JPH1142477A - Treatment of waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the throughput of treated water, the purity of waste gas and the durability of solid catalyst and/or adsorbent and to treat the waste water with high stability by specifying the difference in pH between the raw waste water on the uppermost stream side in the waste water flow direction and the treated water at the outlet of a packed tower on the lowermost stream side. SOLUTION: The waste water through a waste water supply line 6 is boosted by a waste water feed pump, heated by a heat exchanger 3 and supplied to a packed tower 1 from its bottom. Meanwhile, air is supplied to the inlet of the heat exchanger 3 and mixed with the waste water. The packed towers 1 and 2 are kept warm by an electric heater 18, and the waste water is treated. Further, sulfuric acid is supplied between the towers 1 and 2 by the use of a chemical feed pump 7. The wet-oxidized water is cooled by a cooler 4 and separated into gas and liq. by a vapor liq. separator 13. In this case, the difference in pH between the raw water at the inlet of the tower on the uppermost stream side in the waste water flow direction and the treated water at the outlet of the tower on the lowermost stream side is adjusted to >=1.5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention purifies wastewater discharged from various industrial plants such as chemical plants, food processing equipment, metal processing equipment, metal plating equipment, printing plate making equipment, power generation equipment, and photo processing equipment. About the method. More specifically, the present invention relates to a method for purifying wastewater having a high chemical oxygen demand (hereinafter also referred to as “COD”) discharged from various industrial plants. Particularly, the present invention relates to an excellent method for purifying wastewater when the wastewater contains a nitrogen-containing compound, a sulfur-containing compound and a halogen-containing compound. Also, the present invention relates to a particularly excellent wastewater purification method even when the wastewater contains solids and / or scale components. The method of treating the wastewater is as follows:
This is a treatment method for purifying wastewater in the presence of a solid catalyst and / or an adsorbent. For example, wet oxidation method, wet decomposition method,
A wet oxidation method which can be applied to treatment methods such as an ozone oxidation method and a hydrogen peroxide oxidation method and which is particularly effective is a wastewater treatment in which a solid catalyst is present and an oxygen-containing gas is supplied.

[0002]

2. Description of the Related Art As in the method for treating wastewater according to the present invention,
In a method of treating wastewater in the presence of a solid catalyst and / or an adsorbent (hereinafter, also referred to as a packing), the pH of the liquid is determined by adjusting the pH of the wastewater, the durability of the solid catalyst and / or the adsorbent, and the equipment. This greatly affected the corrosion resistance of the material and the stability of the wastewater treatment. In particular, wastewater is cyanide, nitrogen-containing compounds such as ammonia, or sulfides, sulfur-containing compounds such as thiosulfate ions, or p-chlorophenol, halogen-containing compounds such as dioxin,
Alternatively, when the composition contains scale components such as calcium, magnesium, phosphorus, aluminum, silicon, and heavy metals, the pH of the liquid greatly affects the treatment of wastewater. In wastewater containing cyanide, ammonia or sulfide, when adjusting the pH of the liquid, problems such as vaporization of these components occur, and the properties of the exhaust gas in the raw wastewater tank or the exhaust gas after wastewater treatment are reduced. Sometimes worse. In addition, wastewater containing thiosulfate ions or scale components may decompose or react to form solids, which may cause a problem of reducing the stability of wastewater treatment. In the case of wastewater containing a nitrogen-containing compound, a sulfur-containing compound, a halogen-containing compound, or a scale component, the treatment performance of the wastewater often varies greatly depending on the pH of the liquid, and the durability of the solid catalyst and / or the adsorbent often increases. In many cases, it greatly affected sex.

[0003] Therefore, in the conventional treatment method, in order to solve these problems, when gas is generated, after a wastewater is supplied into a wastewater treatment device, a pH adjusting agent is sometimes added, and the wastewater is discharged. In many cases, the treatment of the gas is performed at the same time as the treatment. However, when the conditions of the liquid pH are such that the processing performance of the generated gas is improved, the processing performance of the wastewater may be reduced. Conversely, when the conditions of the liquid pH are such that the treatment performance of the wastewater is improved, the generated gas may not be sufficiently treated.

[0004] In addition, when a solid is produced due to the inclusion of scale components, the pH of the liquid used in the wastewater treatment is often set to a range in which these problems do not always occur. However, in this case, such a pH range is often a condition in which the treatment performance of the wastewater in the wastewater treatment is reduced, or a condition in which the durability of the solid catalyst and / or the adsorbent is reduced.

When a nitrogen-containing compound, a sulfur-containing compound, a halogen-containing compound or the like is contained, the pH of the liquid in the wastewater treatment is set to a region where the solid catalyst and / or the adsorbent hardly deteriorates, and this region is used as the wastewater. In some cases, this was an area where processing performance was sacrificed.

In particular, when performing a wet oxidation treatment or a wet decomposition treatment, the treatment conditions are severe at high temperatures and high pressures.
The pH of the liquid greatly affected the treatment performance of wastewater, the purifying property of exhaust gas, the durability of the solid catalyst and / or adsorbent, the corrosion resistance of equipment materials, and the stability of wastewater treatment.

[0007] Therefore, even in the treatment of wastewater containing components which are liable to cause the above-mentioned problems, the treatment performance of wastewater, purification of exhaust gas, durability of solid catalyst and / or adsorbent, and corrosion resistance of equipment material In addition, there has been a demand for a wastewater treatment method capable of treating wastewater with high stability.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel wastewater treatment method which can solve the above problems. That is, wastewater treatment performance, exhaust gas purification, solid catalyst and / or adsorbent durability,
An object of the present invention is to provide a novel wastewater treatment method capable of treating wastewater in a state where both the corrosion resistance of the apparatus material and the stability of wastewater treatment are high.

In particular, the wastewater is a nitrogen-containing compound such as cyanide or ammonia, or a sulfur-containing compound such as sulfide or thiosulfate, a halogen-containing compound such as p-chlorophenol or dioxin, or calcium, magnesium, aluminum, silicon, or the like. An object of the present invention is to provide a novel wastewater treatment method which is highly effective even when a scale component such as heavy metals is contained.

[0010]

Means for Solving the Problems As a result of diligent research to solve the above-mentioned problems, the present inventor has used a plurality of packed towers filled with a solid catalyst and / or adsorbent, and used a plurality of packed towers before and after.
A new wastewater treatment method for treating wastewater by increasing the difference in H was found, and the present invention was completed.
The present invention is to change the pH of the liquid in each of a plurality of packed towers by taking the difference between the pH of the raw wastewater and the pH of the treated water larger than a predetermined value. That is, by changing the liquid pH in each of the packed towers, the content of the wastewater treatment performed in each of the packed towers is significantly different. Thus, the present invention provides a method for treating wastewater as described below.

(1) A method for treating wastewater using a plurality of packed towers filled with a solid catalyst and / or an adsorbent,
Wastewater characterized in that the difference between the raw wastewater pH at the most upstream packed tower inlet and the treated water pH at the most downstream packed tower outlet with respect to the flow direction of the wastewater is 1.5 or more. Processing method.

(2) A column not filled with a solid catalyst and / or an adsorbent is arranged upstream of a plurality of packed columns filled with the solid catalyst and / or the adsorbent in the flow direction of wastewater. The method for treating wastewater according to (1).

(3) When treating the wastewater containing the scale component, the packed tower filled with the adsorbent is disposed upstream of the packed tower filled with the solid catalyst in the flow direction of the wastewater ( The method for treating wastewater according to 1) or 2).

(4) The method for treating wastewater according to any one of (1) to (3), wherein a chemical for adjusting pH is added between a plurality of packed towers.

Hereinafter, the present invention will be described in detail.

[0016]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, wastewater is treated by installing a plurality of packed towers filled with a solid catalyst and / or an adsorbent in the flow direction of the wastewater. The difference between the raw wastewater pH at the inlet of the most upstream packed tower and the pH of the treated water at the outlet of the most downstream packed tower with respect to the flow direction of the wastewater in the plurality of packed towers is 1.5 or more. , Processing. That is, when treating the wastewater using the plurality of packed towers, the difference between the pH of the raw wastewater and the treated water is set to 1.5 or more. Thereby, the treatment performance of wastewater, the purification property of exhaust gas, the durability of the solid catalyst and / or adsorbent, the corrosion resistance of the material of the apparatus, the stability of wastewater treatment, and the like can be improved.

In the method for treating wastewater according to the present invention, the difference between the pH of the raw wastewater at the inlet of the most upstream packed tower and the pH of the treated water at the outlet of the most downstream packed tower in the flow direction of the wastewater is as follows:
It is not particularly limited as long as it is 1.5 or more.
However, more effectively, the pH is separated by 2 or more, and even more effectively, the pH is separated by 3 or more.

In the wastewater treatment method according to the present invention, the raw wastewater pH refers to the liquid pH of the raw wastewater entering the packing at the most upstream side in the flow direction of the wastewater. Therefore, when acid, alkali, or other chemicals are added to the wastewater for pH adjustment or wastewater treatment, it refers to the pH of the liquid after the addition. Also, when the liquid pH of the raw wastewater changes due to heating with a heat exchanger before entering the packing,
It is the pH of the solution after the change. In the method for treating wastewater according to the present invention, the pH of the treated water refers to the pH of the treated water discharged from the packing material that is the most downstream in the flow direction of the wastewater. Therefore, when an acid, alkali, or other chemical is added to the treated water for pH adjustment or post-treatment, it refers to the pH of the liquid before the addition.

In the method for treating wastewater according to the present invention, an acid or an alkali can be added to adjust the pH of the liquid between a plurality of packed towers. The method for treating wastewater according to the present invention is to treat the wastewater under treatment conditions having a difference in pH between the raw wastewater and the treated water. That is, in the present invention, when treating wastewater with a plurality of packed towers, the wastewater is treated under different processing conditions in the pH of the liquid between the most upstream packed tower and the most downstream packed tower with respect to the flow direction of the wastewater. Is what you do.
Thereby, the method for treating wastewater according to the present invention becomes effective. Therefore, the liquid treated in the packed tower filled with the solid catalyst and / or adsorbent on the upstream side with respect to the flow direction of the wastewater is appropriately treated in the packed tower filled with the solid catalyst and / or adsorbent on the downstream side. It is effective to appropriately adjust the solution pH. The acid or alkali added for this purpose is not particularly limited, and various acids or alkalis can be used as appropriate. In addition, as a drug that can be used at this time,
The agent may be an acid or an alkali by being treated after addition, and is not particularly limited.

In the method for treating wastewater according to the present invention, acids, alkalis and other chemicals can be appropriately added to raw wastewater and treated water, and there is no particular limitation.

In the method for treating wastewater according to the present invention, the wastewater to be treated is not particularly limited. However, the wastewater contains at least one selected from the group consisting of a nitrogen-containing compound, a sulfur-containing compound, and a halogen-containing compound.
When the composition contains seeds or contains scale components, the effect of the wastewater treatment method according to the present invention is particularly enhanced. In the wastewater, the treatment performance of the wastewater is often greatly changed, particularly, depending on the pH of the liquid, and the durability of the solid catalyst and / or the adsorbent is often greatly affected. In particular, when the wastewater contains a nitrogen-containing compound such as cyanide or ammonia or a sulfur-containing compound such as sulfide (hereinafter, also referred to as a component that easily generates gas), when the pH of the liquid is adjusted, Problems such as vaporization of these components may occur, and the properties of the exhaust gas in the raw wastewater tank or the exhaust gas after wastewater treatment may be deteriorated. Further, in wastewater containing sulfur-containing compounds such as thiosulfate ions or scale components (hereinafter also referred to as components that are likely to form solids), solids are generated by decomposition or reaction, and wastewater treatment is performed. May reduce stability.

In the present invention, when the wastewater contains a component which easily generates gas, the treatment in the packed tower on the upstream side with respect to the flow direction of the wastewater is performed in a pH region where the wastewater hardly generates gas. Perform processing. This completely decomposes or reduces components that easily generate gas in the wastewater. In the treatment in the packed tower on the downstream side with respect to the flow direction of the wastewater, the wastewater is treated in a pH region where the pH is changed and the purifying property becomes high in the wastewater treatment. As a result, the properties of the exhaust gas are improved, and the purification of the wastewater is also enhanced. However, when the liquid pH on the downstream side with respect to the flow direction of the wastewater is a pH at which gas in the wastewater is unlikely to be generated, the treatment in the packed tower on the upstream side with respect to the flow direction of the wastewater is particularly difficult. Even if it is not in the pH range where it is difficult to generate water, it can be processed downstream. In the method for treating wastewater according to the present invention, p
H is not particularly limited. However, when the raw wastewater contains a component that easily generates gas, the present invention is effective when the pH of the raw wastewater is, for example, as follows. In the case of ammonia, it is effective that the pH of the raw wastewater is 11 or less, more effectively 10 or less, and even more effectively 9 or less. In the case of cyanide, it is effective that the pH of the raw waste water is 9 or more, more effectively 10 or more, and even more effectively 11 or more. When the pH of the raw wastewater is not the above-mentioned pH, gas is often generated, and the purification property of exhaust gas often decreases. Therefore, the effect of the wastewater treatment method according to the present invention is small.

In the present invention, when the waste water contains sulfur-containing compounds such as thiosulfate ions and sulfides,
Regarding the pH of the liquid supplied to the packed tower on the upstream side with respect to the flow direction of the wastewater, the liquid is supplied in a pH range in which the wastewater hardly generates solids and gas is hardly generated. Thereby, it can be reduced that the sulfur-containing compound in the waste water forms a solid and adheres to the heat exchanger before the packed tower or the inlet of the packed tower. The treatment in the packed tower on the upstream side with respect to the flow direction of the wastewater is performed in a pH range where the wastewater is unlikely to generate solids and generate gas, and can completely decompose or reduce the sulfur-containing compound in the wastewater. Is carried out. Further, in the treatment in the packed tower on the downstream side with respect to the flow direction of the wastewater, the pH of the liquid is changed, and the wastewater is treated in the pH region where the treatment performance of the wastewater and the purification property of the exhaust gas become high during the wastewater treatment. Further, the pH may be a pH of a liquid capable of washing a solid substance or the like adhered on the packing, if necessary, and the processing conditions may be changed to the processing conditions that increase the corrosion resistance of the material of the apparatus. And if necessary,
The processing is performed by exchanging the positional relationship of the plurality of packed towers with respect to the flow direction of the wastewater. That is, drainage treatment is performed using a plurality of packed towers while washing solids and the like adhered on the packing. As a result, it is possible to enhance all of the wastewater treatment performance, the exhaust gas purification property, the durability of the solid catalyst and / or the adsorbent, the corrosion resistance of the apparatus material, and the stability of the wastewater treatment. In the wastewater treatment method according to the present invention, the pH of the raw wastewater is not particularly limited. However, when the raw wastewater contains sulfide, it is effective that the pH of the raw wastewater is 8 or more, more effectively 9 or more, and further more effectively 1 or more.
0 or more. When thiosulfate ions are contained, it is effective that the pH of the raw wastewater is 5 or more,
It is more preferably 6 or more, and even more effectively 7 or more. When the pH of the raw wastewater is not the above-mentioned pH, gas is often generated, and the purification property of exhaust gas often decreases. In addition, solids are formed, and the activity of the filler decreases and / or
Or the pressure loss often rises. Therefore, the effect of the wastewater treatment method according to the present invention is small.

In the present invention, when the wastewater contains scale components and the like, and solid matter is easily produced, the pH of the liquid supplied to the packed tower filled with the adsorbent is adjusted so that the wastewater produces solid matter, The treatment is performed in a pH range where the adsorbent adsorbs. As a result, scale components are removed from the wastewater, and the purification of wastewater and the stability of wastewater treatment can be improved. In addition, when a solid catalyst is used in combination, the liquid from which scale components have been removed in advance using an adsorbent is treated with the solid catalyst, so that the purification of wastewater, the durability of the solid catalyst, and the stability of wastewater treatment can be further improved. Things.

In the present invention, when the wastewater contains scale components and the like, and solids are easily formed, the pH of the liquid supplied to the packed tower filled with the solid catalyst is opposite to that of the adsorbent. The treatment is performed in a pH range where the wastewater does not easily generate solids. As a result, components that easily generate solids in the wastewater are
The amount attached to the solid catalyst can be reduced.

However, in the case of many components that easily produce solids, they often adhere to the solid catalyst even at a pH at which solids are hardly produced due to wastewater treatment using a solid catalyst. In addition, to improve the purification of wastewater,
In some cases, processing must be performed at H. For this reason, in the treatment with the solid catalyst on the downstream side with respect to the flow direction of the waste water, it is effective to change the pH to a liquid pH that can wash solids and the like attached on the solid catalyst. In some cases, it is necessary to increase the durability of the solid material that has been removed by adsorption with the adsorbent, for example, by washing the adsorbent to reactivate the adsorbent. Therefore, the processing can be performed by exchanging the positional relationship of the plurality of packed towers with respect to the flow direction of the wastewater. That is, drainage treatment is performed using a plurality of packed towers while washing solids and the like adhered on the packing. As a result, it is possible to enhance all of the purification properties of the wastewater, the durability of the filler, and the stability of the wastewater treatment.

In the method for treating wastewater according to the present invention, the pH of the treated water is not particularly limited. However, when the raw wastewater contains a component that easily produces a solid, the present invention is effective when the pH of the treated water is, for example, as follows. In the case of phosphorus, the pH of the treated water is 4
The above is effective, more effectively 5 or more, and still more effectively 6 or more. In the case of silicon, it is effective that the pH of the treated water is 8 or more and 6 or less, and more preferably 9 or more or 5 or less. In the case of aluminum, it is effective that the pH of the treated water is 9 or more or 6 or less, more effectively 10 or more or 5 or less, and even more effectively 11 or more or 4 or less. . In the case of calcium, it is effective that the pH of the treated water is 8 or less,
It is more preferably 7 or less, and even more effectively 6 or less. In the case of magnesium, it is effective that the pH of the treated water is 8 or less, more effectively 7 or less, and even more effectively 6 or less. In the case of manganese, it is effective that the pH of the treated water is 8 or less, more effectively 7 or less, and even more effectively 6 or less.
It is as follows. In the case of zinc, it is effective that the pH of the treated water is 9 or more or 6 or less, more preferably 10 or more or 5 or less, and even more preferably 1 or more.
It is 1 or more or 4 or less. In the case of tin, it is effective that the pH of the treated water is 11 or more or 6 or less, more effectively 12 or more or 5 or less, and even more effectively 13 or more or 4 or less. . In the case of lead, it is effective that the pH of the treated water is 11 or more and 6 or less, more effectively 12 or more or 5 or less, and even more effectively 13 or more or 4 or less. . If the pH of the treated water is not the above-mentioned pH, solids are formed, and the activity of the solid catalyst and / or the pressure loss often increase. Therefore, the effect of the wastewater treatment method according to the present invention is small.

In the present invention, when a scale component is positively removed using a packed tower filled with an adsorbent,
Particularly when the pH is not the above, solid substances can be effectively removed.

The nitrogen-containing compound according to the present invention is not particularly limited as long as it is a compound containing nitrogen. For example, cyanide, ammonia, hydrazine, dimethylformamide, pyridine, picoline, acetamido, aniline, glycine, alanine, phenylalanine, glutamic acid, lysine, aspartic acid, serine,
Methionine, histidine, ethylenediamine, ethanolamine, triethanolamine, dodecylamine, polyacrylamide, ammonia, hydrazine, nitric acid,
Various compounds containing nitrogen such as nitrous acid and urea.

The sulfur-containing compound according to the present invention is not particularly limited as long as it is a compound containing sulfur other than sulfate ions. For example, in addition to sulfur itself, various thiosulfates such as sodium thiosulfate and potassium thiosulfate, or various sulfides such as sodium sulfide, potassium sulfide, and sodium hydrogen sulfide, and dimethyl sulfoxide, dimethyl sulfone, methanesulfonic acid, thiophene, and thiophene , P-toluenesulfonic acid, sulfobenzoic acid, thioacetic acid, naphthalenesulfonic acid, dodecylbenzenesulfonic acid and the like.

The halogen-containing compound according to the present invention is an inorganic salt such as sodium chloride, potassium chloride or sodium bromide, or an organic halogen compound such as methyl chloride, tetrachloroethylene, p-chlorophenol or dioxin.

The concentration of these compounds is not particularly limited. For example, in the case of inorganic salts such as sodium chloride, potassium chloride, sodium nitrate, sodium nitrite, etc. Line clogging due to precipitation occurs. Therefore, the total amount of the inorganic salts is preferably less than 200 g / liter, more preferably less than 150 g / liter, and further preferably less than 100 g / liter.

In the case of inorganic COD components such as sulfide and ammonia and organic substances, the total amount of these components in the wastewater is 10 mg / L to 200 g / L, preferably 100 mg / L to 100 g / L. When the amount is less than 10 mg / liter, it is often possible to perform the treatment sufficiently without particularly using the method according to the present invention. When the amount is more than 200 g / liter, the concentration is too high, so that various controls such as temperature are difficult. It is more likely to become.

[0034] The scale component according to the present invention is a component that easily forms a solid by the treatment of wastewater, and is not particularly limited. For example, it contains at least one element selected from the group consisting of heavy metals, aluminum, silicon, phosphorus, calcium and magnesium. The heavy metals are not particularly limited, but cover all heavy metals. For example, cadmium (Cd), nickel (Ni), cobalt (Co), manganese (Mn), copper (Cu), zinc (Zn), silver (A
g), iron (Fe), tin (Sn), antimony (S
b), lead (Pb), thallium (Tl), mercury (Hg),
Examples include arsenic (As), chromium (Cr), and bismuth (Bi).

The state of the scale component according to the present invention is not particularly limited as long as it produces a solid by the treatment of the wastewater. For example, various forms of ions or organometallic compounds may be used. There is. The state of the solid according to the present invention is not particularly limited. For example, insoluble or hardly soluble oxides and salts,
Any of various compounds may be used.

The concentration of these scale components is not particularly limited, but is preferably 1 mg / liter to 1 g / liter in total, and more preferably 2 mg / liter.
Liter to 500 mg / liter, more preferably 5 mg / liter to 100 mg / liter.
When the amount is less than 1 mg / liter, the treatment can be performed sufficiently without particularly using the method according to the present invention, and when the amount is more than 1 g / liter, the concentration is too high. Often causes blockage of the line.

In the wastewater treatment method according to the present invention, when a plurality of packed towers are exchanged with respect to the flow direction of the wastewater to perform the treatment, the packed towers are replaced at two packed towers. In such a case, the upstream and downstream packed towers are exchanged.

When the number of the packed towers is three, the packed tower on the most upstream side and the packed tower on the most downstream side may be simply exchanged. , And the most downstream packed tower may be moved to the most upstream side. Further, the packed tower on the most upstream side may be moved to the most downstream side, and the packed tower in the middle and the packed tower on the most downstream side may be moved to the most upstream side and the middle, respectively.

The timing of changing the position of the packed tower filled with these packing materials is not particularly limited and can be arbitrarily determined. However, an effective time is when a decrease in the activity of the packing is observed or expected or when the pressure drop in the device has increased. It is more effective to carry out the wastewater treatment method according to the present invention at this time. In addition, particularly simple implementation is to be performed at the time of regular maintenance or inspection of the device. The reason for this is that when the maintenance is performed during the regular maintenance or inspection of the apparatus, the processing is often stopped and can be easily performed.

The method of introducing wastewater into the packed tower is a method of introducing wastewater from below the packed tower and discharging treated water from above, or a method of introducing wastewater from above the packed tower and treating from below. Various methods such as a method of discharging the treated water later can be adopted, and the method is not particularly limited. Further, by changing the flow direction of the drainage, the relationship between the upstream and downstream packed towers can be changed, and there is no particular limitation.

In the present invention, a column not filled with a solid catalyst and an adsorbent can be added as appropriate. in this case,
It is effective to arrange the tower not filled with the solid catalyst and the adsorbent at the most upstream side with respect to the flow direction of the wastewater, and to arrange a plurality of packed towers at the downstream side with respect to the flow of the wastewater. A tower that is not filled with a solid catalyst and an adsorbent treats wastewater to some extent before supplying the wastewater to the packed tower, so that the load on the packing can be reduced. In particular, when the wastewater contains at least one selected from the group consisting of a nitrogen-containing compound, a sulfur-containing compound, and a halogen-containing compound, or a scale component, the treatment performance of the wastewater, the purification property of exhaust gas, the solid catalyst and / or the adsorbent Durability, corrosion resistance of equipment materials, and stability of wastewater treatment can be improved.

In the present invention, especially when treating wastewater containing scale components, a packed tower filled with an adsorbent is disposed upstream of the flow direction of the wastewater in the packed tower filled with the solid catalyst. Is effective. By removing the scale component in particular with the adsorbent, the treatment performance of wastewater, the durability of the solid catalyst, and the stability of wastewater treatment can be improved. Liquid pH of wastewater treated with adsorbent in the present invention
It is particularly effective to adjust the pH to a value suitable for removing scale components. Further, it is effective that the liquid pH of the wastewater treated with the solid catalyst is a pH that can enhance the purification performance of the wastewater. As a result, it is possible to improve the treatment performance of the wastewater, the durability of the solid catalyst, the corrosion resistance of the material of the apparatus, and the stability of the wastewater treatment.

In the present invention, in particular, when treating wastewater containing scale components, a plurality of packed towers filled with an adsorbent are arranged so that the arrangement sandwiches a packed tower filled with a solid catalyst. Is more effective. in this case,
A packed tower filled with an adsorbent disposed on the upstream side with respect to the flow of wastewater performs treatment in a pH region where scale components can be effectively removed. In addition, a packed tower filled with an adsorbent disposed downstream of the flow of wastewater performs treatment in a pH range where scale components can be effectively washed. By exchanging the positional relationship of the packed tower filled with the adsorbent and performing the treatment, the wastewater treatment performance, the durability of the solid catalyst and / or the adsorbent, the corrosion resistance of the equipment material, and the stability of the wastewater treatment are improved. Can be increased.

The method for treating wastewater according to the present invention can be applied to various methods for treating wastewater using a packed tower in the presence of a solid catalyst and / or an adsorbent. For example,
The present invention can be applied to processing methods such as a wet oxidation method, a wet decomposition method, an ozone oxidation method, and a hydrogen peroxide decomposition method. In particular, the wet oxidation method, the wet decomposition method, and the ozone oxidation method are effective with the wastewater treatment method according to the present invention. Among them, the wet oxidation method and the wastewater treatment method with the wet decomposition method are particularly effective.

In the wet oxidation method and the wet decomposition method, the wastewater is heated to a high temperature and the treatment is carried out under high pressure. Therefore, the deterioration of the packing and the influence of the components which are liable to produce solids contained in the wastewater are affected. Largely, the above problems often become significant. For this reason, the method for treating wastewater according to the present invention is particularly effective.

The present invention can be used not only for the wet oxidation method but also for various processing methods having the above-mentioned problems. Of these, the wet oxidation method, which is a particularly preferred treatment method, will be specifically described as an example. The wet oxidation method is a method in which waste water is heated to 100 ° C. to 370 ° C., and an oxygen-containing gas is introduced under a pressure at which the waste water maintains a liquid phase to purify the waste water. The maximum temperature in the packed tower in the method for treating wastewater is from 100 ° C to 370 ° C, and preferably from 150 ° C to 300 ° C. 3
When the temperature exceeds 70 ° C., the liquid cannot maintain a liquid phase. On the other hand, when the temperature is lower than 100 ° C., the treatment efficiency is remarkably reduced, and the wastewater cannot be purified in many cases. Also 30
When the temperature exceeds 0 ° C., the pressure for maintaining the liquid phase is very high, and the equipment cost and running cost for this are high. Also, when the temperature is lower than 150 ° C., the treatment efficiency is generally low and the purification of wastewater is often inferior.

In the wastewater treatment method according to the present invention, the treatment pressure for wet oxidation is appropriately selected depending on the correlation with the treatment temperature, and the treatment is performed at a pressure at which the liquid maintains a liquid phase.

[0048] As the space velocity of the wastewater in the treatment process of waste water according to the present invention, 0.1hr ^-1 ~10hr ^-1 is effective. When the space velocity is less than 0.1 hr ^-1 , the amount of treated wastewater decreases, and the equipment becomes excessively large.
If it exceeds ⁰ hr ⁻¹ , the processing efficiency is undesirably reduced. Also preferably, it is 0.3 hr ^{-1 to 5} hr ^-1 .

The oxygen-containing gas according to the present invention is a gas containing oxygen molecules and ozone. When a gas such as ozone or oxygen is used, it can be appropriately diluted with an inert gas or the like. Further, oxygen-enriched gases can be used, and in addition to these gases, oxygen-containing exhaust gas generated from other plants can also be used as appropriate. Most preferred, however, is inexpensive air.

As the wet oxidation treatment apparatus used in the present invention, a commonly used wet oxidation treatment apparatus is used, and the wet oxidation packed tower may be either a single tube type or a multi-tube type.
Preferably, it is a single tube type.

In the wastewater treatment method according to the present invention, "packing tower" refers to a "packing tube", "packing device", "reaction tower", "reaction tube", "reactor", "adsorption". Tower, "adsorption tube", "adsorber".

In the method for treating wastewater according to the present invention, the type of solid catalyst is not particularly limited, and solid catalysts used for various wastewater treatments can be used. For example, a catalyst containing titanium, iron, aluminum, silicon, zirconium, activated carbon, or the like can be used, and preferably, an oxide such as titanium, titanium-zirconium, or titanium-iron is used. These catalysts are composed of the above components (hereinafter referred to as the first component).
Component), a second component may be contained.

As the second component, at least one kind of metal such as manganese, cobalt, nickel, tungsten, copper, tin, chromium, cerium, silver, platinum, palladium, rhodium, gold, iridium, ruthenium or the like; A component composed of a metal compound can be used. This catalyst is based on 75 to 99.95% by weight of the first component.
The proportion of the second component is preferably from 25 to 0.05% by weight.

In the wastewater treatment method according to the present invention, the type of adsorbent is not particularly limited, and various adsorbents used for wastewater treatment can be used. For example, an adsorbent containing titanium, iron, aluminum, silicon, zirconium, activated carbon, or the like can be used. Preferably, an oxide such as titanium, titanium-zirconium, or titanium-iron is used.

The shape of the filler according to the present invention is effectively at least one selected from pellets, spheres, granules, rings and honeycombs, but is not particularly limited. .

In the method for treating wastewater according to the present invention, the packing to be packed into a plurality of packed towers does not need to be particularly packed with the same packing. In treating wastewater, it is only necessary to fill an optimal filler. When the pH of the raw wastewater and the pH of the treated water are relatively largely different, the packing suitable for the treatment on the upstream side of the flow of the wastewater and the packing suitable for the treatment on the downstream side are often different. Therefore, when the positional relationship of the plurality of packed towers with respect to the flow direction of the drainage is not exchanged, it is more effective that the types of the packing materials to be filled in the upstream and downstream packed towers are different. In addition, the amount and shape of these packing materials may be different, and the shapes and sizes of the plurality of packed towers may be different, and are not particularly limited.

[0057]

The method for treating waste water according to the present invention can be applied to various methods for treating waste water using a solid catalyst and / or an adsorbent. The present invention can be achieved only by using a plurality of packed towers, and setting the liquid pH at the most upstream inlet and the most downstream outlet to appropriate different pHs. In the conventional treatment method, the optimum liquid pH for the wastewater treatment performance, exhaust gas purification performance, solid catalyst and / or adsorbent durability, equipment material corrosion resistance, wastewater treatment stability, etc. are different from each other. One had to sacrifice. However, according to the invention, the pH
By changing the values in the middle, all of the wastewater treatment performance, exhaust gas purifying property, solid catalyst and / or adsorbent durability, corrosion resistance of apparatus materials, and wastewater treatment stability can be made high.

In the present invention, a nitrogen-containing compound such as a cyanide compound, ammonia, or a sulfide, a sulfur-containing compound such as thiosulfate ion, or a halogen-containing compound, which is often difficult with conventional wastewater treatment, or calcium, It is particularly effective when it contains scale components such as magnesium, aluminum, silicon, and heavy metals.

In the conventional processing method, the frequency of replacement of the filler is increased, the amount of the filler is increased, the processing conditions are stricter, and the pretreatment is actively performed.
The running cost of wastewater treatment was high, and the equipment cost was high. Further, when the pre-processing was performed, the operation became complicated. However, the present invention can be easily implemented, and not only can the running cost of wastewater treatment be significantly reduced, but also the equipment cost can be reduced, and the treatment conditions can be made milder. It is a wastewater treatment method excellent in practicality.

Further, the method for treating wastewater according to the present invention is a method particularly effective in wet oxidation treatment or wet decomposition treatment, which was difficult with conventional methods.

[0061]

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

(Example 1) Using the wet oxidation treatment apparatus shown in FIG. 1, the treatment was performed under the following conditions for a total of 500 hours. This treatment was continuously performed in a path in which the liquid treated in the packed tower 1 was treated in the packed tower 2. The detailed experimental methods and results are described below.

The solid catalyst used in the treatment was a catalyst composed mainly of titania and ruthenium, and their respective weight ratios were 98.5: 1.5 in terms of TiO ₂ : Ru. The shape was a pellet having a diameter of 5 mmφ and a length of 6.5 mm. This catalyst is then added to two packed
Each 0 liter was filled. The packed tower used in the treatment was a cylindrical packed tower with a height of 6.0 m and an inner diameter of 9.2 c.
m.

The treatment method is as follows: waste water sent from the waste water supply line 6 is supplied to the waste water supply pump 5 at 60 liter / h.
r, pressurized feed at 260 ° C. in heat exchanger 3
And supplied from the bottom of the packed tower 1. In addition, air is supplied from an oxygen-containing gas supply line 10 and the compressor 9
Then, the flow rate is adjusted by the oxygen-containing gas flow control valve 11 so that the ratio of O ₂ / ThOD (the amount of oxygen in the air / theoretical oxygen demand) = 1.1, and the heat exchanger 3 And was mixed into the wastewater. In the packed towers 1 and 2, the temperature was maintained at 260 ° C. using the electric heater 18 to perform the treatment. Further, sulfuric acid was supplied between the packed towers 1 and 2 by using the chemical supply pump 7 at a flow rate of 1.8 liter / hr. The treated water subjected to the wet oxidation treatment was cooled by the cooler 4 through the treated water line 12 and then subjected to the gas-liquid separation treatment by the gas-liquid separator 13. In the gas-liquid separator 13, the liquid level controller (L
C), the liquid level is detected, the liquid level control valve 15 is operated to maintain a constant liquid level, and the pressure controller (P
C) detects the pressure and activates the pressure control valve 14,
It was operated to maintain a pressure of 75 kg / cm ² G.
Then, the treated water was discharged from the treated water discharge line 17.
Packing tower inlet pressure (PI) at the start of treatment is 76 kg / c
m ² G.

The result of the treated water obtained after 100 hours is:
COD (Cr) was 0.5 g / liter and pH 5.8. The pressure (PI) at the inlet of the packed tower was 76 kg / cm ² G.

The result of the treated water obtained after 200 hours is:
COD (Cr) was 0.5 g / liter and pH 5.8. The pressure (PI) at the inlet of the packed tower was 76 kg / cm ² G.

The result of the treated water obtained after 300 hours is:
COD (Cr) was 0.7 g / liter and pH was 5.9. The pressure (PI) at the inlet of the packed tower was 76 kg / cm ² G.

The result of the treated water obtained after 400 hours is:
COD (Cr) was 1.1 g / liter and pH was 6.0. The pressure at the inlet (PI) of the packed tower was 77 kg / cm ² G.

The result of the treated water obtained after 500 hours is:
COD (Cr) was 1.5 g / liter and pH was 6.1. The pressure at the inlet (PI) of the packed tower was 77 kg / cm ² G.

(Comparative Example 1) Using the wet oxidation treatment apparatus shown in FIG. 1 and adding sulfuric acid from between the packed towers 1 and 2, the liquid continuously treated in the packed tower 1 was treated in the packed tower 2. The processing was performed under the same processing conditions as in Example 1 except that the processing was performed along the same route. Packing tower inlet pressure (PI) at the start of treatment is 76 kg
/ Cm ² G.

The result of the treated water obtained after 100 hours is:
COD (Cr) was 2.1 g / liter and pH was 8.5. The pressure (PI) at the inlet of the packed tower was 76 kg / cm ² G.

The result of the treated water obtained after 200 hours is:
COD (Cr) was 2.8 g / liter and pH was 8.6. The pressure at the inlet (PI) of the packed tower was 77 kg / cm ² G.

The result of the treated water obtained after 300 hours is:
COD (Cr) was 4.2 g / liter and pH was 8.8. The pressure (PI) at the inlet of the packed tower was 79 kg / cm ² G.

Further processing was performed, but after 360 hours, the pressure (PI) at the inlet of the packed tower increased, and the processing was stopped.

Example 2 The same procedure as in Example 1 was carried out except that the positional relationship with respect to the flow direction of the wastewater in the packed tower before and after every 100 hours was exchanged using the wet oxidation treatment apparatus shown in FIG. 2 and the treatment was continued. The processing was performed for 500 hours by the same processing method. The detailed experimental methods and results are described below.

The treatment of the waste water starts with the packed tower switching valve 1
9, 22, 23, 25 are open and 20, 21, 24, 2
6 was closed. Packing tower inlet pressure at the start of treatment (PI)
Was 76 kg / cm ² G. The same waste water as that of Example 1 was used as the waste water subjected to the treatment.

The result of the treated water obtained after 100 hours is:
COD (Cr) was 0.5 g / liter and pH 5.8. The pressure at the inlet of the packed tower was 76 kg / cm ² G.

Thereafter, the positional relationship between the packed tower 1 and the packed tower 2 was exchanged. That is, the packed tower switching valves 19, 22, 2
3, 25 were closed and 20, 21, 24, 26 were open. And after processing for 100 hours, that is, a total of 20
The result of the treated water after treatment for 0 hours is COD (Cr) 0.5
g / liter, pH 5.8. The pressure at the inlet of the packed tower was 76 kg / cm ² G.

Similarly, after that, the positional relationship of the packed tower was exchanged and the treatment was performed for 100 hours. That is, the packed tower switching valves 19, 22, 23, 25 are opened, and 20, 21, 22,
4, 26 were closed. After a total of 300 hours of treatment, the result of the treated water was COD (Cr) 0.5 g / liter, pH 5.
It was 8. The packed tower inlet pressure is 76 kg / cm ²
G.

Similarly, after that, the positional relationship of the packed tower was exchanged and the treatment was performed for 100 hours. That is, the packed tower switching valves 19, 22, 23, and 25 are closed, and
4, 26 were opened. After a total of 400 hours of treatment, the result of the treated water was COD (Cr) 0.5 g / liter, pH 5.
It was 8. The packed tower inlet pressure is 76 kg / cm ²
G.

Similarly, after that, the positional relationship of the packed tower was exchanged and the treatment was carried out for 100 hours. That is, the packed tower switching valves 19, 22, 23, 25 are opened, and 20, 21, 22,
4, 26 were closed. After a total of 500 hours of treatment, the result of the treated water is COD (Cr) 0.5 g / liter, pH 5.
It was 8. The packed tower inlet pressure is 76 kg / cm ²
G.

(Comparative Example 2) The treatment was performed under the same treatment conditions as in Example 2 except that sulfuric acid was not added between the packed towers 1 and 2 using the wet oxidation treatment apparatus shown in FIG. The packed tower inlet pressure (PI) at the start of the treatment is 76 kg / cm ²
G.

The result of the treated water obtained after 100 hours is:
COD (Cr) was 2.1 g / liter and pH was 8.5. The pressure (PI) at the inlet of the packed tower was 76 kg / cm ² G.

The result of the treated water obtained after 200 hours is:
COD (Cr) was 2.3 g / liter and pH was 8.5. The pressure (PI) at the inlet of the packed tower was 76 kg / cm ² G.

The result of the treated water obtained after 300 hours is:
COD (Cr) was 2.7 g / liter and pH was 8.6. The pressure at the inlet (PI) of the packed tower was 77 kg / cm ² G.

The result of the treated water obtained after 400 hours is:
COD (Cr) was 3.5 g / liter and pH was 8.7. The pressure (PI) at the inlet of the packed tower was 79 kg / cm ² G.

Further treatment was carried out, but after 440 hours, the pressure (PI) at the inlet of the packed tower increased, and the treatment was stopped.

Example 3 Using the wet oxidation apparatus shown in FIG. 3, a column (empty column) 27 not filled with the solid catalyst and the adsorbent was provided before the packed column to perform the treatment. This treatment was performed continuously for a total of 500 hours under the following conditions in the same manner as in Example 1 except for the following. The detailed experimental methods and results are described below.

The solid catalyst packed in the packed tower 1 is 30 liters of a catalyst mainly composed of titania and manganese.
The weight ratio of each was 96: 4 in terms of TiO ₂ : Mn. The shape was a pellet having a diameter of 5 mmφ and a length of 7 mm. The solid catalyst packed in the packed tower 2 is 30 liters of a catalyst mainly composed of titania and ruthenium, and their weight ratio is 99.5 in terms of TiO ₂ : Ru.
0.5. The shape is 5mm diameter x 6m length.
m pellets. Empty tower 27 used for treatment
Is a cylindrical tower with a height of 6.0 m and an inner diameter of 9.2
cm.

The method of treatment is as follows.
And the air was mixed at a ratio of O ₂ / COD (Cr) (oxygen amount in air / required amount of chemical oxygen) = 1.5, processing pressure 50 kg / cm ² G, processing temperature 240 ° C. Processed. Further, sulfuric acid is supplied between the packed towers 1 and 2 by the chemical supply pump 7.
And supplied at a flow rate of 0.7 liter / hr. The packed tower inlet pressure (PI) at the start of the treatment is 51 kg / cm ²
G.

The wastewater subjected to the treatment was waste soda wastewater discharged from an ethylene plant and had the following properties. COD (Cr) 24g / liter, pH 13.2
And contained 27 g / liter of sodium sulfide.
The pH of the outlet liquid of the empty column 27, that is, the pH of the inlet to the packed column 1 was always 13.0 during the treatment.

The results of the treated water obtained after 100 hours are:
COD (Cr) was 0.23 g / liter and pH was 7.5.
The pressure (PI) at the inlet of the packed tower was 51 kg / cm ² G.

The results of the treated water obtained after 200 hours are:
COD (Cr) was 0.23 g / liter and pH was 7.5.
The pressure (PI) at the inlet of the packed tower was 51 kg / cm ² G.

The results of the treated water obtained after 300 hours are:
COD (Cr) was 0.23 g / liter and pH was 7.5.
The pressure (PI) at the inlet of the packed tower was 51 kg / cm ² G.

The results of the treated water obtained after 400 hours are:
COD (Cr) was 0.23 g / liter and pH was 7.5.
The pressure (PI) at the inlet of the packed tower was 51 kg / cm ² G.

The results of the treated water obtained after 500 hours are:
COD (Cr) was 0.23 g / liter and pH was 7.5.
The pressure (PI) at the inlet of the packed tower was 51 kg / cm ² G.

Comparative Example 3 Processing was performed under the same processing conditions as in Example 3 except that sulfuric acid was not supplied using the wet oxidation apparatus shown in FIG. The packed tower inlet pressure (PI) at the start of the treatment was 51 kg / cm ² G.

The results of the treated water obtained after 100 hours are:
COD (Cr) was 0.70 g / liter and pH was 12.7. The packed tower inlet pressure (PI) is 51 kg / cm ²
G.

The results of the treated water obtained after 200 hours are:
COD (Cr) was 0.76 g / liter and pH was 12.7. The packed tower inlet pressure (PI) is 51 kg / cm ²
G.

The result of the treated water obtained after 300 hours is:
COD (Cr) was 0.85 g / liter and pH was 12.7. The packed tower inlet pressure (PI) is 51 kg / cm ²
G.

The results of the treated water obtained after 400 hours are:
COD (Cr) was 1.0 g / liter and pH was 12.8.
The pressure (PI) at the inlet of the packed tower was 51 kg / cm ² G.

The results of the treated water obtained after 500 hours are:
COD (Cr) was 1.3 g / liter and pH was 12.9.
The pressure (PI) at the inlet of the packed tower was 51 kg / cm ² G.

Example 4 Using the wet oxidation treatment apparatus shown in FIG. 2, the treatment was carried out for a total of 500 hours in the same manner as in Example 2 except for the following. Also, as in Example 2, in this treatment, the positional relationship with respect to the flow direction of the wastewater in the packed tower was changed every 100 hours. The detailed experimental methods and results are described below.

The solid catalyst used in the treatment was a catalyst comprising titanium and iron oxides and palladium as main components, and their weight ratio was 10:10 in terms of TiO ₂ : Fe ₂ O ₃ : Pd.
89.5: 0.5. Also, the shape is 3mm diameter x
It was a pellet having a length of 5 mm. And this catalyst is 2
30 liters were packed in each of the packed towers.

The treatment method is as follows.
, And air was mixed at a ratio of O ₂ / ThOD (oxygen amount in air / theoretical oxygen demand) = 1.2, and then processed at a processing pressure of 80 kg / cm ² G and a processing temperature of 270 ° C. . Further, a 25% by weight aqueous sodium hydroxide solution was supplied between the packed towers 1 and 2 using the chemical supply pump 7 at a flow rate of 2.1 liter / hr. The packed tower inlet pressure (PI) at the start of the treatment was 81 kg / cm ² G.

The wastewater subjected to the treatment had the following properties. ThOD was 17 g / l, COD (Cr) was 9.1 g / l, pH was 6.1, and 0.35 g / l of p-chlorophenol, 61 mg / l of silicon, and 15 mg / l of phosphorus were contained. .

The results of the treated water obtained after 100 hours are:
COD (Cr) was 1.7 g / liter and pH was 9.2. The pressure (PI) at the inlet of the packed tower was 81 kg / cm ² G.

The results of the treated water obtained after 200 hours are:
COD (Cr) was 1.7 g / liter and pH was 9.2. The pressure (PI) at the inlet of the packed tower was 81 kg / cm ² G.

The result of the treated water obtained after 300 hours is:
COD (Cr) was 1.7 g / liter and pH was 9.2. The pressure (PI) at the inlet of the packed tower was 81 kg / cm ² G.

The results of the treated water obtained after 400 hours are:
COD (Cr) was 1.7 g / liter and pH was 9.2. The pressure (PI) at the inlet of the packed tower was 81 kg / cm ² G.

The results of the treated water obtained after 500 hours are:
COD (Cr) was 1.7 g / liter and pH was 9.2. The pressure (PI) at the inlet of the packed tower was 81 kg / cm ² G.

Comparative Example 4 A wet oxidation apparatus shown in FIG. 2 was used, except that sodium hydroxide was not added.
Processing was performed under the same processing conditions as in Example 4. The packed tower inlet pressure (PI) at the start of the treatment was 81 kg / cm ² G.

The results of the treated water obtained after 100 hours are:
COD (Cr) was 1.5 g / liter and pH was 5.6. The pressure (PI) at the inlet of the packed tower was 81 kg / cm ² G.

The result of the treated water obtained after 200 hours is:
COD (Cr) was 1.6 g / liter and pH was 5.6. The pressure (PI) at the inlet of the packed tower was 81 kg / cm ² G.

The results of the treated water obtained after 300 hours are:
COD (Cr) was 1.8 g / liter and pH was 5.6. The pressure (PI) at the inlet of the packed tower was 81 kg / cm ² G.

The results of the treated water obtained after 400 hours are:
COD (Cr) was 2.2 g / liter and pH was 5.7. The pressure (PI) at the inlet of the packed tower was 82 kg / cm ² G.

The result of the treated water obtained after 500 hours is:
COD (Cr) was 2.7 g / liter and pH was 5.7. The pressure (PI) at the inlet of the packed tower was 83 kg / cm ² G.

Example 5 Using the wet oxidation treatment apparatus shown in FIG. 4, a treatment was carried out for a total of 500 hours in the same manner as in Example 2 except for the following. Also, as in Example 2, this process exchanges the positional relationship of the packed tower 1 and the packed tower 2 with respect to the flow direction of the drainage every 100 hours so that the packed tower 28 is always between the packed towers 1 and 2. did. The detailed experimental methods and results are described below.

The solid catalyst used in the treatment was a catalyst composed mainly of a composite oxide of titanium and zirconium and ruthenium, and their respective weight ratios were TiO ₂ : ZrO ₂ : Ru.
It was 49.5: 49.5: 1.0 in conversion. The shape was a pellet having a diameter of 5 mmφ and a length of 7 mm.
Then, 30 liters of this catalyst was packed in the packed tower 28.

The adsorbent used in the treatment is an adsorbent composed of a composite oxide of titanium and zirconium as a main component, and the weight ratio of each is 50:80 in terms of TiO ₂ : ZrO _2.
It was 50. The shape is 5mm diameter x 7mm length.
In the form of pellets. Then, the adsorbent was packed into the packed towers 1 and 2 by 30 L each.

The treatment method is as follows.
And the air was mixed at a ratio of O ₂ / ThOD (oxygen amount in air / theoretical oxygen demand) = 1.2, and then processed at a processing pressure of 70 kg / cm ² G and a processing temperature of 250 ° C. . Also, the sulfuric acid is supplied to the chemical supply pump 7 before the packed tower 28.
And supplied at a flow rate of 0.7 liter / hr. The packed tower inlet pressure (PI) at the start of the treatment is 71 kg / cm ²
G.

The wastewater subjected to the treatment had the following properties. ThOD 22g / liter, COD (Cr) 1
8 g / l, pH 11.1, 0.6 g / l of organic nitrogen compound (converted to nitrogen element), 15 mg / lead
Liter, manganese 22 mg / l and calcium 11 mg / l.

The treated water obtained after 100 hours, 200 hours, 300 hours, 400 hours, and 500 hours shows that COD (Cr) is 0.5 g / liter and pH is 0.5.
It was 2. The packed tower inlet pressure (PI) is always 71
kg / cm ² G.

(Comparative Example 5) The treatment was carried out under the same treatment conditions as in Example 5 except that the wet oxidation treatment apparatus shown in FIG. 4 was used and sulfuric acid was not added. The packed tower inlet pressure (PI) at the start of the treatment was 71 kg / cm ² G.

The results of the treated water obtained after 100 hours are:
COD (Cr) was 1.3 g / liter and pH was 10.3.
The pressure at the inlet of the packed tower (PI) was 71 kg / cm ² G.

The results of the treated water obtained after 200 hours are:
COD (Cr) was 1.3 g / liter and pH was 10.3.
The pressure at the inlet of the packed tower (PI) was 71 kg / cm ² G.

The result of the treated water obtained after 300 hours is:
COD (Cr) was 1.7 g / liter and pH was 10.5.
The pressure at the inlet of the packed tower (PI) was 71 kg / cm ² G.

The result of the treated water obtained after 400 hours is:
COD (Cr) was 2.1 g / liter and pH was 10.7.
The packed tower inlet pressure (PI) was 72 kg / cm ² G.

The result of the treated water obtained after 500 hours is:
COD (Cr) was 2.9 g / liter and pH was 10.8.
The pressure (PI) at the inlet of the packed tower was 74 kg / cm ² G.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a processing apparatus according to the present invention.

FIG. 2 is an embodiment of a processing apparatus according to the present invention.

FIG. 3 is an embodiment of a processing apparatus according to the present invention.

FIG. 4 is an embodiment of a processing apparatus according to the present invention.

[Explanation of symbols]

 1. Packing tower 2. Packed tower 3. Heat exchanger 4. Cooler 5. Drainage supply pump 6. 6. Wastewater supply line 7. Drug supply pump 8. Drug supply line Compressor 10. Oxygen-containing gas supply line 11. Oxygen-containing gas flow control valve 12. Treated water line 13. Gas-liquid separator 14. Pressure control valve 15. Liquid level control valve 16. Gas discharge line 17. Treated water discharge line 18. Electric heater 19. Packing tower switching valve 20. Packing tower switching valve 21. Packing tower switching valve 22. Packing tower switching valve 23. Packing tower switching valve 24. Packing tower switching valve 25. Packing tower switching valve 26. Packing tower switching valve 27. Empty tower 28. Packed tower

Claims (4)

[Claims] 1. A wastewater treatment method using a plurality of packed towers filled with a solid catalyst and / or an adsorbent, wherein the raw wastewater p at the inlet of the packed tower at the most upstream side in the flow direction of the wastewater.
A method for treating wastewater, wherein the difference between H and the pH of treated water at the outlet of the most downstream packed tower is 1.5 or more. 2. The method according to claim 1, wherein the column not filled with the solid catalyst and the adsorbent is disposed upstream of the plurality of packed columns filled with the solid catalyst and / or the adsorbent in the flow direction of the wastewater. A method for treating wastewater according to claim 1. 3. The process of treating wastewater containing scale components, wherein the packed tower filled with the adsorbent is disposed upstream of the packed tower filled with the solid catalyst in the flow direction of the wastewater. 3. The method for treating wastewater according to 1 or 2. 4. The method for treating wastewater according to claim 1, wherein a pH adjusting agent is added between the plurality of packed towers.