JP2022102367A - Treatment method for water containing neutral polysaccharides - Google Patents

Abstract

To provide a method for treating neutral polysaccharide-containing water that can efficiently aggregate and settle neutral polysaccharides such as SS and starch in water containing neutral polysaccharides such as boiling water of noodles, for example, Japanese wheat noodles and pasta, and rice washing water.SOLUTION: In a method for treating neutral polysaccharide-containing water by adding a coagulant, an aluminum-based coagulant is used as the coagulant, and the pH of the neutral polysaccharide-containing water is adjusted to 8 or higher. Prior to the addition of the aluminum-based coagulant, a polymer having a site hydrogen-bondable with the neutral polysaccharides may be added.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for treating neutral polysaccharide-containing water. One aspect of the present invention relates to a method for coagulating wastewater containing a large amount of starch, such as boiled noodle soup such as udon and pasta, and rice soup.

When the food industry considers water saving, especially water reuse, a method of reusing water without crossing the production line is required from the viewpoint of preventing contamination with allergens. In addition, in order to reuse water in the manufacturing process, it is reluctant to use a surfactant or a special chemical substance as a coagulant and condensing agent for reforming and cleaning wastewater.

Wastewater from food factories, especially boiled noodle juice such as udon and pasta, and wastewater such as rice broth contains high-concentration starch and high-concentration SS (suspended solids) mainly composed of aged starch. Very high concentrations of inorganic flocculants are used to aggregate these. Neutral polysaccharides such as starch are poorly charged by themselves and are less susceptible to charge neutralization by cationic / anionic coagulants and inorganic flocculants. Therefore, starch-containing wastewater is very difficult to aggregate.

During the production of udon and pasta, an aqueous solution of inorganic carbonate and an aqueous solution of phosphate are mixed with the raw materials. Therefore, wastewater such as boiled noodle soup and rice soup contains a large amount of carbonate ions and phosphate ions having the effect of dispersing the aggregating agent, so that poor aggregation is likely to occur, and the required amount of the aggregating agent required for the aggregating treatment. There are many. In addition, since a large amount of coagulant is added, a large amount of coagulated sludge is generated.

Patent Document 1 describes a technique for precipitating insoluble starch in wastewater by self-aggregation using an enzyme. However, this technique has the disadvantage that the enzymatic reaction takes time.

Patent Document 2 describes a highly viscous organic substance obtained by crushing okra as a flocculant for agglomerating boiled udon juice and rice broth, a flocculant component (aluminum flocculant and anion, cation, and nonionic polymer). A flocculant composition containing an amphoteric surfactant and a flocculation aid (inorganic substances such as bentonite and kaolin) is described. However, this flocculant composition has a large amount of chemicals, the addition point and the stirring equipment are complicated and heavy, and since a surfactant is used, there is a possibility of foaming. In general, the inclusion of a polymer slows the sedimentation rate of aggregated sludge and increases the turbidity of the supernatant. Therefore, it is considered that the sedimentation property of floc is maintained by using an inorganic substance as a flocculant. The amount of sludge increases by the amount contained.

Japanese Unexamined Patent Publication No. 2007-38214 Japanese Unexamined Patent Publication No. 2012-61372

INDUSTRIAL APPLICABILITY According to the present invention, SS of water containing neutral polysaccharides such as boiled noodle juice such as udon and pasta and neutral polysaccharide-containing water of rice and neutral polysaccharides such as starch can be efficiently aggregated and settled to quickly obtain clean water. It is an object of the present invention to provide a possible method for treating neutral polysaccharide-containing water.

The gist of the method for treating neutral polysaccharide-containing water of the present invention is as follows.

[1] In a method of adding a flocculant to a neutral polysaccharide-containing water for treatment, an aluminum-based flocculant is used as the flocculant, and the pH of the neutral polysaccharide-containing water is set to 8 or more. A method for treating water containing neutral polysaccharides.

[2] The method for treating neutral polysaccharide-containing water according to [1], wherein the aluminum-based flocculant is highly basic aluminum chloride.

[3] The method for treating neutral polysaccharide-containing water according to [1] or [2], wherein the pH of the neutral polysaccharide-containing water is pH 8 to 10.

[4] The neutral polysaccharide according to any one of [1] to [3], which comprises adding a polymer having a hydrogen-bondable moiety to the neutral polysaccharide before the addition of the aluminum-based flocculant. Method of treating contained water.

[5] The method for treating neutral polysaccharide-containing water according to [4], wherein the polymer is a phenol resin and / or a melamine resin.

[6] The method for treating neutral polysaccharide-containing water according to any one of [1] to [5], which comprises passing the aggregated treated water through the ceramic membrane.

According to the method for treating neutral polysaccharide-containing water of the present invention, neutral polysaccharide-containing water can be efficiently aggregated and settled, and clean water (aggregated treated water) can be quickly obtained.

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In the method for treating neutral polysaccharide-containing water of the present invention, an aluminum-based flocculant is added to the neutral polysaccharide-containing water, and the pH of the neutral polysaccharide-containing water is set to 8 or more, preferably 8 to 10. ..

Examples of the neutral polysaccharide-containing water include boiled noodle soup such as udon and pasta, rice soup, and wastewater containing the boiled soup and soup. When the neutral polysaccharide-containing water is boiled noodle soup such as udon or pasta or rice soup, the concentration of starch in the boiled soup or soup is about 50 to 10,000 mg / L.

In addition to soluble starch, reducing sugars in which proteins, amino acids, and starch are decomposed are present as soluble organic substances in the wastewater containing a large amount of starch such as boiled noodle juice such as udon and pasta and starch juice of rice. is doing. The insoluble component includes aged starch and the like.

Highly basic aluminum chloride is suitable as the aluminum-based flocculant to be added to the neutral polysaccharide-containing water. Highly basic aluminum chloride is represented by the general formula Al _n (OH) _m Cl _{3 nm} . As the one used in the present invention, 1 ≦ n ≦ 5 and m ≦ 10 are suitable.

The amount of highly basic aluminum chloride added varies depending on the wastewater concentration, but is about 50 to 10,000 mg / L. Highly basic aluminum chloride is preferably added to neutral polysaccharide-containing water in the form of an aqueous solution.

The pH of the neutral polysaccharide-containing water to which the highly basic aluminum chloride is added is 8 or more, and 8 to 10 is particularly preferable, and 8 to 9 is particularly preferable. When the pH of the neutral polysaccharide-containing water is out of this range, the pH of the neutral polysaccharide-containing water may be adjusted with NaOH, hydrochloric acid, sulfuric acid, etc. before or after the addition of the highly basic aluminum chloride. preferable.

SS, which is mainly composed of starch, has a neutral surface charge in the acidic to neutral region, so that it is difficult to aggregate. Easy to receive and agglomerate. Further, since the aggregated flocs are also negatively charged in a basic environment, the flocs tend to grow and settle through the coexisting cation component.

Organic substances such as starch do not contain charged functional groups and have low affinity for anionic / cationic polymers and inorganic flocculants. However, the inventor's tests have revealed that they are subject to coprecipitation in aggregation. That is, it was possible to reduce the SS concentration and the starch concentration in the liquid by using a cationic polymer coagulant under basic conditions. Starch also has water in its molecular structure. As a result, it was found that a polymer having a hydrogen-bondable site such as a phenol resin can form a hydrogen-bonding bond with starch and water molecules contained in the starch and can be condensed.

In these two types of starch removing methods, the removal method using a cationic coagulant utilizes a coprecipitation effect, and therefore, naturally, the higher the polymer and the larger the molecular structure, the higher the starch removing effect. However, as a reaction to its structure, the flocs are brittle and light, thus increasing the supernatant turbidity of the aggregates. On the other hand, in the resin using hydrogen bonds, the condensed resin and starch itself become the core of aggregation, so that the addition of the coagulant did not increase the turbidity of the supernatant.

From the above, by adding a coagulant containing a polymer having a hydrogen-bondable site as an active ingredient and then adding highly basic aluminum chloride to aggregate at pH 8 to 10, it is very easy to make noodles such as udon and pasta. It is possible to quickly obtain clean water by precipitating SS and starch in wastewater such as boiled juice and rice broth by aggregation. It is desirable that the highly basic aluminum chloride flocculant aggregates at pH 8 to 9, which is difficult to redissolve due to an increase in pH.

The phenolic resin used in the present invention is a condensate or a modified product of a phenol such as monovalent phenol such as phenol, cresol, xylenol and an aldehyde such as formaldehyde, and is a phenolic resin before cross-linking and curing. Resin is mentioned. Specific examples include the following.
[1] Condensate of phenol and formaldehyde
[2] Condensate of cresol and formaldehyde
[3] Condensate of xylenol and formaldehyde
[4] Alkyl-modified phenolic resin obtained by alkylating the phenolic resins of [1] to [3] above.
[5] Polyvinyl phenol

These phenolic resins may be novolak type or resol type. As the novolak-type phenol-based resin, the resol-type phenol-based resin, or the polyvinylphenol, those represented by the following general formula are suitable.

In the present invention, the agglomeration-treated water generated by the above-mentioned agglomeration treatment may be further subjected to a solid-liquid separation treatment to separate flocs. As the solid-liquid separation treatment, water flow through the ceramic film is preferable, but a floating treatment or the like may be used.

[Evaluation test of inorganic flocculants]
<Test water>
Boiled drainage of noodles at a domestic frozen noodle manufacturing factory (starch concentration 496 mg / L, IC (inorganic carbonic acid) 200 mg / L)

<Starch measurement method>
It was measured by the following method using a HACH residual chlorine meter (HACH2470).
(1) Add 4.4 mL of 1 + 10 hydrochloric acid to 3.2 mL of test water to adjust to zero.
(2) Add 0.4 mL of N / 500 iodine solution and measure the absorbance after 3 minutes.
(3) The starch concentration of the sample is determined using the calibration curve prepared by measuring the known starch concentration solution by the methods (1) and (2).

<Turbidity measurement method>
It was measured using a HACH turbidity meter (2100Q).

<Test method>
While stirring 300 mL of the above test water at 150 rpm at room temperature, the inorganic flocculant described below was added at the concentration described below.

Immediately after the addition, the pH was adjusted to 6, 7, _{8, 9, 10 or 12 with 10 g / L H2 SO 4 or} 10 g / L NaOH, and 6 minutes after the addition of the inorganic flocculant, the stirring speed was reduced to 50 rpm 5 Stir slowly for 1 minute. After slow stirring and allowing to stand for 5 minutes, about 10 mL of the supernatant was sampled, and the turbidity and starch concentration were measured.

<Inorganic flocculant and amount added>
The following flocculants were added in the form of an aqueous solution. The amount added as a solid content is as follows.
Example 1 Highly basic aluminum chloride 3000 mg / L
([Al ₂ (OH) _n Cl _6-n ] _m (0 <n <6, m ≦ 10),
Al ₂ O ₃ conversion 15 wt%)
Example 2 PAC (Al ₂ O ₃ about 10 wt%) 3000 mg / L
Comparative Example 1 35% FeCl ₃ 3000 mg / L
-Comparative Example 2 FeSO _{4.7H 2} O 5000 mg / L

<Results and discussion>
The measurement results of the supernatant turbidity and the starch concentration of the aggregated water are shown in FIGS. 1 and 2.
As shown in FIGS. 1 and 2, the turbidity and starch concentration of the aggregate-treated water supernatant are lower in Examples 1 and 2 (addition of aluminum-based flocculant) than in Comparative Examples 1 and 2 (addition of iron-based flocculant). The appropriate pH at that time was 8 to 10.

The Al concentration in the supernatant after aggregation in this test is shown in FIG. As shown in FIG. 3, although the amount of Al added in Example 1 is larger, the amount of Al remaining in the treated water is smaller than that in Example 2. Generally, Al exists in water as an ^acocomplex [Al (OH ₂ ) ₆ ] ₃₊ in which 6 _H2O molecules are coordinated to a regular octahedron, and even when the PAC of Example 2 is added. It exists in that state. On the other hand, in highly basic aluminum chloride, hydrated OH is crosslinked to form a kind of polymer in which several aluminums are polycondensed, so Al can be efficiently used for floc formation. Therefore, there is an advantage that Al does not easily remain in the treated water.

[Evaluation test of coagulant]

<Test water>
Boiled drainage of noodles at a domestic frozen noodle manufacturing factory (starch concentration 2112 mg / L, IC 18 mg / L)

<Measurement method of turbidity / starch concentration>
As above.

<Test method>
While stirring 300 mL of the above test water at room temperature at 150 rpm, the coagulant described below was added, and about 5 minutes after the addition, the above highly basic aluminum chloride was added as a solid content at 500 mg / L in the form of an aqueous solution. ..

Immediately after the addition, the pH was adjusted to 8.5 with 10 g / L NaOH, and 6 minutes after the addition of the inorganic flocculant, the stirring speed was reduced to 50 rpm and the mixture was slowly stirred for 5 minutes.

After slow stirring and allowing to stand for 5 minutes, about 10 mL of the supernatant was sampled, and the turbidity and starch concentration were measured.

<Caking agent>
The following coagulants were used. DAA is dimethylaminoethyl acrylate, DADMAC is diallyldimethylammonium chloride, DAMBz is dimethylaminoethyl methacrylate benzyl chloride quaternary salt homopolymer, and AAm is acrylamide.
-Reference Example 1 Melamine-formaldehyde condensate-Reference Example 2 Phenol resin-Reference Example 3 DAA and AAm copolymer (DAA / AAm = 50 mol% / 50 mol%, weight average molecular weight 2 million)
Reference Example 4 DAA and AAm copolymer (DAA / AAm = 95 mol% / 5 mol%, weight average molecular weight 4 million)
-Reference Example 5 DADMAC homopolymer-Reference Example 6 DAMBS homopolymer (weight average molecular weight 14 million)
-Reference Example 7 DAA methiculo / DAABz / AAm copolymer (weight average molecular weight 8 million)

<Results and discussion>
The measurement results of the starch concentration and the turbidity of the supernatant water of the condensed water are shown in FIGS. 4 and 5.

As shown in FIGS. 4 and 5, the starch removing effect of the strong cationic polymer (Reference Examples 3, 4 and 5) was superior to that of the low cationic polymer having a non-cationic structure (Reference Examples 6 and 7). Further, the starch removing effect of the strong cationic polymer was superior as the molecular weight increased (Reference Example 4> Reference Example 3> Reference Example 5). However, the addition of high molecular weight polymers with a weight average molecular weight of 2 million or more increased the supernatant turbidity.

With respect to the structure and effect of these polymers, the resins shown in Reference Examples 1 and 2 immediately lowered the starch concentration in the supernatant with the addition of a small amount, and exhibited a remarkable starch removing effect. In addition, no increase in supernatant turbidity was observed with the increase in the amount added.

Claims (7)

In the method of adding a flocculant to water containing neutral polysaccharides for treatment.
An aluminum-based flocculant is used as the flocculant.
A method for treating neutral polysaccharide-containing water, which comprises setting the pH of the neutral polysaccharide-containing water to 8 or more. The method for treating neutral polysaccharide-containing water according to claim 1, wherein the aluminum-based flocculant is highly basic aluminum chloride. The method for treating neutral polysaccharide-containing water according to claim 1 or 2, wherein the pH of the neutral polysaccharide-containing water is pH 8 to 10. The method for treating neutral polysaccharide-containing water according to any one of claims 1 to 3, wherein a polymer having a hydrogen-bondable moiety with the neutral polysaccharide is added before the addition of the aluminum-based flocculant. .. The method for treating neutral polysaccharide-containing water according to claim 4, wherein the polymer is a phenol resin and / or a melamine resin. The method for treating neutral polysaccharide-containing water according to any one of claims 1 to 5, wherein the agglomerated treated water is passed through a ceramic membrane. Treatment of the neutral polysaccharide-containing water according to any one of claims 1 to 6, wherein the neutral polysaccharide-containing water is boiled noodle juice, rice broth, or wastewater containing the boiled juice or broth. Method.

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