KR101778562B1 - Treating apparatus and method for ro concentrated waste water - Google Patents

Abstract

The present invention is to provide an apparatus and a method for treating RO concentrated wastewater which can effectively obtain fresh water from high concentration wastewater and also has a stable fresh water process. According to the present invention, the RO concentrated wastewater treating apparatus comprises: a positive osmotic filtration unit for supplying an induction solution having a concentration higher than that of wastewater, diluting and discharging the induction solution by osmotic pressure, and concentrating and discharging the wastewater; and an evaporation condensation unit connected to a lower end of the positive osmotic filtration unit, and evaporating and condensing the diluted induction solution to concentrate the induction solution again.

Description

TECHNICAL FIELD [0001] The present invention relates to a RO concentration wastewater treatment apparatus,

The present invention relates to an apparatus and a method for treating RO concentrated wastewater. More particularly, to an apparatus and method for treating RO concentrated wastewater using FO (Forward Osmosis) and mechanical vapor recompression (MVR).

BACKGROUND ART Generally, a reverse osmosis (RO) method is mainly used as a method of reusing steel wastewater. In this reverse osmosis system, ionic substances dissolved in water are almost eliminated, and pure water is passed through the reverse osmosis membrane to remove the ionic substances dissolved in the wastewater. In order to separate ionic substances and pure water from such raw water, a high pressure higher than osmotic pressure is required. This pressure is called reverse osmosis pressure, and seawater desalination requires a high pressure of about 50 to 70 bar. In order to provide such a reverse osmosis pressure, a desalination apparatus using a reverse osmosis method is provided with raw water supply means (high pressure pump or the like) for pressurizing the raw water. Since the high-pressure pump consuming a large amount of electric power is used as the raw water supply means, there is a disadvantage that considerable energy is consumed in the desalination of the wastewater.

In reverse osmotic desalination process, RO concentrated water is produced. The RO concentration water has a high COD (Chemical Oxygen Demand) and it must be purified and discharged once more.

As a conventional technique for treating wastewater of high concentration such as RO concentrated water, Japanese Patent No. 1319411 relates to an apparatus and method for FO / RO hybrid seawater desalination, wherein the secondary treated inflow sewage is supplied through a sewage supply line A first forward osmosis membrane module installed in the immersion tank to dilute seawater having a high concentration to be supplied as an induction solution due to a difference in concentration between the seawater and the inflow sewage supplied to the infiltration tank; A low pressure pump for supplying the diluted seawater to the reverse osmosis membrane module, a foul reducing means for reducing fouling occurring in the first osmosis membrane module, The dense concentrated water in the membrane module is supplied to the induction solution and the secondary treated sewage of the immersion bath in which the first fixed osmosis membrane module is immersed, That the seat comprises two forward osmosis membrane module. According to the present invention, there is provided a hybrid seawater desalination apparatus and method of a forward osmosis and a reverse osmosis, wherein a high concentration of seawater is diluted by non-dynamic force by the difference in the concentration of seawater as an induction solution, It is possible to reduce the power consumption of the reverse osmosis process, which consumes the most energy in the seawater desalination process.

In addition, the registered patent No. 1144316 relates to a device for treating a membrane-separated wastewater with a combined osmosis and reverse osmosis membrane, a device for controlling the membrane separation process for treating the wastewater and a control method, SS, nitrogen, phosphorus, E. coli, and dissolved contaminants contained in the wastewater can be treated first by the positive osmosis phenomenon by the osmotic pressure gradient of the supply water and the induction solution by installing the positive osmosis unit to be used, And a reverse osmosis combined type membrane separation and wastewater advanced treatment device capable of passing the diluted induction solution through a reverse osmosis unit and concentrating and reusing it, and a membrane separation process control device and a control method for the wastewater treatment.

Finally, Patent No. 1110341 discloses a cleansing osmosis desalination method and a cleansing osmosis desalination system using the cleansing osmosis desalination system, comprising the steps of: inputting a solution containing a salt and an induction solution having a higher concentration than a solution containing the salt into an osmotic chamber; In the osmotic chamber, a part of the fresh water contained in the solution containing the salt moves to the induction solution by the difference in concentration between the solution containing the salt and the induction solution, and the fresh water is mixed with the induction solution A positive osmosis step of producing a mixed solution; A fresh water separation step of distilling fresh water in a part of the mixed solution; And a step of preparing an inducing solution by mixing the remainder of the mixed solution and the mixed solution obtained through the desalting step to prepare an inductive solution and supplying the solution to the introducing step.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an apparatus and a method for treating RO concentrated wastewater which can effectively obtain fresh water from high concentration wastewater and is stable in desalination process.

In order to achieve the above object, the present invention provides a water purifying apparatus comprising: a positive osmosis filtration unit for supplying wastewater and an induction solution having a concentration higher than that of the wastewater, diluting the induction solution by osmotic pressure and discharging the wastewater; And an evaporation condenser connected to a rear end of the quasi-osmosis filtration unit for evaporating and condensing the diluted induction solution to concentrate the induction solution again; And a control unit.

Furthermore, it is preferable that the quasi-osmotic filtration unit includes a filtration membrane, and a region into which the wastewater flows and a region into which the induction solution flows are separated based on the membrane, and water in the wastewater moves toward the induction solution through the filtration membrane Do.

And an induction solution adjusting unit provided between the constant osmosis filtration unit and the evaporation condensation unit to adjust a flow rate of the concentrated induction solution supplied from the evaporation condensation unit to the osmosis filtration unit.

The induction solution adjusting unit increases the supply amount of the inducing solution when the induction solution of the purified osmosis filtration unit is lost or the concentration of the rust inhibitor is decreased. When the induction solution loss of the osmosis filtration unit is small or the rust- And the supply amount is reduced.

And a production water quality measuring unit provided at a downstream end of the evaporation condensing unit for measuring a quality of final production water produced after the evaporation and condensation process of the evaporation condensation unit.

The production water quality measuring unit measures the quality of the produced water through the TDS and increases the inflow amount of the wastewater flowing into the purified osmosis filtration unit when the quality of the produced water is higher than the reference value, It is possible to reduce the inflow amount of wastewater flowing into the osmotic filtration unit.

And a concentrated water quality measuring unit provided at a downstream end of the purified osmotic filtration unit for measuring the quality of the concentrated water discharged after being concentrated in the filtration process of the purified osmosis filtration unit.

Furthermore, the concentrated water quality measuring unit measures the total dissolved solids (TDS), and when the water quality of the concentrated water is higher than the reference value, the amount of wastewater flowing into the purified osmosis filtration unit is increased, It is preferable to reduce the inflow amount of the wastewater flowing into the osmosis filtration unit.

And the wastewater inflow amount Q ₁ is controlled so that Q ₀ is constant in the following formula.

Q ₀ = filtration membrane filtration flow rate of the osmosis filtration unit (10)

Q ₁ = wastewater inflow amount of the osmotic filtration unit 10

TDS ₁ = TDS of incoming wastewater

TDS ₃ = TDS measured at the concentrated water quality measuring part (12)

It is also possible to control the inductive solution effluent Q ₄ such that Q ₀ is constant in the formula below.

Q ₀ = filtration membrane filtration flow rate of the osmosis filtration unit (10)

Q ₄ = flow rate of dilution inducing solution discharged from the osmosis filtration part (10)

TDS ₂ = TDS of the concentrated inductive solution supplied to the osmotic filtration unit 10 in the inductive solution adjustment unit 15

TDS ₄ = TDS of the dilution inducing solution discharged from the osmotic filtration unit 10

Meanwhile, the method for treating RO-enriched wastewater according to the present invention is a method for treating RO-enriched wastewater using a RO concentration wastewater treatment apparatus including a purified osmosis filtration unit and an evaporation condenser, (S10); Diluting and discharging the inducing solution by osmotic pressure in the osmotic filtration unit, and concentrating and discharging the wastewater (S20); And a step (S30) of concentrating the induction solution by evaporating and condensing the diluted induction solution and supplying it to the positive osmosis filtration part.

Further, in the step (S30), when the induction solution of the purified osmotic filtration part is lost or the concentration of the rust inhibitor is decreased, the supply amount of the induction solution is increased, and when the induction solution loss of the purified osmosis filtration part is small, It is preferable to further include a step (S35) of reducing the solution supply amount.

The method may further include a step (S37) of discharging the produced water generated in the evaporative condensation process after the step (S30) and measuring the quality of the discharged production water.

When the water quality of the produced water is higher than the reference value, the inflow amount of the wastewater flowing into the purified osmosis filtration unit is increased from the water quality measured in the step (S35). If the water quality of the produced water is not better than the reference value, The amount of wastewater flowing into the osmotic filtration unit can be reduced.

The method may further include the step (S25) of measuring the quality of the discharged concentrated water after the step (S20).

Further, when the water quality of the concentrated water is higher than the reference value, the inflow amount of the wastewater flowing into the purified osmosis filtration unit is increased and the inflow amount of the wastewater flowing into the osmosis filtration unit is decreased when the quality of the concentrated water is lower than the reference value desirable.

The apparatus and method for treating RO-enriched wastewater according to the present invention provide the effect of providing an apparatus and a method for treating RO-enriched wastewater, which can efficiently obtain fresh water from high concentration wastewater and is also stable in the desalination process.

1 is a schematic diagram of an apparatus for treating RO enriched wastewater according to the present invention;
2 is a detailed view of an apparatus for treating RO enriched wastewater according to the present invention;
FIG. 3 is a partial view showing the 'osmotic filtration' portion in FIG. 2; FIG.
FIG. 4 is a partial view showing the 'evaporative condensation' part in FIG. 2; FIG.
FIG. 5 is a partial view showing the 'induction solution circulation' part in FIG. 2; FIG.
FIG. 6 is a partial view showing a final processing portion in FIG. 2; FIG. And,
FIG. 7 is a graph showing the flow rate Q and the TDS in each part of FIG. 2. FIG.

While the present invention has been described in connection with certain embodiments, it is obvious that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

In the drawings, the same reference numerals are used for the same reference numerals, and in particular, the digits of the tens and the digits of the digits, the digits of the digits, the digits of the digits and the alphabets are the same, Members referred to by reference numerals can be identified as members corresponding to these standards.

In the drawings, the components are expressed by exaggeratingly larger (or thicker) or smaller (or thinner) in size or thickness in consideration of the convenience of understanding, etc. However, It should not be.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the term " comprising " or " consisting of ", or the like, refers to the presence of a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

1 is a schematic diagram of an apparatus for treating RO enriched wastewater according to the present invention. Referring to FIG. 1, an apparatus for treating RO-enriched wastewater according to the present invention includes a normal osmosis filtration unit 10 and an evaporation condenser 20.

The purified osmosis filtration unit 10 extracts only water from the wastewater by using a draw solution having a higher concentration than the wastewater to be treated and extracts the inductive solution separately to extract pure water. The osmosis filtration unit 10 is divided into two regions, that is, a region into which wastewater is introduced by a filtration membrane (not shown) and a region into which an induction solution is introduced. There is a filtration membrane between these two regions, and only the water in the wastewater flows through the filtration membrane to the induction solution side due to the difference in concentration between the two regions, thereby diluting the induction solution. The diluted induction solution is discharged to the evaporation condenser 20 by this process, and the concentrated wastewater is discharged to the outside. The derived solutions can comprise NaCl or MgSO ₄ comprising a corrosion inhibitor.

The evaporation condenser 20 is connected to the rear end of the osmosis filtration unit 10 and transforms water vapor evaporated by heating wastewater or seawater as a kind of evaporation process into a form that is relatively easy to transfer heat through mechanical compression, To water vapor to obtain fresh water while minimizing energy loss.

The water vapor evaporated through the evaporation condensation of the evaporation condenser 20 is discharged as final production water (fresh water), evaporated and condensed, and steam is evaporated, and the more concentrated induction solution is supplied again to the osmotic filtration unit 10 So that it is used in the forward osmosis process.

2 is a detailed view of an apparatus for treating RO concentrated wastewater according to the present invention. Referring to FIG. 2, an induction solution adjusting unit 15, a production water quality measuring unit 22, and a concentrated water quality specifying unit 12 are further provided in addition to the components described in FIG.

The induction solution adjusting unit 15 is provided between the osmosis filtration unit 10 and the evaporation condensation unit 20 and adjusts the concentration of the concentrated induction solution supplied from the evaporation condensation unit 20 to the osmotic filtration unit 10 . When the induction solution is lost during the operation or when the rust inhibitor concentration in the osmosis filtration part 10 decreases (the rust inhibitor is contained in the induction solution), the supply amount of the concentrated induction solution is increased. Conversely, if the flow solution loss is low or the rust inhibitor concentration is not reduced, the supply of the concentrated induction solution is reduced.

The concentrated water quality measuring unit 12 is provided at the downstream end of the purified osmotic filtration unit 10 and is provided at a portion where the concentrated water gradually condensed by the osmotic pressure in the filtration process in the purified osmotic filtration unit 10 is discharged, And the water quality of the concentrated water is measured. It is preferable to perform the measurement through the TDS as in the production water quality measurement section 22. [ The apparatus for treating RO-enriched wastewater according to the present invention adjusts the amount of wastewater fed to the osmotic filtration unit 10 from the concentrated water quality measured by the concentrated water quality measuring unit 12. The method of adjusting the amount of wastewater inflow increases the wastewater inflow when the water quality of the concentrated water is lower than the reference value and decreases the wastewater inflow when the water quality of the concentrated water is higher than the reference value.

Hereinafter, the operation of the apparatus for treating RO-enriched wastewater according to the present invention will be described with reference to FIGS. 3 to 6. FIG.

FIG. 3 is a partial view showing the 'osmotic filtration' portion in FIG. 2. FIG. Referring to FIG. 3, waste water (RO concentrated wastewater) flows into the osmotic filtration unit 10, while the inductive solution also flows from the inductive solution adjusting unit 15. The osmotic filtration unit 10 is divided into two zones through a thin filtration membrane (not shown). Due to the difference in concentration between the wastewater and the induction solution, only water in the wastewater passes through the filtration membrane by the osmotic pressure and moves toward the induction solution. This results in further dilution of the derivatized solution and wastewater becoming more concentrated. The diluted induction solution moves to the evaporation condenser 20, and the concentrated wastewater is discharged and moved to the concentrated water quality measuring portion 12 side.

4 is a partial view showing the 'evaporative condensation' part in FIG. Referring to FIG. 4, the induction solution diluted in the osmotic filtration unit 10 flows into the evaporative condensation unit 20, and the steam evaporated through the evaporative condensation process in the evaporative condenser is discharged to the production water, And moves to the measuring section 22. As the water vapor evaporates and condenses, the induction solution is again concentrated and moves to the induction solution regulator 15. At this time, the sensor provided in the evaporation condenser 20 measures the water quality (TDS), and the measured water quality is determined as the water vapor evaporation amount.

FIG. 5 is a partial view showing the 'induction solution circulation' part in FIG. As shown in FIG. 5, the inductive solution is supplied to the purified osmosis filtration unit 10 by supplying the concentrated solution concentrated in the evaporation condenser 20 to the purified osmosis filtration unit 10, Afterwards, the induction solution is re-introduced so as to correspond to the reduced amount of the inducing substance and the antirusting agent.

Fig. 6 is a partial view showing the final processing portion in Fig. 2. Fig. Referring to FIG. 6, the product water evaporated and condensed in the evaporation condenser 20 and the concentrated wastewater discharged from the osmosis filtration unit 10 are supplied to respective water quality measurement units (production water quality measurement unit 22, concentrated water quality measurement unit 12 Each water quality measuring unit measures the water quality (TDS) of the produced water and the concentrated water, and adjusts the amount of wastewater to be injected into the osmotic filtration unit 10 from the measured water quality.

FIG. 7 is a graph showing the flow rate Q and the TDS in each part of FIG. 2. FIG. Referring to FIG. 7, a method for controlling the flow rate from the measured water quality in the RO concentrated wastewater treatment apparatus according to the present invention will be described. Q ₁ to Q ₅ denote the flow rates at the respective portions, and TDS ₁ to TDS ₅ denote the total evaporation residue (TDS) at the corresponding portion. Q ₀ represents the flow rate through the filtration membrane (not shown) in the osmosis filtration unit 10.

First, the following equation is established between the wastewater flow rate Q ₁ flowing into the purified osmosis filtration section 10, the concentrated wastewater Q ₃ discharged, and the filtration flow rate Q ₀ of the osmosis filtration section 10.

Assuming that the TDS of the osmosis filtration unit 10 is 0, the value obtained by multiplying the flow rate Q _{1 of the} wastewater by the TDS ₁ of the wastewater (total TDS of the wastewater) is obtained by multiplying the flow rate Q _{3 of the} concentrated wastewater by TDS ₃ of the concentrated wastewater Value (the total TDS of the concentrated wastewater). Therefore, Q ₁ is organized by _{Q 3 * TDS 3 / TDS 1} ( see equation below).

Since Q ₃ = Q ₁ - G ₀ in Equation (1), if Equation (2) is substituted into Equation (2), the relation between Q ₀ and Q ₁ is summarized as follows.

Here, for stable water production, the filtration flow rate Q ₀ of the osmosis filtration unit 10 should be constant. Through the above equation (3), Q ₁ is calculated from the measured TDS ₁ and TDS ₃ , and the wastewater inflow amount Q ₁ is controlled so that Q ₀ is constant.

Then, between the flow rate Q ₂ of the concentrate inducing solution and the flow rate Q ₄ of the dilution inducing solution and the flow rate Q _{0 of the} osmosis filtration section 10 about the evaporation condenser 20, the following equation is obtained, and the flow rate Q ₄ * TDS ₄ , the concentration inducing solution flow rate Q ₂ * TDS ₂ , and the production water flow rate Q ₅ * TDS ₅ are as follows.

Here, since TDS5 is almost zero as distilled water, substituting this into Equation 4 above, the following equation is established between Q ₀ and Q ₄ .

Similarly, since Q ₀ must be constant, the calculated TDS ₂ and TDS ₄ to Q ₄ are calculated, and the induced solution discharge amount Q ₄ and the wastewater inflow amount Q ₁ are controlled so that Q ₀ is constant.

Since the apparatus for treating RO-enriched wastewater according to the present invention uses a forward osmosis (FO), it operates at a pressure as low as about 1 bar, so that film contamination is small and scale generation can be suppressed. Therefore, it is easy to treat wastewater with high calcium ion and it can reduce the cost of wastewater management because there is little membrane contamination.

And the induction materials (NaCl, MgSO ₄ ) having high osmotic pressure are completely separated by the evaporation condensation process in the evaporation condenser 20, and the distilled water is discharged to the production water. Thus, the discharged product water can be applied as the process water or the time constant, and the induction solution can be continuously reused. In addition, since the inducing solution contains a certain concentration of rust inhibitor, it is possible to prevent corrosion of facilities including the osmotic filtration unit 10 and the evaporative condensation unit 20.

Finally, since the production water discharged from the process and the concentrated water and the concentrated water quality of the induction solution are measured and managed through the TDS measurement and the treatment device of the RO concentrated wastewater is automatically controlled and controlled from the measured water quality, Can be efficiently managed.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims. Of the present invention.

10: chilled osmotic filtration unit 12: concentrated water quality measurement unit
15: induction solution adjusting unit 20: evaporation condensing unit
22: Production water quality measurement unit

Claims (18)

By using a draw solution at a concentration higher than that of the wastewater to be treated, only water is extracted from the wastewater, and the induction solution is also extracted and treated to extract pure water. The area where the wastewater is introduced by the filtration membrane and the induction solution And an induction solution of a higher concentration than that of the wastewater is supplied to dilute the induction solution containing NaCl or MgSO ₄ by osmotic pressure to concentrate and discharge the wastewater. (10); And
Is divided into two regions, that is, a region to which the wastewater is introduced by the filtration membrane and a region to which the induction solution is injected, and the diluted induction solution is evaporated and condensed to connect the induction solution The evaporation condensation part 20, which is evaporated through evaporation condensation, is discharged as final production water, evaporated and condensed, and evaporated while steam is further concentrated, and then the induction solution is further supplied to the above described osmosis filtration part;
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The purified osmosis filtration unit 10 includes a filtration membrane and is divided into a region into which the wastewater flows and a region into which the induction solution flows based on the membrane and water in the wastewater flows toward the inductive solution through the filtration membrane and,
The flow rate of the concentrated inductive solution supplied from the evaporation and condensation section 20 to the purified osmosis filtration section 10 is adjusted between the purified osmosis filtration section 10 and the evaporation condensation section 20, And an induction solution adjusting unit (15)
The induction solution adjusting unit 15 increases the supply amount of the induction solution when the induction solution of the purified osmosis filtration unit 10 is lost or the concentration of the rust inhibitor is decreased and the induced solution loss of the purified osmosis filtration unit 10 is low Or if the rust inhibitor concentration is not decreased,
And a production water quality measuring unit 22 provided at a downstream end of the evaporation and condensation unit 20 for measuring a quality of final production water produced after the evaporation and condensation process of the evaporation and condensation unit 20,
The production water quality measuring unit 22 measures the quality of the produced water through the TDS and increases the inflow amount of the wastewater flowing into the osmosis filtration unit 10 when the quality of the produced water is higher than the reference value, The flow rate of the wastewater flowing into the osmosis filtration unit 10 is reduced,
Further comprising a concentrated water quality measuring unit (12) provided at a rear end of the purified osmosis filtration unit (10) for measuring the quality of the concentrated water discharged after being concentrated in the filtration process of the osmosis filtration unit (10)
The concentrated water quality measuring unit 12 increases the amount of wastewater flowing into the osmotic filtration unit 10 when the water quality of the concentrated water is higher than the reference value and when the water quality of the concentrated water is lower than the reference value , The amount of wastewater flowing into the osmosis filtration unit (10) is reduced,

In the formula below, the wastewater inflow Q ₁ is controlled so that Q ₀ is constant,

Q ₀ = filtration membrane filtration flow rate of the osmosis filtration unit (10)
Q ₁ = wastewater inflow amount of the osmotic filtration unit 10
TDS ₁ = TDS of incoming wastewater
TDS ₃ = TDS measured at the concentrated water quality measuring part (12)

Wherein an induction solution flow rate Q ₄ is controlled such that Q ₀ is constant in the following equation.

Q ₀ = filtration membrane filtration flow rate of the osmosis filtration unit (10)
Q ₄ = flow rate of dilution inducing solution discharged from the osmosis filtration part (10)
TDS ₂ = TDS of the concentrated inductive solution supplied to the osmotic filtration unit 10 in the inductive solution adjustment unit 15
TDS ₄ = TDS of the dilution inducing solution discharged from the osmotic filtration unit 10
By using a draw solution at a concentration higher than that of the wastewater to be treated, only water is extracted from the wastewater, and the induction solution is also extracted and treated to extract pure water. The area where the wastewater is introduced by the filtration membrane and the induction solution And an induction solution of a higher concentration than that of the wastewater is supplied to dilute the induction solution containing NaCl or MgSO ₄ by osmotic pressure to concentrate and discharge the wastewater. And a region connected to the rear end of the quasi-osmosis filtration unit (10), where the wastewater is introduced by the filtration membrane and the region where the induction solution is introduced. The diluted induction solution is evaporated and condensed, The water vapor evaporated through evaporation condensation is discharged as final production water, evaporated and condensed, The RO concentrate wastewater treatment method using RO concentrating wastewater treatment apparatus including an evaporation condensation unit that is supplied to the above-mentioned osmosis filtration unit,
Supplying the derived solution containing the waste water and NaCl or MgSO ₄ to the forward osmosis filtration unit (S10);
Diluting and discharging the inducing solution by osmotic pressure in the osmotic filtration unit, and concentrating and discharging the wastewater (S20); And
(S30) of evaporating and condensing the diluted inductive solution, thereby concentrating the inductive solution and supplying it to the positive osmosis filtration unit,
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In the step (S30), when the induction solution of the quasi-osmosis filtration unit is lost or the concentration of the rust inhibitor is decreased, the supply amount of the induction solution is increased. When the induction solution loss of the quasi- Further comprising a step (S35) of reducing the supply amount,
Further comprising the step (S37) of discharging the produced water generated in the evaporative condensation process after the step (S30) and measuring the quality of the produced water to be discharged,
If the water quality of the produced water is higher than the reference value, the amount of wastewater flowing into the purified osmosis filtration unit is increased from the water quality measured in the step (S35). If the water quality of the produced water is not better than the reference value, The amount of wastewater flowing into the filtration unit is reduced,
Further comprising the step of measuring the quality of the discharged concentrated water after the step (S20), wherein when the quality of the concentrated water is higher than the reference value, the flow rate of the wastewater flowing into the purified osmosis filtration unit is increased, When the water quality of the concentrated water is lower than the reference value, the amount of wastewater flowing into the osmosis filtration unit is reduced,
In the formula below, the wastewater inflow Q ₁ is controlled so that Q ₀ is constant,

Q ₀ = filtration membrane filtration flow rate of the osmosis filtration unit (10)
Q ₁ = wastewater inflow amount of the osmotic filtration unit 10
TDS ₁ = TDS of incoming wastewater
TDS ₃ = TDS measured at the concentrated water quality measuring part (12)
In the formula: RO treatment method for concentrated waste water, characterized in that for controlling the induction solution flow Q ₄ is Q ₀ is constant.

Q ₀ = filtration membrane filtration flow rate of the osmosis filtration unit (10)
Q ₄ = flow rate of dilution inducing solution discharged from the osmosis filtration part (10)
TDS ₂ = TDS of the concentrated inductive solution supplied to the osmotic filtration unit 10 in the inductive solution adjustment unit 15
TDS ₄ = TDS of the dilution inducing solution discharged from the osmotic filtration unit 10 delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

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