JP2001070989A - Method and apparatus for treating organic wastewater containing high concentration of salts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recycle a salt component as a raw material for industrial salt by a method in which in the treatment of organic wastewater containing a high concentration of salts, before desalination by a reverse osmosis membrane and/or electrodialysis membrane or after the desalination, heavy metals are removed, and a salt component free from the heavy metals is recovered as a solid. SOLUTION: Organic wastewater containing a high concentration of salfs is introduced from a raw water introduction pipe 1 into a softening apparatus 2 to be softened and introduced into a bio-treatment apparatus 3 and a precision flocculation filter 4 to remove organic pollutants. After that, the wastewater is led to a heavy metal removing apparatus 5 to remove heavy metals harmful to industrial salt, etc., and led to a reverse osmosis apparatus 6 to be subjected to reverse osmosis treatment. Reverse osmosis concentrated water is introduced into an electrodialyzer 8, the electrodialysis desalted water is returned to piping to the apparatus 6 through an electrodialysis desalted water return pipe 9. The electrodialysis concentrated water is led to an evaporation drier 10 and evaporated/dried to be separated into water and salts, and the salts are separated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for desalinating organic wastewater containing high concentrations of salts and removing organic substances, and particularly to a method for removing organic matter from landfill leachate and human waste. The present invention relates to a treatment method that can be used for advanced treatment, desalination treatment, concentration and recovery of salt substances, recovery and reuse of treated water, etc., with high salt concentration.

[0002]

2. Description of the Related Art Organic wastewater having a high salt concentration, such as leachate from landfills, generally contains high concentrations of pollutants such as salts such as calcium ions and organic substances. often,
Biochemical oxygen demand (BOD) or chemical oxygen demand (C
OD), contains many suspended substances (SS), and has a chromaticity caused by colloid substances and the like. For this reason, they cannot usually be directly reused for some purpose or directly discharged to rivers. As a method for treating such organic wastewater, a treatment method mainly for removing organic pollutants has been conventionally used. The main treatment methods include, for example, biological treatment for removing BOD, coagulation sedimentation treatment for removing chromaticity, COD and SS, sand filtration and microfiltration for removing turbidity such as SS. There is a film (MF film) treatment. Further, as an advanced treatment method, there is generally a method using ozone or activated carbon.

[0003]

In the above-mentioned method for treating organic wastewater, a combination of these treatments has reached a state of the art in which organic components such as BOD and COD can be sufficiently removed. ing. However, organic wastewater generally contains a variety of salts in addition to organic matter, and in some cases can contain significantly higher concentrations of salts. When treating such wastewater and discharging it to rivers, etc., it is necessary to consider the impact on the water quality protection of the discharge water area and agricultural water, and recently, not only organic pollutants but also such salts There is an increasing need to remove them together from wastewater. Since the conventional methods of purifying organic wastewater are mainly intended to remove organic pollutants therein, there is no effect of removing salts, and the salt concentration of the treated water is almost the same as that of the influent raw water. It has become about.

A treatment method for removing salts from an aqueous phase containing salts is a well-known technique per se, and examples thereof include a reverse osmosis method, an electrodialysis method, and an evaporation method. In the case of the reverse osmosis method, there is a disadvantage that the efficiency depends on the salt concentration of the salt water. When the concentration of saline water is high, the recovery rate of demineralized water is low. For example, 3.5 wt% NaC
When desalting an aqueous solution, the processing pressure is 60 kgf /
The water recovery rate is at most 35-40% in cm ² . To achieve a water recovery of 50% or more, the operating pressure should be 70
It must be at least kgf / cm ² . However, such a pressure not only increases the processing cost, but also has a limit in consideration of the life of the reverse osmosis treatment apparatus and the like. Further, when the salt water contains calcium ions at a high concentration, there is a risk that calcium scale is deposited on the surface of the semipermeable membrane. Even when the salt concentration is relatively low, the amount of permeated water decreases due to the precipitation of calcium scale on the surface of the semipermeable membrane, and it becomes difficult to treat the treated water at a high recovery rate.

[0005] In the electrodialysis method, basically, a high water recovery rate can be obtained. However, if the water to be electrodialyzed contains calcium ions at a high concentration, calcium scale precipitates in the apparatus. In particular, in the electrodialysis method, calcium scale is easily generated due to a change in pH caused by the movement of hydrogen ions from the anode and hydroxyl ions from the cathode. As with the case of the reverse osmosis method, a high water recovery rate cannot be obtained if calcium scale is precipitated. In addition, since organic matter such as COD cannot be removed by this method, it is necessary to remove organic matter by another treatment method such as an activated carbon treatment method in order to obtain high quality treated water. Further, since the evaporation method involves a phase change of the system, there is a problem that the required energy is large and the processing cost is greatly increased. Furthermore, if the wastewater contains volatile organic substances, ammoniacal nitrogen (NH ₄ —N), etc., these may be mixed into the treated water, and there is a problem that it is difficult to obtain high-quality treated water.

Furthermore, metals, especially heavy metals, cannot be effectively removed by any of the above-mentioned softening treatment, biological treatment, coagulation treatment, sand filtration treatment, and microfiltration membrane treatment. Selective and complex formation with metal ions in water must be achieved by chelating resin adsorption, otherwise heavy metals will be contained in the recovered salt concentrated by reverse osmosis membrane treatment or electroosmosis treatment There were also problems.

[0007] The present invention has been made in view of such a conventional problem, and is intended to treat an organic wastewater containing a high concentration of salts so that the wastewater can be reused or discharged directly to a river or the like. When efficiently purifying, it is possible to not only sufficiently remove the organic components, but also sufficiently remove the salts, and at the time of the treatment, without causing a problem that the treatment effect such as precipitation of calcium scale is reduced. It is an object of the present invention to provide a method that can purify and obtain a treated water having a low salt concentration and containing no heavy metal with high efficiency and can also recycle recovered salt.

[0008]

As described above, chelating resins are widely used as the most advanced tertiary treatment technology in the field of treating wastewater containing heavy metals. The present inventors studied a combination of such heavy metal adsorption technology and various separation technologies used in a conventional method for treating organic wastewater containing high concentrations of salts, and studied reverse osmosis membrane and electrodialysis. By arranging the heavy metal adsorption means before or after the membrane separation means using a membrane, it has been found that heavy metals can be effectively adsorbed and separated, and the present invention has been completed.

That is, the present invention has solved the above-mentioned problems by the following method and apparatus for treating organic wastewater. (1) After softening the organic wastewater containing a high concentration of salts to reduce the calcium concentration therein, the wastewater is selected from the group consisting of biological treatment, coagulation treatment, sand filtration treatment, and microfiltration membrane treatment. A treatment comprising one or more treatments or a combination of two or more treatments is carried out, and then a desalination treatment is carried out by a reverse osmosis membrane and / or an electrodialysis membrane. In the method for treating organic wastewater that is recovered as a solid matter, a heavy metal removal treatment is performed before or after the desalination treatment is performed by a reverse osmosis membrane and / or an electrodialysis membrane to remove heavy metals. A method for treating organic wastewater containing a high concentration of salts, wherein the salt-free material is recovered as a solid. (2) The method for treating organic wastewater containing high-concentration salts according to the above (1), wherein the treatment for removing heavy metals is an adsorption treatment using a chelate resin.

(3) In a wastewater treatment apparatus for treating organic wastewater containing high concentrations of salts and recovering salts containing no heavy metals as solids, a treated water inflow pipe 1 for supplying organic wastewater is connected. A softening treatment device 2, a biological treatment device 3 on the discharge side thereof, a coagulation microfiltration device 4, a heavy metal removal device 5, and a reverse osmosis treatment device 6 provided with a reverse osmosis treatment permeated water drainage pipe 7 on the discharge side. An electrodialysis treatment apparatus 8 provided with an electrodialysis desalination treatment water return pipe 9 to a reverse osmosis treatment apparatus 6 on the concentrated water discharge side, and a solid matter containing no heavy metal on the concentrated water discharge side. Evaporative drying treatment equipment 1
A wastewater treatment apparatus for recovering salt, which is characterized by comprising: (4) A treated water inflow pipe 11 for supplying organic wastewater in a wastewater treatment apparatus that treats organic wastewater containing high concentrations of salts and recovers salts containing no heavy metals as solids.
, A biological treatment device 13 on the discharge side thereof, a coagulation microfiltration device 14, and a reverse osmosis treatment permeated water drainage pipe 16 on the discharge side.
5 and an electrodialysis treatment apparatus 1 provided with an electrodialysis desalination treatment water return pipe 18 to a reverse osmosis treatment apparatus 15 on the concentrated water discharge side.
Wastewater treatment for recovering salt, characterized by comprising a heavy metal removal device 19 on the discharge side of the concentrated water, and an evaporative drying treatment device 20 for converting heavy metal-free salt into solids. apparatus.

[0011]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an embodiment of a treatment apparatus for performing the wastewater treatment method of claim 1 according to the present invention. The organic wastewater treatment apparatus shown in FIG. 1 is provided with a softening treatment apparatus 2 connected to a treated water inflow pipe 1 for supplying the organic wastewater, a biological treatment apparatus 3 on the discharge side, and a coagulation microfiltration apparatus 4 ( In the figure, “Aggregation MF filtration device 4” is provided). Coagulation microfiltration device 4
Is a device that adds an inorganic coagulant or the like to biologically treated water discharged from or inside the biological treatment device 3 and filters water generated as an aggregate through a microfiltration membrane (MF membrane). The outlet of the filtration water pipe of the coagulation microfiltration device 4 is connected to a chelate resin tower which is a heavy metal removing device 5, and the outlet of the water pipe of the treatment is open to the reverse osmosis treatment device 6.

From the reverse osmosis treatment apparatus 6, a reverse osmosis concentrated water pipe and a reverse osmosis treated permeated water drain pipe 7 are separately provided. The reverse osmosis concentrated water piping from the reverse osmosis treatment device 6 extends to the electrodialysis treatment device 8. The electrodialysis treatment device 8 further includes an electrodialysis concentrated water pipe and an electrodialysis desalination water return tube separately extending from the electrodialysis treatment water return tube 9. The electrodialysis concentrated water pipe is connected to a pipe, which leads to the evaporative drying treatment apparatus 10.

FIG. 2 is a schematic diagram showing an embodiment of a treatment apparatus for performing the wastewater treatment method according to claim 4 of the present invention. The organic wastewater treatment apparatus shown in FIG.
The only difference is that the arrangement of the heavy metal removal device is reversed before and after the membrane separation treatment including the reverse osmosis treatment and the electrodialysis treatment. I do.

In the present invention, the organic wastewater to be treated can be treated even if it is not so high as an organic component. If the organic component enters the electrodialysis treatment, it has an adverse effect. So it can be removed in the reverse osmosis treatment. In addition, the salt concentration in the organic wastewater is not always intended to be a remarkably high concentration, but as described above, a concentration high enough to hinder the discharge, or a higher concentration. It is suitable for high concentration objects. The method for treating organic wastewater of the present invention may be implemented using such an apparatus, for example, as follows.
An organic wastewater containing salts at a high concentration is introduced into the softening treatment device 2 from the treated water inflow pipe 1 to perform a softening treatment. The softening treatment is performed, for example, by replacing a hard water component (a hardly soluble salt forming component) of calcium or magnesium in water with a readily soluble forming component such as sodium by a lime soda softening method or an ion exchange soft water softening method. Can be. By this softening treatment, generation of calcium scale in the reverse osmosis treatment device 6 or the electrodialysis treatment device 8 can be effectively prevented.

The wastewater from which calcium ions have been removed in this way is then subjected to a biological treatment device 3, a coagulation microfiltration device 4
To remove most of the organic pollutants. Examples of the biological treatment method performed by the biological treatment device 3 include, in addition to the standard activated sludge method, a biological digestion and denitrification method. By using these methods, BOD
Can be reduced. As a method of the coagulation microfiltration (coagulation MF membrane filtration) performed by the coagulation microfiltration device 4, specifically, as described above, a biologically treated water obtained by adding an inorganic coagulant and coagulating is filtered through a microfiltration membrane. To do that. By using such a method, turbid substances such as SS can be particularly removed from wastewater.

The wastewater subjected to the organic substance removal treatment is then guided to a heavy metal removal device 5, a reverse osmosis treatment device 6, and further to an electrodialysis treatment device 8, where salts are removed. The electrodialysis apparatus 8 can perform batch or continuous processing. Then, it is guided from the coagulation microfiltration device 4 to the heavy metal removing device 5 to remove heavy metals harmful to industrial salt and snow melting agent, and then guided to the reverse osmosis treatment device 6, where the reverse osmosis treatment is performed. In reverse osmosis treatment, 3Mp
A mechanical pressure equal to or higher than a is applied to separate the reverse osmosis concentrated water and the reverse osmosis treatment water, and the desalted reverse osmosis treatment water is discharged through the reverse osmosis treatment water pipe 7.

When this reverse osmosis treatment is carried out, high-concentration saline water having a high concentration of evaporation residue can be obtained as reverse osmosis concentrated water, and salts in wastewater can be concentrated.
Efficient. The reverse osmosis concentrated water is introduced from the reverse osmosis treatment device 6 to the electrodialysis treatment device 8.

Electrodialysis treatment (also called "ED treatment")
A large number of electrodialysis membranes are arranged, and reverse osmosis concentrated water is supplied to a concentration chamber and a dilution chamber which are alternately formed. This is for obtaining electrodialysis-treated water having a concentration. The electrodialysis treatment may be performed batchwise. When performed batchwise, the salt concentration ratio between the desalted low-concentration electrodialysis treatment and the electrodialysis concentrated water can be set to 150 or more, and the evaporation residue component concentration is 13% or more (130% or more).
000 mg / liter or more). Batch processing has higher desalination rate and processing efficiency than continuous processing. In this case, 99% or more of the salts are usually removed from the electrodialyzed desalted water separated from the electrodialysis concentrated water, and the salt concentration is reduced to 1000 mg / liter or less.

The electrodialysis-desalted water returns to the pipe to the reverse osmosis treatment device 6 through the electrodialysis-desalted water return pipe 9. If any organic matter remains, it is filtered by the reverse osmosis treatment device 6. The electrodialysis concentrated water is led from the electrodialysis concentrated water pipe to the evaporative drying treatment device 10 and is separated into water and salts by evaporative drying to isolate the salts. As described above, a high concentration reverse osmosis concentrated water can be recovered in a reduced volume. The electrodialysis treatment is then performed on such a reduced volume of the reverse osmosis retentate.

Therefore, the quantitative load of the electrodialysis treatment is not large, and the amount of water to be treated is further reduced in the subsequent evaporation and drying treatment. Evaporation drying treatment requiring a large amount of energy with a phase change can be performed efficiently, and the salt component can be easily isolated as a solid component. Electrodialysis desalted water of low concentration generated in the electrodialysis treatment is refluxed to the reverse osmosis treatment device 6, and the reverse osmosis treatment water is treated by the reverse osmosis treatment. Even if it remains, it hardly flows into the reverse osmosis treated water. In the above embodiment, a biological treatment method and a coagulation microfiltration membrane treatment method are employed for removing organic substances, but other methods are employed in practice if organic substances can be sufficiently removed. You may. For example, a coagulation sedimentation method or a sand filtration method may be employed. According to the coagulation-sedimentation method, chromaticity and SS are removed, and COD can be reduced. According to the sand filtration method, turbid substances such as SS can be removed. Although FIG. 1 shows the case where both the reverse osmosis treatment device 6 and the electrodialysis treatment device 8 are provided, the concentration of organic matter is low before the reverse osmosis treatment device 6 or the electrodialysis treatment device If it is not necessary to use both devices together because the salt concentration is not too high in the stage prior to step 8, only one may be used.

In the above description, the process shown in FIG. 1 has been described in detail. However, the process shown in FIG.
Since the location of the heavy metal removal device is only before or after the membrane separation process, the detailed description thereof will not be repeated.

Next, as described above, the present invention aims not only to obtain treated water having a low salt concentration with high efficiency but also to recycle recovered salt, and This will be described in detail below. Industrial salt and snow melting agents can be used for the reuse of the recovered salt. At that time, if a heavy metal is contained, the heavy metal is a harmful substance and cannot be reused as it is. Therefore, removal of heavy metals has become an indispensable problem.

By the way, the characteristics of the chelate resin are that it has high selective capturing performance for specific metals including heavy metals, and that it exhibits good capturing performance even from a low concentration solution. Thus, in the method for treating organic wastewater containing high concentrations of salts, if the water to be treated is pretreated, concentrated by reverse osmosis treatment, electrodialysis treatment, and further solidified by evaporative drying treatment, A trace amount of heavy metal contained in the solid is contained in the solid, and it is difficult to reuse the solid. For this reason, the heavy metal-free salt is obtained as a solid by removing the heavy metal and performing concentration by adsorption treatment with a chelating resin or the like before the salt is concentrated. Further, after concentration by reverse osmosis treatment and electrodialysis treatment, heavy metal is removed by evaporative drying after removing heavy metals by adsorption treatment with a chelating resin before evaporative drying, etc., so that heavy metal-free salts can be obtained as solids. That is, in the present invention, by utilizing the above-mentioned characteristics of the chelate resin, heavy metal removal of the recovered salt was achieved, and the solid recovered solid was successfully reused.

As a method for removing heavy metals with a chelate resin, an adsorption treatment in a chelate resin tower and a coagulation-sedimentation treatment with a liquid chelate resin can be considered. It is known that the concentrations (mg / liter) at which various metals can be removed by the chelating resin are as follows. Kind of metal Concentration Fe <0.1 Mn <0.1 Zn <0.1 Cu <0.05 T-Cr <0.1 Pb <0.1 Cd <0.05

As the industrial salt for use of the recovered salt solids, in addition to the use in the soda industry, porpoise of ceramics,
Applications include salting out soap and cryogens. The recovered salt used in the soda industry is required to have high purity as NaCl. The target composition value of the industrial salt is shown as follows (content is expressed in mg / kg). Composition Component Content Na 378,000-389,000 K 100-300 Ca 200-1200 Mg 100-500 Cl 586,000-599,000 SO ₄ 1,000-3,200

[0026]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited by these Examples.

Example 1 Organic wastewater containing high concentrations of salts was treated using the organic wastewater treatment apparatus shown in FIG. That is, the wastewater discharged from the landfill was treated and the contained soluble substances were separated as solids. Each component analysis of the treated water ("heavy metal treated water") after adsorption in the chelate resin tower as the heavy metal treatment device and the solid after the evaporation and drying treatment was performed. Table 1 shows the measurement results. From the results in Table 1, copper, chromium, lead,
It can be seen that the content of heavy metals such as cadmium and zinc is reduced, and the recovered salt can be reused as an industrial salt.

[0028]

[Table 1]

COMPARATIVE EXAMPLE 1 In the treatment apparatus shown in FIG. 1, wastewater discharged from a landfill was treated without passing through a chelating resin tower, and contained dissolved biomaterials were separated as solids. Table 2 shows the concentrations of the components in the solid. According to Table 2, compared to Example 1,
It is understood that the content of heavy metals such as copper, chromium, lead, and zinc is large, and it is difficult to reuse the recovered salt as an industrial salt.

[0030]

[Table 2]

Example 2 Using the organic waste water treatment apparatus shown in FIG. 2, the same waste landfill leach wastewater as in Example 1 was treated, and the contained soluble substances were separated as solids. The components of the treated water after adsorption in the chelate resin tower ("heavy metal-treated water") and the solid matter after the evaporation and drying treatment were analyzed. Table 3 shows the measurement results. From the results in Table 3, it is understood that the content of the heavy metal is reduced as in Example 1, and the recovered salt can be reused as an industrial salt.

[0032]

[Table 3]

[0033]

According to the present invention, the organic wastewater containing high-concentration salts is subjected to a softening treatment to lower the concentration of dissolved calcium beforehand, to remove organic substances, and then to a reverse osmosis treatment, and / or to electrodialysis. Performing treatment and desalination,
In recovering salts as solids by evaporating the reverse osmosis membrane concentrated water or electrodialysis concentrated water to dryness, performing a heavy metal removal treatment before or after the desalination treatment has a very low heavy metal content. A recovered salt can be obtained and reused as a raw material for an industrial salt. In particular, when the reverse osmosis treatment and the electrodialysis treatment are combined, high efficiency is obtained in both treatments, and the salt can be effectively recovered. Since the reverse osmosis treatment water is collected by the reverse osmosis treatment, even if an organic component is contained, it is removed by filtration, and there is almost no leakage into the treated water. In addition, since the softening treatment is performed, there is no trouble of calcium scale precipitation in the treatment using both membranes. According to this method, organic wastewater containing a high concentration of salts is efficiently desalinated and reused. It can be discharged directly to dripping or rivers.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an organic wastewater treatment apparatus of the present invention in which a heavy metal removal apparatus is provided in front of a reverse osmosis treatment apparatus.

FIG. 2 is a schematic diagram of an organic wastewater treatment apparatus of the present invention in which a heavy metal removal apparatus is provided after an electrodialysis treatment apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inflow pipe of treated water 2 Softening equipment 3 Biological treatment equipment 4 Coagulation precision membrane filtration equipment 5 Heavy metal removal equipment 6 Reverse osmosis treatment equipment 7 Reverse osmosis treatment permeate drainage pipe 8 Electrodialysis treatment equipment 9 Electrodialysis desalination treatment water return pipe DESCRIPTION OF SYMBOLS 10 Evaporation drying processing apparatus 11 Inflow pipe of treated water 12 Softening processing apparatus 13 Biological processing apparatus 14 Coagulation precision membrane filtration apparatus 15 Reverse osmosis processing apparatus 16 Reverse osmosis processing permeated water drain pipe 17 Electrodialysis processing apparatus 18 Electrodialysis desalination processing water return Pipe 19 Heavy metal removal device 20 Evaporation drying treatment device

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 9/00 502 C02F 9/00 502F 502G 502J 502L 502P 502Z 504 504A 504E 1/04 1/04 D 1 / 42 1/42 H 1/44 1/44 F 1/469 5/00 610C 5/00 610 1/46 103 F term (reference) 4D006 GA05 GA07 GA17 JA71 KA01 KA03 KA53 KA72 KB11 KB12 KB14 KB21 KB30 KD08 KD17 PA01 PA02 PB08 PC61 PC80 4D025 AA09 AA10 AB18 AB21 AB22 AB23 AB25 AB28 BA17 BB01 DA02 DA05 DA06 DA10 4D034 AA16 AA26 BA01 CA12 4D061 DA08 DA10 DB13 EA09 EB02 EB12 FA02 FA06 FA08 FA09 FA13 FA14 FA15

Claims (4)

[Claims] 1. An organic wastewater containing a high concentration of salts is subjected to a softening treatment to reduce the calcium concentration therein, and then a biological treatment, a coagulation treatment, a sand filtration treatment, and a precision membrane filtration treatment are performed. A treatment consisting of one or more treatments or a combination of two or more treatments is performed, and then a desalination treatment is performed with a reverse osmosis membrane and / or an electrodialysis membrane, and the remaining reverse osmosis membrane concentrate or electrodialysis membrane concentrate is evaporated. In a method for treating organic wastewater that is dried and recovered as a solid, before performing a desalination treatment with a reverse osmosis membrane and / or an electrodialysis membrane, or performing a heavy metal removal treatment after the desalination treatment, A method for treating organic wastewater containing high concentrations of salts, wherein the salt containing no heavy metal is recovered as a solid. 2. The method for treating organic wastewater containing high-concentration salts according to claim 1, wherein the treatment for removing heavy metals is an adsorption treatment using a chelating resin. 3. A wastewater treatment apparatus for treating an organic wastewater containing a high concentration of salts and recovering salts containing no heavy metals as solids, wherein a softened water connected to a treated water inflow pipe 1 for supplying the organic wastewater. Treatment device 2, biological treatment device 3 on the discharge side, then coagulation precision membrane filtration device 4, and heavy metal removal device 5, and reverse osmosis treatment permeated water drainage pipe 7 on the discharge side
A reverse osmosis treatment device 6 provided with a dialysis treatment device, an electrodialysis treatment device 8 provided with an electrodialysis desalination treatment water return pipe 9 to the reverse osmosis treatment device 6 on the concentrated water discharge side, and heavy metals on the concentrated water discharge side Evaporative drying treatment apparatus 10 for converting salt not containing into solid matter
A wastewater treatment apparatus for recovering salt content, comprising: 4. A wastewater treatment apparatus for treating organic wastewater containing high-concentration salts and recovering heavy metal-free salts as solid matter, wherein a treated water inflow pipe 11 for supplying organic wastewater is connected. A treatment device 12, a biological treatment device 13 on the discharge side thereof, a coagulation precision membrane filtration device 14, a reverse osmosis treatment device 15 provided with a reverse osmosis treatment permeated water drainage pipe 16 on the discharge side thereof, and a concentrated water discharge side thereof. Reverse osmosis treatment equipment 1
5, an electrodialysis treatment device 17 provided with an electrodialysis desalination treatment water return pipe 18 to the heavy metal removal device 1
9. A wastewater treatment device for recovering salt, further comprising an evaporative drying treatment device 20 for converting salt that does not contain heavy metals into a solid substance.