JP2002361269A - Method for treating water containing phosphorus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating water containing phosphorus, by which a reaction probability is increased without using a special catalyst to increase a reaction rate and water can be economically treated in an industrial scale. SOLUTION: A chemical which generates hydroxyl radicals is dissolved in water containing phosphorus to generate hydroxyl radicals. By the homogeneous liquid phase oxidation treatment of the hydroxyl radicals and the phosphorus in the water containing phosphorus, the phosphorus is oxidized to produce orthophosphate ions so as to separate and remove phosphorus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating phosphorus-containing water, and more particularly, to a method for producing corresponding alcohols produced by a gas-phase hydration reaction of an olefin using a phosphoric acid catalyst. The present invention relates to a method for economically treating water containing water or phosphorus-containing water containing organic phosphorus discharged during production or use of agricultural chemicals or raw materials for chemical industry at a high reaction rate.

[0002]

2. Description of the Related Art Phosphorus flowing into water bodies has been attracting attention as a substance causing eutrophication of the water environment for a long time. However, recently, in closed water areas and low-velocity water areas, phosphorus is associated with the growth of algae and aquatic plants. Was statistically evident.

[0003] From such a background, phosphorus itself is not a substance that immediately causes damage by water pollution, but phosphorus may cause remarkable proliferation of plankton. In general, the standard value of phosphorus for phosphorus is 16 mg /
L was revised and enforced on October 1, 1993 with a daily average of 8 mg / L.

[0004] Further, for the purpose of further improving the water environment, not only the reduction of the discharge amount of phosphorus by the total amount regulation is considered, but also the improvement of the water environment is strongly demanded by the society. I'm going.

[0005] Wastewater treatment (hereinafter abbreviated as phosphorus treatment) for reducing phosphorus generally used in various industries, commerce and public works, includes, for example, coagulation sedimentation treatment, flotation treatment, biological treatment, and the like. There are various methods such as a membrane separation treatment, an ion exchange treatment, an adsorption treatment, an electrostatic deionization treatment and a crystallization treatment, and the most suitable method is adopted according to the form and properties of the wastewater to be treated. Generally, coagulation sedimentation treatment,
Biological treatment or crystallization treatment is used.

In the alcohol synthesis industry, corresponding alcohols are produced by a gas-phase hydration reaction of an olefin using a catalyst. In the gas phase hydration reaction of olefins having 2 to 4 carbon atoms, particularly ethylene or propylene, a catalyst obtained by impregnating a porous siliceous carrier with an aqueous solution of orthophosphoric acid is mainly used from the viewpoint of reaction activity and catalyst life. I have.

[0007] In the gas phase hydration reaction of ethylene or propylene having a relatively high reaction temperature, particularly in the gas phase hydration reaction of ethylene, a phenomenon in which a small amount of phosphoric acid in the phosphoric acid catalyst constantly flows out together with the reaction stream from the phosphoric acid catalyst bed (weeping). ) Is allowed.
The amount of phosphoric acid carried in the phosphoric acid catalyst is reduced by this weeping, and the catalytic activity is also reduced. Therefore, usually, about 3 to 15% by weight of an orthophosphoric acid aqueous solution is sprayed continuously or intermittently from the upper portion of the reaction tower. A method for maintaining the catalyst activity for a long time is generally used.

[0008] A small amount of phosphoric acid weeped from the catalyst bed is neutralized with an aqueous alkaline solution such as sodium hydroxide to form a phosphate, and is introduced into a distillation purifier together with a reaction mixture containing alcohol and water. The alcohol is refined in a distillation purification device and distilled as product alcohol. on the other hand,
The phosphate is discharged out of the system together with the water separated from the alcohol. Phosphorus contained in the wastewater is usually contained as a phosphorus atom (hereinafter abbreviated as P) at a concentration of about 5 to 300 mg / L in the wastewater.

As described above, the content of phosphorus in the wastewater discharged when producing the corresponding alcohol by the gas phase hydration reaction of an olefin using a phosphoric acid catalyst (hereinafter abbreviated as alcohol synthesis) is water pollution. In some cases, the standard value of phosphorus in the wastewater exceeds the standard value in the Prevention Law. The water is drained after treatment until the value falls below the value.

Next, the prior art of a method for treating phosphorus in alcoholic synthetic wastewater will be described.

No harmful substances are contained in the alcohol synthesis wastewater, and among water pollutants, BOD and CO
Water pollutants other than phosphorus, such as D, SS, and nitrogen, are extremely small, and, except for phosphorus, sufficiently satisfy the wastewater standard values of the Water Pollution Control Law. Therefore, when phosphorus is reduced by biological treatment, it is necessary to newly add water pollutants such as nitrogen, BOD and COD as nutrients in order to maintain biological activity. The method of reducing phosphorus by biological treatment is not suitable for alcohol synthesis wastewater because it increases pollutants and is not adopted.

Phosphorus in alcohol synthesis wastewater can be separated by reverse osmosis membrane separation, but BOD, COD, S
Components contained in trace amounts such as S components are concentrated in a membrane separation device, and these concentrated COD, BOD and SS components adhere to the membrane surface and rapidly deteriorate the membrane separation performance. It is necessary to perform a reverse osmosis membrane separation treatment after performing a pretreatment such as filtration with sand or adsorption using activated carbon or the like. Nevertheless, a small amount of leaked COD and BOD components are concentrated and adhere to the membrane surface, so the degradation of membrane separation performance has not been solved at present. Is not industrialized in terms of membrane life.

[0013] It is possible to separate and remove phosphorus from alcohol synthesis wastewater by ion exchange treatment, adsorption treatment and electrostatic deionization treatment. Various environmental problems occur in the treatment of the concentrated phosphorus component. In order to avoid this problem, the ion-exchanger containing phosphorus, the adsorbent, or the concentrated water of the phosphorus component must be treated as industrial waste as it is. The ion exchange treatment, adsorption treatment and electrostatic deionization treatment also separate other anions such as sulfate ions and chloride ions in addition to the phosphate ions contained in the alcohol synthesis wastewater. There is also a serious drawback on the industrial scale, which is significant, and this method is not used at present.

[0014] The crystallization treatment is effective in the case of removing low-concentration phosphorus components. However, as described above, the alcohol synthesis wastewater has a relatively low phosphorus concentration to be treated, and thus has a small treatment effect. Not suitable. Of course, the problem of crystallization waste is the same as in the case of ion exchangers and adsorbents containing phosphorus, and this method has not been adopted.

[0015] The phosphorus treatment method of the alcohol synthetic wastewater generally employs coagulation sedimentation treatment or flotation treatment from the characteristics of the wastewater. Specifically, the orthophosphate ions contained in the alcohol synthesis wastewater include metal ions, for example, one or more metal ions such as calcium ions, magnesium ions, aluminum ions, and iron ions, and water-insoluble metal phosphates. This is a method in which a salt is formed, and the floc of the water-insoluble metal phosphate is separated from the wastewater as sludge by coagulation sedimentation treatment or floating treatment.
According to this phosphorus treatment method, orthophosphate ions in the treated water can be reduced to 1 mg / L or less as P. In practice, the only method used in the treatment of alcohol synthetic wastewater is the only coagulation-sedimentation method in Japan due to the characteristics of the wastewater.

[0016] If the method for phosphorus treatment by coagulation and sedimentation treatment of the alcohol synthesis wastewater by the supply of metal ions is used, the phosphorus concentration in the treated water should originally be 1 mg / L or less. Phosphorus concentration in water is P
Approximately 1 to 20 mg / L remains, and the concentration of phosphorus in the factory wastewater is 8 mg / L per day on average, which is somehow lower than the wastewater standard value, which is not a satisfactory condition.

Recently, as a method for treating phosphorus-containing water, a phosphorus compound is converted into phosphate ions by irradiating ultraviolet rays while contacting the phosphorus-containing water with a photocatalyst made of titanium dioxide, and then reacting with polyvalent metal ions. A method for removing a phosphorus compound in water as a solid phase has been disclosed (JP-A-2001-29).
945).

According to Japanese Patent Application Laid-Open No. 2001-29945, the main point of this method is to irradiate phosphorous-containing water with ultraviolet rays while contacting it with a photocatalyst made of titanium dioxide.
It is stated that the conversion of phosphorus compounds to phosphate ions is based on the fact that the generated oxygen atoms and ozone have oxidizing power together with titanium dioxide.

However, the basic concept of the photocatalytic reaction of titanium dioxide or the like is described as the "Honda Fujishima effect". That is, when a semiconductor such as titanium dioxide is excited by light having an energy greater than its hand gap, an electron-hole pair is generated inside the semiconductor.
The feature of titanium oxide lies in the extremely strong oxidizing power of holes rather than the reducing power of excited electrons. The paired reduction reaction is reduction of oxygen in water or air. By the reduction of oxygen (omitted on the way), it becomes a hydroxyl radical (OH.) With stronger oxidizing power. "(Akira Fujishima: Applied Physics, No. 64)
Vol. 8, No. 803-807 (1995)) is a general interpretation. And the quantum yield of ultraviolet light 10
From the calculation of the reaction amount at 0%, the discoverer of this effect himself acknowledged that "titanium dioxide photocatalytic reaction is unsuitable for reacting many things" (see above).

It is very important to note that the photocatalytic reaction occurs only on the surface of the photocatalyst. That is, reactive species such as OH radicals exist only on the surface of the photocatalyst. It is safe to say that it is not released to the atmosphere, but on the other hand, unless the reactant reaches the surface of the photocatalyst, no reaction occurs,
No reaction occurs if the surface is coated with any material and light does not reach the surface of the photocatalyst. We are seeing that we have done terrible experiments, forgetting the above, in actual application situations. ”(Takeshi Kodo, Seiji Kaji: Industrial Materials, No. 4
5, No. 7, pp. 65-67 (1997)). As described above, since the photocatalytic reaction is a heterogeneous solid / liquid contact reaction on the catalyst surface, the reaction product and the photocatalytic activity When the probability of contact with a point is low, the reaction speed is extremely slow. Therefore, JP-A-2001-29945
In the method of No. 2, a photocatalyst molded into a special shape is used, and one is provided inside the reactor and nine are provided on the entire outer periphery, for a total of 10
A method of installing a UV lamp and reacting the book is disclosed.

[0021] Even in this case, P
In order to treat as little as 1 ppm of a phosphorus compound, it is necessary to provide an expensive specially shaped photocatalyst and as many as 10 ultraviolet lamps (114 W in total). However, it is not completely satisfactory not only in terms of reaction speed but also in terms of economics such as equipment cost, catalyst cost, and electric power cost.

[0022]

SUMMARY OF THE INVENTION In order to complete the present invention, the present inventors have firstly conducted a coagulation and sedimentation treatment of alcohol synthesis wastewater by a conventional metal ion supply.
We started by exploring the cause of the phosphorus concentration in the treated water being about 1 to 20 mg / L as P and less than the average of 8 mg / L per day.

As described above, the phosphoric acid catalyst for alcohol synthesis is prepared by impregnating an orthophosphoric acid aqueous solution with a porous siliceous carrier, and spraying an orthophosphoric acid aqueous solution onto the upper part of the catalyst bed to maintain the catalytic activity. ing. Phosphorus components other than orthophosphoric acid are not detected in these aqueous solutions of orthophosphoric acid. Therefore, the phosphorus component necessarily contained in the wastewater should be orthophosphoric acid.

The present inventors have conducted intensive studies on the phosphorus component in the alcohol synthesis wastewater. As a result, the wastewater was not present in the raw orthophosphoric acid aqueous solution and formed a water-insoluble metal salt with the metal ions. It was discovered that about 1 to 20 mg / L of a phosphorus component other than orthophosphoric acid was present as P, and in the conventional coagulation and precipitation treatment for supplying metal ions, the phosphorus component other than orthophosphoric acid (hereinafter, unknown phosphorus component) ) Could not be separated and was found to be contained in treated water as it was and discharged out of the system.

For this reason, according to the conventional phosphorus treatment method of alcohol synthetic wastewater, 1 to 20 mg / L as P is contained in the treated water.
It was found that wastewater was discharged containing phosphorus at an average concentration of about 8 mg / L per day. It was also found that this unknown phosphorus component could not be separated and removed by adsorption treatment or crystallization treatment.

Therefore, in these conventional coagulation and sedimentation treatment methods, orthophosphoric acid can be removed, but the unknown phosphorus component cannot be removed and is discharged as it is, so that the phosphorus concentration in the wastewater is lower than the current wastewater standard value. Although it is possible to reduce to the extent, the present situation is that it is not satisfactory as a phosphorus treatment method for further improving the water environment.

The present inventors have conducted a detailed study on the alcohol synthesis wastewater in this regard, and as a result, it has been found that the unknown phosphorus component is reduced by the reduction action of the alcohol generated under the olefin hydration reaction conditions to form orthophosphoric acid as a catalyst. The part is reduced to a mixture of several reduced phosphoric acids such as phosphorous oxyacid (H3PO3) or hypophosphorous acid (H4P2O6), with a low oxidation number, from the reaction column along with the weeping phosphoric acid. I found it leaked. And this unknown phosphorus component, that is, the oxygen acid of low oxidation number phosphorus is a metal ion,
For example, it does not form a water-insoluble metal salt with calcium ion, magnesium ion, aluminum ion or iron ion. Therefore, it is unknown from the wastewater in coagulation sedimentation treatment, flotation treatment, crystallization treatment or adsorption treatment that supplies metal ions. It was found that the phosphorus component could not be removed, and that the treated water contained phosphorus at an average concentration of about 8 mg / L as P and was discharged.

Since the unknown phosphorus component is an oxygen acid of phosphorus having a low oxidation number, that is, an oxygen acid of reduced phosphorus, it should be oxidized to orthophosphoric acid by oxidative decomposition treatment.
However, even with relatively inexpensive oxidizing agents commonly used in industry, for example, oxygen, chlorine, hypochlorite ion or hydrogen peroxide, or the combination of these oxidizing agents and oxidation catalysts, unknown phosphorus components (hereinafter referred to as “oxidizing agents”). In other words, those having a PP bond, such as hypophosphoric acid, are stable and have been found that they are not oxidized at all even when oxidized by a general method using a commonly used oxidizing agent.

Therefore, the present inventors have proposed that if reduced phosphorus can be stably oxidized to orthophosphoric acid by an inexpensive industrial oxidative decomposition method, it can be combined with conventionally known methods such as coagulation sedimentation treatment to produce alcohol synthesis wastewater. It has been conceived that phosphorus-containing water containing not only reduced phosphorus but also hardly decomposable organic phosphorus used in various chemical industries can be treated and the water environment can be further improved.

The present invention has been made in view of such circumstances, and does not use a special catalyst, increases the reaction probability, increases the reaction rate, and enables economical treatment on an industrial scale. The purpose of the present invention is to provide a processing method.

[0031]

Means for Solving the Problems In order to achieve the above object, the present inventors have intensively searched for an industrial oxidation method of reduced phosphorus contained in alcoholic synthetic wastewater, and as a result, have found that the reduction in alcoholic synthetic wastewater can be achieved. Found that it can be easily oxidized to orthophosphate ions by a homogeneous liquid-phase oxidation treatment that dissolves a hydroxy radical-generating agent in phosphorus-containing water such as amorphous phosphorus or a hardly decomposable organic phosphorus compound and generates hydroxyl radicals in the phosphorus-containing water. The present invention has been completed.

That is, the present invention oxidizes phosphorus to orthophosphate ions by dissolving a hydroxyl radical-generating agent in phosphorus-containing water and subjecting the generated hydroxyl radical to phosphorus in the phosphorus-containing water by a homogeneous liquid phase oxidation treatment. It is characterized in that phosphorus is separated and removed by the treatment.

The term "hydroxyl radical-forming agent" as used in the present invention refers to a compound for dissolving the agent in phosphorus-containing water and activating it by a chemical or physicochemical method to generate hydroxy radicals in the phosphorus-containing water. A gas, liquid or solid drug that acts as a precursor.

The homogeneous liquid phase reaction referred to in the present invention is usually carried out in a homogeneous liquid phase reaction in the absence of a solid, but a solid which does not hinder the reaction may be present. In short, it is sufficient that phosphorus and hydroxyl radicals come into contact with each other in the phosphorus-containing water so that the reaction itself becomes a homogeneous liquid phase reaction.

Examples of the activation of the hydroxy radical-forming drug include a chemical reaction method by dissolving the drug in combination, a photochemical reaction method of dissolving the drug and irradiating ultraviolet rays, and a thermal decomposition reaction method of dissolving and heating the drug. Can be exemplified.

When the hydroxyl radicals thus generated in the water containing phosphorus react in a homogeneous liquid phase system, they quickly react with phosphorus, and the high oxidation-reduction potential (2.85 V) of the phosphorous reduces the phosphorus in the water containing phosphorus. Effectively oxidizes to orthophosphate ions.

On the other hand, the phosphorus treatment method using a solid photocatalyst such as titanium dioxide does not effectively use ultraviolet rays and the catalyst, and also involves the reaction between the hydroxyl radicals generated on the surface of the solid catalyst by the irradiation of ultraviolet rays and phosphorus in the aqueous solution. Since the reaction is a heterogeneous solid-liquid contact reaction, the reaction rate is extremely low because the probability of contact between reactants is small.

As one of the methods for generating a hydroxyl radical, a Fenton oxidation method has been known for a long time. This oxidation method was found by Fenton in 1899 to be able to oxidize organic matter well by adding ferrous sulfate to hydrogen peroxide in aqueous solution.

The present inventors have discovered that reduced phosphorus in alcohol synthesis wastewater can be oxidized to orthophosphate ions by the Fenton oxidation method, and based on the hypothesis that the oxidation mechanism is based on hydroxy radicals, various studies have been made. Investigating using a method for generating hydroxyl radicals, confirming that the hypothesis is correct, and in addition to conventionally known methods for generating hydroxyl radicals such as the Fenton oxidation method, industrially economical hydroxyl radicals The present inventors have also newly found a method of generating radicals, and have completed the present invention.

A treatment method by oxidizing a COD component or a BOD component with ozone has been known for a long time. Typically,
The method of oxidizing by dissolving ozone in an aqueous solution is performed at normal temperature. The oxidation-reduction potential of ozone itself is 2.07
The redox potential of V and the hydroxyl radical is lower than 2.85 V, and the oxidizing power is lower accordingly. It is known that when ozone is dissolved in water, a small amount of hydroxyl radical is generated. However, in the conventional method of dissolving and oxidizing ozone at room temperature, since the generated hydroxyl radical is extremely small, the reduced phosphorus in the alcohol synthesis wastewater is hardly oxidized, and the present invention as an industrially economical method is used. The objective was not sufficiently achieved.

The reason that the method of dissolving ozone in an aqueous solution and oxidizing the solution is carried out at normal temperature is that the water to be treated is usually at room temperature. It is considered that the energy cost has increased and it has not been economically viable.

However, in the alcohol synthesis, the water separated from the alcohol in the distillation column usually flows out from the bottom of the distillation column as waste water. Usually it is about 100-130 ° C. After lowering this to normal temperature by heat recovery and cooling,
Draining outside the system.

The present inventors heated the oxidizing method by dissolving ozone of reduced phosphorus in alcoholic synthetic wastewater, that is, at a temperature of about 60 to 130 ° C., for example, in the bottom wastewater of the distillation column or after heat recovery of the wastewater. It has also been found that when ozone-containing gas is blown into wastewater at ℃ to dissolve and decompose by heating to generate and oxidize a large amount of hydroxyl radicals, reduced phosphorus is oxidized economically and effectively.

In recent years, oxidation using a combination of ozone and ultraviolet irradiation, oxidation using a combination of hydrogen peroxide and ultraviolet irradiation, oxidation by dissolving ozone and hydrogen peroxide, or oxidation using a combination of dissolution of ozone and hydrogen peroxide and ultraviolet irradiation Studies on oxidation methods for generating hydroxy radicals have been actively conducted. The new oxidation method using these hydroxyl radicals is called "promoted oxidation method (AOP method)", which is distinguished from the conventional Fenton oxidation method and the oxidation method using only ozone (Sota Nakagawa et al .: Water Environment Journal, Vol. 22, No. 4, p. 308 (1
999) and I. Arslan, et al: Environmental Techn
ology, Vol.20, p.921 (1999)). Of course, these accelerated oxidation methods are also one of the methods for generating a hydroxyl radical in the present invention.

The present inventors have found that reduced phosphorus in alcohol synthesis wastewater is not oxidized by hydrogen peroxide at normal temperature, but hydrogen peroxide is not oxidized at a temperature of 400 to 573K (12 ° C).
The fact that hydroxy radicals are generated when thermally decomposed in water at high temperatures (7-300 ° C) (K. Hatakeda, et al.
al: Chemical Engineering Science, Vol.54, p.3079 (1
From 999)), it was conceived that it would be possible to oxidize reduced phosphorus by a method of generating hydroxy radicals by a thermal decomposition method using hydrogen peroxide, and dissolve the hydrogen peroxide in phosphorus-containing water and heat it. Various studies were conducted on the oxidation method of the reduced phosphorus, and the temperature was lower than the known fact, that is, the reduced phosphorus in the phosphorus-containing water was heated to 60 ° C. or higher, preferably 80 ° C. or higher, more preferably 100 ° C. using hydrogen peroxide. The inventors have also found out that when heated, they are substantially oxidized to orthophosphate ions. This method is also a simple, economical and effective method for oxidizing reduced phosphorus by simply adding hydrogen peroxide to high-temperature wastewater from a distillation column for separating alcohol.

It is known that when a solid photocatalyst made of a metal oxide such as titanium dioxide is irradiated with ultraviolet rays of 380 nm or less, hydroxyl radicals are generated on the surface of the solid catalyst and various oxidatively decomposable organic substances can be oxidatively decomposed. However, when irradiating the solid photocatalyst with ultraviolet light in the wastewater treatment, the catalyst surface in the shaded portion of the photocatalyst solid is not used at all, so the photocatalyst is applied to the surface of a glass tube or the like, and the treated water is applied to the photocatalytic reaction tube. Ultraviolet rays must be irradiated so that the surface area to be irradiated with ultraviolet rays can be widened by passing water or by making the powder into a fine powder and making the solid-liquid suspension in the treated water. Nevertheless, solid photocatalysts are effectively used only on the surface of the catalyst that is exposed to limited ultraviolet light. Also, as is well known, since the hydroxyl radical is present only on the catalyst surface, the reaction rate is reduced as a result of a heterogeneous contact reaction between solid and liquid on the catalyst surface.

In the photocatalytic reaction, even if measures such as improvement of the catalyst surface and effective use of light have not been taken, the problem of two-dimensional spread has not been solved yet, so that an extremely long reaction time and a large capacity reactor are required. There are drawbacks such as necessity.
In addition, it is extremely difficult to separate the photocatalyst of fine particles from the treated water with the fine powder suspended photocatalyst, and it is still in the stage of engineering research, and the method using the suspended photocatalyst is still in the process of researching water treatment. It has not been.

Therefore, the method of irradiating phosphorus-containing water to a solid-state photocatalyst such as titanium dioxide by irradiating ultraviolet rays to express hydroxyl radicals on the surface of the catalyst to oxidize phosphorus on the surface of the solid-state catalyst is industrially economical. The object of the present invention of separating and removing phosphorus is not effectively achieved.

The fact that the present inventors found that reduced phosphorus in alcoholic synthetic wastewater is oxidized by hydroxyl radicals is based on the fact that reduced phosphorus can be reduced in temperature by using an oxidizing agent such as oxygen or hypochlorite ion. Hydroxyl is not oxidized at all even when reacted at 120 ° C., is not oxidized at all by the oxidation method using a combination of oxygen and ultraviolet irradiation, and is not oxidized at all by the oxidation method using the combination of hypochlorite ion and ultraviolet irradiation. This is supported by the fact that the inventors conducted the experiments that the reduced phosphorus is not oxidized at all by the oxidation method in which no radical is generated.

According to the present invention, the hydroxyl radical is generated in the phosphorus-containing water by dissolving the hydroxyl radical-generating agent in the alcohol synthesis wastewater, and the reduced phosphorus is oxidized to orthophosphate ions. Orthophosphate ions are separated and removed, but when hydroxyl radicals are generated and oxidized, the strong oxidizing power of the hydroxyl radicals causes not only reduced phosphorus in alcohol synthesis wastewater but also organic substances such as COD and BOD components contained in trace amounts. Is also oxidatively decomposed and eventually becomes carbon dioxide gas and water, so that an effect of almost removing COD and BOD components was also recognized. In addition, since most of the COD and BOD components can be removed, the orthophosphate ions are separated and removed. Among the methods for separating and removing the orthophosphate ions by the reverse osmosis membrane separation method, which has been conventionally industrially difficult, the membrane life is reduced. Has been remarkably improved, and a new development has been recognized in which orthophosphate ions can be stably separated.

[0051]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below.

As shown in FIG. 1, the method for treating phosphorus-containing water according to the present invention can be carried out using a phosphorus treatment apparatus comprising a hydroxy radical generator (I) and an orthophosphate ion separator (II). it can.

The phosphorus treatment apparatus used in the method for treating phosphorus-containing water according to the present invention introduces phosphorus-containing water into the hydroxyl radical generator (I), dissolves the hydroxyl radical-generating agent therein, and converts the hydroxyl radical into the phosphorus-containing water. Is generated, phosphorus is oxidized to orthophosphate ions, and orthophosphate ions are separated and removed as a phosphorus concentrate in the orthophosphate ion separation section (II), and treated water is discharged.

First, a detailed description of the method for treating phosphorus-containing water of the present invention will be given with a specific example of an apparatus for treating alcohol-synthesized phosphorus-containing wastewater.

In the present invention, an alcohol-synthesized phosphorus-containing wastewater is introduced into the hydroxyl radical generating section (I) to dissolve the hydroxyl radical-generating agent, generate hydroxyl radicals in the phosphorus-containing water, and oxidize phosphorus to orthophosphate ions. However, when the hydroxyl radical generator (I) is operated at room temperature, the high-temperature wastewater flowing out of a distillation column (not shown) used in alcohol synthesis may be subjected to a heat exchanger if necessary. Heat recovery and / or cooling with 1 and the like is carried out, and the mixture is cooled to room temperature and then introduced into the hydroxyl radical generating section (I).

When the hydroxy radical generating section (I) is operated under heating, if necessary, the heat exchanger 1
The temperature is adjusted to a predetermined temperature by, for example, and then introduced into the hydroxyl radical generating section (I). Here, the phosphorus in the wastewater is oxidized to orthophosphate ions by hydroxy radicals generated in the phosphorus-containing water.

This is introduced into the orthophosphate ion separation section (II). For example, an orthophosphate ion separation process such as a coagulation precipitation process for supplying metal ions, a floating process, a reverse osmosis membrane separation process, an adsorption process, or an ion exchange process. Since it is preferable to operate the part (II) at normal temperature, if necessary, heat recovery and / or cooling is performed by the heat exchanger 2 or the like, and the temperature is then returned to normal temperature before being introduced into the orthophosphate ion separation part (II).

Depending on the situation, even if the hydroxy radical generating section (I) and the orthophosphate ion separating section (II) are carried out in the same vessel, it is particularly acceptable if the hydroxy radical is generated in the phosphorus-containing water. Absent. Also,
In the present invention, the presence or absence of the heat exchanger is not specified.

Although the hydroxyl radical corrodes iron due to its strong oxidizing power, stainless steel of SUS304 grade or higher is hardly corroded. Therefore, the structural material of the hydroxy radical generating part (I) is made of stainless steel of SUS304 grade or higher. Is preferred.

The remaining hydroxy radical which has not been consumed in the hydroxy radical generating section (I) or the residual hydroxy radical-generating agent dissolved to generate the hydroxy radical is added with a decomposing agent such as a reducing agent or decomposed with hydroxy radical. The effluent from the hydroxy radical generating unit (I) is treated by a known method, such as catalytic decomposition with activated carbon or a metal oxide catalyst, or decomposition by a method such as ultraviolet irradiation. It is no longer necessary to take measures against corrosion of the materials of the heat exchanger 2 and the orthophosphate ion separating section (II) due to residual hydroxyl radicals and a hydroxy radical generating agent. Hydroxyl radicals are not very stable species and will disappear in a relatively short time. In addition, if a commonly used stainless steel material is used, it is not necessary to consider the effects of the residual hydroxyl radical and the hydroxyl radical-generating agent. Is not specified.

The oxidized water oxidized in the hydroxyl radical generating section (I) is converted into an orthophosphate ion separating section (II)
And the orthophosphate ions are separated as a solid or liquid phosphorus concentrate, and the treated water from which the orthophosphate ions have been removed is discharged out of the system as treated water.

The phosphorus concentrate separated by the treatment method of the present invention may be further concentrated, if necessary, by means such as dehydration and drying. The present invention does not specify a method for further concentrating the phosphorus concentrate separated in the orthophosphate ion separation section.
In any case, since the phosphorus concentrate of the present invention has a stable chemical composition, it can be recycled for use as a fertilizer raw material or a chemical raw material. That is, the treatment method of the present invention can not only improve the water environment by advanced purification of wastewater but also prevent secondary pollution and save resources by recycling phosphorus concentrates.

Next, a specific example of a method of dissolving a hydroxyl radical-generating agent in phosphorus-containing water, generating hydroxyl radicals in the phosphorus-containing water and oxidizing phosphorus to orthophosphate ions, which is a constituent feature of the present invention, will be described.

The method of the present invention for dissolving a hydroxy radical-forming agent in phosphorus-containing water to generate hydroxyl radicals in the phosphorus-containing water and for oxidizing phosphorus to orthophosphate ions comprises dissolving two types of hydroxy radical-forming agents in combination. Method, or dissolve the hydroxy radical generating agent,
In addition, a method of heating and / or irradiating ultraviolet rays may be used.

Specifically, for example, an oxidation treatment for dissolving ozone and hydrogen peroxide, an oxidation treatment for dissolving ozone and / or hydrogen peroxide and heating at a temperature of 60 ° C. or more, ozone and / or peroxide Dissolves hydrogen and
UV-irradiation oxidation treatment, Fenton oxidation treatment, UV-irradiation Fenton oxidation treatment or UV irradiation with peroxodisulfate ion or halogenated oxyacid ion, such as perchlorate ion, periodate ion or hypochlorite ion A method of generating hydroxyl radicals in phosphorus-containing water, such as a combined oxidation treatment, may be mentioned.

The method of dissolving a hydroxyl radical-generating agent in phosphorus-containing water, generating hydroxyl radicals in the phosphorus-containing water and oxidizing phosphorus to orthophosphate ions, which is particularly preferably used in the present invention, comprises dissolving ozone and hydrogen peroxide. Oxidation treatment in which ozone and / or hydrogen peroxide is dissolved and heating is performed at a temperature of 60 ° C. or higher, and oxidation treatment in which ozone and / or hydrogen peroxide is dissolved and ultraviolet irradiation is performed. Can be.

Next, an embodiment of the method for oxidizing phosphorus to orthophosphate ions by dissolving a hydroxyl radical-generating agent in phosphorus-containing water, generating hydroxy radicals in the phosphorus-containing water, and particularly preferably used in the present invention. Details will be described.

As the hydroxy radical generating section (I), a tank-type or tubular-type reactor for retaining and oxidizing phosphorus-containing water for a certain time can be suitably used. From the viewpoint of chemical engineering, a method in which a plurality of reactors are provided in series or in parallel, or a baffle plate is arranged in the reactors to react in multiple stages is also suitable.

Since the operating pH range in the reactor may be any of acidic, neutral and alkaline pHs, the phosphorus-containing water may be directly introduced into the hydroxyl radical generator (I). Since the vessel needs to be made of an expensive corrosion-resistant material, it is necessary to reduce the cost from the viewpoint of economy.
It is preferred to operate above H3.

The processing time in the reactor is set at 0.1 as the so-called liquid superficial velocity (LHSV (unit: h-1)) shown in the formula (I).
It is particularly preferable to operate at 05 to 10, preferably 0.1 to 2 in terms of equipment scale, economy and operability.

Formula (I): LHSV = phosphorus-containing water supply rate (m3
/ H) / reactor capacity (m3) The method for supplying ozone and hydrogen peroxide of the present invention will be described.

The supply of ozone is performed by supplying air or oxygen to a commercially available ozone generator to react as ozone-containing gas such as ozone-containing air or ozone-containing oxygen or ozone-containing water obtained by a commercially available ozone water producing machine. Can be supplied to the vessel. When the ozone-containing gas is supplied to the reactor, a method in which an air diffusion nozzle or an air diffusion plate is provided at a lower portion of the reactor and bubbling is performed in countercurrent or cocurrent in the phosphorus-containing water is preferable. When supplying the ozone-containing water, a method of injecting the ozone-containing water near the inlet of the reactor in parallel with the phosphorus-containing water is preferable.

For the supply of hydrogen peroxide, commercially available aqueous hydrogen peroxide (30 to 60%) as it is or appropriately diluted with water,
A preferred method is to inject into the phosphorus-containing water in a co-current flow near the inlet of the reactor by pumping using an inert gas such as air or nitrogen.

Next, the supply amounts of ozone and hydrogen peroxide will be described.

In the case of the oxidation treatment in which ozone and hydrogen peroxide are dissolved to generate hydroxyl radicals in the phosphorus-containing water, the total amount of the supplied hydroxy radical-forming agent is the reduced phosphorus to be treated contained in the phosphorus-containing water. 1 to 100 times, preferably 2 to 100 times the number of moles of the P atom
A 50-fold molar is preferred. The supply amount of ozone is 0.2 to 50 times, preferably 0.5 to 30 times, the mole number of the P atom of the reduced phosphorus to be treated contained in the phosphorus-containing water. The supply amount of hydrogen peroxide is 0.05 to 30 times, preferably 0.1 to 15 times, the mole number of the supplied ozone.

In the case of oxidation treatment in which ozone and / or hydrogen peroxide is dissolved and heating is performed at a temperature of 60 ° C. or higher, a reactor is required to effectively convert these dissolved hydroxy radical-forming agents into hydroxy radicals. The temperature is maintained at 60 ° C or higher. In the case of alcohol synthesis wastewater, the wastewater discharged from the distillation column is used as it is, or heat is recovered or cooled with a heat exchanger or the like as necessary to reach 60 ° C or higher. This can be achieved by supplying the temperature-controlled wastewater into the reactor and directly supplying these hydroxy radical-generating agents to the reactor in the manner described above.

The total amount of the hydroxy radical-generating agent to be supplied is 1 to 100 with respect to the number of moles of the P atoms of the reduced phosphorus to be treated contained in the phosphorus-containing water, whether used alone or in combination. Times molar, preferably 2 to
A 50-fold molar is preferred.

The reaction temperature is 60 ° C. or higher, preferably 80 ° C.
The oxidation treatment is preferably performed as described above. When hydrogen peroxide is used alone, the temperature is preferably 100 ° C. or higher. The higher the treatment temperature, the more effectively the oxidation of reduced phosphorus can be achieved, but a separate heating device is required to treat at a temperature higher than the effluent temperature of the distillation column, usually about 130 ° C. or higher. Preferably, the treatment is performed at a temperature of about 130 ° C. or less. Of course, when processing at a temperature of 100 ° C. or higher, it is needless to say that the processing pressure needs to be set to a pressure higher than the water vapor pressure at the processing temperature in order to maintain a liquid phase.

In the oxidation treatment of dissolving ozone and / or hydrogen peroxide and irradiating ultraviolet rays, the supply method of ozone and hydrogen peroxide is the same as the above-described method of supplying ozone and hydrogen peroxide. It is preferably supplied to the vessel.

As described above, the supply amount of ozone and / or hydrogen peroxide is the same as that described above, irrespective of whether it is used alone or in the case of two types, the reduction amount to be treated contained in the wastewater as the total amount of the hydroxy radical-forming agent 1 to 100 times, preferably 2 to 50 times the mole of the P atom of the raw phosphorus is suitable.

Ultraviolet irradiation for effectively converting the dissolved hydroxy radical-forming agent into hydroxy radical is performed by a light source capable of irradiating a large amount of short-wave ultraviolet rays having a wavelength of 300 nm or less, such as a low-pressure mercury lamp, a medium-pressure mercury lamp, and a black light. Can be easily achieved by using.
Although a high-pressure mercury lamp is effective when a photocatalyst is used, the high-pressure mercury lamp is not preferred in the method of the present invention because the amount of ultraviolet light having a wavelength of 300 nm or less is small.

The irradiation amount of the ultraviolet ray is 0.05 to 5 kW / mo per unit number of moles of the dissolved hydroxy radical-forming agent.
1, preferably 0.1 to 3 kW / mol.

Next, the orthophosphate ion separation section (II), which is another component of the present invention, will be described in detail using a specific example of alcohol synthesis wastewater.

As the orthophosphate ion separation section (II) used in the present invention, a conventionally known general method for reducing phosphorus, for example, coagulation sedimentation treatment, flotation treatment, biological treatment, membrane separation treatment, Examples of the method include an ion exchange treatment, an adsorption treatment, an electrostatic deionization treatment, and a crystallization treatment. From the characteristics of alcohol synthesis wastewater properties, coagulation sedimentation treatment, flotation treatment or membrane separation treatment is particularly suitable.

Next, the embodiment of the orthophosphate ion separation section (II) particularly preferably used in the present invention will be described in detail.

The coagulation-precipitation treatment used in the present invention is preferably a metal ion which reacts with the orthophosphate ion in the oxidized water flowing out of the hydroxyl radical generating part (I) to form a water-insoluble metal orthophosphate, preferably, for example, One or two or more metal ions such as calcium ion, magnesium ion, aluminum ion and iron ion are supplied to cause a metal orthophosphate to react and precipitate in a reaction tank. Aluminum chloride, ferric chloride, or a polymer flocculant is added and flocculated in a flocculation tank. A general method of sedimenting the aggregated metal salt in a sedimentation tank to separate a solid precipitate as a phosphorus concentrate and draining supernatant water as treated water can be suitably used.

The metal ions may be supplied as an aqueous solution or suspension of hydroxide, chloride or sulfate, or
In general, a method is used in which a current is supplied to a metal electrode at a voltage equal to or higher than a decomposition voltage to directly dissolve metal ions from the metal electrode.

In the flotation treatment used in the present invention, the metal ion which reacts with the orthophosphate ion in the oxidized water from the hydroxyl radical generating part (I) to form a water-insoluble metal orthophosphate, similarly to the coagulation precipitation treatment, Preferably, one or two or more metal ions such as calcium ions, magnesium ions, aluminum ions and iron ions are supplied to react and precipitate a metal orthophosphate, which is used as such or as a coagulant such as aluminum sulfate , Polyaluminum chloride, ferric chloride or a polymer flocculant is added for coagulation. During or after the reaction and / or aggregation, a fine gas, for example, air, oxygen, hydrogen, or nitrogen is supplied to cause air bubbles to adhere to or be incorporated into the aggregated solid, thereby causing the solid to float. Scraped and separated as a phosphorus concentrate,
A general method of draining clarified water as treated water from below is suitably used.

A method for generating and floating fine bubbles is as follows.
Pressurized levitation method, in which air is dissolved under pressure to return to normal pressure, metal ions by dispersion air method, in which bubbles are mechanically refined under normal pressure and adhered to particles, or electrolysis using metal electrodes, etc. Can be suitably achieved by an ionizing ion method or the like in which fine oxygen or hydrogen generated simultaneously with the supply of oxygen is taken in.

In the present invention, the supply amount of the metal ions in the coagulation sedimentation treatment or the levitation treatment is not particularly limited in the present invention since the orthophosphate ions can be sufficiently separated and removed by a conventionally known method.

The impurities contained in the oxidized water flowing out from the hydroxyl radical generating section (I) are inorganic ions mainly containing orthophosphate ions, and the organic components are decomposed into carbon dioxide gas and water by the hydroxyl radicals. In the removal of phosphorus from the alcohol synthesis wastewater, a membrane separation treatment which has conventionally been difficult due to membrane deterioration can be suitably employed. The membrane separation treatment used in the present invention is preferably a reverse osmosis membrane treatment or an ion exchange membrane treatment. In terms of economy, reverse osmosis membrane treatment is particularly preferred.

For the membrane separation treatment, a reverse osmosis membrane or an ion exchange membrane made of a polymer is generally used. Since polymer membranes are susceptible to oxidative deterioration due to their properties, generally, a reducing agent such as a sulfite ion is added to an oxidized water or a hydroxyl radical decomposing means such as an activated carbon or a metal oxide catalyst. In some cases, the film is subjected to a pretreatment such as catalytic decomposition or decomposition by a method such as ultraviolet irradiation to improve the film life.

Further, if the active layer on the membrane surface is covered with an organic substance such as oil, the separation performance cannot be exhibited. Therefore, there is a case where an adsorption treatment using activated carbon or the like is performed as a pretreatment to improve the membrane life. In the method of the present invention, the organic matter in the alcohol synthesis wastewater is almost completely decomposed into carbon dioxide gas and water in the hydroxyl radical generating section (I), so that the membrane separation treatment can be suitably performed without a pretreatment such as activated carbon. In the present invention, the presence or absence of these pretreatments and the method are not particularly limited.

In the reverse osmosis membrane treatment, oxidized water from the hydroxy radical generator (I) is supplied to the membrane module under pressure, and inorganic ions including orthophosphate ions are concentrated on the high pressure side through the reverse osmosis membrane. Simultaneously with obtaining the phosphorus concentrate from the non-permeate side, the phosphorus-free water can be permeated through the membrane on the low-pressure side, so that the permeate without phosphorus can be drained from the permeate side as treated water.

Thus, the phosphorus content of the phosphorus-containing water treated in the present invention is extremely low, and can be reduced to below the concentration required for improving the water environment. Specifically, P
5 mg / L or less, 2 mg / L or less at high altitude, and 1 mg / L or less at high altitude.

The phosphorus concentrate separated by the method of the present invention has a high phosphorus content, so that it can be effectively used as a fertilizer raw material.

[0097]

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

Example 1 Phosphorus-containing water discharged from ethyl alcohol synthesis by a hydration reaction of ethylene using a phosphoric acid catalyst (phosphorus concentration as P: total phosphorus: 42.3 mg / L, orthophosphate ion phosphorus; 3)
0.2 mg / L, reduced phosphorus; 12.1 mg / L, pH:
8.4) 6L is converted to an inner diameter of 134 mm and a height of 550 shown in FIG.
mm and a 40 W low-pressure mercury lamp 3 built-in through a quartz protection tube 2 in the center (SUS31
6) The reactor was charged into the reactor 1, the low-pressure mercury lamp 3 was removed, and the reactor was heated to 80 ° C. by the external mantle heater 4 without irradiating ultraviolet rays. The ozone-containing oxygen gas having an ozone concentration of 25 mg / L generated by using the ozone generator 6 is dissolved by bubbling at a rate of 2 L / min for 20 minutes in a charged solution heated to 80 ° C. to generate hydroxy radicals in the phosphorus-containing water. Thus, an oxidation reaction of reduced phosphorus (hereinafter abbreviated as RP) was performed. RP was completely oxidized to 100% orthophosphate ions (hereinafter abbreviated as OP).

The phosphorus analysis was carried out according to JIS K0102 46.3 Potassium peroxodisulfate decomposition method.
Was analyzed, and the OP concentration (as P) was analyzed according to JIS K0102 46.1 molybdenum blue (ascorbic acid reduction) absorption spectrophotometry. The RP concentration (as P) was determined from the difference between the total phosphorus concentration and the OP concentration.

Example 2 The same ozone as in Example 1 except that 6 L of the same phosphorus-containing water as in Example 1 was charged into the same reactor as in Example 1, and the ozone-containing oxygen gas was bubbled and dissolved at a temperature of 60 ° C. for 40 minutes. Hydroxyl radicals were generated in the phosphorus-containing water under the conditions of dissolution and heating to oxidize RP. 84% of RP is oxidized to OP, and the residual RP concentration in the treated water is 1.9 as P
mg / L.

Comparative Example 1 The same ozone dissolution reaction as in Example 1 was carried out except that 6 L of the same phosphorus-containing water as in Example 1 was charged into the same reactor as in Example 1, and the reaction time was 40 minutes at room temperature (23 ° C.). The oxidation reaction of RP was performed under the conditions. Only 6.6% of RP was oxidized, and the residual RP concentration in the treated water was 11.3 mg / L.

As described above, in the ozone dissolution oxidation at room temperature, the oxidation reaction rate of RP is extremely higher than that of the method of the present invention in which ozone is dissolved at a temperature of 60 ° C. or higher and hydroxyl radicals are generated in phosphorus-containing water to oxidize phosphorus. It is late industrially impossible.

Examples 3 and 4 The same phosphorus-containing water as in Example 1 was used, except that the hydrogen peroxide concentration was 200 mg.
/ L of hydrogen-containing aqueous solution in which hydrogen peroxide is dissolved so as to have a capacity of 50 / L in two sealed heat-resistant bottles having a screw cap with an inner volume of 100 mL.
30 minutes at 100 ° C and another at 30 ° C in boiling water.
Then, under the heating conditions of 120 ° C. and 100 ° C., respectively, a hydroxyl radical was generated in the phosphorus-containing water to carry out an oxidation reaction of RP. RP is 100% in the oxidation reaction at 120 ° C
All were oxidized to OP. In the oxidation reaction at 100 ° C., 78% of RP was oxidized to OP, and the residual RP concentration in the treated water was reduced to 2.7 mg / L as P.

Comparative Example 2 The same heat-resistant bottle as in Example 3 was charged with 50 mL of a phosphorus-containing aqueous solution in which sodium hypochlorite was added to the same phosphorus-containing water as in Example 1 so that the sodium hypochlorite concentration became 500 mg / L. The reaction was carried out at 120 ° C. for 30 minutes using a steam sterilizer to try to oxidize RP. RP was not oxidized at all.

As described above, RP cannot be oxidized by the conventional method of oxidizing by heating using sodium hypochlorite.

Example 5 6 L of the same phosphorus-containing water as in Example 1 was charged into the same reactor as in Example 1, the low-pressure mercury lamp was removed, and no ultraviolet light was irradiated. The concentration of hydrogen peroxide was 200 mg / L. And an ozone concentration of 10 mg / L at room temperature (23 ° C.).
The ozone-containing oxygen gas was dissolved by bubbling at 2 L / min for 1 hour to generate hydroxyl radicals in the phosphorus-containing water, thereby performing an oxidation reaction of RP. RP is 100
% And all became OP.

Example 6 6 L of the same phosphorus-containing water as in Example 1 was charged into the same reactor as in Example 1, and a low-pressure mercury lamp was attached to the reactor, and while irradiating ultraviolet rays, the external mantle heater was not heated and at room temperature (26 ° C.).
Then, by bubbling and dissolving ozone-containing oxygen gas having an ozone concentration of 25 mg / L at 2 L / min for 30 minutes, hydroxyl radicals were generated in the phosphorus-containing water to carry out an oxidation reaction of RP. The RP was 100% oxidized to all OP.

Example 7 6 L of the same phosphorus-containing water as in Example 1 was charged into the same reactor as in Example 6 in which the line from the ozone generator was cut off and the diffuser plate was removed in advance, and hydrogen peroxide was added. Water is added to a concentration of 200 mg / L, and normal temperature (27 ° C.)
By irradiating ultraviolet rays from a low-pressure mercury lamp for 30 minutes to generate hydroxyl radicals in the phosphorus-containing water, the RP
Was oxidized. RP is 100% oxidized and all O
It became P.

Comparative Example 3 100 mL of the same phosphorus-containing water as in Example 1 was used, and the inner diameter of the reaction part was 50 m.
m, height 125 mm, charged into a Pyrex photochemical reactor having a built-in 100 W high-pressure mercury lamp via a Pyrex (registered trademark) protective tube at the center, and anatase type titanium dioxide, which is a fine powder photocatalyst. 1g (1
000 mg / L) and irradiating it with ultraviolet light for 1 hour using a high-pressure mercury lamp at room temperature (28 ° C.) while stirring and suspending, to express hydroxyl radicals on the catalyst surface and to carry out the oxidation reaction of RP. Was.

[0110] Only 19% of RP is oxidized, the residual RP concentration in the treated water is 9.8 mg / L, and the reaction rate is slow in the RP oxidation method using a photocatalyst and ultraviolet irradiation in combination. There is.

Comparative Example 4 6 L of the same phosphorus-containing water as in Example 1 was charged into the same reactor as in Example 6, and pure oxygen was supplied at 2 L / min while irradiating ultraviolet rays with a low-pressure mercury lamp at normal temperature (26 ° C.). The RP was oxidized by bubbling and dissolving for 1 hour. RP was not oxidized at all.

As described above, RP cannot be oxidized by the oxidation method using both oxygen and ultraviolet irradiation at normal temperature.

Example 8 The same reactor as in Example 1 was charged with 6 L of phosphorus-containing water containing 52.6 mg / L of phenylphosphonic acid (total phosphorus concentration as P: 10.3 mg / L). Hydroxy radicals were generated in the phosphorus-containing water in the same manner as in Example 1, and the oxidation reaction of phenylphosphonic acid was performed for one hour. 5-1 during this time
Sampling was performed at 0 minute intervals, and the total phosphorus and OP were determined by the same phosphorus analysis and ion chromatography analysis as in Example 1.
And phenylphosphonic acid analysis was performed.

Table 1 below shows the concentration of phosphorus phenylphosphonate, the concentration of phosphorus orthophosphate, the pH of the reaction solution, and the phenylphosphonic acid oxidation reaction rate as P for each reaction time. FIG.
Shows the time-dependent changes in the concentrations of phosphorus phenylphosphonate and orthophosphate ion phosphorus as P in this reaction. As is clear from FIG. 3, phenylphosphonic acid is 100% oxidized in a reaction time of 50 minutes, and
It became.

[0115]

[Table 1]

Example 9 Slaked lime milk having a calcium hydroxide concentration of 5 g / L was added to 500 mL of the oxidized water oxidized in Example 1 so that the calcium hydroxide concentration became 250 mg / L, and further 10%
After adjusting the pH to 10 by dropwise addition of a sulfuric acid aqueous solution, the mixture was reacted for 1 hour while stirring slowly. Add 0. 0 to this reaction suspension.
A 2% polyamide-based polymer flocculant aqueous solution was used when the flocculant concentration was 3
mg / L, then add dropwise while stirring slowly.
The mixture was allowed to stand for coagulation and sedimentation. The total phosphorus (hereinafter abbreviated as TP) concentration as P in the supernatant water was 0.1 mg / L.

The phosphorus content in the coagulated and settled sludge was 37.1% as P2O5 on a dry sludge basis.

Comparative Example 5 Using the same phosphorus-containing water as in Example 1, the reaction and coagulation and sedimentation were carried out in the same manner as in Example 9. Total phosphorus concentration of supernatant water (P
) Was 12.2 mg / L, but the OP concentration (P
As) was 0.1 mg / L.

When the phosphorus-containing water discharged in the synthesis of ethyl alcohol was simply treated by the conventional coagulation-sedimentation method, OP could be removed but RP could not be removed at all.

Example 10 500 mL of the oxidized water oxidized in Example 5 was placed in a beaker, an aluminum electrode with an electrode interval of 10 mm was inserted, and a current of 0.25 A was applied from a DC power supply at a voltage of 15 V to elute aluminum ions. Further, a 0.1% aqueous ferric chloride solution was added dropwise and stirred at a concentration of 10 mg / L to cause a reaction. The reaction was carried out for 40 minutes while scraping the slag which was agglomerated and floated by the bubbles coming out of the electrode. The total phosphorus concentration (as P) in the lower clear water was 0.1 mg / L or less.

Example 11 A cellulose acetate-based reverse osmosis membrane was attached using a reverse osmosis membrane performance test apparatus comprising a reverse osmosis membrane separation cell having an effective diameter of 64 mm (effective membrane area 32 cm 2), a raw water supply high pressure pump and a raw water tank. Then, 5 L of the oxidized water oxidized in Example 6 was filtered through a 10-micron filter in advance and charged in a raw water tank, and the wastewater in the raw water tank was supplied to the reverse osmosis membrane separation cell at 300 mL / h. At this time,
The supply pressure was adjusted within a range of 1 to 3 MPa so that the permeated water was transmitted at a constant rate of 100 mL / h. The non-permeated water on the high pressure side is returned to the raw water tank, and 2
Reverse osmosis membrane separation was performed for consecutive days. 4.5L of permeated water
The total phosphorus concentration (as P) was 0.1 mg / L or less.

Example 12 The same reverse osmosis membrane performance test apparatus as in Example 11 was used.
The same membrane as that used in Example 1 was newly installed, and the same amount of phosphorus-containing water as in Example 1 was oxidized by the same method as in Example 7. The required amount of oxidized water (3.6 L / d) was filtered through a 10-micron filter in advance. The reverse osmosis membrane separation was carried out continuously for 7 days in the same manner as in Example 11 except that the non-permeated water was allowed to flow out as it was without refluxing, while replenishing the raw water tank sequentially while replenishing the raw water tank. A degradation test was performed. Permeate water volume 10
The supply pressure for maintaining 0 mL / h remained almost constant at 1 MPa. During this time, no particular decrease in fresh water production capacity was observed. After completion of the experiment, the membrane surface was observed, but no particular abnormality was observed.

Comparative Example 6 The same reverse osmosis membrane performance testing apparatus as in Example 11 was used.
A reverse osmosis membrane separation was continuously carried out for 7 days in the same manner as in Example 12, using the same membrane as that used in Example 1, and using the same phosphorus-containing water as in Example 1 filtered through a 10-micron filter. A performance degradation test was performed. Permeate amount 100
The supply pressure for maintaining mL / h was initially 1 MPa, but on the fourth day, the supply pressure was increased to 3 MPa. On the seventh day, the supply pressure was 3 MPa, the permeated water amount was 45 mL / h, and the fresh water production capacity was 1. / 2 or less. After the experiment was completed, the surface of the film was observed. As a result, adhesion of a brown oily substance was observed on the film surface.

[0124]

The oxidation treatment for dissolving a hydroxyl radical-generating agent in phosphorus-containing water and generating hydroxyl radicals in the phosphorus-containing water, which is a feature of the method of the present invention, is a homogeneous liquid phase reaction for generating hydroxyl radicals in the phosphorus-containing water. Because there is
It acts very effectively on the oxidation of phosphorus compounds dissolved in water. That is, in the method of the present invention, since the phosphorus compound is reacted with the hydroxyl radical in a homogeneous aqueous solution, the reaction probability is dramatically increased, and the reaction speed is correspondingly high, and it can be economically achieved even on an industrial scale.

On the other hand, a reaction using a conventional solid photocatalyst is as follows.
Since the reaction is a liquid / solid heterogeneous contact reaction between a hydroxyl radical expressed only on the surface of the solid photocatalyst and a phosphorus compound in an aqueous solution as a reactant, the reaction probability is low and the reaction rate is correspondingly low.

In the activation by irradiation with ultraviolet rays, the method of the present invention is more effective than the conventional method using a solid-state photocatalyst, because the irradiated ultraviolet rays are not shielded because the solid is not present. It also has the advantage of being very economical.

[0127]

According to the present invention, by dissolving a hydroxyl radical-generating agent in phosphorus-containing water to generate hydroxyl radicals in the phosphorus-containing water and oxidizing phosphorus in a homogeneous liquid phase system, a high reaction rate can be obtained. In addition, it is a simple method that does not use special catalysts, and it is stable with inexpensive equipment and low operating cost even in large-scale phosphorus treatment such as phosphorus treatment of alcohol synthesis wastewater and phosphorus removal in phosphorus-containing water, which were difficult in the past. Can be implemented. In addition, since the wastewater can be treated and treated at an extremely high level to a phosphorus concentration of 1 mg / L or less in the treated wastewater, not only the water environment is greatly improved, but also the phosphorus concentrate separated from the wastewater can be used as a fertilizer raw material or industrial material. Since it can be effectively used as a raw material, it has many advantages such as resource saving.

[0128]

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a method of the present invention.

FIG. 2 is a sectional view of a reactor used in Examples.

FIG. 3 is a graph showing the relationship between the reaction time obtained in Example 8 and the concentrations of the phosphorus compound to be treated and the phosphorus compound treated.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 1/44 C02F 1/44 E 1/52 1/52 K 1/78 1/78 F term (reference) 4D006 GA03 KA01 KB04 KB13 KB30 KE07Q MC18 PA01 PB08 PB70 PC80 4D015 BA19 BA22 BA23 BB05 CA18 DA04 DA06 DA13 DB01 DB02 DC02 EA32 EA33 FA01 FA24 FA29 4D037 AA13 AB15 BA03 BA04 BA18 BB05 BB08 BB09 CA04 BB09 CA04 AB08 BB09 BB13 BB20 BC09 BD03 BD06 BD08 CA04 CA06 CA08 CA09 CA10 CA16 CA17 CA20

Claims (7)

[Claims] 1. A method for dissolving a hydroxy radical-generating agent in water containing phosphorus and oxidizing phosphorus to orthophosphate ions by a homogeneous liquid phase oxidation treatment reaction between the generated hydroxyl radical and phosphorus in the water containing phosphorus. A method for treating phosphorus-containing water. 2. The method for treating phosphorus-containing water according to claim 1, wherein said hydroxyl radical-generating agent is ozone and hydrogen peroxide. 3. The treatment of phosphorus-containing water according to claim 1, wherein the hydroxy radical-generating agent is ozone and / or hydrogen peroxide, and the oxidation treatment is an oxidation treatment in which the temperature is raised to 60 ° C. or higher. Method. 4. The method for treating phosphorus-containing water according to claim 1, wherein the hydroxy radical-generating agent is ozone and / or hydrogen peroxide, and the oxidation treatment is an oxidation treatment of irradiating ultraviolet rays. 5. The method for separating and removing phosphorus is a coagulation sedimentation treatment or a floating treatment for supplying one or more metal ions forming a water-insoluble metal phosphate by reacting with orthophosphate ions. Item 5. The method for treating phosphorus-containing water according to any one of Items 1 to 4. 6. The method for treating phosphorus-containing water according to claim 1, wherein the method for separating and removing the phosphorus is a membrane separation treatment using a reverse osmosis membrane. 7. The phosphorus-containing water according to claim 1, wherein the phosphorus-containing water is discharged when a corresponding alcohol is produced by a gas-phase hydration reaction of an olefin using a phosphoric acid catalyst. The method for treating phosphorus-containing water according to the above item.