was added to
After standing at 24 ° C. for 24 hours and immersion treatment, the mixture was filtered to obtain an extract. Next, this extract was diluted 5-fold,
After adjusting the pH to 7.0 and 9.0, the 50 ml
Was added to the extract, and the mixture was shaken for 1 hour. Thereafter, the extract was removed from the extract, and the amount of metal ions in the solution was measured. Table 1 shows the obtained results.

[0043]

[Table 1]

Example 2 (1) 70% by mass of chelate fiber (H type) and 30% by mass of polyethylene terephthalate fiber were mixed, and the thickness was 40%.
A nonwoven web having a thickness of 500 mm and a width of 500 mm was produced. next,
This was roll-wound, compressed to a thickness of 25 mm, and filled into a stainless steel cylinder having a diameter of 20 mm and a height of 800 mm to produce a chelate fiber column. (2) Uro (Cd: 7.27 ppm, Zn: 24.1 pp) collected from December 2000 and collected from the Saroma outskirts of Hokkaido
m, 88.3% of water) with an equal volume of a 0.1 molar sulfuric acid aqueous solution, stir at 24 ° C. for 24 hours, dilute the extract obtained by centrifugation twice, and mix with 0.1 ml. Using 1 liter of a sample adjusted to pH 6.0 with a 1 molar sodium hydroxide aqueous solution, the solution was passed through the above-mentioned chelate fiber column at a flow rate (SV value) of 10. This operation was repeated five times, and the content of Cd and Zn in the processing solution was measured each time. Table 2 shows the results.

Comparative Example 1 A strong cation-type ion exchange fiber (trade name “IEF-SC”, manufactured by Nichibi Co., Ltd., trade name: IEF-SC) used in Reference Example 1 instead of the chelate fiber column in (1) of Example 2
5 meq / g), and a strong ion exchange fiber column manufactured in the same manner as (1) of Example 2 was used.
An experiment similar to (2) was performed. Table 2 shows the results.

[0046]

[Table 2]

As is clear from this table, when the strong cation type ion exchange fiber is used, the adsorption rate of Cd and Zn other than the second time sharply decreases, so that it must be regenerated every time. In the case where is used, the adsorption rate does not decrease at all up to at least 5 times, and it can be seen that it can be used without regeneration treatment.

Example 3 In a 300 liter volume tank made of SUS316 stainless steel, scallop (Cd: 7.27 ppm, Zn: 24.1 ppm,
A mixture of 88.3% by mass of water) and twice the amount of a 0.1 molar aqueous sulfuric acid solution (pH 1.1) was added, and immersed at 25 ° C. for 20 hours. Next, the immersion liquid was removed from the mixture by decantation, and the remaining soft solid was squeezed with a screw press (manufactured by Okawara Seisakusho) to recover 18.8 kg of solids and 40.2 kg of squeezed liquid. Next, the squeezed liquid (pH 3.6) was filtered through a 150-mesh sieve, and adjusted to pH 5.9 with an aqueous potassium hydroxide solution to obtain 39.0 kg of a uro-containing liquid. Separately, a stainless steel cylinder having an inner diameter of 100 mm and a height of 2 m is filled with 200 pieces of water-resistant chelate fibers (H ⁺ type) cut into a disk having a diameter of 100 mm and a thickness of 8 mm, and compressed to a height of 1 m. Thus, an ion adsorption column was prepared. The above uro-containing liquid was applied to the ion adsorption column thus prepared at a liquid temperature of 15 ° C. at a rate of 4 kg / min (S
The solution was passed at a V value of 9) and subjected to ion adsorption treatment. At this time, in order to increase the passing speed, suction was performed from below the column by a Teflon tube pump (made by Bredel, The Netherlands). 34.7 kg of the uro-containing liquid thus treated (pH
4.0) using an evaporator (trade name “CEP-1”, manufactured by Okawara Seisakusho), heating temperature 90 ° C., evaporation temperature 4
Evaporation and concentration were performed at 0 ° C. and an average evaporation rate of 58.0 kg / h to obtain 2.56 kg of a concentrate. At this time, 33.0 kg of pure water was by-produced. The cadmium content in the concentrate thus obtained was 0.062 ppm.

Example 4 18.8 kg of the solid content separated from the squeezed liquid by the screw press of Example 3 was crushed using a pressing roll (manufactured by Kawamura Burner Mfg., Product number “LY-0264”), and then crushed. With twice the volume of a 0.1 molar aqueous sulfuric acid solution, 2
The immersion treatment was performed at 5 ° C. for 48 hours. Next, a separating plate type centrifuge (ADS3001P, manufactured by Kokusan)
S ") to obtain 54.5 kg of a uro-containing liquid (pH 2.7). This uro-containing liquid was subjected to ion adsorption treatment and evaporation concentration treatment in the same manner as in Example 3 to obtain 3.47 kg of a concentrate. The cadmium content in the concentrate thus obtained was 0.044 ppm.

Reference Example 2 250 liters of 40 ° C. warm water was added to 45 kg of scallops of Hokkaido Saloma Open Sea, collected in November 2000, which was used in Reference Example 1, stirred for 3 hours, and squeezed.
The first washing solution was collected. Next, water 250 ° C at 25 ° C was added to the residue.
Liters, immersed for 22.5 hours, squeezed,
The second washing liquid and 18.34 kg of solid content were recovered. Table 3 shows the results of measuring the total nitrogen content by the Kehldahl method, the lipid content by the Soxhlet extraction method, and the amino acid content by the automatic amino acid analysis method for the first and second washing solutions thus obtained. .

[0051]

[Table 3]

As is clear from this table, it is understood that the soluble amino acid is eluted by washing with water prior to the acid immersion treatment of uro.

[0053]

According to the present invention, food processing residues of mollusks, for example, harmful metals contained in scallop urine can be almost removed, so that the residues can of course be used as fertilizers and animal feeds. It can also be used safely and effectively as a food and nutrient source. In addition, since there is no reduction in the removal ability due to alkali metals such as sodium and potassium which coexist with harmful metals, the operation can be performed for a long period without conversion of the adsorbent.

[Brief description of the drawings]

FIG. 1 is a schematic anatomy of a scallop.

FIG. 2 is a block diagram of the processing process of the present invention.

FIG. 3 is a partially cutaway perspective view of an example of a cartridge used in the processing process of the present invention.

FIG. 4 is a partially cutaway perspective view of another example of the cartridge used in the process of the present invention.

[Explanation of symbols]

 Reference Signs List 1 cylindrical support 2 water-resistant chelate fiber web 3 water-resistant chelate fiber cloth

Claims (9)

[Claims] 1. A mollusc food processing residue containing harmful metal ions is immersed in a dilute acid aqueous solution, and then an immersion liquid flowing out and separated from the mollusk food processing residue is brought into contact with a water-resistant chelate fiber, and the harmful metal in the immersion liquid is removed. A treatment method for removing harmful metals from mollusc food processing residues, wherein ions are removed by adsorbing ions. 2. The treatment method according to claim 1, wherein the mollusc food processing residue containing harmful metal ions is a scallop or squid offal. 3. The treatment method according to claim 1, wherein the harmful metal ion is cadmium ion. 4. A first step in which mollusc food processing residues containing harmful metal ions are immersed in a dilute acid aqueous solution to elute harmful metal ions, and (2) an immersion liquid is discharged leaving soft solids. 2nd step, (3) pH of the immersion liquid discharged in (2) is adjusted with alkali.
A third step of adjusting the pH to 5.5 to 9.0, (4) a step of bringing the pH-adjusted immersion liquid into contact with the water-resistant chelate fiber, absorbing and removing harmful metal ions, and discharging the detoxified treated water. 4th step, (5) 5th step of cutting the membrane tissue in the soft solids left in the 2nd step, (6) squeezing the soft solids cut in the 5th step to remove the liquid component The sixth step of squeezing, (7) the seventh step of removing the solid content from the squeezed liquid of the sixth step and adjusting the pH, (8) bringing the squeezed liquid adjusted to pH into contact with the water-resistant chelate fiber, and An eighth step of adsorbing and removing the harmful metal ions of (9) evaporating and concentrating the extracted liquid from which the harmful metal ions have been removed;
A process for treating harmful metal-containing mollusc food processing residues, comprising a ninth step of obtaining a harmless useful concentrate. 5. The process according to claim 4, wherein the mollusc food processing residue is washed with water prior to the first step. 6. A dip tank having a liquid drain hole and a mollusk food processing residue outlet at the bottom, a pH adjusting tank and a water-resistant chelate fiber packed column connected in series to the liquid drain hole. And a mollusc food processing residue treatment in which a membrane cutting machine, a pressing machine, a filter, a pH adjusting tank, a water-resistant chelate fiber-filled column, and an evaporator are connected in series with the mollusk food processing residue outlet. apparatus. 7. The processing apparatus according to claim 6, wherein the water-resistant chelate fiber-filled column has a structure in which a water-resistant chelate fiber-filled cartridge is exchangeably housed in a cylindrical container which is opened up and down. 8. The processing apparatus according to claim 7, wherein the cartridge is formed by rolling a water-resistant chelate fiber web into a cylindrical support and filling the same. 9. The processing apparatus according to claim 7, wherein the cartridge is formed by stacking a large number of water-resistant chelate fiber cloths cut in accordance with the shape of the bottom surface of the cylindrical support into the cylindrical support.