JP2001151541A - Process and equipment for treating wastewater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wastewater treatment process which enables recycling of sludge generated by wastewater treatment as a cement raw material, and also to provide a wastewater treatment equipment for the process. SOLUTION: This wastewater treatment process comprises: introducing sludge from a sedimentation section 8 of a reaction vessel 3 into a sludge measuring tank 30; then transferring the sludge from the measuring tank 30 to a phosphorus elution tank 33; subsequently, in the phosphorus elution tank 33, adding an acid to the transferred sludge to elute phosphorus in the sludge; thereafter transferring the resulting mixture to a phosphorus separation tank 35; and in the phosphorus separation tank 35, subjecting the mixture to solid-liquid separation into a supernatant liquid having a high phosphorus content and separated sludge that has a reduced phosphorus concentration and can be recycled as a cement raw material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment method and a wastewater treatment apparatus capable of producing sludge made into a cement raw material. More specifically, the present invention relates to a wastewater treatment method and a wastewater treatment apparatus for reducing phosphorus in sludge and recycling the sludge without any problem.

[0002]

2. Description of the Related Art Converting sludge generated from wastewater treatment equipment into a raw material for cement is more specific from the viewpoint of sludge recycling and the direction of efforts to reduce industrial waste generated from today's factories. Many have been implemented.

[0003] Cement raw materials include limestone, viscosity, silica stone, iron raw materials, gypsum, and the like. Even if a predetermined amount or less of sludge is mixed as a cement raw material as an impurity, there is no problem in terms of cement quality. There is a report from a cement manufacturer.

[0004] Therefore, in a cement manufacturing company, sludge as an impurity of a predetermined amount or less is regarded as a cement raw material as know-how of the cement manufacturing company and is recycled.

However, sludge having a high phosphorus content affects the quality of cement due to the phosphorus in the sludge, and is mixed with other sludge having a low phosphorus content to adjust the phosphorus content in the sludge to a predetermined level. It was reduced to a value and recycled.

Accordingly, when there is no other sludge having a low phosphorus content, sludge having a high phosphorus content has not been recycled as a cement raw material due to quality problems.

A related prior art is disclosed in
No. 156400. In this treatment method, lime is added to sludge generated in industrial wastewater treatment and the like.When flocculation and dewatering are performed, iron salts and aluminum are added to the sludge so that the inorganic component composition of the dewatered cake is similar to the composition of cement clinker. Add one or more of salt, silicate, etc., and add slaked lime to agglomerate
This is a treatment method for making sludge into cement, which is characterized by dewatering. Therefore, this prior art is not a treatment method for removing phosphorus which affects the quality of cement.

[0008] Another conventional technique is disclosed in Japanese Patent Application Laid-Open No. 11-35353. This method is a method for producing a raw material for cement production from sewage sludge to be dried powder by dewatering and drying sewage sludge to dry sludge, mixing quicklime with the dried sludge and reacting with an aging machine. . Therefore, this conventional technique is not a treatment method for removing phosphorus which affects the quality of cement.

[0009]

Generally, semiconductor factories use a large amount of hydrofluoric acid or phosphoric acid, so there is wastewater containing hydrofluoric acid or phosphoric acid, and slaked lime is used to treat the wastewater. As a result of wastewater treatment using a wastewater, a large amount of sludge was generated from the wastewater treatment equipment.

[0010] Today, minimizing industrial waste generated from factories has become an important theme for companies.

[0011] From the background, when industrial waste generated from wastewater treatment equipment in a semiconductor factory is reduced to the maximum extent, reaction efficiency and the like are improved, excess chemicals are not added, and wastewater treatment equipment generates wastewater. The concentrations of fluorine and phosphorus in the sludge that was produced tended to increase within the disposal limit.

As a raw material for cement, a problem arises when the fluorine concentration in the sludge also exceeds a certain concentration. However, sludge with an increased phosphorus concentration has a problem in cement quality, which particularly affects the cement strength. It became necessary to quickly reduce the phosphorus concentration in the material.

[0013] In order to reduce the phosphorus content of the sludge generated from the wastewater treatment apparatus, a method of adding a large amount of chemicals to reduce the phosphorus content in the sludge may be considered. Will be reversed from the direction of reduction.

For this reason, conventionally, when the phosphorus concentration of a specific sludge is high, it is mixed and stirred with other sludge having a low phosphorus concentration in the sludge in a cement plant to reduce the concentration to a level at which no quality problem occurs. Was. In this case, a step of mixing and stirring the sludge and the sludge is required, and the mixing and stirring of the sludge, including the control of the phosphorus concentration, is a serious operation. Also,
In the near future, if industrial waste is reduced and all sludge becomes sludge with a high phosphorus concentration, it may not be possible to recycle it as a cement raw material from the viewpoint of the quality.

In particular, in the case of a wastewater treatment system in a semiconductor factory, phosphorus in the sludge is a mixture with other components such as fluorine, so that only phosphorus which particularly affects the quality of cement can be easily removed from the sludge. There was no way.

Accordingly, an object of the present invention is to provide a wastewater treatment method and a wastewater treatment apparatus that can reuse sludge generated by wastewater treatment as a cement raw material.

[0017]

Means for Solving the Problems To achieve the above object, the wastewater treatment method of the present invention is characterized in that it has a step of producing sludge for a cement raw material for controlling the phosphorus concentration in the sludge as a cement raw material.

Further, the wastewater treatment apparatus of the present invention is characterized in that it has a means for producing sludge for a cement raw material for controlling the phosphorus concentration in the sludge as a cement raw material.

According to the above invention, sludge that can be recycled as a cement raw material can be obtained by controlling the phosphorus concentration in sludge generated by wastewater treatment. It is a feature of the present invention to have a step of controlling the phosphorus concentration in the sludge (a step of producing a sludge for a cement raw material) so that the sludge can be recycled as a cement raw material.

In a general wastewater treatment method, since a large amount of slaked lime is used, the phosphorus concentration in the sludge is low, and it can be used as a raw material for cement. However, the amount of slaked lime is minimized and the amount of waste is suppressed. In the wastewater treatment method, as a result, the phosphorus concentration in the sludge is twice or more as compared with ordinary sludge. For example, in a general method, the phosphorus concentration in sludge is
While the content is usually 2.5% or less in terms of weight, the phosphorus concentration in the sludge generated in the wastewater treatment method with a reduced amount of waste is 6 to 8%. In the wastewater treatment method in which the amount of waste is suppressed, the present invention is effective for producing sludge that can be recycled as a cement raw material.

The wastewater treatment apparatus according to one embodiment comprises a means for producing sludge for cement raw material for controlling the phosphorus concentration in sludge as cement raw material, and a means for producing sludge for industrial waste for producing sludge as industrial waste. And with.

According to this embodiment, of the sludge generated by the wastewater treatment, the component suitable as the cement raw material is discharged as the cement raw material sludge by controlling the phosphorus concentration by the “cement raw material sludge production means”. . On the other hand, of the produced sludge, components that are not suitable as cement raw materials
It is discharged from “means for producing sludge for industrial waste”. Therefore, according to the sludge generated in the wastewater treatment process, the treatment route can be divided into two treatment systems, a recycling sludge system and a waste sludge system, and the degree of freedom of the treatment process can be improved and optimization can be achieved.

That is, according to this embodiment, the reduction of waste by recycling unreacted slaked lime and reducing the amount of slaked lime and the recycling of sludge as a raw material for cement are both achieved, thereby saving resources. Can contribute to

A wastewater treatment apparatus according to another embodiment is a wastewater treatment apparatus for treating phosphorus-containing fluorine wastewater, wherein the means for producing sludge for cement raw material comprises a primary treatment for primary treatment of phosphorus-containing fluorine wastewater. Means, phosphorus reduction means and PH
Adjustment means is provided.

According to this embodiment, since the phosphorus reduction step by the phosphorus reduction unit and the PH adjustment step by the PH adjustment unit are present, the sludge to be discharged is simultaneously reduced in phosphorus content in the sludge. PH is prepared and made into cement raw material.

In one embodiment of the present invention, the phosphorus reducing means comprises a sludge measuring tank, a phosphorus elution tank, and a phosphorus separation tank. Sludge is introduced in order.

According to this embodiment, since the phosphorus reducing means is composed of the sludge measuring tank, the phosphorus elution tank and the phosphorus separation tank, the sludge amount can be measured and managed in the sludge measuring tank. The phosphorus in the sludge can be eluted, and the phosphorus and the sludge can be separated in the phosphorus separation tank. In addition, since sludge is introduced in the order of a sludge measuring tank, a phosphorus elution tank, and a phosphorus separation tank, it is necessary to introduce sludge measured by the required amount in the sludge measuring tank into the phosphorus elution tank to elute phosphorus from the sludge. Can be. Then, in the next phosphorus separation tank, phosphorus and sludge
(Other hardly soluble components such as calcium fluoride).
Thereby, sludge with reduced phosphorus is obtained.

In the above-mentioned phosphorus elution tank, the reaction principle is that calcium phosphate as sludge dissolves in an acidic region, whereas calcium fluoride as sludge does not dissolve in an acidic region. In other words, the mechanism of phosphorus reduction is constructed focusing on the fact that calcium fluoride, which occupies most of the sludge, is hardly soluble in the acidic region, whereas calcium phosphate is soluble in the acidic region. In the above phosphorus reduction, P of calcium fluoride and calcium phosphate
The point is the difference in solubility due to H (acidic region).

In another embodiment of the wastewater treatment apparatus, an acid is added to the phosphorus elution tank.

According to this embodiment, since the acid is added to the phosphorus elution tank, the sludge is dissolved by the acid, the hardly soluble substance is not dissolved, and the soluble substance can be dissolved. Sludge generated from a semiconductor factory is composed of calcium fluoride which is hardly soluble in an acidic region and calcium phosphate which is soluble in an acidic region. Therefore, the sludge is introduced into the phosphorus elution tank, the acid is added, and the mixture is stirred by the stirring means.
The acidic region can be confirmed by the measured value of the meter. Then, the hardly soluble calcium fluoride in the acidic region and the soluble calcium phosphate in the acidic region are subjected to solid-liquid separation. As a result of this solid-liquid separation, phosphorus is removed from the sludge, and the phosphorus concentration in the sludge decreases.

In one embodiment of the present invention, the phosphorus elution tank is provided with at least one of a stirring means comprising a stirrer and a stirring means by air aeration.

According to this embodiment, at least one of the stirrer and the air stirring provided in the phosphorus elution tank is used.
Sludge can be reliably dissolved, and a wastewater treatment device can be easily and economically constructed.

In another embodiment of the present invention, a pH meter is installed in the phosphorus elution tank.

According to this embodiment, the amount of phosphorus eluted from sludge in the phosphorus elution tank can be controlled by the PH meter installed in the phosphorus elution tank.

In one embodiment of the present invention, the primary treatment means for the primary treatment of the phosphorus-containing fluorine waste water includes a reaction tank having a settling portion into which raw water is introduced, and a slaked lime tank to which slaked lime is added. And a polymer flocculant tank to which a polymer flocculant is added, and a sedimentation tank, and wastewater is introduced in the order of the reaction tank, slaked lime tank, polymer flocculant tank, and sedimentation tank. Return sludge is introduced into the settling section of the reaction tank.

According to this embodiment, in the reaction tank,
Raw water as wastewater can be treated by unreacted chemicals in the returned sludge from the settling tank. In addition, slaked lime tank (third water tank)
In the above, slaked lime is added, so that fluorine in wastewater can be converted into calcium fluoride and phosphorus in wastewater can be converted into calcium phosphate.

Further, since the polymer flocculant is added to the polymer flocculant tank (fourth water tank), the fine flocs formed by adding slaked lime in the slaked lime tank can be made more stable flocs. Further, in the sedimentation tank (fifth water tank), sludge as solid matter in the wastewater can be sedimented to obtain treated water as a supernatant.

Further, in the wastewater treatment apparatus of another embodiment, the sludge in which the unreacted chemicals in the returned sludge from the settling tank are completely consumed by the raw water moves to the settling section of the reaction tank.

According to this embodiment, the reaction tank (second water tank)
The unreacted chemicals in the sludge returned from the settling tank are completely consumed by the raw water, so that the amount of generated sludge can be minimized.

In one embodiment of the present invention, the means for producing sludge for industrial waste comprises:
A secondary treatment means for performing a secondary treatment, the secondary treatment means comprising a slaked lime tank to which slaked lime is added, a polyaluminum chloride tank to which polyaluminum chloride is added, and a high-pressure tank to which a polymer flocculant is added. It has a molecular coagulant tank and a sedimentation tank, and wastewater is introduced in the order of slaked lime tank, polyaluminum chloride tank, polymer coagulant tank, and sedimentation tank.

According to this embodiment, since slaked lime is added in the slaked lime tank (sixth water tank), phosphorus in the wastewater can be treated as calcium phosphate. In addition, in the polyaluminum chloride tank (seventh water tank), polyaluminum chloride is added, so even if the amount of fluorine in the wastewater is low, it can be highly treated, that is, a small amount of fine calcium fluoride is flocculed. It can be processed in a state. In the polymer flocculant tank (eighth water tank), the polymer flocculant is added, so that the flocs formed in the polyaluminum chloride tank can be made more stable and large flocs. Further, in the sedimentation tank (ninth water tank), sludge as solid matter in the wastewater can be sedimented to obtain treated water as a supernatant.

In another embodiment of the present invention,
The H adjusting means is a P adjusting tank having a PH meter and a rapid stirrer or a P meter having a PH meter and stirring means by air aeration.
H adjustment tank.

According to this embodiment, sulfuric acid is added by the phosphorus reduction means, and the sludge which has become acidic due to the reduction of phosphorus in the sludge is pH-adjusted (that is, neutralized) in the PH adjustment tank.
it can.

Further, the wastewater treatment apparatus according to one embodiment has a PH
Slaked lime as a PH adjuster is added to the adjusting tank.

According to this embodiment, slaked lime containing a large amount of calcium is added to the pH adjusting tank as a pH adjusting agent, so that the sludge can be adjusted for pH, and at the same time, the sludge can be used as an optimum material as a cement raw material. Can be

As a cement raw material, a material containing a large amount of calcium (slaked lime) is suitable. Therefore, the above P
As a chemical added to the H adjusting tank, slaked lime containing calcium is more suitable than an alkali agent such as caustic soda.

In another embodiment of the present invention, a calcium carbonate mineral as a pH adjuster is added to the pH adjuster.

According to this embodiment, the calcium carbonate mineral containing a large amount of calcium is added to the pH adjusting tank as a pH adjusting agent, so that the sludge is adjusted at the same time as the pH and the optimum material is used as a cement raw material. Can be

In another embodiment of the wastewater treatment apparatus, limestone is added as a pH adjuster to the pH adjuster.

According to this embodiment, since limestone containing a large amount of calcium is added to the pH adjusting tank as a pH adjusting agent, the sludge is adjusted to pH and at the same time, this sludge is made the optimum material as a cement raw material. be able to.

Limestone is chemically calcium carbonate and is the most typical cement raw material. In addition, limestone has a pH adjusting ability to neutralize acidic waste liquid.

Further, the wastewater treatment apparatus according to one embodiment has a PH
A mixture of slaked lime, calcium carbonate mineral, and limestone is added to the adjustment tank as a pH adjuster.

According to this embodiment, the proportions of slaked lime, calcium carbonate mineral and limestone are determined by means of phosphorus reduction (phosphorus separation tank).
It can be adjusted according to the acidity of the settled sludge from the wastewater to increase the economic efficiency as a chemical.

Specifically, when the acidity of the settled sludge from the phosphorus reduction means (phosphorus separation tank) is close to PH1 (the acidity is strong), the ratio of slaked lime which is alkaline is increased. on the other hand,
When the acidity of the sedimentation sludge from the phosphorus separation tank is close to PH7, the economics of the wastewater treatment system can be improved by increasing the proportion of limestone having a low neutralization capacity and a low unit price.

In another embodiment of the wastewater treatment device, the acid added to the phosphorus elution tank is sulfuric acid.

In this embodiment, since the acid added to the phosphorus elution tank is sulfuric acid, not only is the unit price low and economical, but also there is no problem of corrosion by chlorine ions such as hydrochloric acid. Further, since the solubility of sulfate ions is high, there is no concern about sludge generation due to sulfuric acid even after the reaction, and the amount of waste can be reduced.

Further, in the wastewater treatment apparatus according to one embodiment, the PH adjustment tank is previously filled with a calcium carbonate mineral.

In this embodiment, the pH adjustment tank is
Since the calcium carbonate mineral is filled, it is possible to adjust the pH of the phosphorus-free sludge from the phosphorus separation tank acidified by the calcium carbonate mineral. At the same time, there is no mechanical trouble such as pH adjustment for adding a normal chemical, and the system is stable.

In another embodiment of the wastewater treatment apparatus, the PH adjustment tank is preliminarily filled with limestone.

In this embodiment, since the limestone is previously filled in the PH adjustment tank, the pH of the phosphorus-free sludge from the acidified phosphorus separation tank can be adjusted. At the same time, the system is stable without mechanical troubles such as pH adjustment for adding a normal chemical.

In one embodiment of the present invention, the pH adjustment tank is pre-filled with calcium carbonate mineral or limestone in granular form.

In this embodiment, the pH adjustment tank is
Since it is filled with granular limestone or calcium carbonate mineral, the pH of phosphorus-free sludge from the acidified phosphorus separation tank can be more easily adjusted with granular limestone and calcium carbonate mineral. At the same time, there is no mechanical trouble such as pH adjustment for adding a normal chemical, and the system is stable.

[0063]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

[First Embodiment] FIG. 1 shows a first embodiment of a wastewater treatment apparatus according to the present invention. In the first embodiment, the phosphorus-containing fluorine wastewater is subjected to wastewater treatment to generate sludge as a cement raw material and sludge as industrial waste.

In this wastewater treatment apparatus, first, phosphorus-containing fluorine wastewater is introduced into a first water tank 1 as a storage tank.
The acid wastewater introduced into the first water tank 1 is introduced by a first water tank pump 2 into a sludge production process 40 as a cement raw material. In the sludge production process 40, sludge as a cement raw material is generated. Next, the wastewater that has passed through the sludge production process 40 as a cement raw material is introduced into the next sludge production process 41 as industrial waste and is treated. In the sludge production process 41 as industrial waste, sludge as industrial waste is generated.

According to the first embodiment, in the process of treating the phosphorus-containing fluorine wastewater, in the first sludge production step 40, which is the preceding treatment step, the phosphorus-containing fluorine wastewater is subjected to the primary treatment of the phosphorus-containing fluorine wastewater. Sludge which is a cement material with a low content is produced. On the other hand, in a second sludge production process 41, which is a subsequent treatment process, sludge that becomes an industrial waste having a high phosphorus content is produced in the process of secondary treatment of the phosphorus-containing fluorine wastewater.

[Second Embodiment] Next, FIG. 2 shows a wastewater treatment apparatus according to a second embodiment of the present invention.

In the second embodiment, similarly to the first embodiment, phosphorus-containing fluorine wastewater is introduced into the first water tank 1.

In the second embodiment, the phosphorus-containing fluorine wastewater primary treatment step 42 and the secondary treatment step 44 of the wastewater, and the phosphorus reduction step in which the sludge generated in the phosphorus-containing fluorine wastewater primary treatment step 42 is introduced. 43 and a PH adjustment step 45 in which phosphorus-reduced sludge is introduced from the phosphorus reduction step 43.

The phosphorus-containing fluorine wastewater introduced into the first water tank 1 is stored in the first water tank 1 for a certain period of time, and then introduced into the phosphorus-containing fluorine wastewater primary treatment step 42 by the first water tank pump 2. You. In the primary treatment step 42 of the phosphorus-containing fluorine wastewater, phosphorus and fluorine in the wastewater are treated,
Sludge mainly composed of calcium phosphate and calcium fluoride is generated.

Next, a primary treatment step 42 of the above-mentioned fluorine wastewater is performed.
The sludge generated in the above is introduced into the phosphorus reduction step 43, and the phosphorus in the sludge is reduced. Next, the sludge from which phosphorus has been reduced is introduced into a pH adjustment step 45, where the pH is adjusted. This pH-adjusted sludge is transferred to a cement company as sludge as a cement raw material.

On the other hand, the wastewater (water to be treated) treated in the above-mentioned phosphorus-containing fluorine wastewater primary treatment step 42 is further introduced into a phosphorus-containing fluorine wastewater secondary treatment step 44, where fluorine and phosphorus contained in the wastewater are treated. Is treated and discharged as treated water.

Secondary treatment step 4 of this phosphorus-containing fluorine wastewater
From No. 4, sludge as industrial waste having a high phosphorus concentration in the sludge is generated and disposed as industrial waste.

The high-concentration phosphorus-containing wastewater is generated from the phosphorus reduction step 43, and the high-concentration phosphorus-containing wastewater is introduced into a wastewater secondary treatment step 44 for treatment.

[Third Embodiment] Next, FIG. 3 shows a third embodiment of the wastewater treatment apparatus according to the present invention.

In the third embodiment, as in the first embodiment, the phosphorus-containing fluorine wastewater is introduced into the first water tank 1.

After the phosphorus-containing fluorine wastewater introduced into the first water tank 1 is stored in the first water tank 1 for a certain period of time, the first water tank pump 2 passes through the lower inflow pipe 4 to the second water tank (reaction tank). 3 is introduced into the lower part 3-2. In the lower part 3-2 of the second water tank 3, return sludge from the fifth water tank (first sedimentation tank) 14 is introduced via the return sludge inflow pipe 5, and forms a sludge zone 6. A settling portion 8 exists adjacent to the sludge zone 6.

The second water tank 3 is provided between the upper part 3-1 of the second water tank and the second water tank 3.
It comprises a lower part 3-2 of the water tank and a settling part 8. Second
A blocking wall 7 is provided between the lower part 3-2 of the water tank and the settling section 8, and the uppermost sludge of the sludge zone 6 moves to the settling section 8 over the blocking wall 7.

The settling section 8 is provided with a settling section submersible pump 9, and the sludge moved from the sludge zone 6 to the settling section 8 and settled is introduced into the sludge measuring tank 30 by the settling section submerged pump 9. Is done.

The settled sludge introduced into the sludge measuring tank 30 is subjected to gravity so that a predetermined amount as required is added to the phosphorus elution tank 3.
3 and another predetermined amount of settled sludge is introduced into the PH adjustment tank 37.

The phosphorus elution tank 33 has a rapid stirrer 31
And a PH meter 32 are installed. Sulfuric acid is added to the sludge introduced into the phosphorus elution tank 33. By the addition of sulfuric acid, calcium phosphate in the sludge is dissolved, and phosphorus is eluted. On the other hand, even under the acidic condition using sulfuric acid, calcium fluoride in the sludge is hardly soluble and therefore does not dissolve. In the phosphorus elution tank 33, the solution containing the sludge treated by adding sulfuric acid is then introduced into the phosphorus separation tank 35 by gravity. In the phosphorus separation tank 35, the phosphorus in the solution is introduced into the sixth water tank (second slaked lime reaction tank) 17 as a supernatant.

On the other hand, in the phosphorus separation tank 35, the hardly soluble precipitated calcium fluoride sludge is scraped to the center of the bottom of the phosphorus separation tank 35 by the phosphorus separation tank scraper 34 installed in the phosphorus separation tank 35. , Is introduced into a PH adjustment tank 37 by a phosphorus separation tank pump 36. The calcium fluoride sludge introduced into the PH adjustment tank 37 is
The pH is adjusted by slaked lime added to the pH adjusting tank 37.

Further, a predetermined amount of phosphorus-containing sludge from the sludge measuring tank 30 is also introduced into the PH adjusting tank 37. The reason is that sludge containing no phosphorus is not required as sludge as a cement raw material, and there is no problem even if phosphorus is contained to some extent as long as the quality of cement can be maintained. is there. As an example, the phosphorus content allowable amount in this sludge has a value of 2.5% or less in terms of weight.

The wastewater containing the sludge whose pH has been adjusted in the PH adjustment tank 37 is then introduced into a tenth water tank (first concentration tank) 23. In the tenth water tank 23, the sludge in the drainage precipitates and is concentrated in the lower part of the tenth water tank 23. The supernatant in the tenth water tank 23 moves to the second water tank 3 by gravity (not shown). The sludge concentrated in the tenth water tank 23 is
The liquid is introduced into a first filter press 28 which is a dehydrator and dehydrated by the concentration tank pump 24. The water content of the cake in the first filter press 28 varies depending on the type of the filter press, but is about 60%. This sludge has a low phosphorus content and is treated as sludge for cement raw materials.

The supernatant from the sedimentation section 8 of the second water tank 3 is introduced into a third water tank (first slaked lime reaction tank) 10. This third
Slaked lime is added to the water tank 10. Unreacted fluorine and phosphorus in the wastewater react with the calcium component of slaked lime to form fine calcium fluoride and calcium phosphate. The wastewater containing the fine calcium fluoride and calcium phosphate is then introduced into a fourth water tank (polymer flocculant flocculation tank) 12 to which a polymer flocculant is added. Large and stable flock
(Sludge). Next, the large and stable floc
The (sludge) is introduced into a fifth water tank (first sedimentation tank) 14 and is separated into a solid and a liquid.

The sludge settled in the fifth water tank (first sedimentation tank) 14 is returned by the first sedimentation tank pump 16 to the lower part 3-2 of the second water tank, where the sludge containing phosphorus from the first water tank 1 is removed. Reacts on contact.

The supernatant from the first precipitation tank 14 and the supernatant from the phosphorus separation tank 35 are both introduced into a sixth water tank (second slaked lime reaction tank) 17. The supernatant from the first settling tank 14 contains some phosphorus and fluorine.
The supernatant from the phosphorus separation tank 35 contains a particularly high concentration of phosphorus.

The sixth water tank (second slaked lime reaction tank) 17
Then, slaked lime is added, the phosphorus in the wastewater becomes fine calcium phosphate, and the fluorine becomes fine calcium fluoride. Next, the wastewater is introduced into a seventh water tank (polyaluminum chloride flocculation tank) 18 to which polyaluminum chloride is added, and subsequently, an eighth water tank (polymer flocculant flocculation tank) to which a polymer flocculant is added. Introduced in 19, fine calcium phosphate and fine calcium fluoride result in larger stable flocs. These flocs are introduced into a ninth water tank (second sedimentation tank) 20 having a second sedimentation tank scraper 21, where they are separated into a supernatant and a precipitate. This supernatant is discharged as treated water. On the other hand, the sludge precipitated in the ninth water tank (second sedimentation tank) 20 contains a large amount of phosphorus,
It is introduced into a water tank (second concentration tank) 26 and concentrated. The concentrated sludge is supplied to the second condensing tank pump 27 for
The water is introduced into the filter press 29 and dewatered to form a dewatered cake. The water content of the dewatered cake varies depending on the type of the filter press, but is about 60%.
Since the dewatered cake dewatered by the second filter press 29 contains phosphorus at a high concentration, it cannot be recycled as a cement raw material and is generally landfilled as industrial waste.

FIG. 4 (A) shows an example of the residence time in each water tank when the phosphorus-containing fluorine wastewater has a normal concentration. FIG. 4 (B) shows that the phosphorus-containing fluorine wastewater has a low concentration. An example of the residence time in each water tank in the case is shown.

[Fourth Embodiment] FIG. 5 shows a fourth embodiment of the wastewater treatment apparatus according to the present invention.

The fourth embodiment is different from the fourth embodiment only in that calcium carbonate mineral is added to PH adjusting tank 37 instead of slaked lime.
This is different from the third embodiment. Therefore, the third
The same components as those of the embodiment are denoted by the same reference numerals, and detailed description will be omitted.

In the fourth embodiment, the PH adjustment tank 37
Then, a calcium carbonate mineral is added instead of slaked lime.
Although slaked lime also contains a large amount of calcium, the calcium carbonate mineral also contains a large amount of calcium, and it goes without saying that sludge resulting therefrom becomes a cement raw material. Also, calcium carbonate minerals, like slaked lime,
The pH of acid wastewater can be adjusted (neutralized).

[Fifth Embodiment] FIG. 6 shows a wastewater treatment apparatus according to a fifth embodiment of the present invention.

The fifth embodiment differs from the third embodiment only in that limestone is added to the PH adjustment tank 37 instead of slaked lime.
Different from the embodiment. Therefore, in the fifth embodiment, the same components as those in the above-described third embodiment are denoted by the same reference numerals, and detailed description is omitted.

In the fifth embodiment, the pH adjustment tank 37
Add limestone to Although slaked lime contains a large amount of calcium, limestone also contains a large amount of calcium, and it goes without saying that sludge resulting therefrom becomes a cement raw material. Limestone is a typical raw material as a cement raw material, and generally, 70% or more of the cement raw material is limestone.

[0096] Limestone can adjust (neutralize) acidic wastewater in the same manner as slaked lime. To use limestone for pH adjustment (neutralization), it is necessary to grind it finely, but limestone has the lowest cost.

[Sixth Embodiment] Next, FIG. 7 shows a wastewater treatment apparatus according to a sixth embodiment of the present invention. The sixth embodiment differs from the third embodiment only in that three kinds of materials, slaked lime, calcium carbonate mineral, and limestone, are added to the PH adjustment tank 37. Therefore, the same components as those of the above-described third embodiment are denoted by the same reference numerals, and detailed description is omitted.

In the sixth embodiment, the pH adjusting tank 37
, Three kinds of materials such as slaked lime, calcium carbonate mineral and limestone are added.

Although slaked lime also contains a large amount of calcium, calcium carbonate minerals and limestone also contain a large amount of calcium, and it goes without saying that sludge resulting therefrom becomes a raw material for cement. Limestone is a typical raw material as a cement raw material, and generally, 70% or more of the cement raw material is limestone.

In the sixth embodiment, since the above three kinds of materials can be supplied, the ratio of addition can be changed as necessary, and the cost can be always controlled.

From the viewpoint of the ability of pH adjustment (neutralization),
First, slaked lime is superior, followed by calcium carbonate minerals, and third, limestone. On the other hand, from a cost perspective, limestone is the best, followed by calcium carbonate minerals, followed by slaked lime third. Therefore, the addition ratio of the above three kinds of substances (slaked lime, calcium carbonate mineral, and limestone) can be adjusted according to the purpose and necessity, and sludge to be used as a cement raw material can be produced at a minimum cost.

[Seventh Embodiment] FIG. 8 shows a wastewater treatment apparatus according to a seventh embodiment of the present invention.

The seventh embodiment differs from the third embodiment only in the method of adjusting the PH in the PH adjustment tank 37. Therefore, the same components as those of the above-described third embodiment are denoted by the same reference numerals, and detailed description is omitted.

In the third embodiment, the pH adjusting tank 37 is used.
In the seventh embodiment, a calcium carbonate mineral 38 is filled in advance in a PH adjustment tank 37, and a phosphorus separation tank pump 36 is supplied by air discharged from a blower 46. PH is adjusted by reacting the acidic sludge introduced from the reactor with the calcium carbonate mineral 38.

In the seventh embodiment, since a large amount of neutral calcium carbonate mineral 38 is previously filled in the PH adjustment tank 37, the acidity of the acidic sludge introduced from the phosphorus separation tank pump 36 changes. However, there is an advantage that the pH can be stably adjusted. Since the calcium carbonate mineral 38 contains a large amount of calcium, it goes without saying that the sludge after the pH adjustment becomes a cement raw material.

FIG. 9 (A) shows an example of the residence time in each water tank when the phosphorus-containing fluorine wastewater has a normal concentration. FIG. 9 (B) shows the case where the phosphorus-containing fluorine wastewater has a low concentration. An example of the residence time in each water tank in the case is shown.

[Eighth Embodiment] FIG. 10 shows an eighth embodiment of the wastewater treatment apparatus according to the present invention.

The eighth embodiment differs from the third embodiment only in the method of pH adjustment in the PH adjustment tank 37. Therefore, the same components as those of the above-described third embodiment are denoted by the same reference numerals, and detailed description will be omitted.

In the third embodiment, slaked lime is added to the pH adjusting tank 37. On the other hand, in the eighth embodiment, the limestone 39 is filled in the PH adjustment tank 37 in advance. The limestone 39 is reacted with acidic sludge introduced from the phosphorus separation tank pump 36 by the air discharged from the blower 46 to adjust the pH.

In the eighth embodiment, the pH adjustment tank 37
Is filled with a large amount of neutral limestone 39 in advance,
There is an advantage that the pH can be stably adjusted even if the acidity of the acidic sludge introduced from the phosphorus separation tank pump 36 changes. Since the limestone 39 contains a large amount of calcium, it goes without saying that it is a cement raw material.

[First Experimental Example] Next, as a specific example, an experimental example of drainage treatment using an experimental apparatus having the same structure as the third embodiment shown in FIG. 3 will be described.

In this first experimental example, the capacity of the first water tank 1 was set to 1 cubic meter, the capacity of the second water tank 3 was set to 3 cubic meters, and the capacities of the third water tank 10 and the fourth water tank 12 were each set to 0.3. Cubic meters and the capacity of the fifth water tank 14 is 1
Cubic meters. In addition, the capacity of the sixth water tank 17, the seventh
The capacity of the water tank 18 and the capacity of the eighth water tank 19 are
It was 3 cubic meters, and the capacity of the ninth water tank 20 was 1 cubic meter. The capacity of the tenth water tank 23 was set to 0.3 cubic meters, and the capacity of the eleventh water tank 26 was set to 0.3 cubic meters. Further, the capacity of the phosphorus elution tank 33 was set to 0.1 cubic meters, the capacity of the phosphorus separation tank 35 was set to 0.3 cubic meters, and the capacity of the PH adjustment tank 37 was set to 0.3 cubic meters.

The wastewater was treated with the apparatus having the above configuration, and the sludge obtained from the tenth water tank 23 was dewatered with the first filter press 28. The phosphorus content was 2.5% by weight and the water content was 56%. A dehydrated cake was obtained. This dehydrated cake is
Since the phosphorus content is 2.5%, it is a dewatered cake which has no problem as a raw material for cement.

On the other hand, when the sludge obtained from the eleventh water tank 26 was dewatered by the second filter press 29, a dewatered cake having a phosphorus content of 12.5% by weight and a water content of 57% was obtained. Since this dewatered cake had a phosphorus content of 12.5%, it was not suitable as a cement raw material and was landfilled as industrial waste.

[Second Experimental Example] Next, as a specific example, an experimental example of drainage treatment using an experimental apparatus having the same structure as the fifth embodiment shown in FIG. 6 will be described.

In the second experimental example, the capacity of the first water tank 1 was 1 cubic meter, the capacity of the second water tank 3 was 3 cubic meters, and the capacity of the third water tank 10 and the fourth water tank 12 was 0.3 cubic meters. The capacity of the fifth water tank 14 was 1 cubic meter. The capacity of the sixth water tank 17, the capacity of the seventh water tank 18, and the capacity of the eighth water tank 19 were each set to 0.3 cubic meters, and the capacity of the ninth water tank 20 was set to 1 cubic meters. Further, the capacity of the tenth water tank 23 is set to 0.3 cubic meters, the capacity of the eleventh water tank 26 is set to 0.3 cubic meters, and the capacity of the phosphorus elution tank 33 is set to 0.1 cubic meters.
The capacity of the phosphorus separation tank 35 is set to 0.3 cubic meters,
The wastewater was treated by adjusting the capacity of the adjusting tank 37 to 0.3 cubic meters.

The sludge obtained from the tenth water tank 23 is
After dewatering with a filter press 28, a dewatered cake having a phosphorus content of 1.2% by weight and a water content of 58% was obtained. Since this dewatered cake has a phosphorus content of 1.2%, it is a dewatered cake having no problem as a cement raw material.

On the other hand, when the sludge obtained from the eleventh water tank 26 was dewatered by the second filter press 29, a dewatered cake having a phosphorus content of 12.3% and a water content of 59% was obtained. This dehydrated cake has a phosphorus content of 12.3%
Therefore, it was a dehydrated cake that was not suitable as a raw material for cement and was landfilled as industrial waste.

[0119]

As is clear from the above, the wastewater treatment method and wastewater treatment apparatus of the present invention can control the phosphorus concentration in sludge and recycle sludge to produce a cement raw material.

Further, the wastewater treatment apparatus of one embodiment controls the phosphorus concentration in the sludge to produce sludge as a cement raw material, and transfers sludge components that are not suitable for cement raw material to sludge as industrial waste. Let it. Thereby, the sludge can be recycled as a cement raw material.

Further, since the wastewater treatment apparatus of another embodiment treats phosphorus-containing fluorine wastewater, sludge from a factory having a large amount of wastewater and generating a large amount of sludge such as a semiconductor factory or a liquid crystal factory is recycled as a cement raw material. it can. Further, since the amount of phosphorus in the sludge can be reduced and the pH can be adjusted, the quality as a cement raw material can be maintained.

Further, in the wastewater treatment apparatus of one embodiment, the sludge is measured, phosphorus in the sludge can be eluted in a phosphorus elution tank, and then phosphorus can be separated in a phosphorus separation tank. The phosphorus in the affected sludge can be reduced.

Further, in the wastewater treatment apparatus of another embodiment, an acid is added to a phosphorus elution tank to dissolve calcium phosphate that has become sludge, and phosphorus can be transferred from sludge to a solution. Phosphorus can be reduced.

In one embodiment of the present invention, the stirring means of the phosphorus elution tank is stirred by a stirrer, stirred by air, or both. Therefore, the wastewater treatment device can be easily constructed, and the sludge in the phosphorus elution tank can be sufficiently stirred.

Further, in the wastewater treatment apparatus of another embodiment, since the PH meter is installed in the phosphorus elution tank, the optimal PH, that is, the optimal acidity can be maintained without causing excessive injection of acid or insufficient injection of acid. Thus, phosphorus can be eluted from the sludge. That is, calcium phosphate sludge can be converted into phosphorus ions and calcium ions.

Further, in the wastewater treatment apparatus of one embodiment, since the returned sludge and the raw water from the precipitation tank are introduced into the primary treatment means of the phosphorus-containing fluorine wastewater, the returned sludge containing unreacted chemicals and the raw water are mixed. To eliminate sludge caused by unreacted chemicals. Therefore, it is possible to minimize the amount of the sludge (dewatered cake) for the cement raw material to be recycled at a cost.

Further, in the wastewater treatment apparatus according to another embodiment, the sludge moving from the settling tank to the settling portion of the second water tank (reaction tank) is
Unreacted chemicals are completely consumed by raw water. Therefore, unreacted chemicals are eliminated, resources are effectively used, and running costs can be minimized. Further, the amount of sludge (dewatered cake) as a cement raw material to be recycled at a cost can be minimized, and the running cost can be reduced.

In one embodiment of the present invention, the sludge producing means as industrial waste has secondary treatment means for phosphorus-containing fluorine wastewater, and the secondary treatment means uses slaked lime for the wastewater. , Polyaluminum chloride and polymer flocculant are added. Therefore, even if the wastewater having a low fluorine concentration after the primary treatment of the phosphorus-containing fluorine wastewater, fluorine and the like can be reliably and highly treated. In other words, a small amount of fluorine in wastewater is converted into fine calcium fluoride with slaked lime,
Polyaluminum chloride can be used as a fine floc, and a polymer flocculant can be used as a larger and more stable floc for processing.

Further, in another embodiment of the wastewater treatment apparatus,
Since the H adjusting means is a PH adjusting tank provided with a PH meter and a rapid stirrer, the pH of sludge can be easily adjusted while rapidly stirring with a rapid stirrer. Further, since the PH adjusting means is a PH meter and a PH adjusting tank using air aeration, the pH of sludge can be easily adjusted.

[0130] Further, the wastewater treatment apparatus of one embodiment has a PH
Since the pH adjusting agent added to the adjustment tank is slaked lime, the pH adjustment of sludge can be easily performed, and slaked lime contains a large amount of calcium, so sludge after pH adjustment is used as a cement raw material. Can be recycled.

Further, a wastewater treatment apparatus according to another embodiment has a P
Since the pH adjusting agent added to the H adjusting tank is a calcium carbonate mineral, it is possible to adjust the pH of the sludge if it takes a long time, and since the calcium carbonate mineral contains a large amount of calcium, the pH adjusting agent is used. Later sludge can be recycled as a raw material for cement.

[0132] Further, the wastewater treatment apparatus of one embodiment has a PH
Since the pH adjusting agent added to the adjusting tank is limestone, it is possible to adjust the pH of the sludge if it takes time, and
Since limestone contains a large amount of calcium, the sludge after pH adjustment can be recycled as a raw material for cement.

Further, a waste water treatment apparatus according to another embodiment has a P
Since the pH adjusting agent added to the H adjusting tank is a mixture of slaked lime, calcium carbonate mineral, and limestone, the pH of sludge can be adjusted. Further, since each component of the mixture contains a large amount of calcium, sludge generated from the wastewater treatment device can be recycled as a cement raw material.

Further, in the wastewater treatment apparatus according to one embodiment, since the acid added to the phosphorus elution tank is sulfuric acid, the unit price is low and the economic efficiency is high. Absent. Further, since the solubility of sulfate ions is high, there is no concern about sludge generation due to sulfuric acid even after the reaction, and the amount of waste can be reduced.

Further, a wastewater treatment apparatus according to another embodiment has a P
Since the H adjusting tank is previously filled with the calcium carbonate mineral, it is possible to adjust the PH of the phosphorus-free sludge from the phosphorus separation tank that has been acidified with the calcium carbonate mineral. At the same time, there is no mechanical trouble such as pH adjustment for adding a normal chemical, and the system is stable.

[0136] Further, the wastewater treatment apparatus of one embodiment has a PH
Since the adjusting tank is preliminarily filled with limestone, it is possible to adjust the PH of the phosphorus-free sludge from the phosphorus separating tank that has become acidic with limestone. At the same time, the system is stable without mechanical troubles such as pH adjustment for adding a normal chemical.

Further, a wastewater treatment apparatus according to another embodiment has a P
Since the H adjustment tank is pre-filled with granular limestone or calcium carbonate mineral, the pH of phosphorus-free sludge from the acidified phosphorus separation tank with granular limestone or calcium carbonate mineral is easier. Can be adjusted. At the same time, there is no mechanical trouble such as pH adjustment for adding a normal chemical, and the system is stable.

As described above, according to the present invention, while reducing the sludge generated from the wastewater treatment apparatus, it is possible to easily reduce and control only phosphorus in the sludge which hinders the conversion to the cement raw material. That is, in the wastewater treatment method and wastewater treatment device of the present invention, calcium phosphate as a component of sludge is dissolved by an acid,
They discovered that calcium fluoride, a component of sludge, was not dissolved by acid, and built them as a wastewater treatment system, resulting in the formation of sludge as a raw material for cement.
This is a wastewater treatment system that can form sludge as (low phosphorus content) and industrial waste (high phosphorus content).

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a wastewater treatment device of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the wastewater treatment device of the present invention.

FIG. 3 is a configuration diagram showing a third embodiment of the wastewater treatment device of the present invention.

FIG. 4 is a timing chart of wastewater treatment according to the third embodiment.

FIG. 5 is a configuration diagram showing a fourth embodiment of the wastewater treatment apparatus of the present invention.

FIG. 6 is a configuration diagram showing a fifth embodiment of the wastewater treatment apparatus according to the present invention.

FIG. 7 is a configuration diagram showing a sixth embodiment of the wastewater treatment apparatus of the present invention.

FIG. 8 is a configuration diagram illustrating a seventh embodiment of the wastewater treatment apparatus according to the present invention.

FIG. 9 is a timing chart of wastewater treatment according to the seventh embodiment.

FIG. 10 is a configuration diagram showing an eighth embodiment of the wastewater treatment apparatus according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st water tank, 2 ... 1st water tank pump, 3 ... 2nd water tank (reaction tank with a precipitation part), 3-1 ... upper part of 2nd water tank, 3-2
... lower part of the second water tank, 4 ... lower inflow pipe, 5 ... returned sludge inflow pipe, 6 ... sludge zone, 7 ... barrier wall, 8 ... sedimentation part, 9 ... sedimentation part submersible pump, 10 ... third water tank (first slaked lime) Reaction tank),
11: Rapid stirrer, 12: Fourth water tank (polymer flocculant flocculation tank), 13: Slow stirrer, 14: Fifth water tank (first sedimentation tank), 15: First sedimentation tank scraper, 16 ... First settling tank pump, 17: sixth water tank (second slaked lime reaction tank), 18: seventh water tank (polyaluminum chloride coagulation tank), 19: eighth water tank
(Polymer flocculant flocculation tank), 20 ... ninth water tank (second sedimentation tank),
21: second settling tank scraping machine, 22: first thickening tank scraping machine, 23: tenth water tank (first thickening tank), 24: first thickening tank pump, 25: second thickening tank scraping machine, 26 ... 11
Water tank (second concentration tank), 27: second concentration tank pump, 28: first filter press, 29: second filter press, 3
0: Sludge measuring tank, 31: Rapid stirrer, 32: PH meter, 3
3: Phosphorus elution tank, 34: Phosphorous separation tank scraper, 35 ...
Phosphorus separation tank, 36: phosphorus separation tank pump, 37: PH adjustment tank, 38: calcium carbonate mineral, 39: limestone, 40 ...
Sludge production process as a cement raw material, 41: sludge production process as industrial waste, 42: primary treatment process of phosphorus-containing fluorine wastewater, 43 ... phosphorus reduction process, 44 ... secondary treatment process of phosphorus-containing fluorine wastewater, 45 ... PH Adjustment process, 46 ... blower.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C02F 1/58 C02F 1/58 RM 11/00 11/00 J C04B 7/38 C04B 7/38 (72 ) Inventor Sumi Nakajo 22-22, Nagaike-cho, Abeno-ku, Osaka City, Osaka F-term (reference) 4D015 BA04 BA19 BA23 BA24 BA25 BB01 BB09 BB12 CA17 CA18 DA04 DB01 DC02 EA32 FA01 FA03 FA11 FA12 FA19 FA28 4D038 AA08 AB41 AB45 BA04 BA06 BB13 BB18 4D059 AA18 AA19 BE16 BE34 BF11 BH05 BJ01 CA28 CC04 DA03 DA05 DA33 DA51 EA02 EA05 4D062 BA04 BA19 BA23 BA24 BA25 BB01 BB09 BB12 CA17 CA18 DA04 DB01 DC02 EA32 FA01 FA03 FA11 FA03

Claims (20)

[Claims] 1. A wastewater treatment method comprising a step of producing sludge for a cement raw material for controlling the phosphorus concentration in sludge as a cement raw material. 2. A wastewater treatment apparatus having a means for producing sludge for a cement raw material for controlling the phosphorus concentration in sludge as a cement raw material. 3. A method for producing sludge as a cement raw material for controlling the phosphorus concentration in sludge as a cement raw material, and a method for producing sludge as an industrial waste sludge for industrial waste. Wastewater treatment equipment. 4. The wastewater treatment device according to claim 2, wherein the wastewater treatment device for treating phosphorus-containing fluorine wastewater is characterized in that the means for producing sludge for cement raw material performs primary treatment of phosphorus-containing fluorine wastewater. Treatment means, phosphorus reduction means and P
A wastewater treatment apparatus comprising H adjusting means. 5. The wastewater treatment apparatus according to claim 4, wherein the phosphorus reducing means comprises a sludge measuring tank, a phosphorus elution tank, and a phosphorus separation tank. A wastewater treatment device characterized by introducing sludge in order. 6. The wastewater treatment apparatus according to claim 5, wherein an acid is added to the phosphorus elution tank. 7. The wastewater treatment device according to claim 6, wherein the phosphorus elution tank includes at least one of a stirring device including a stirrer and a stirring device using air aeration. 8. The wastewater treatment apparatus according to claim 7, wherein a PH meter is installed in the phosphorus elution tank. 9. The wastewater treatment apparatus according to claim 4, wherein the primary treatment means for treating the phosphorus-containing fluorine wastewater as a primary treatment comprises: a reaction tank having a settling portion into which raw water is introduced; and slaked lime. A slaked lime tank, a polymer flocculant tank to which a polymer flocculant is added, and a sedimentation tank, and drainage is introduced in the order of the reaction tank, slaked lime tank, polymer flocculant tank, and sedimentation tank. A wastewater treatment device, wherein sludge returned from the reactor is introduced into a settling section of the reaction tank. 10. The wastewater treatment apparatus according to claim 9, wherein unreacted chemicals in the returned sludge from the settling tank are completely consumed by raw water, and the sludge moves to the settling section of the reaction tank. Characterized wastewater treatment equipment. 11. The wastewater treatment apparatus according to claim 3, wherein the means for producing sludge for industrial waste includes a secondary treatment means for secondary-treating the fluorine-containing fluorine wastewater. Slaked lime tank to which slaked lime is added,
A polyaluminum chloride tank to which polyaluminum chloride is added, and a polymer coagulant tank to which a polymer coagulant is added,
A wastewater treatment apparatus having a sedimentation tank and introducing wastewater in the order of a slaked lime tank, a polyaluminum chloride tank, a polymer flocculant tank, and a sedimentation tank. 12. The wastewater treatment apparatus according to claim 4, wherein the PH adjusting means is a PH adjusting tank provided with a PH meter and a rapid stirrer or a PH adjusting tank having a PH meter and a stirring means by air aeration. A wastewater treatment device, comprising: 13. The wastewater treatment apparatus according to claim 12, wherein the PH adjuster added to the PH adjustment tank is slaked lime. 14. The wastewater treatment apparatus according to claim 12, wherein the PH adjuster added to the PH adjustment tank is a calcium carbonate mineral. 15. The wastewater treatment apparatus according to claim 12, wherein limestone is added as a PH adjuster to the PH adjustment tank. 16. The wastewater treatment apparatus according to claim 12, wherein a mixture of slaked lime, calcium carbonate mineral, and limestone is added to the PH adjustment tank as a pH adjuster. 17. The wastewater treatment device according to claim 6, wherein the acid added to the phosphorus elution tank is sulfuric acid. 18. The wastewater treatment apparatus according to claim 12, wherein the PH adjustment tank is previously filled with a calcium carbonate mineral. 19. The wastewater treatment apparatus according to claim 12, wherein the PH adjustment tank is previously filled with limestone. 20. The wastewater treatment device according to claim 18 or 19, wherein the calcium carbonate mineral or limestone previously filled in the PH adjustment tank is granular.