JPH1157695A - Treatment process for phosphorus-containing wastewaer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phosphorus-recovering process in which the phosphorus adsorption capacity is high and regeneration is available. SOLUTION: A phosphorus-containing wastewater treatment process in which phosphorus and nitrogen removing wastewater treatment agent is used comprises the step of bringing phosphorus-containing wastewater into contact with a substance represented by a chemical formula of M1 -x <2+> Mx<3+> (OH<-> )2+x-y (A<n-> )y/n [In the formula, M<2+> represents Mg<2+> , Ni<2+> , Zn<2+> , Fe<2+> , Ca<2+> or Cu<2+> , M<3+> represents Al<3+> or Fe<3+> , A<n-> represents monovalent or bivalent anion and 0.1<=x<=0.5; 0.1<=y<=0.5], a process for bringing a phosphorus adsorbent having adsorbed the phosphorus content into contact with an alkali water to desorb and recover the phosphorus content, a process for calcinating the phosphorus adsorbent at 430-600 deg.C and a process for treating the phosphorus adsorbent with an electrolytic solution containing A<n> - ions and regenerating and reusing the phosphorus adsorbent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for treating phosphorus-containing wastewater and a wastewater treatment agent.

[0002]

2. Description of the Related Art In recent years, a large amount of organic substances, nitrogen, phosphorus and the like contained in rivers, various industrial wastewaters or domestic wastewaters cause eutrophication which leads to water pollution of lakes and marshes which promote the generation of algae and red tide generation in the coastal waters. It is listed as a factor of the phenomenon. It is said that the limiting concentrations of nitrogen and phosphorus that cause eutrophication are 0.15 ppm of nitrogen and 0.02 ppm of phosphorus. Establishment of advanced water treatment technology capable of removing nitrogen and phosphorus from high to low concentrations. Is strongly desired.

[0003] Methods for removing phosphorus in wastewater are roughly classified into two types: biological treatment and physicochemical treatment.
Among physicochemical treatment methods, a coagulation precipitation method of removing a phosphorus component as a poorly soluble phosphate using a coagulant from the viewpoint of economy, treatment efficiency, and the like is generally used. However, the outflow of salts derived from the flocculant to the wastewater with the flocculant addition,
Issues to be studied in the future include problems such as sludge treatment and phosphorus recovery and reuse, and insufficient phosphorus removal in low concentration areas.

As a method other than the coagulation-sedimentation method, an adsorption treatment method of a phosphorus component using a phosphorus adsorbent has been attempted. In the adsorption method, aluminum hydroxide gel, magnesium oxide, titanium oxide-activated carbon composite agent, zirconium oxide-activated carbon composite agent, volcanic ash soil and the like have been studied as phosphorus adsorbents.

[0005]

In recent years, one of the water environment problems that has attracted particular attention is the problem of eutrophication in closed water areas such as swamps and lakes, and in rivers and coasts. The government has taken measures to address this problem, and the Lake Law has been enacted, and regulations on phosphorus, one of the nutrient salts, have become stricter. However, it is difficult to comply with this regulation value in the current wastewater treatment process without a phosphorus removal process, and it is necessary to incorporate an appropriate tertiary treatment process for removing phosphorus. From such a background, various wastewater treatment facilities require a phosphorus adsorbent that can recover and remove phosphorus from wastewater with high efficiency and that can be reused from the viewpoint of effective use of resources and post-treatment of the phosphorus adsorbent. . Also, from a resource perspective, it is clear that the construction of a phosphorus recovery and reuse system from water systems will be an important issue, as there is a prediction that phosphorus will be limited and depleted in the near future.
In addition, the methods provided for this collection and reuse system are:
It is required that the method is of a low environmental load type that does not generate waste as much as possible.

At present, closed water bodies such as swamps and lakes and rivers,
The main cause of coastal eutrophication is domestic wastewater such as detergents discharged from ordinary households, and the removal of phosphorus in various domestic wastewater treatment facilities mainly consists of iron salts and aluminum salts. It is performed by a coagulation sedimentation method using a coagulant or an anaerobic aerobic method which is a biological phosphorus removal method. These existing phosphorus removal methods are methods that make use of the characteristics of each.However, the coagulation sedimentation method has a problem of sludge treatment, and the anaerobic aerobic method has a problem that it is difficult to obtain a stable treatment efficiency. In order to improve these points, a phosphorus adsorbent which has a stable treatment efficiency in a neutral pH range and has a large adsorption capacity is required. In addition, future phosphorus regulations will be strengthened gradually, and it is expected that it will eventually become an essential condition to reduce the phosphorus concentration to 0.02 ppm or less, which is the limit concentration that suppresses the generation of phytoplankton. There is a need for a high-performance phosphorus adsorbent that can not only remove phosphorus from water but also remove phosphorus from low phosphorus concentrations such as rivers. For the prevention of eutrophication, it is also important to remove nitrogen components along with phosphorus, and there is a long-felt need for a method capable of efficiently removing nitrogen components simultaneously with phosphorus.

The present invention provides a reasonable method for treating and recovering wastewater containing a phosphorus component, which satisfies these needs and has a large phosphorus adsorption capacity and includes a regeneration treatment method using a renewable phosphorus adsorbent. The purpose is to do.

Another object of the present invention is to provide a wastewater treatment agent capable of simultaneously removing phosphorus and nitrogen.

[0009]

SUMMARY OF THE INVENTION The present invention provides the following wastewater treatment method and wastewater treatment agent.

Item 1. The following steps (I) and (II)
Method for treating phosphorus-containing wastewater containing: Step (I) Chemical composition formula (1): M _1−x ²⁺ M _x ³⁺ (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1) ^{among, M 2+, M 3+, a} n-, x, y and n are as defined above. Contacting a phosphorus-containing wastewater with the composite metal hydroxide represented by the formula (1) to adsorb the phosphorus component; Step (II): converting the phosphorus adsorbent obtained in Step (I) to adsorb the phosphorus component with an alkali metal carbonate And a step of regenerating and reusing the phosphorus adsorbent by treating with at least one phosphorus desorbing solution selected from the group consisting of alkali metal salts and alkaline earth metal salts excluding alkaline earth metal carbonates.

Item 2. The following steps (I), (Ia) and (I
Method for treating phosphorus-containing wastewater containing b) and (II): Step (I) Chemical composition formula (1): M _1−x ²⁺ M _x ³⁺ (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1) [wherein, M ²⁺ , M ³⁺ , A ⁿ⁻ , x, y and n are the same as above. Contacting a phosphorus-containing wastewater with the composite metal hydroxide represented by the formula (1) to adsorb the phosphorus component; step (Ia): converting the phosphorus adsorbent obtained in step (I) to adsorb the phosphorus component with an alkali metal carbonate or brought into contact with an aqueous solution containing a ^n- ions, a step of desorbing and recovering phosphorous components; step (Ib) step phosphorus adsorbent after phosphorus desorption calcined at four hundred and thirty to six hundred ° C.; and step (II) calcination The subsequent phosphorus adsorbent is treated with at least one phosphorus desorbing solution selected from the group consisting of alkali metal salts and alkaline earth metal salts excluding alkali metal carbonates and alkaline earth metal carbonates to regenerate the phosphorus adsorbent , Reuse process.

Item 3. Method for treating phosphorus-containing wastewater including the following steps (I) to (Ic): Step (I) Chemical composition formula (1): M _1-x ²⁺ M _x ³⁺ (OH ⁻ ) _{2 + xy} (A ^n- ) _{y / n} (1) [wherein, M2 ⁺ , M3 ⁺ , ^An- , x, y and n are the same as above. Contacting a phosphorus-containing wastewater with the composite metal hydroxide represented by the formula (1) to adsorb the phosphorus component; step (Ia): converting the phosphorus adsorbent obtained in step (I) to adsorb the phosphorus component with an alkali metal carbonate Or a step of contacting with an aqueous solution containing ^An- ions to desorb and recover the phosphorus component; step (Ic): dissolving the phosphorus adsorbent after phosphorus desorption with acid, and reusing the solution as a raw material for producing the phosphorus adsorbent. .

Item 4. The calcined phosphorus adsorbent obtained in the step (Ib) of the item 2 is (1) treated in the order of the following steps (III) and (IV); or (2) treated in the step (Ic) of the item 3 (III) a step of contacting the calcined phosphorus adsorbent with a phosphorus component-containing wastewater to adsorb a phosphorus component; and (IV) a step (III) obtained in the step (III). The step (II) of item 1 or the step (I) of item 2 is performed using the phosphorus adsorbent that has adsorbed the phosphorus component thus obtained.
Repeat a), (Ib) and (II).

Item 5. Chemical composition formula (1): M _1−x ²⁺ M _x ³⁺ (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1) [where M ²⁺ , M ³⁺ , A ⁿ⁻ , X, y and n are the same as above. ] A wastewater treatment agent for simultaneous removal of phosphorus and nitrogen components in wastewater comprising a composite metal hydroxide represented by the formula:

Item 6. Chemical composition formula (1): M _1−x ²⁺ M _x ³⁺ (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1) [where M ²⁺ , M ³⁺ , A ⁿ⁻ , X, y and n are the same as above. ] A wastewater treatment agent granulated product of phosphorus-containing wastewater, comprising 99 to 60% by weight of the composite metal hydroxide represented by the formula (1) and 1 to 40% by weight of a binder.

Item 7. Item 7. The granulated product according to Item 6, wherein the binder contains an aminated polyacrylamide.

Item 8. The binder is a polyamide
It is a mixture of 1 to 40% by weight of at least one selected from the group consisting of epichlorohydrin resin, vinyl acetate / vinyl versatate copolymer resin and styrene / acrylic resin, and 99 to 60% by weight of aminated polyacrylamide. Item 7. The granulated product according to Item 6.

[0018]

Composite metal hydroxide used in the Detailed Description of the Invention The present invention provides a chemical composition formula ^{_{(1) M 1-x 2+}} M x 3+ (OH -) 2 + xy (A n-) y / n (1) [wherein M ²⁺ is Mg ²⁺ , Ni ²⁺ , Zn ²⁺ , Fe ²⁺ , Ca 2
^At least one divalent metal ion selected from the group consisting of ²⁺ and Cu ²⁺ , and M ³⁺ represents at least one trivalent metal ion selected from the group consisting of Al ³⁺ and Fe ³⁺ And A ^n- represents an n-valent anion, and 0.1 ≦ x ≦
0.5, 0 ≦ y ≦ 0.5, and n is 1 or 2
It is. ] Is represented.

As the divalent metal ion represented by M ²⁺ ,
^Examples include Mg ²⁺ , Ni ²⁺ , Zn ²⁺ , Fe ²⁺ , Ca ²⁺ , and Cu ²⁺ , and preferably include Mg ²⁺ and Ca ²⁺ . M
^As trivalent metal ions represented by ³⁺ , Al ³⁺ , Fe
³⁺ , preferably Fe ³⁺ .

A ^n- represents an n-valent anion (n = 1 or 2). That, A ^n-consists either alone monovalent or divalent anion, including both monovalent anions and divalent anions. However, the divalent anion is preferably smaller in molar ratio than the monovalent anion. The monovalent ^{anion, OH -, Cl -, NO} 2 -, NO 3 -, F -, Br -, H
CO ₃ ^- and the like, preferably Cl ^-, and the like.
As the divalent anion, SO ₄ ^2- , CO ₃ ^2- , SO ₃ ^2-
And the like, and preferably SO ₄ ^2- .

X is usually 0.1 ≦ x ≦ 0.5,
Preferably 0.2 ≦ x ≦ 0.4, more preferably 0.2
≤ x ≤ 0.35.

Y is usually 0.1 ≦ y ≦ 0.5,
Preferably 0.2 ≦ y ≦ 0.4, more preferably 0.2
≤ y ≤ 0.35.

In the compound of the general formula (1) of the present invention,
The divalent metal ion M ²⁺ , the trivalent metal ion M ³⁺ and the carbonate ion are values measured by a titration method, and the measurement of Cl ⁻ ion is performed by an ion meter equipped with a chloride ion selective electrode. a measured value, carbonate ion and Cl ^- NO _2, except for ions _{^{-, NO 3 -, F -}} , Br -, HCO 3 - anions and SO ₄ ^{2-monovalent,} such as, second SO ₃ ^2-like a ^n- is made from the valence of the anion, a value measured by ion chromatography. In addition, "y" regarding a divalent anion
Is a value in which the number of moles measured by the above method is represented as A ²⁻ . Hydroxide ions OH ^- are, M ^2+, is a value obtained by calculation M ³⁺ and A ^n- in the measurements from the original to the electrical neutrality condition.

If it is desired to remove both the phosphorus component and the nitrogen component, NO (A ⁿ⁻ ) is used as a monovalent anion.
₂ ^-, NO ₃ ^- halogen ions except for (Cl ^{-, F -,} B
r ^-) and it can be used hydroxide ions, from environmental problems, Cl ^- being most preferred.

These composite metal hydroxides may be used alone or as a mixture of two or more types of composite metal hydroxides prepared by combining the above ions. As the shape, it is possible to use the powder as it is, but it is preferable to use it as a granulated material and a filter agent in consideration of filling and using in a treatment tank of a purification facility. The binder used for granulation is not particularly limited, but is an aminated polyacrylamide such as polyamide / epichlorohydrin resin, vinyl acetate / vinyl versatate copolymer resin, styrene / acrylic resin and polyacrylic hydrazide. And the like, celluloses such as ethylcellulose and carboxymethylcellulose, and polysaccharides such as carrageenan. Among them, organic resin compounds are preferably used. Preferred binders include organic resin compounds such as aminated polyacrylamide, and more preferably aminated polyacrylamide.

The binder may be a mixture of an aminated polyacrylamide and another binder component. Other binders to be mixed with the aminated polyacrylamide include at least one selected from the group consisting of polyamide / epichlorohydrin resin, vinyl acetate / vinyl versatate copolymer resin, and styrene / acrylic resin.
Seeds.

When an aminated polyacrylamide is used as a binder among the organic resin compounds, a granulated product excellent in both phosphorus adsorption capacity and mechanical strength can be obtained by adding a small amount. For the purpose of lowering the viscosity of the mixture during granulation and improving workability, aminated polyacrylamides include polyamide / epichlorohydrin resin, vinyl acetate / vinyl versatate copolymer resin and styrene / acrylic resin. It is preferable to use another binder in combination. By using a mixture of these and an aminated polyacrylamide as a binder, it becomes possible to obtain a granulated product having excellent mechanical strength, phosphorus adsorption ability and workability. The binder is 1 to 1 for the whole granulated material.
It is used in an amount of 40% by weight, preferably about 1 to 20% by weight, and more preferably 1 to 10% by weight.

[0028] At this time, the granulation method is such that at least one selected from the group consisting of polyamide / epichlorohydrin resin, vinyl acetate / vinyl versatate copolymer resin and styrene / acrylic resin is used as a binder. 1 to 40% by weight based on the aminated compound
Of a binder, preferably about 1 to 20% by weight, more preferably about 1 to 10% by weight, and a binder of about 1 to 40% by weight, preferably 1 to 20% by weight, based on the whole granulated material. % By weight, more preferably 1 to 10
A required amount of water is added to the mixture blended at a ratio of about weight%, and the mixture is kneaded well and kneaded, and then formed into a molded body using a granulator. As the kneader and the granulator, those generally used can be used, but preferably, a kneader having two or more rotating shafts as a kneader, and an upward-push-type extrusion granulator as a granulator. A type can be suitably used. The obtained compact is dried and cured to obtain a granulated product. When drying and curing, it is desirable to dry at a temperature equal to or higher than the minimum film forming temperature of the binder. However, when drying at a temperature equal to or lower than the minimum film forming temperature, it is possible to cope by increasing the drying time.

The composite metal hydroxide used as the phosphorus adsorbent in the present invention is an n-valent anion (n = 1 or 2) in the composition.
Phosphate ions are trapped by an anion exchange reaction between and phosphate ions, and the trapped phosphate ions must be desorbed using an alkali metal carbonate, an alkali metal salt and an alkaline earth metal salt as a desorption solution. Is possible.

The phosphate ion desorbing solution is preferably an aqueous alkali metal carbonate solution, preferably sodium carbonate,
Aqueous solutions of potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium carbonate, lithium carbonate and the like can be mentioned, and more preferably, an aqueous solution of sodium carbonate or sodium hydrogen carbonate can be mentioned. As an aqueous alkali metal salt solution, preferably ammonium hydroxide, sodium hydroxide, potassium hydroxide, sodium chloride, potassium chloride,
Sodium fluoride, potassium fluoride, sodium bromide,
Examples include aqueous solutions of potassium bromide, sodium sulfate, potassium sulfate, sodium sulfite, potassium sulfite, and the like, and more preferably, aqueous solutions of sodium hydroxide and sodium chloride. As the alkaline earth metal salt aqueous solution, preferably, an aqueous solution of magnesium chloride, calcium chloride, magnesium sulfate, magnesium bromide, calcium bromide or the like is used, and more preferably, an aqueous solution of magnesium chloride or magnesium sulfate is used. By this desorption liquid treatment, the phosphorus component in the phosphorus adsorbent can be recovered and reused as a water-soluble phosphate.

The wastewater contains nitrogen components (nitric acid, nitrous acid)
Is contained at the same time as the phosphorus component, the nitrogen component is simultaneously recovered by the above-mentioned desorption solution treatment.

The composite metal hydroxide has a temperature of about 250 to 550 ° C.
Shows an endothermic reaction having endothermic peaks due to decomposition at about 380 ° C. and about 430 ° C. in the range of above, so that the composite metal hydroxide after desorption of the phosphorus component is heated above its decomposition temperature, that is, about 430 to 600 ° C., preferably Is calcined at about 550 ° C. to become a composite metal oxide containing no anion acting as an ion exchange group.

The composite metal hydroxide is stirred in an electrolyte solution containing an n-valent anion by applying the property that the composite metal oxide becomes a composite metal hydroxide by coming into contact with an electrolyte solution containing an anion. Thereby, a composite metal hydroxide having an n-valent anion as an ion exchange group can be regenerated. Examples of the electrolyte solution used at this time include sodium chloride, potassium chloride, ammonium chloride, and lithium chloride. Among them, sodium chloride is inexpensive and suitable. The concentration of these electrolyte solutions was 0.5 M
５5M, and the time required for reproduction is about 2-4 hours. It is also possible to recycle the composite metal oxide after it is brought into direct contact with the phosphorus-containing wastewater to adsorb the phosphorus component.

Further, since the composite metal hydroxide and the composite metal oxide dissolve in the acidic region of pH 5 or less, the composite metal hydroxide and the composite metal oxide after the desorption of the phosphorus component were dissolved in an acid to obtain. The solution can be reused as a raw material for preparing the composite metal hydroxide. Examples of the acidic solution used at this time include hydrochloric acid, aluminum chloride, and ferric chloride, and hydrochloric acid is particularly preferable.

Regeneration of the composite metal hydroxide after the acid treatment can be easily performed, for example, according to the description in the literature (Langmuir, 9, 1418-1422 (1993)).

Further, by using a phosphate ion desorbing solution in combination, the phosphorus removing ability of the phosphorus adsorbent can be efficiently regenerated. That is, an aqueous solution of an alkali metal salt and an alkaline earth metal salt excluding an alkali metal carbonate is used as a single component or a mixed aqueous solution of two or more components in a phosphate ion desorbing solution of a phosphorus adsorbent after adsorption of a phosphorus component. Can be played. As the alkali metal salt used at this time, preferably, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium chloride, potassium chloride, lithium chloride and the like are used, and more preferably, sodium hydroxide and sodium chloride are used. Preferred examples of the metal salt include magnesium chloride, magnesium sulfate, magnesium nitrate, calcium chloride, calcium nitrate and the like, and more preferred are magnesium chloride and magnesium sulfate. In this case, the treatment may be performed several times by combining an aqueous solution treatment of an alkali metal salt and an aqueous solution treatment of an alkaline earth metal salt.

[0037]

According to the present invention, by using a phosphorus adsorbent containing a composite metal hydroxide having a large phosphorus component adsorption capacity, the phosphorus component in the waste water can be efficiently adsorbed, and inexpensively and efficiently. The phosphorus component can be recovered and reused, and the phosphorus adsorbent can be recycled.

In particular, the fact that the phosphorus adsorbent itself can be reused does not cause secondary pollution due to the disposal of the phosphorus adsorbent, which is a problem in the past, and the environmentally friendly load that allows the recovery and reuse of the phosphorus component, which is a finite resource. It is effective for the construction of a type of phosphorus component recycling system, and is very effective from the viewpoints of eutrophication prevention, water environment preservation and resource environment.

Further, the wastewater treatment agent of the present invention is very preferable as a wastewater treatment agent because it can remove phosphorus components (phosphoric acid) and nitrogen components (nitric acid and nitrous acid) simultaneously.

Furthermore, wastewater having a phosphorus concentration of 0.02 ppm or less can be reduced to a detection limit or less.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

[0042]

【Example】

Example 1 Phosphorus adsorbent (Mg ²⁺ _0.665 Fe ³⁺ _0.335 (OH ⁻ ) _2.099 Cl ⁻ _0.124 (C
O ₃ ²⁻ ) _0.056 ; hereinafter, referred to as “Cl / HT-Fe”) 20 g was added to 1600 cm ^{3 of an} aqueous solution of Na ₂ HPO ₄ adjusted to a phosphorus concentration of 26.7 mM-P, followed by stirring at 25 ° C. for 4 hours. . After stirring, the phosphorus adsorbent was separated by filtration, and the phosphate ion concentration in the filtrate was quantified by the molybdenum blue method.

From the difference between the initial concentration of phosphate ions and the residual concentration after adsorption equilibrium, the amount of phosphate ions adsorbed
It was calculated as the amount of adsorption per g. The pH of the aqueous solution during phosphate ion adsorption was adjusted to pH 6.93 with hydrochloric acid.

As a result, the phosphorus adsorption amount was 1.17 mmolP / g.

Further, phosphate binders ^{_{(Mg 2+ 0.683 Al 3+ 0.317 (}} O
^{_{H -) 2.033 Cl - 0.238 (}} CO 3 2-) 0.023; hereinafter "Cl / HT-Al" and denoted) result was evaluated in the same manner and found to be adsorption capacity of 2.13mmolP / g.

Example 2 For the purpose of phosphorus desorption, 16 g of each of the phosphorus component-containing phosphorus adsorbents (each represented by P / HT-Fe and P / HT-Al) obtained in Example 1 was treated with 2M-Na ₂
CO ₃ was added to an alkaline aqueous solution of 1280 cm ³ , and ion exchange between phosphate ions and carbonate ions was performed. After stirring at 90 ° C. for 4 hours, the phosphorus adsorbent was separated by filtration, washed with water, dried, and dissolved in hydrochloric acid, and the phosphate ion concentration in the solution was quantified in the same manner as in Example 1. Was determined for the residual phosphorus concentration. As a result, the phosphorus adsorbents P / HT-Fe and P / HT-Al were 0.09 and 0.
It was 29 mmolP / g, and about 90% phosphorus desorption was confirmed for each sample.

Example 3 The phosphorus adsorbent obtained after desorbing the phosphorus component obtained in Example 2 (each CO
₃ / HT-Fe, CO ₃ / HT-Al) were fired at 550 ° C. for 3 hours to prepare a composite metal oxide. As a result of powder X-ray diffraction measurement, the composite metal oxide shows a diffraction pattern due to the magnesium oxide structure.

Example 4 5 g of each of the composite metal oxides (each represented by MgFeO and MgAlO) obtained in Example 3 was added to 400 cm ^{3 of a} 5M aqueous solution of NaCl, followed by stirring at 90 ° C. for 4 hours. After stirring, the dried product obtained through filtration, washing and drying was subjected to powder X-ray diffraction measurement. As a result, the structure of the composite metal hydroxide (Cl / HT-Fe, Cl / HT-Al) was confirmed. Was.

Example 5 1 g of the phosphorus adsorbent (Cl / HT-Fe) regenerated in Example 4 was added to 80 cm ^{3 of an} aqueous solution of Na ₂ HPO ₄ adjusted to a phosphorus concentration of 26.7 mM-P. Stirred for hours. After the stirring, the phosphorus adsorbent was separated by filtration, and the phosphate ion concentration in the filtrate was quantified in the same manner as in Example 1 to determine the phosphate ion adsorption amount. As a result, it was 1.00 mmolP / g with the regenerated phosphorus adsorbent Cl / HT-Fe, and an adsorption capacity of about 85% with respect to the phosphorus adsorbent before regeneration was recognized.

Example 6 3 g of each of the composite metal hydroxide and the composite metal oxide obtained in Examples 2 and 3 was dissolved in 6N-hydrochloric acid, and a mixed solution of MgCl ₂ + FeCl _{3 was obtained.}
(Mg / Fe molar ratio = 1.99) and a mixed solution of MgCl ₂ + AlCl ₃ (Mg / Al molar ratio = 2.15) 100 cm ³ each were prepared.

After boiling and decarboxylation of the mixture, Langmuir, 9,
A composite metal hydroxide was prepared by the method described in 1418-1422 (1993).

As a result, Cl / HT-Fe (Mg ²⁺ _0.651 Fe ³⁺ _{0.349
^{(OH -) 2.183 Cl - 0.090}} (CO 3 2-) 0.038) and Cl / HT-Al (Mg ^{2+
_{0.676 Al 3+ 0.324 (OH -)}} 2.082 Cl - 0.214 (CO 3 2-) 0.014) was obtained.

The phosphorus adsorption capacity was determined in the same manner as in Example 1. As a result, an adsorption capacity of 0.97 mmol P / g was obtained with Cl / HT-Fe and 2.13 mmol P / g was obtained with Cl / HT-Al.

Example 7 1 g of each of the composite metal oxides obtained in Example 3 was used at a phosphorus concentration of 2
Na ₂ HPO ₄ aqueous solution adjusted to 6.7 mM-P was added in 80 cm ³ ,
The mixture was stirred at 5 ° C for 4 hours. After stirring, the phosphorus adsorbent was filtered off, the phosphate ion concentration in the filtrate was quantified in the same manner as in Example 1, and the phosphate ion adsorption was determined. MgFeO and MgA
It was 1.00 and 0.87 mmol P / g, respectively, in lO.

Subsequently, for the purpose of phosphorus desorption, 0.3 g of each of the composite metal oxides (expressed as P / MgFeO, P / MgAlO) after phosphorus adsorption was added to 2M-Na ₂ C
It was added to 24 cm ^{3 of an} O ₃ alkaline aqueous solution to perform ion exchange between phosphate ions and carbonate ions. After stirring at 90 ° C. for 2 hours, the phosphorus adsorbent was separated by filtration, washed with water, dried, and dissolved in hydrochloric acid, and the phosphate ion concentration in the solution was quantified in the same manner as in Example 1. Was determined for the residual phosphorus concentration. As a result, the samples P / MgFeO and P / MgAlO
/ g, about 90% in the former case and about 46% in the latter case. As a result of powder X-ray diffraction measurement of the sample after phosphorus desorption, regeneration of the CO ₃ / HT-Fe and CO ₃ / HT-Al structures was observed. These recycled products can be reused by the methods of Embodiments 3, 4 to 6.

[0056] EXAMPLE 8 Various ion (2.0ppm-P, 10.4ppm-NO 2 -, 7.0ppm-NO 3 - and
Phosphorus adsorbent Cl / in 40 ml of simulated wastewater containing 16.5 ppm-SO ₄ ^2- )
HT-Fe or Cl / HT-Al (0.01 g each) was added, and the mixture was stirred at room temperature for 4 hours. After stirring, the phosphorus adsorbent was filtered off, the phosphate ion concentration in the filtrate was measured by the method of Example 1, and the other ion concentrations were measured by ion chromatography. Table 1 shows the results. Table 1 shows that treating the simulated wastewater with the phosphorus adsorbent significantly reduces not only phosphorus but also other ions.

[0057]

TABLE 1 Ion Concentration (ppm) wastewater treatment agent _{^{P NO 2 - NO 3 - SO}} 4 2- Cl / HT-Fe 0.7 2.9 1.5 12.1 Cl / HT-Al 0.2 2. 4 1.1 8.0 Example 9 0.5 g of a phosphorus component-containing phosphorus adsorbent (P / HT-Al) was placed in a stoppered Erlenmeyer flask, and 6% NaOH + 30% Na was used as a desorption solution.
A Cl mixed aqueous solution (20 ml) was added, and the mixture was shaken horizontally (170 times / minute) at 30 ° C. for 14 hours. Subsequently, the phosphorus adsorbent was separated by filtration, the filtered phosphorus adsorbent was washed with water, and then reprocessed in the same manner as above using a 79.3% MgCl ₂ aqueous solution as a desorbing liquid. The phosphorus desorption amount was determined by measuring the phosphorus concentration in the filtrate by the method of Example 1 and calculating as the phosphorus desorption amount per 1.0 g of the phosphorus adsorbent.

As a result, the phosphorus desorption amount was 1.73 mm
olP / g was obtained.

Example 10 The same procedure as in Example 9 was carried out except that the desorption solution was treated with a 3% aqueous solution of NaOH and then retreated with a 79.3% aqueous solution of MgCl ₂ to determine the amount of phosphorus desorbed. .

As a result, the phosphorus desorption amount was 1.50 mm
olP / g was obtained.

Example 11 The regenerated phosphorus adsorbent obtained in Examples 9 and 10 was treated in the same manner as in Example 1 to determine the amount of phosphorus adsorbed.

As a result, the phosphorus adsorption amount was 1.79 mmo.
1P / g (Example 9), 1.65 mmol P / g (Example 10), and 84% and 77%, respectively, as the regeneration rates with respect to the saturated phosphorus adsorption amount of the phosphorus adsorbent Cl / HT-Al of 2.13 mmol P / g. In each case, a high regeneration rate of about 80% of phosphorus adsorption ability was obtained.

Example 12 The method for producing a granulated product was a phosphorus adsorbent (Cl / HT-Al)
A predetermined amount of polyacrylic hydrazide and polyamide-epichlorohydrin resin is added as a binder to 4 kg, and a 2-axis kneader having an output of 1.5 kw, a total capacity of 20 L, a 2-axis rotation speed of 29.20 rpm, and an output 3.7
Using a top-up granulator having a kw of 3 mm and a screen speed of 135 rpm, the mixing time of the phosphorus adsorbent and the binder was 1 minute, and the required amount of water was added, followed by kneading for 5 minutes. Thereafter, cylindrical granules having a diameter of 3 mm and a length of 5 to 10 mm were prepared and dried at 80 ° C. for 15 hours.

Example 13 The granules prepared in Example 12 were subjected to a strength test and a phosphorus adsorption test of the granules. The strength test method is as follows: 1.0 g of the granulated material is precisely weighed in a stoppered Erlenmeyer flask, and 20 ml of water is added.
The mixture was shaken at 30 ° C. and 170 times / minute for 3 hours in a horizontal shake-type thermostat. After shaking, the mixture was filtered and dried, and the total weight of the granules was measured. Subsequently, the particles are sized with a 10 mesh sieve, and
h The weight of the residual product and the passing product was measured, and the crushing strength (L) was calculated by the following equation. In practice, the crushing strength is 8
5 or more is required.

Crushing resistance = 100− [P / (S + P)] × 100 P: Weight of 10 mesh-passed product S: Weight of 10-mesh residual product In the phosphorus adsorption test, a granulated product was placed in a conical flask with a stoppered stopper in an amount of 1.0.
20 g of the aqueous solution of Na ₂ HPO ₄ used in Example 1
Was added and shaken horizontally (170 times / minute) at 30 ° C. for 3 hours. After shaking, the mixture was filtered off, the phosphorus concentration in the filtrate was determined in the same manner as in Example 1, and the amount of phosphorus adsorbed was calculated. Table 3 shows the results.

[0066]

[Table 3] Pinterer Top-press type granulator Phosphorus adsorption amount of processing capacity of binder blended amount per 1g of granulated product Crushing resistance (wt.%) (Kg / hr) (mmolP / g) Polyacrylic acid 1.0 70 0.69 86.4 human Bu Hydrazide port Riakuriru acid 3.0 60 0.60 99.5 human Bu Hydrazide Po Riamito Bu-epi 5.0 150 1.28 33.5 Kurorohito Bu phosphoric resin Po Riakuriru acid 1.0 human Bu Hydrazide 110 0.67 97. 3 Po Riamito Bu-epi 4.0 Kurorohito Bu phosphorus resin these results, phosphorus adsorbent of the present invention, septic tanks, wastewater standards such as sewer and rural village wastewater can be reliably cleared, further also fully compatible to become stricter in the future regulation value It indicates that you have the ability to do so.

Example 14 The granulated product prepared in Example 12 was pulverized to obtain a pulverized product (particle size:
200-280 mesh) and aqueous NaH ₂ PO ₄ solution adjusted to phosphorous concentration 1ppm-P (pH6.8) 2000ml
The mixture was stirred at 25 ° C., and the change in the phosphorus concentration with respect to the stirring time was determined. The measurement of the phosphorus concentration was obtained in the same manner as in Example 1. The results are shown in FIG. FIG.
From the results, it can be seen that the phosphorus adsorption rate increases in response to the increase in the addition amount, and that the phosphorus is adsorbed and removed within only 10 minutes after the addition of 0.025% of the phosphorus adsorbent.

Example 15 The phosphorus adsorbing ability of a phosphorus adsorbent was evaluated using actual wastewater having a low phosphorus concentration.

0.1 g of a phosphorus adsorbent (Cl / HT-Al) was added to 400 ml of treated water in a domestic wastewater treatment facility (tank for 220 people), followed by stirring with a magnetic stirrer for 4 hours. After stirring, the treated water was filtered through a 0.45 μm-membrane filter, and the phosphorus concentration in the filtrate was analyzed according to the phosphorus determination method described in JIS. As a result, it was clarified that the phosphorus concentration (0.18 ppm-P) in the actual effluent was reduced to below the detection limit of phosphorus after the adsorption treatment, and the phosphorus adsorbent of the present invention in the actual effluent and low-phosphorus concentration effluent etc. Has proven its effectiveness.

According to the wastewater treatment method of the present invention, the phosphorus component can be separated and removed from the wastewater.
As shown in Table 1 above, the composite metal hydroxide can remove both the phosphorus component and the nitrogen component. Therefore, the present invention is applicable not only to the method for treating the phosphorus-containing wastewater, but also to the following items 1A to 4
A, also relates to items 6A to 8A.

Item 1A. The following step (I) and step (I
Processing method of phosphorus and nitrogen-containing waste water containing I): step (I) Chemical formula _{(1): M 1-x} 2+ M x 3+ (OH -) 2 + xy (A n-) y / n ( 1) ^{wherein, M 2+, M 3+, a} n-, x, y and n are as defined above. Contacting a phosphorus-containing wastewater with the composite metal hydroxide represented by the formula (1) to adsorb the phosphorus component; Step (II): converting the phosphorus adsorbent obtained in Step (I) to adsorb the phosphorus component with an alkali metal carbonate And a step of regenerating and reusing the phosphorus adsorbent by treating with at least one phosphorus desorbing solution selected from the group consisting of alkali metal salts and alkaline earth metal salts excluding alkaline earth metal carbonates.

Item 2A. The following steps (I), (Ia),
Method for treating phosphorus- and nitrogen-containing wastewater containing (Ib) and (II): Step (I) Chemical composition formula (1): M _1−x ²⁺ M _x ³⁺ (OH ⁻ ) _{2 + xy} (A ⁿ⁻⁾ ) _{Y / n} (1) [wherein, M ²⁺ , M ³⁺ , A ⁿ⁻ , x, y and n are the same as above. Contacting a phosphorus-containing wastewater with the composite metal hydroxide represented by the formula (1) to adsorb the phosphorus component; step (Ia): converting the phosphorus adsorbent obtained in step (I) to adsorb the phosphorus component with an alkali metal carbonate or brought into contact with an aqueous solution containing a ^n- ions, a step of desorbing and recovering phosphorous components; step (Ib) step phosphorus adsorbent after phosphorus desorption calcined at four hundred and thirty to six hundred ° C.; and step (II) calcination The subsequent phosphorus adsorbent is treated with at least one phosphorus desorbing solution selected from the group consisting of alkali metal salts and alkaline earth metal salts excluding alkali metal carbonates and alkaline earth metal carbonates to regenerate the phosphorus adsorbent , Reuse process.

Item 3A. The following steps (I) to (Ic)
Method for treating phosphorus and nitrogen-containing wastewater containing: Step (I) Chemical composition formula (1): M _1−x ²⁺ M _x ³⁺ (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1) [Wherein, M ²⁺ , M ³⁺ , A ⁿ⁻ , x, y and n are the same as above. Contacting a phosphorus-containing wastewater with the composite metal hydroxide represented by the formula (1) to adsorb the phosphorus component; step (Ia): converting the phosphorus adsorbent obtained in step (I) to adsorb the phosphorus component with an alkali metal carbonate Or a step of contacting with an aqueous solution containing ^An- ions to desorb and recover the phosphorus component; step (Ic): dissolving the phosphorus adsorbent after phosphorus desorption with acid, and reusing the solution as a raw material for producing the phosphorus adsorbent. .

Item 4A. The calcined phosphorus adsorbent obtained in the step (Ib) of the item 2A is (1) the following step (III) and step (I)
V), or (2) the step (I)
Step (III): a step of contacting the calcined phosphorus adsorbent with the phosphorus component-containing wastewater to adsorb the phosphorus component; and a step (IV) of step (III). The step (II) of item 1A or the steps (Ia), (Ib) and (II) of item 2A are repeated using the phosphorus adsorbent having adsorbed the phosphorus component obtained in III).

Item 6A. Chemical composition formula (1): M _1−x ²⁺ M _x ³⁺ (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1) [where M ²⁺ , M ³⁺ , A ⁿ⁻ , X, y and n are the same as above. ] A wastewater treating agent granulated product of phosphorus and nitrogen-containing wastewater, comprising 99 to 60% by weight of the composite metal hydroxide represented by the formula (1) and 1 to 40% by weight of a binder.

Item 7A. The granulated product according to item 6A, wherein the binder contains an aminated polyacrylamide.

Item 8A. The binder is at least one selected from the group consisting of polyamide / epichlorohydrin resin, vinyl acetate / vinyl versatate copolymer resin and styrene / acrylic resin, and 1 to 40% by weight of aminated polyacrylamide and 99 to 60% Item 7. The granulated product according to Item 6, which is a mixture by weight.

[Brief description of the drawings]

FIG. 1 shows the results of X-ray diffraction measurement of the samples obtained in Examples 1 to 7 of the present invention.

FIG. 2 is a flowchart showing a method for treating a phosphorus-containing wastewater according to an example of the present invention in the order of steps.

FIG. 3 is a graph showing a change in a phosphorus concentration with respect to a stirring time of a pulverized product obtained in Example 14 of the present invention.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Mikiko Mihara 161-8 Shimomoto Castle, Myojin Setocho, Naruto City, Tokushima Prefecture

Claims (8)

[Claims] 1. A method for treating a phosphorus-containing wastewater comprising the following steps (I) and (II): Step (I) Chemical composition formula (1): M _{1 -x} ²⁺ M _x ³⁺ (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1) [wherein M ²⁺ is Mg ²⁺ , Ni ²⁺ , Zn ²⁺ , Fe ²⁺ , Ca
^At least one divalent metal ion selected from the group consisting of ²⁺ and Cu ²⁺ , and M ³⁺ represents at least one trivalent metal ion selected from the group consisting of Al ³⁺ and Fe ³⁺ And A ^n- represents an n-valent anion, and 0.1 ≦ x ≦
0.5, 0.1 ≦ y ≦ 0.5, and n is 1 or 2. Contacting a phosphorus-containing wastewater with the composite metal hydroxide represented by the formula (1) to adsorb the phosphorus component; Step (II): converting the phosphorus adsorbent obtained in Step (I) to adsorb the phosphorus component with an alkali metal carbonate And a step of regenerating and reusing the phosphorus adsorbent by treating with at least one phosphorus desorbing solution selected from the group consisting of alkali metal salts and alkaline earth metal salts excluding alkaline earth metal carbonates. 2. A method for treating a phosphorus-containing wastewater comprising the following steps (I), (Ia), (Ib) and (II): Step (I) Chemical composition formula (1): M _{1 -x} ²⁺ M _x ³⁺ (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1) [wherein, M ²⁺ is Mg ²⁺ , Ni ²⁺ , Zn ²⁺ , Fe ²⁺ , Ca
^At least one divalent metal ion selected from the group consisting of ²⁺ and Cu ²⁺ , and M ³⁺ represents at least one trivalent metal ion selected from the group consisting of Al ³⁺ and Fe ³⁺ And A ^n- represents an n-valent anion, and 0.1 ≦ x ≦
0.5, 0.1 ≦ y ≦ 0.5, and n is 1 or 2. Contacting a phosphorus-containing wastewater with the composite metal hydroxide represented by the formula (1) to adsorb the phosphorus component; step (Ia): converting the phosphorus adsorbent obtained in step (I) to adsorb the phosphorus component with an alkali metal carbonate or brought into contact with an aqueous solution containing a ^n- ions, a step of desorbing and recovering phosphorous components; step (Ib) step phosphorus adsorbent after phosphorus desorption calcined at four hundred and thirty to six hundred ° C.; and step (II) calcination The subsequent phosphorus adsorbent is treated with at least one phosphorus desorbing solution selected from the group consisting of alkali metal salts and alkaline earth metal salts excluding alkali metal carbonates and alkaline earth metal carbonates to regenerate the phosphorus adsorbent , Reuse process. 3. A method for treating a phosphorus-containing wastewater comprising the following steps (I) to (Ic): Step (I) Chemical composition formula (1): M _{1 -x} ²⁺ M _x ³⁺ (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1) [wherein M ²⁺ is Mg ²⁺ , Ni ²⁺ , Zn ²⁺ , Fe ²⁺ , Ca
^At least one divalent metal ion selected from the group consisting of ²⁺ and Cu ²⁺ , and M ³⁺ represents at least one trivalent metal ion selected from the group consisting of Al ³⁺ and Fe ³⁺ And A ^n- represents an n-valent anion, and 0.1 ≦ x ≦
0.5, 0.1 ≦ y ≦ 0.5, and n is 1 or 2. Contacting a phosphorus-containing wastewater with the composite metal hydroxide represented by the formula (1) to adsorb the phosphorus component; step (Ia): converting the phosphorus adsorbent obtained in step (I) to adsorb the phosphorus component with an alkali metal carbonate Or a step of contacting with an aqueous solution containing ^An- ions to desorb and recover the phosphorus component; step (Ic): dissolving the phosphorus adsorbent after phosphorus desorption with acid, and reusing the solution as a raw material for producing the phosphorus adsorbent. . 4. The calcined phosphorus adsorbent obtained in the step (Ib) of the second step (1) is treated in the order of the following steps (III) and (IV); or (2) A method for treating a phosphorus-containing wastewater, which is treated in the step (Ic) of step (III); step (III) of contacting the calcined phosphorus adsorbent with phosphorus-containing wastewater to adsorb the phosphorus component; and step (IV). The step (II) of claim 1 or the steps (Ia), (Ib) and (II) of claim 2 are repeated using the phosphorus adsorbent that has adsorbed the phosphorus component obtained in step (III). 5. A chemical composition formula (1): M _1−x ²⁺ M _x ³⁺ (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1) wherein M ²⁺ is Mg ^{2 +} , Ni ²⁺ , Zn ²⁺ , Fe ²⁺ , Ca
^At least one divalent metal ion selected from the group consisting of ²⁺ and Cu ²⁺ , and M ³⁺ represents at least one trivalent metal ion selected from the group consisting of Al ³⁺ and Fe ³⁺ And A ^n- represents an n-valent anion, and 0.1 ≦ x ≦
0.5, 0.1 ≦ y ≦ 0.5, and n is 1 or 2. ] A wastewater treatment agent for simultaneous removal of phosphorus and nitrogen components in wastewater comprising a composite metal hydroxide represented by the formula: 6. A chemical composition formula (1): M _1−x ²⁺ M _x ³⁺ (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1) wherein M ²⁺ is Mg ^{2 +} , Ni ²⁺ , Zn ²⁺ , Fe ²⁺ , Ca
^At least one divalent metal ion selected from the group consisting of ²⁺ and Cu ²⁺ , and M ³⁺ represents at least one trivalent metal ion selected from the group consisting of Al ³⁺ and Fe ³⁺ And A ^n- represents an n-valent anion, and 0.1 ≦ x ≦
0.5, 0.1 ≦ y ≦ 0.5, and n is 1 or 2. ] The composite metal hydroxide 99 to 60 represented by
A wastewater treatment agent granulated product of a phosphorus-containing wastewater, which comprises 1% by weight of a binder and 1 to 40% by weight of a binder. 7. The granulated product according to claim 6, wherein the binder contains an aminated polyacrylamide. 8. The polyacrylamide as claimed in claim 1, wherein the binder is at least one selected from the group consisting of polyamide / epichlorohydrin resin, vinyl acetate / vinyl versatate copolymer resin and styrene / acrylic resin, and 1 to 40% by weight of polyacrylamide. The granulated product according to claim 6, which is a mixture of 99 to 60% by weight of the aminated product.