JPH1080688A - Demineralizing treatment of processed water exuded from filled-up land and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance efficiency and stabilization of demineralization processing cost at economical site by maintaining consumption of fuel for drying per unit quantity of salt at almost definite estimated value even when salt concentration in water exuded from a filled-up land is lower than a set value or exuded water quantity is lower than a set value. SOLUTION: A demineralization processing device is constituted by providing a storage water tank 11 of exuded water, a demineralization concentration device 21 which executes demineralization and concentration of the exuded water A supplied from the storage water tank 11 and discharges demineralization processed water B, a heating-drying device 51 which recovers salt by drying and solidifying a salt enriched liquid C2 subjected to demineralization and concentration by the demineralization concentration device 21 and a system control device 31 which sets salt concentration at exit of the demineralization concentration device 21 to a salt concentration of the salt concentrated liquid C2 to be dried and solidified by the heating-drying device 51 and circulates a salt concentrated liquid C1 to the storage water tank 11 via a circulating means 41 until salt concentration in the salt concentrated liquid C2 reaches a set value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a desalination treatment of treated water (leached water treated water) which has been treated to remove components other than salt from the landfill leachate as required so as to meet the discharge standard. More specifically, the present invention relates to a method and an apparatus for discharging treated water of leachate generated in a landfill filled with waste and / or incinerated ash into a waterway, particularly an agricultural waterway to be used as a part of agricultural water. By desalinating this treated leachate into salt-free treated water, the effects on agricultural crops are avoided, and at the same time, the local residents around the selected landfill are asked for sufficient understanding to secure land. The present invention relates to an improvement in a method and an apparatus for desalination treatment of a treated landfill leachate, which is also effectively applied for use.

[0002]

2. Description of the Related Art Conventionally, various kinds of waste generated in connection with life and industry are separated into non-flammable and twistable types according to their types. In general, methods such as incineration of flammable waste that have been landfilled after the collection of valuable resources, and inflammable waste have been taken. As an effective means for finally disposing of waste residues (hereinafter collectively referred to as waste residues), landfills with waste residues at a final disposal site using fallow land or a hybrid land equivalent thereto are performed.

In the case where the waste residue is landfilled at a landfill site as a final disposal site as described above, water leached from the landfill along with infiltration of rainwater or the like, that is, so-called leachate, is subjected to environmental destruction. It must be considered that the water can be released in some way so as not to invite water. BOD,
Although COD, heavy metals, etc. are treated according to the discharge standard, there is no regulation on salt content.
In other words, when the landfill is, for example, close to agricultural land or the like, the treated water must be discharged to the agricultural land or the agricultural irrigation canal, and this leachate is discharged to the agricultural irrigation canal. However, this is a major problem from the standpoint of impact on the cultivation of crops and environmental conservation.

[0004] Therefore, conventionally, salt contained in the treated leachate from the above-mentioned landfill is desalinated, converted into desalinated water with reduced salt, and discharged into an agricultural waterway to reduce the influence on agricultural crops. In addition to avoiding them altogether, from the other side, in order to help secure and conserve the landfill, the local residents around the landfill should be able to show with sufficient persuasion that the results after landfilling are harmless. Is what it is.

[0005] The prior art for desalination treatment includes similar general means which can be used for desalination treatment of the present leachate treatment water, for example, electrodialysis applied to the production of sodium chloride (sodium chloride). Equipment utilizing the method. This salt production technology is a system in which the sodium chloride component in seawater is desalted and concentrated by electrodialysis, and then the concentrated solution is evaporated and dried to solidify the salt. , Usually
Seawater having a substantially constant concentration of dissolved sodium chloride is used as a raw material for production (desalting raw material), and a design value corresponding to a desalinable salt concentration is set for the equipment and the design value is set in advance. A corresponding amount of seawater is supplied to a desalination / concentration device, and the seawater is once desalinated and concentrated to near the limit of desalination, and seawater having a reduced salt concentration as a result of the desalination is removed. The unnecessary wastewater thus treated is optionally discharged and treated, and the concentrated liquid, that is, the entire amount of the salt concentrated liquid is supplied to a heating / drying apparatus and evaporated to dryness. The sodium chloride component is solidified to obtain salt, and a vacuum evaporator or a drum dryer is used as the heating and drying device at this time.

[0006]

In the conventional general salt production system, as described above, seawater in which the concentration of dissolved sodium chloride is substantially constant is used as the desalted raw water, and the amount of the salt is always supplied to the apparatus side sequentially. In this case, the target salt can be obtained at an economically appropriate production cost.

On the other hand, treated leachate from landfills usually has a constant fluctuation in the amount of leachate and salt concentration depending on the amount of salt contained in the landfill, the amount of rainfall, and the like. For example, in many cases, the concentration of the salt dissolved in the water is lower than the design value set in the above-described conventional salt production facility.

[0008] Therefore, unlike the conventional salt production system in which the salt water is produced by desalinating the water to be treated (in this case, seawater) containing salt, which is the original function, in a device form as it is, the salt is produced. If the water to be treated (treated water treated with leachate in this case) containing salt in the present invention is diverted to obtain treated water from which salt has been removed by desalination, the following problems will occur. (A) In many cases, leachate treated water having a salt concentration substantially lower than the design value of the equipment is desalinated and then evaporated to dryness. Fuel consumption increases. (b) Even if the amount of the leachate treatment water is smaller than the design value of the device, the heating and drying device must be operated, and as a result, the drying fuel is always consumed as much as the design value. Etc. respectively.

The present invention has been made to solve such a conventional problem, and its object is to provide:
Even when the salt concentration of the leachate from the landfill is lower than the set value or when the amount of leachate is lower than the set value, the consumption of the drying fuel per unit of salt is maintained at almost the expected value. It is an object of the present invention to provide a method and an apparatus for desalinating treated water from a landfill leachate in which the desalination treatment cost is made more efficient and more stable in terms of economy.

[0010]

In order to achieve the above object, a method and an apparatus for desalination of treated leachate in a landfill according to the present invention are provided with a desalination and concentration treatment of treated leachate to remove salt content. And the salt concentration at the treatment outlet side of the desalting and concentration means is set to the salt concentration of the salt concentrate to be evaporated to dryness by heating and drying means. The leachate treated water to be supplied to the salt concentrating means and desalted and concentrated is refluxed until the salt concentration set value of the salt concentrate is reached.
Here, salts containing various impurities (hereinafter simply referred to as “salts”) dissolved in the leachate treatment water are finally evaporated to dryness and collected.

That is, the invention according to claim 1 of the present invention is characterized in that treated leachate containing salt from a landfill is treated by a desalting and concentrating means to obtain desalted treated water that can be discharged. A method for recovering salts by evaporating the concentrated salt concentrate to dryness by heating and drying means, wherein the salt concentration at the treatment outlet side of the desalting and concentration means is evaporated to dryness by the heating and drying means. The salt concentration is set to a predetermined value, and the leachate treated water to be supplied to the desalting / concentrating means and subjected to desalting / concentration is supplied to the inlet of the desalting / concentrating means until the salt concentration of the salt concentrate reaches the set value. A method for desalinating treated water from a landfill leachate, characterized in that the wastewater is returned to the side to continue the desalination treatment.

Therefore, according to the first aspect of the present invention, the leachate treated water supplied to the desalination and concentration means for desalination and concentration treatment can be sequentially discharged as desalinated treated water, and at the same time, the leachate is treated. When the salt concentration of the water treatment water is lower than the salt concentration set value set in the desalination concentration means, the desalination concentration treatment for the leachate treatment water is repeated until the salt concentration set value of the desalination concentration means is reached. As a result, the salt concentration of the salt concentrate after the desalting and concentration treatment is controlled to be substantially constant, and as a result, the consumption of the drying fuel required for evaporating and drying the salt concentrate with the heating and drying means is reduced. It is maintained at a substantially constant set value.

[0013] The invention according to claim 2 of the present invention is characterized in that treated leachate treated water containing salt from a landfill is treated by a desalting and concentrating means to obtain desalted and dischargeable demineralized water and to concentrate the treated water. In the apparatus for recovering the salt by evaporating the salt concentrated liquid by heating and drying to dryness, the storage tank for the leachate treated water,
Desalting and treating the leachate treated water supplied from the storage water tank,
A desalting / concentrating apparatus for discharging desalinated water, a heating / drying apparatus for evaporating and drying the concentrated salt solution that has been desalinated and concentrated by the desalting / concentrating apparatus, and a salinity concentration at the outlet of the desalting / concentrating apparatus. The salt concentration is set to the salt concentration of the salt concentrate to be evaporated to dryness by the heating and drying device, and the salt concentrate is returned to the storage tank via a reflux unit until the salt concentration of the salt concentrate reaches the set value. A desalination treatment device for treating treated landfill leachate, comprising a control device for refluxing.

According to a third aspect of the present invention, in the desalination treatment apparatus for treated landfill leachate of the second aspect, the reflux means substantially comprises the control device and the storage tank. It is characterized in that it is a circulating conduit for communication.

According to a fourth aspect of the present invention, in the desalination treatment apparatus for treated landfill leachate according to the second aspect, the desalination and concentration apparatus uses a desalination and concentration method by electrodialysis. It is characterized by having been.

According to a fifth aspect of the present invention, there is provided the desalination treatment apparatus for treated landfill leachate according to the second aspect, wherein the drying apparatus is a batch-type heat evaporation type centrifugal thin film drying apparatus. It is characterized by being used.

Therefore, claim 2 and claims 3 to 5
In the apparatus invention, the treated leachate supplied from the storage water tank is desalinated and concentrated by the desalination / concentration device, and then can be discharged as treated water which is sequentially desalinated. If the salt concentration is lower than the set value of the salt concentration set in the desalination / concentration means, the control is performed until the desalination / concentration treatment for the treated leachate reaches the salt concentration set value of the desalination / concentration means. The salt concentration of the salt concentrate after the desalting and concentration treatment is controlled to be substantially constant by repeating the circulation treatment through the reflux means by the device, and as a result, the evaporation of the salt concentrate by the heating and drying means is performed. The consumption of the drying fuel required for drying is maintained at a substantially constant set value.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of a method and an apparatus for desalinating treated landfill leachate according to the present invention will be described.
This will be described in detail with reference to FIGS.

FIG. 1 shows a whole system of a desalination treatment water for leachate treated water in which a desalination concentration device and a heating / drying device by an electrodialysis method to which the present embodiment is applied are incorporated and controllable by a system controller. FIG. 2 is a block diagram showing an outline, and FIG. 2 is a circuit configuration diagram schematically illustrating an example of a system control device according to the first embodiment. FIG. It is sectional explanatory drawing which shows a schematic structure typically.

In the apparatus configuration shown in FIG. 1, the desalination system for leachate treated water according to this embodiment includes a storage tank 11 for receiving and temporarily storing leachate treated water A from a landfill (not shown). A desalination / concentration apparatus 21 by electrodialysis, which demineralizes and concentrates leachate-treated water A supplied from the storage water tank 11 and discharges desalinated deionized water B
And whether the salt concentration of the salt concentrate concentrated by the desalting / concentrating apparatus 21 is equal to or less than a salt concentration set value described below (salt concentrate C1) or within the range (salt concentrate C2). A system controller 31 for detecting and controlling the apparatus, and, when the salt concentration of the salt concentrate is below the range of the salt concentration set value (salt concentrate C1), the salt concentrate C1 is stored again. By refluxing in the water tank 11, the salt concentrate C
And a recirculation means 41 for re-concentrating until the salt concentration reaches 2, and a salt concentrate C2 supplied from the desalting / concentrating apparatus 21 via the system controller 31 is evaporated to dryness to solidify the salt content. In this case, the salt concentration set value is set to such a level that the drying performance of the heating and drying device 51 with respect to the salt concentrate C2 can be effectively utilized. I do.

The storage tank 11 receives the treated leachate A containing salt through the collecting pipe 12, temporarily stores the leachate A, and removes the stored treated leachate A through the supply pipe 13. It is supplied to the salt concentrator 21. In the storage tank 11, since the leachate treated water A having a flow rate corresponding to the amount of leachate from the landfill is constantly stored, the water level is not always constant. The supply amount of the leachate treatment water A to the desalination / concentration device 21 is also the supply water amount corresponding to the water level difference and, consequently, the water pressure difference.

Here, in order to keep the dialysis load in the desalting / concentrating apparatus 21 constant and steady, etc., the leachate treated water A is used.
When it is necessary to quantitatively or substantially quantify the amount of supplied water, for example, the diameter of the water tank itself in the storage water tank 11 may be widened to reduce the influence of the water level difference, or the amount of water supplied to the supply line 13 may be reduced. It suffices to take measures such as forced supply through a feed pump.

The desalting / concentrating apparatus 21 may be of a construction employing a known desalting / concentrating method by electrodialysis, and is a treatment for leachate containing salt supplied or quantitatively supplied from the supply line 13. As is well known, the water A is desalinated and concentrated through a dialysis membrane built in the present desalination and concentration device 21, and the treated water B, which has been subjected to desalination treatment to remove salt, is discharged from a discharge line. From 22, water is discharged as it is into an agricultural waterway (not shown).

On the other hand, in the case of the salt concentrate in which the salt is concentrated, if the salt concentration of the supplied leachate treatment water A is within the above-mentioned set value of the salt concentration, the salt concentration corresponding to the set salt concentration is set. The salt concentrate C1 is discharged from the concentration outlet line 23 as a salt concentrate C2 having a concentration lower than the set salt concentration if the concentration is below the range. As described above, the treated leachate A treated in the present embodiment has a relatively low salt concentration. Therefore, in the desalination and concentration by dialysis about once, the leachate treated water A is still higher than the set salt concentration. In most cases, the concentration of the concentrated salt solution is low.

As shown in FIG. 2 as an example, the system controller 31 is located at the upstream side of the concentration outlet pipe 23, and constantly detects the salt concentration and the flow rate of the salt concentrate to obtain the concentration. Detection value signal S1 and flow detection value signal S2
Is provided on the downstream side, and a three-way switching valve 33 is interposed in each of them. From the three-way switching valve 33, a salt concentrate C2 within the range of the salt concentration set value is detected. A liquid supply line 34 for supplying liquid to the heating and drying device 51 of the stage, and a liquid supply amount variable pump as the reflux means 41 used for refluxing the salt concentrate C1 below the range to the storage water tank 11 of the foremost stage Reflux line 4 including 43
In the normal switching mode, the three-way switching valve 33 connects the concentration outlet line 23 to the reflux line 42 side.

The system controller 31 includes an operation controller 3 using an arithmetic device such as a microcomputer.
The operation controller 35 includes a salt concentration setting circuit 3
6 and a concentration comparing circuit 37 and a pump driving circuit 38 are provided. Here, the above-mentioned salinity concentration setting value is externally set to the salinity concentration setting circuit 36, and the salinity concentration setting value set in the salinity concentration setting circuit 36 is set to the concentration in the concentration comparing circuit 37. Compared with the density detection value signal S1 input from the detector 32, when the density detection value signal S1 is below the range of the salt concentration set value,
That is, when the salt concentrate C1 is detected, the discharge amount variable operation signal S3 of the variable liquid supply amount pump 36 is output to the pump drive circuit 38, and when it is within the range of the salt concentration set value, that is, when the salt concentration is within the range. When the concentrated liquid C2 is detected, a valve switching operation signal S4 is output to the three-way switching valve 33. The pump drive circuit 38 is responsive to the flow rate detection value signal S2 input from the concentration detector 32 on condition that the discharge amount variable operation signal S3 from the density comparison circuit 37 is input. Is variably adjusted.

As described above, in the concentration detector 32,
The three-way switching valve 33 connects the concentration outlet line 23 to the feed line 3
In the state of being blocked on the 4 side and communicating with the reflux line 42 side, the salt concentration (corresponding to either the salt concentration of the salt concentrate C1 or C2) of the salt concentrate concentrated by the desalination concentrator 21 is shown. The flow rates (similarly, corresponding to the flow rates of the salt concentrates C1 and C2) are respectively detected, and the detected concentration signal S1 and the detected flow rate signal S2 are output. Depending on the output, the operation controller 35
Works as follows.

(1) The salt concentration value of the concentration detection value signal S1 detected and output by the concentration detector 32 is below the range of the salinity concentration set value, and substantially the concentration detection value signal S1 When C1 applies. The concentration comparing circuit 37 compares the inputted detected concentration signal S1 with the set value of the salt concentration of the salt concentration setting circuit 36, and when the values do not match, this state is regarded as that in which the salt concentrate C1 is detected. Judgment is made and the discharge amount variable operation signal S3 is output, and the valve switching operation signal S4 is not output. For this reason, the three-way switching valve 33 is maintained in a normal state in which the concentration outlet pipe 23 and the reflux pipe 42 are communicated. On the other hand, in the pump drive circuit 38 to which the flow rate detection value signal S2 is input, the operation is started by the simultaneously input discharge amount variable operation signal S3, and the calculation is performed based on the detected flow rate calculated based on the flow rate detection value signal S2. The discharge amount of the liquid supply amount variable pump 43 is automatically adjusted in accordance with the result and then driven, and while the concentration detection value signal S1 is determined to correspond to the salt concentrate C1, that is,
As long as the salt concentrate C1 is discharged, the whole amount is returned to the storage tank 11 through the reflux line 42, and the refluxed salt concentrate C1 is re-concentrated by the desalting / concentrating apparatus 21. It keeps circulating. In other words, in this case, until the concentration detection value signal S1 is determined to correspond to the salt concentrate C2, in other words, as the concentration treatment condition of the leachate treatment water A, the salt concentration set value is used. The process is repeated until the salt concentration reaches a level at which the specified drying performance of the heating and drying device 51 can be effectively utilized.

(2) The salt concentration value of the concentration detection value signal S1 detected and outputted by the concentration detector 32 is within the range of the salinity concentration set value, and the concentration detection value signal S1 is substantially equal to the salt concentration solution. If C2 applies. The density comparison circuit 37 compares the similarly detected density detection value signal S1 with the salinity concentration set value of the salinity concentration setting circuit 36, and when they match,
In this state, it is determined that the salt concentrate C2 has been detected, and the valve switching operation signal S4 is output without outputting the discharge amount variable operation signal S3. Thereby, the three-way switching valve 33
Is switched, and the concentration outlet line 23 is switched and connected from the reflux line 42 side to the liquid supply line 34 side. On the other hand, the pump drive circuit 38 to which the flow rate detection value signal S2 is input is not operated because the discharge amount variable operation signal S3 is not input. Accordingly, in this state, the entire amount of the salt concentrate C2 discharged from the concentration outlet line 23 is supplied to the heating / drying device 51 through the liquid supply line 34.

As the heating and drying device 51, for example, a batch type heating and evaporation type centrifugal thin film drying device can be used. FIG.
As shown in FIG. 3, a drying centrifugal impeller 5 rotationally driven by an electric motor 55 is provided at a central portion in a drying chamber 53 of an apparatus housing 52.
4 is provided, and is formed so as to surround a heating steam generation source, for example, a heating jacket 56 for supplying heating steam from a boiler 57 at the outer peripheral portion of the housing. Further, the salt concentrate C2 supplied through the liquid supply line 34
Is once stored in a salt concentrate tank 58 and then supplied into a drying chamber 53 by a salt concentrate pump 59. In addition,
In the drawing, reference numeral 60 denotes a recovery port for recovering the salt D obtained by evaporating the salt concentrate C2 to dryness, and 61 denotes a drain of the heating jacket 56.

Therefore, in the heating and drying apparatus 51, the inside of the drying chamber 53 is sufficiently heated according to the drying performance by the heating steam supplied from the boiler 57 through the heating jacket 56, and the salt is dried. With the concentrated liquid pump 59, the drying chamber 5
An appropriate amount of the salt concentrate C2 supplied into the tank 3 is scattered by the rotating centrifugal impeller 54 and is instantaneously evaporated to dryness. In this case, as described above,
Since the salt concentration of the salt concentrate C2 to be dried is set to such an extent that the drying performance of the apparatus itself can be effectively utilized, the consumption of the drying fuel is reduced and the set value is almost constant. The amount of treated leachate water A is small, and it is possible to effectively prevent meaningless fuel consumption together with the shutdown when the salt concentrate C2 of a certain amount or more is not stored and there is no waste. .

[0032]

[Experimental example 1] A desalination / concentration device in which two electrodialysis tanks each having 200 ion exchange membranes each having a length of 190 cm, a width of 30 cm and a thickness of 0.05 cm are arranged in series, and a batch-type heat evaporation type. Using a desalination facility composed of a centrifugal thin-film dryer and desalination of landfill leachate under the conventional method, the results were as follows. Leachate treatment water volume 30 T / day (chlorine ion concentration: 6000 ppm) Operating conditions of electrodialysis equipment First electrodialysis tank Applied current 24 A, Applied voltage 80 V Second electrodialysis tank Applied current 6 A, Applied voltage 80 V Desalination Treated water volume 27 T / day (chlorine ion concentration: 300 ppm) Concentrate water volume 3 T / day (chlorine ion: 6%) Heating fuel consumption 72 liters / day

[0033]

[Experimental example 2] When the above desalination equipment was operated according to the method of the present invention, the power consumption was hardly changed, and the fuel consumption for heating was 35 liters / day, less than half the amount. It has been confirmed that it will decrease sharply.

[0047]

As described above in detail in the embodiment, according to the present invention, the treated leachate containing salt from the landfill is desalted and concentrated, and the desalted treated water that can be discharged is desalted. When the salt is recovered by evaporating the concentrated salt concentrate to dryness and recovering the salt, the salt concentration of the leachate treated water to be desalinated and concentrated by the desalting and concentration means is adjusted by heating and drying by the heating and drying means. A predetermined salt concentration of the concentrated liquid, here, a salt concentration that is set so as to effectively utilize the drying performance of the heating and drying means,
The leachate treated water to be supplied to the desalting / concentrating means and desalted and concentrated is returned to the inlet side of the desalting / concentrating means until the salt concentration of the salt concentrate reaches the set value of the salt concentration to continue the desalting treatment. Therefore, the desalination and concentration treatment for the leachate treated water having a low salt concentration is generally repeated until the salt concentration set value of the desalination and concentration means is reached, whereby the salt concentration after the desalination and concentration treatment is performed. The salt concentration of the liquid can always be controlled to be almost constant. As a result, despite the relatively simple means, the consumption of the drying fuel required for evaporating and drying the salt concentrate by the heating and drying means is reduced. It has an excellent feature that it can save much.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the overall structure of a desalination treatment water desalination system in which a desalination concentration device and a heating / drying device by an electrodialysis method to which an embodiment of the present invention is applied are incorporated and controllable by a system controller. It is a block diagram showing an outline.

FIG. 2 is a circuit diagram schematically illustrating an example of the system control device.

FIG. 3 is an explanatory cross-sectional view schematically showing a schematic configuration of a batch-type heating-evaporation type centrifugal thin-film drying apparatus as the heating and drying apparatus.

[Explanation of symbols]

 A Leachate treated water B Treated water C1 Salt concentrate below the range of salinity set value C2 Salt concentrate within the range of salinity set value D Salt evaporated and dried 11 Storage tank 12 Consolidating line 13 Supply line 21 Desalting / concentrating apparatus by electrodialysis method 22 Drainage line 23 Concentration outlet line 31 System controller 32 Concentration detector 33 Three-way switching valve 34 Liquid supply line 35 Operation controller 36 Salt concentration setting circuit 37 Concentration comparison circuit 38 Pump Drive circuit 41 Reflux means 42 Reflux line 43 Liquid supply amount variable pump 51 Heating / drying device S1 Concentration detection value signal S2 Flow detection value signal S3 Discharge amount variable operation signal S4 Valve switching operation signal

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication C02F 1/04 C02F 1/04 C (72) Inventor Kiyoshi Narita 7-25 Nishigotanda, Shinagawa-ku, Tokyo ─19 Kyowa Kako Co., Ltd. (72) Inventor Hidenori Shibata 2-25-14 Kameido, Koto-ku, Tokyo Asahi Glass Co., Ltd. (72) Inventor Hiroshi Kobayashi 2-25-14 Kameido, Koto-ku, Tokyo Asahi Glass Co., Ltd.

Claims (5)

[Claims] 1. A treated leachate containing salt from a landfill is treated by desalting and concentrating means to obtain desalinated water, and the concentrated salt concentrate is evaporated to dryness by heating and drying means to recover salt. In the method, the salt concentration on the processing outlet side of the desalting / concentrating means is set to a predetermined salt concentration of the salt concentrated solution evaporated and dried by the heating / drying means, and then supplied to the desalting / concentrating means for desalination. Until the salt-concentrated leachate-treated water reaches the salt concentration set value of the salt concentrate, it is refluxed to the inlet side of the desalting / concentrating means to continue the desalting / concentrating process. Desalination method of landfill leachate. 2. A treated leachate containing salt from a landfill is treated by desalting and concentrating means to obtain demineralized water, and the concentrated salt concentrate is evaporated to dryness by means of heating and drying to recover salt. A desalination / concentration device for desalting and condensing leachate-treated water supplied from the storage water tank, and discharging the desalinated water; and desalination with the desalination / concentration device. A heating and drying device for evaporating the concentrated salt concentrate to dryness to recover salt, and a salt concentration at a processing outlet side of the desalting and concentration device, the salt concentration of the salt concentrate to be evaporated and dried by the heating and drying device. Landfill leaching, comprising: a control device for setting the salt concentration and returning the salt concentrate to the storage tank via a reflux means until the salt concentration of the salt concentrate reaches the set value. Desalination equipment for water treatment water. 3. The desalination treatment of landfill leachate according to claim 2, wherein the reflux means is a reflux pipe which substantially connects the control device and the storage tank. apparatus. 4. The desalination treatment device for treated landfill leachate according to claim 2, wherein the desalination concentration device uses a desalination concentration method by electrodialysis. 5. The desalination treatment device for treated landfill leachate according to claim 2, wherein a batch-type heat evaporation type centrifugal thin film drying device is used as the heating and drying device.