JP5222526B2 - Water treatment method and water treatment apparatus - Google Patents

Description

  The present invention relates to a water treatment method and a water treatment apparatus in which raw water containing salts is separated by a reverse osmosis membrane.

Conventionally, in areas where it is difficult to obtain fresh water such as remote islands and low rain areas, it has been practiced to produce fresh water using seawater as raw water and use the obtained fresh water as drinking water or agricultural water.
In water treatment such as desalination of seawater, it is necessary to remove various salts contained in seawater in the state of anions, cations, etc., and thus membrane separation using a reverse osmosis membrane has been conventionally performed. Yes.

  Usually, in this membrane separation using a reverse osmosis membrane, raw water containing salts is introduced into one side of the space separated by the reverse osmosis membrane, and the desalinated treated water having a lower salt concentration than the raw water is used as the above-mentioned. A permeation process is performed in which concentrated water having a higher salt concentration than raw water is allowed to flow out from one side and treated water is continuously flowed out from the other side by passing through the reverse osmosis membrane to the other side.

For example, Patent Document 1 described below describes desalination of seawater using a membrane separation module having a supply water chamber and a permeate chamber separated by a reverse osmosis membrane.
More specifically, the following Patent Document 1 discloses a desalinated treatment in which the concentration of salts (hereinafter also referred to as “salt concentration”) is low by continuously flowing raw water into the supply water chamber of the membrane separation module. It is described that water is permeated through the reverse osmosis membrane to the permeate water chamber side so that fresh water is continuously flowed out from the permeate water chamber and concentrated water with increased salt concentration is continuously flowed out from the supply water chamber. Yes.

  In addition to desalination of seawater, for example, reverse osmosis membranes are also used in cases where metal salts contained in washing wastewater, etc. in metal refining factories are removed and reused as industrial water in the factories. Water treatment by is carried out.

  In such desalination of seawater and reuse of industrial wastewater, it is usually required to produce a stable amount of water having a certain level of water quality.

In response to such demands for stabilizing the water quality level and ensuring a stable amount of water, the amount of treated water that permeates the reverse osmosis membrane is set to the adjacent space (for example, supply) through the reverse osmosis membrane. Since it can be easily changed by the pressure difference between the water chamber and the permeated water chamber), it can be implemented relatively easily.
On the other hand, the quality of water, that is, the amount of salts contained in the treated water varies depending on the amount of salts that pass through the reverse osmosis membrane, and the amount of salts that pass through the reverse osmosis membrane usually passes through the reverse osmosis membrane. Depending on the amount of salt contained in the adjacent concentrated water and the performance of the reverse osmosis membrane.

Therefore, for example, if water treatment is performed using raw water having a constant salt concentration at all times, it is relatively easy to stably supply water having a certain level of water quality. The salt concentration of wastewater varies greatly depending on the operating conditions of the factory and the type of product being manufactured, and the salt concentration also changes depending on the tidal current and the weather even during seawater desalination.
Therefore, it is practically difficult to obtain such raw water having a constant salt concentration, and it has been difficult to stabilize the water quality level.

Also, for such a problem, conventionally, little has been studied and no solution has been obtained.
That is, the conventional water treatment method and water treatment apparatus have a problem that it is difficult to stably obtain water having a certain level of water quality.

JP-A-9-299944

  An object of the present invention is to provide a water treatment method and a water treatment apparatus that stably obtain water having a certain level of water quality.

In order to solve the above problems, the present invention allows raw water containing salts to flow into a membrane separation module in which a reverse osmosis membrane is used, treated water having a lower salt concentration than the raw water, and more than the raw water. Separated into concentrated water having a high salt concentration by the reverse osmosis membrane, and by continuously flowing the raw water into the membrane separation module, the concentrated water is continuously discharged from the membrane separation module, and A water treatment method for continuously treating treated water from a membrane separation module, wherein the amount of treated water discharged from the membrane separation module is controlled to be constant, and the salt concentration of the treated water is controlled to a predetermined value or less. determine the amount of salt that passes through the reverse osmosis membrane so as to an electric conductivity of the raw water, the membrane fraction when the amount of salts that passes through the reverse osmosis membrane obtained from the electric conductivity is increased It provides a water treatment method by increasing the inflow of raw water to the module, characterized in that to suppress the increase in the amount of salts that the transmission.

The present invention also includes a membrane separation module in which a reverse osmosis membrane is used to solve the above problems, and raw water containing salts is flowed into the membrane separation module, so that the concentration of salts is higher than that of the raw water. It is separated by the reverse osmosis membrane into low treated water and concentrated water having a higher salt concentration than the raw water, and the raw water is continuously flowed into the membrane separation module, whereby the concentrated water is separated into membranes. A water treatment apparatus in which the treated water is continuously discharged from the module and the treated water is continuously discharged from the membrane separation module, and a control mechanism for controlling a flow amount of the treated water from the membrane separation module to be constant A control mechanism for controlling the salt concentration of the treated water to a predetermined value or less by changing the inflow amount of the raw water according to the amount of the salt that permeates the reverse osmosis membrane , Concentration The control mechanism that controls the constant value or less includes an electrical conductivity meter that measures the electrical conductivity of the raw water in order to determine the amount of salts that permeate the reverse osmosis membrane, and the electrical conductivity meter transmits the reverse osmosis membrane. When the amount of salts to be increased is required to increase, the amount of raw water flowing into the membrane separation module is increased to suppress an increase in the amount of the permeating salts. A water treatment device is provided.

  According to the present invention, the raw water is allowed to flow into a membrane separation module in which a reverse osmosis membrane is used, treated water having a lower salt concentration than the raw water, and concentrated water having a higher salt concentration than the raw water, In addition, since the outflow amount of the treated water is controlled to be constant in the water treatment method and the water treatment apparatus for performing membrane separation with the reverse osmosis membrane, a stable amount of water is ensured.

Moreover, since the outflow amount of the treated water is controlled to be constant, the amount of treated water that passes through the reverse osmosis membrane and is removed among the amount of water that flows into the membrane separation module is constant.
That is, for example, the concentration degree of concentrated water can be controlled by changing the amount of water flowing into the membrane separation module per unit time.
Therefore, for example, the amount of salt permeating the reverse osmosis membrane can be adjusted by adjusting the salt concentration of the concentrated water by changing the inflow amount of the raw water according to the amount of the salt permeating the reverse osmosis membrane.
That is, according to the present invention, the salt concentration of the treated water is controlled to a predetermined value or less by changing the inflow amount of the raw water, and a stable water quality is ensured.
Moreover, the contamination rate of the reverse osmosis membrane can be suppressed by adjusting the salt concentration of the concentrated water.

  Thus, according to the present invention, water having a certain level of water quality can be obtained in a stable amount in the water treatment method and the water treatment apparatus.

  In the following, preferred embodiments of the present invention will be described with reference to washing wastewater from a metal smelting plant (hereinafter also referred to as “drainage”) as raw water, and the wastewater is in a state where the contained salts can be reused as industrial water. An example of water treatment that separates into reduced treated water and concentrated water having a higher salt concentration than the raw water will be described.

First, the water treatment apparatus will be described.
FIG. 1 is a schematic block diagram showing the configuration of the water treatment apparatus in the present embodiment.
1 in FIG. 1 represents a membrane separation module, and 11 is a housing in which an outer shell of the membrane separation module 1 is formed and an accommodation space for storing raw water and treated water is formed therein. Is a reverse osmosis membrane housed inside the housing 11, and the space inside the housing 11 is divided into two by the reverse osmosis membrane 12.

  Examples of the reverse osmosis membrane 12 include a so-called hollow fiber membrane formed of a material such as cellulose acetate, aromatic polyamide, polyvinyl alcohol or the like and formed into a hollow fiber shape having a diameter of several millimeters. A so-called tubular membrane having a diameter of several centimeters larger than that of the membrane, and also used by being wound into a roll with a support material such as a mesh disposed inside when used. Conventionally known ones such as an envelope-shaped so-called spiral membrane can be employed.

Reference numeral 13 in FIG. 1 is a feed water chamber which is one of the internal spaces of the membrane separation module 1 divided into two by the reverse osmosis membrane 12, and 14 is the other of the two divided spaces. This is a permeate chamber.
Further, a raw water inlet for allowing raw water to flow in and a concentrated water outlet for allowing concentrated water to flow out are opened on the supply water chamber 13 side of the casing 11, and on the permeate water chamber 14 side. Is opened with a treated water discharge port for discharging treated water having a reduced salt concentration through the reverse osmosis membrane 12.

Reference numeral 2 in FIG. 1 is a raw water transport mechanism provided to allow raw water (drainage) to flow into the membrane separation module 1, and 21 is a raw water piping section that serves as a flow path for raw water.
One end side of the raw water pipe section 21 is connected to a raw water supply point (not shown), and the other end of the raw water piping section 21 is connected to the supply water chamber 13 from the supply point. It is connected to the raw water inlet formed in the housing 11.
Reference numeral 22 denotes a transport pump for transporting raw water (hereinafter also referred to as “raw water transport pump”). The raw water transport pump 22 distributes the raw water from the raw water supply point toward the membrane separation module 1. It is provided in the middle part of the raw water piping part 21 so as to obtain.

In FIG. 1, 3 is a treated water transport mechanism provided to supply treated water from which salts have been removed by the membrane separation module 1 to a use point (not shown) of the treated water, and 31 is treated water. It is the treated water piping part used as the distribution flow path.
The treated water piping part 31 is connected to a permeated water discharge port formed in the casing 11 of the membrane separation module 1 so as to discharge treated water from the permeated water chamber 14 and is provided in a water treatment device. It has been.
Reference numeral 32 denotes a treated water quantification mechanism provided in the treated water piping section 31 in order to control the discharge amount of treated water to a constant amount. The treated water quantification mechanism 32 includes, for example, a constant flow rate. For example, the constant flow valve is equipped with an orifice on the inlet side of the valve, and the opening of the main valve is adjusted by the differential pressure generated before and after the orifice due to fluctuations in the flow rate. Thus, a type that keeps the flow rate constant can be adopted.
Reference numeral 33 denotes a salt concentration measuring mechanism for measuring the salt concentration of the treated water flowing through the treated water piping section 31, and the salt concentration measuring mechanism 33 of the present embodiment signals the obtained measurement result as a signal. It is formed so that it can be transmitted as.
Examples of the salt concentration measuring mechanism 33 include those equipped with an electric conductivity meter, an ion meter, or the like for measuring the salt concentration.
In addition, since the electrical conductivity has a correlation with the salt concentration and can be easily measured, the salt concentration measuring mechanism 33 preferably has a mechanism for measuring the electrical conductivity.
Moreover, since the electric conductivity meter is inexpensive and easy to maintain, the salt concentration measuring mechanism 33 provided with the electric conductivity meter is effective in reducing the apparatus cost and maintenance cost of the water treatment device.

In FIG. 1, 4 is a concentrated water transport mechanism provided to discharge concentrated water having a concentrated salt concentration out of the membrane separation module 1, and 41 is a concentrated water flow path for concentrated water. It is a water piping part.
The concentrated water pipe section 41 is connected to a concentrated water discharge port formed in the casing 11 of the membrane separation module 1 so that the concentrated water is discharged from the supply water chamber 13 and is provided in the water treatment apparatus. It has been.
Reference numeral 42 denotes a concentrated water amount adjusting mechanism provided to adjust the amount of concentrated water flowing out from the membrane separation module 1. The concentrated water amount adjusting mechanism 42 is transmitted from the salt concentration measuring mechanism 33. An opening degree adjusting valve such as a butterfly valve is used to change the amount of concentrated water flowing out from the membrane separation module 1 based on the signal.

  Reference numeral 5 in FIG. 1 designates a signal transmission mechanism for transmitting a signal transmitted from the salt concentration measuring mechanism 33 to the concentrated water amount adjusting mechanism 42 as a control signal for changing the opening of the opening adjusting valve, for example. Represents.

As described above, the water treatment apparatus of the present embodiment is provided with the treated water quantification mechanism 32 as a control mechanism for controlling the outflow amount of treated water to be constant. The water amount adjusting mechanism 42 functions as a control mechanism that controls the amount of raw water flowing into the membrane separation module 1.
Further, the concentrated water amount adjusting mechanism 42 that controls the inflow amount of the raw water includes a salt concentration measuring mechanism 33 and a signal transmission mechanism 5 that transmits a signal based on the measured value of the salt concentration measuring mechanism 33 to the concentrated water amount adjusting mechanism 42. The water treatment apparatus is provided so that the inflow amount of the raw water can be controlled in accordance with the amount of salts that permeate the reverse osmosis membrane 12.
A control method for controlling the amount of raw water flowing into the membrane separation module 1 according to the amount of salts permeating the reverse osmosis membrane 12 will be described in detail later.

  Although not described in detail here, various devices used in conventionally known water treatment devices can be employed in the water treatment device as long as the effects of the present invention are not impaired.

Next, a water treatment method that is performed to reuse wastewater as industrial water using such a water treatment apparatus will be described.
Examples of the waste water include those containing salts to such an extent that the electrical conductivity is from several thousand μS / cm to several thousand μS / cm, and the electrical conductivity is 1000 μS. / Cm or less, for example, by making it into a soft water state of several hundred μS / cm, it can be made reusable as general industrial water.
In the water treatment of this embodiment, the upper limit value of the electrical conductivity of the treated water can be set to, for example, any value of 200 μS / cm to 300 μS / cm, and the treatment can be performed.
As described above, a water treatment method for regenerating wastewater as industrial water (treated water) that can be reused as raw water is performed as follows.

  First, the raw water transport pump 22 of the raw water transport mechanism 2 is operated at a constant rotational speed, and raw water (drainage) is sucked from the raw water supply point, and the wastewater flows into the feed water chamber 13 of the membrane separation module 1 through the raw water piping section 21. Let

  At this time, in the inside of the housing 11 of the membrane separation module 1, the raw water comes into contact with the reverse osmosis membrane 12, so that mainly water in the raw water permeates the reverse osmosis membrane 12 and flows into the permeated water chamber and supply water. In the chamber 13, concentrated water having a salt concentration increased is formed in a state where moisture has been removed from the original raw water.

Subsequently, the raw water is continuously flowed into the supply water chamber 13 by the raw water transport mechanism 2 so that the supply water chamber 13 is filled with concentrated water having a salt concentration higher than that of the raw water, and the permeate water chamber 14 is more salted than the raw water. Fill with low concentration treated water.
Further, the raw water is continuously flowed into the supply water chamber 13 by the raw water transport mechanism 2 so that the treated water in the permeated water chamber 14 is discharged from the treated water discharge port and is transported to the use point by the treated water transport mechanism 3.
At this time, for example, the control is performed so that the flow rate of the treated water flowing out from the permeate chamber 14 of the membrane separation module 1 becomes a constant flow rate by the treated water quantification mechanism 32 using a constant flow valve or the like.

On the other hand, the raw water is caused to flow into the supply water chamber 13 by the raw water transport mechanism 2 to push out the concentrated water in the supply water chamber 13 from the concentrated water discharge port and to discharge out of the system by the concentrated water transport mechanism 4.
At this time, the concentrated water amount adjusting mechanism 42 using a butterfly valve or the like adjusts the flow rate of the concentrated water discharged outside the system by adjusting the opening degree of the butterfly valve, for example, from the amount of raw water that has been introduced so far. Set the amount smaller than the amount obtained by subtracting the outflow of treated water.

By setting the total amount of the flow rate of the treated water and the flow rate of the concentrated water to be smaller than the raw water inflow rate so far, the water pressure in the supply water chamber 13 is increased, and the load on the raw water transport pump 22 is slightly increased. .
As the water pressure inside the supply water chamber 13 increases, the load of the raw water transport pump 22 increases, the amount of raw water flowing into the supply water chamber 13 decreases, and the flow rate of concentrated water passing through the butterfly valve is slightly reduced. Decrease.
Thereafter, the total amount of the treated water flow rate and the concentrated water flow rate is balanced with the inflow amount of the raw water.
Since the treated water is controlled at a constant flow rate by a constant flow valve or the like, even if the water pressure in the supply water chamber 13 increases, the water pressure in the permeate water chamber 14 increases so as to antagonize the increase in the water pressure. Therefore, the flow rate does not change.

  At this time, water treatment is carried out while measuring the quality of the treated water with an electric conductivity meter, etc., for example, when an increase in the salt concentration of the treated water is observed due to an increase in the salt concentration of the raw water, A control signal is transmitted to increase the opening of the butterfly valve.

As a result, by increasing the flow rate of the concentrated water, the water pressure in the supply water chamber 13 decreases, the load of the raw water transport pump 22 decreases, and the inflow amount of the raw water increases.
And the salt concentration of the supply water chamber 13 is reduced by increasing the inflow amount of raw | natural water, and the salt concentration of treated water is controlled below to a predetermined value.

  A method for controlling the concentration of the treated water salt to a predetermined value or less by changing the amount of the raw water inflow will be described in more detail.

The amount of water that passes through the reverse osmosis membrane in a certain time is usually the difference between the area and the water pressure in the adjacent space through the reverse osmosis membrane (hereinafter referred to as “differential pressure”) if the type of reverse osmosis membrane is constant. It is also determined by the water temperature.
On the other hand, the amount of salts that pass through the reverse osmosis membrane in a certain time usually varies depending on the amount of salts contained in the concentrated water and the performance of the reverse osmosis membrane.

In this embodiment, since the outflow amount of the treated water is controlled to be constant, the amount of water that passes through the reverse osmosis membrane in a certain time even if the salt concentration of the raw water flowing into the supply water chamber 13 increases. Is constant.
Therefore, when there is no change in the inflow amount of the raw water, only a fixed amount of treated water is removed from the constant amount of raw water, and a concentrated water that is constantly concentrated is formed in the supply water chamber 13.
Further, the amount of salts passing through the reverse osmosis membrane is small compared to the amount of salts contained in the raw water, and most of the salts contained in the raw water are discharged from the membrane separation module 1 together with the concentrated water. The
And when the salt concentration of the raw | natural water which flows in rises, if the amount of raw | natural water which flows in into the membrane separation module 1 is made into the same amount as before salt concentration rises, the salt concentration of the supply water chamber 13 will also rise, The amount of salts that move from the feed water chamber 13 side to the permeate water chamber 14 side through the reverse osmosis membrane 12 will increase.

However, in the water treatment method of the present embodiment, when the salt concentration of the raw water increases and the amount of salts moving to the permeate water chamber 14 increases, the inflow amount of the raw water (concentrated water outflow amount) is increased. Therefore, an increase in the amount of salts moving to the permeate water chamber 14 side can be suppressed.
If the flow rate per unit of raw time V _0, the flow per unit of treated water time and V _T, if the outflow amount per unit of concentrated water time and V _C, per unit of concentrated water time The outflow amount V _C is given by the following formula (1).

The amount of salts contained in the raw water having the amount of V ₀ is C ₀ , the amount of salts contained in the treatment of the amount of V _T is C _T, and contained in the treated water of the amount of V _C. the amount of salt When C _C that, since the amount of salts contained in the treated water as compared to the amount of salt to be contained is very small (C ₀ >> C _T) in the raw water, the amount of V _C The amount C _C of salts contained in the concentrated water is given by the following formula (2).

Therefore, when the salt concentration of the concentrated water and D _C, salt concentration, and thus given by the following formula (3).

ここで、本実施形態の水処理方法においては処理水の量（Ｖ_T）が一定とされている。
したがって、原水の塩濃度が上昇し、原水中に含有される塩類の量（Ｃ₀）が増大したとしても、原水の流入量（Ｖ₀）を増大させることで濃縮水の塩濃度（Ｄ_C）の上昇を抑制させることができ供給水室１３側の塩濃度が上昇することを抑制させることができる。
このことにより、逆浸透膜１２を透過して透過水室１４に移動する塩類の量が増大することを抑制させることができる。

Here, in the water treatment method of the present embodiment, the amount of treated water (V _T ) is constant.
Therefore, even if the salt concentration of the raw water increases and the amount of salts (C ₀ ) contained in the raw water increases, the salt concentration (D _C of concentrated water is increased by increasing the inflow amount (V ₀ ) of the raw water. ) Can be suppressed, and the salt concentration on the supply water chamber 13 side can be suppressed from increasing.
This can suppress an increase in the amount of salts that permeate the reverse osmosis membrane 12 and move to the permeate chamber 14.

  The amount of salts that permeate the reverse osmosis membrane 12 and move to the permeated water chamber 14 after changing the inflow amount of the raw water that flows into the supply water chamber 13 side is not necessarily before the salt concentration of the raw water increases. It is not necessary to adjust to the same value, and if necessary, the amount of salt that moves through the reverse osmosis membrane 12 to the permeate chamber 14 by lowering the salt concentration of the concentrated water from before the increase in the salt concentration of the raw water. Can be reduced as compared with the state before the salt concentration of the raw water is increased.

  In addition, when the salt concentration of the treated water is much smaller than the upper limit of the range that can be used for industrial water, and a slight increase in salt concentration is allowed, the reverse osmosis membrane 12 is used. It is also possible to make the raw water inflow amount that increases the amount of salts that permeate and move to the permeated water chamber 14 as compared to before the salt concentration rises in the raw water.

  As described above, in the water treatment method of the present embodiment, the control mechanism that changes the inflow amount of raw water that flows into the feed water chamber 13 according to the amount of salts that permeate the reverse osmosis membrane 12 into the water treatment apparatus. Is provided, the control mechanism can control the salt concentration of the treated water to be equal to or lower than a predetermined value to perform water treatment.

  In the above control, when the salt concentration of the raw water increases, the opening of the opening adjustment valve that regulates the flow rate of the concentrated water is improved and the water pressure in the supply water chamber 13 is reduced. Along with this, the water pressure in the permeate water chamber 14 also decreases, balances in a state having a differential pressure commensurate with the outflow amount of the treated water, and the treated water amount is maintained constant.

Further, although not described in detail here, the reverse osmosis membrane generally tends to permeate salts when the temperature rises.
Therefore, even when there is no change in the salt concentration of the raw water, the quality of the treated water may be affected by the change in the temperature of the raw water.
Even in such a case, similarly to the above, the outflow amount of the treated water is controlled to be constant, and the concentration of the salt of the treated water is controlled to a predetermined value or less by changing the inflow amount of the raw water flowing into the supply water chamber 13. Can be made.

In the above description, the control of reducing the salt concentration of the treated water to a predetermined value or less when the salt concentration of the raw water is increased is described. For example, while the predetermined value is set as the upper limit value, the lower limit value is separately set. It is also possible to control the treated water within a predetermined salt concentration range.
That is, for example, the upper limit value of the salt concentration of the treated water is set in the control mechanism that changes the inflow amount of the raw water that flows into the supply water chamber 13 according to the amount of salts that permeate the reverse osmosis membrane 12, and the lower limit value is set. Set and control to increase the inflow of raw water when the salt concentration of treated water is predicted to exceed the upper limit, and to reduce the inflow of raw water when it is expected to be less than the lower limit It is also possible to make it.

  Further, although not described in detail here, various controls and facility operation methods in a conventionally known water treatment method can also be adopted in the present invention.

For example, the water treatment method can be carried out by equipment as shown in the schematic block diagrams of FIGS.
In the water treatment apparatus shown in FIG. 1, the raw water transport pump 22 is operated at a constant rotation speed, and the concentrated water outflow amount is controlled by the concentrated water amount adjusting mechanism 42 based on the measurement result of the salt concentration measuring mechanism 33. The signal from the salt concentration measuring mechanism 33 is transmitted to the concentrated water amount adjusting mechanism 42 in order to change the amount of raw water flowing into the supply water chamber 13 and control the salt concentration of the treated water below a predetermined value. A transmission mechanism 5 is provided.

On the other hand, in the water treatment apparatus of FIG. 2, the concentrated water transport mechanism 4 is not provided with a concentrated water amount adjusting mechanism, and the number of rotations of the raw water transport pump 22 is changed based on the measurement result of the salt concentration measuring mechanism 33. In order to change the amount of raw water flowing into the supply water chamber 13, an inverter 51 is provided for changing the rotational speed of the raw water transport pump 22, and the signal transmission mechanism 5 is connected to the inverter 51.
The water treatment method using the water treatment apparatus of FIG. 2 can be carried out similarly to the case of the water treatment apparatus shown in FIG.

For example, when an increase in the salt concentration of the treated water is observed, the amount of raw water flowing into the feed water chamber 13 by operating the raw water transport pump 22 at a high speed by the inverter 51 (“V in the above equation (3)”) By increasing “ ₀ ”), it is possible to suppress an increase in the amount of salts that permeate the reverse osmosis membrane 12 and move to the permeate water chamber 14 side.
Also, if necessary, the amount of salts that pass through the reverse osmosis membrane 12 and move to the permeate chamber 14 side can be increased or decreased compared to the amount before the increase in the salt concentration of the treated water is observed. It is.
By using the water treatment device of FIG. 2, it is possible to change the inflow amount of raw water while suppressing fluctuations in the water pressure inside the membrane separation module 1, compared to the water treatment device illustrated in FIG. Water treatment can be carried out while suppressing troubles such as breakage of the osmotic membrane 12.

The water treatment apparatus shown in FIGS. 1 and 2 is provided with a salt concentration measuring mechanism 33 for measuring the salt concentration of treated water flowing through the treated water piping section 31, but will be described with reference to FIG. The water treatment apparatus shown in FIG. 4 is different in that the salt concentration measuring mechanism 33 is provided to measure the salt concentration of raw water flowing through the raw water piping section 21.
That is, when the salt concentration on the raw water side increases, the salt concentration in the supply water chamber 13 usually increases, and the salt concentration of the treated water that permeates from the supply water chamber 13 to the permeate water chamber 14 increases. Therefore, control of the raw water inflow amount to the supply water chamber 13 by the concentrated water amount adjusting mechanism 42 (in the case of FIG. 3) or the raw water inflow amount to the supply water chamber 13 by controlling the number of revolutions of the raw water transport pump 22 in the inverter 51. Control (in the case of FIG. 4) is performed.
By using the water treatment apparatus of FIGS. 3 and 4, it is possible to grasp the increase in the salt concentration of the treated water and to maintain the quality of the treated water more reliably.

Moreover, the water treatment apparatus shown in FIGS. 5 and 6 recirculates a part of the concentrated water flowing out from the supply water chamber 13 to the raw water piping section 21 upstream (raw water supply point side) from the raw water transport pump 22. 2 except that a concentrated water recirculation mechanism 6 is provided and a recirculation piping section 61 constituting the concentrated water recirculation mechanism 6 is provided in a state where the raw water piping section 21 and the concentrated water piping section 41 are connected. These are the same as the water treatment apparatus shown in FIG.
In addition, the reflux pipe unit 61 is provided with a reflux water quantification mechanism 63 for controlling the amount of concentrated water to be refluxed at a constant level.
In addition, as this reflux water quantification mechanism 63, the constant flow valve etc. which were used for the treated water quantification mechanism 32 can be employ | adopted.

In the water treatment apparatus shown in FIGS. 5 and 6, since the mixed water in which a part of the concentrated water is mixed with the raw water flows into the membrane separation module 1 through the raw water piping section 21, the operating condition of the raw water transport pump 22 Are equivalent, the amount of raw water collected from the supply point is reduced by the amount of concentrated water that has been refluxed compared to the water treatment apparatus shown in FIGS.
Moreover, the amount of concentrated water discharged out of the system will be reduced.

Therefore, when it is difficult to ensure a sufficient amount of raw water, the amount of raw water varies so much that the water treatment apparatus shown in FIGS. 2 and 4 is difficult to ensure a stable operation state. It can be said that there is.
That is, there is an effect that the operation state of the facility can be stabilized by performing water treatment with the water treatment apparatus shown in FIGS.
Further, in the case where some kind of post-treatment must be performed on the concentrated water, there is an effect that the labor can be reduced.
Since the mixed water of the concentrated water and the raw water flowing into the membrane separation module 1 in the water treatment apparatus shown in FIGS. 5 and 6 has a higher salt concentration than the raw water, the concentrated water or the raw water has a relatively high salt concentration. It can be said that this is a water treatment method particularly suitable when the concentration is low.

  Furthermore, when water treatment is performed with the water treatment apparatus shown in FIG. 6, it is possible to grasp in advance that the salt concentration of the treated water increases, and in that the quality of the treated water can be more reliably maintained. This is the same as the case where the water treatment is performed with the water treatment apparatus shown in FIG.

  The water treatment apparatus shown in FIGS. 7 and 8 is provided with a reflux pipe section 61 that connects the raw water pipe section 21 and the concentrated water pipe section 41, and the reflux pipe section 61 is upstream of the raw water transport pump 22. A portion of the concentrated water that is connected to the raw water pipe section 21 (on the raw water supply point side) and flows out from the supply water chamber 13 of the membrane separation module 1 is upstream of the raw water transport pump 22 (raw water supply point side). It differs from the water treatment apparatus shown in FIGS. 1 and 3 in that a concentrated water recirculation mechanism 6 that recirculates the pipe portion 21 is provided.

  In the water treatment apparatus shown in FIGS. 7 and 8, the concentrated water piping section is upstream of the connection position with the reflux piping section 61 (between the connection section with the reflux piping section 61 and the membrane separation module 1). 41 is provided with a concentrated water amount adjusting mechanism 42 for adjusting the amount of concentrated water flowing out from the supply water chamber 13, and the amount of concentrated water flowing out from the water supply chamber 13 is fixed to the concentrated water amount adjusting mechanism 42. 1 and 3 is different from the water treatment apparatus shown in FIGS.

  Furthermore, a discharge amount adjusting mechanism 62 for adjusting the amount of concentrated water to be discharged out of the system is provided in the concentrated water piping portion 41 on the downstream side of the connection point with the reflux piping portion 61, and salt concentration measurement is performed. Based on the result of the salt concentration of the treated water measured by the mechanism 33 (in the case of FIG. 7) or the salt concentration of the mixed water of the raw water and the refluxed concentrated water (in the case of FIG. 8), the discharge amount adjusting mechanism 62 It differs from the water treatment apparatus shown in FIGS. 1 and 3 in that a signal transmission mechanism 5 is arranged so as to control the amount of concentrated water discharged from the system.

In the water treatment using the water treatment apparatus shown in FIGS. 7 and 8, the outflow amount of the treated water from the permeate water chamber 14 and the outflow amount of the concentrated water from the supply water chamber 13 are both constant. In addition, since the treated water quantification mechanism 32 and the concentrated water amount adjustment mechanism 42 are provided, the amount of mixed water flowing into the membrane separation module 1 is constant.
The water treatment apparatus shown in FIGS. 7 and 8 is common to the water treatment apparatus shown in FIGS. 5 and 6 in that the concentrated water reflux mechanism 6 is provided, but the concentrated water discharged out of the system. This is different from the water treatment apparatus shown in FIGS. 5 and 6 in that the amount of water is controlled based on the salt concentration of the treated water or the salt concentration of the mixed water.

Since the amount of concentrated water discharged out of the system is controlled based on the salt concentration of the treated water or the salt concentration of the mixed water, for example, the amount of salts that permeate the reverse osmosis membrane 12 is increased. When the concentration measuring mechanism 33 senses, the ratio of the raw water to the mixed water by increasing the discharged amount of concentrated water to the outside by the discharge amount adjusting mechanism 62 and decreasing the amount of concentrated water recirculated by the reflux pipe unit 61 Can be increased.
That is, the amount of raw water flowing into the feed water chamber 13 is increased, and the mixed water is allowed to flow into the feed water chamber 13 in a state where the salt concentration is lowered, thereby reducing the salt concentration inside the feed water chamber 13. Thus, the salt concentration of the treated water can be controlled to a predetermined value or less.

  In the point which can expect the effect which stabilizes the driving | running state of an installation in the water treatment using these water treatment apparatuses shown in these FIG. 7, FIG. 8, and the point which can anticipate the effort reduction of concentrated water Is the same as the case of using the water treatment apparatus shown in FIGS.

  In addition, when the water treatment is performed with the water treatment apparatus shown in FIG. 8, it is possible to grasp in advance that the salt concentration of the treated water becomes a predetermined value or more, and the quality of the treated water is more reliably determined. In the point which can be maintained, it is the same as the case where a water treatment is implemented with the water treatment apparatus shown in FIG.

  The water treatment apparatus shown in FIG. 9 and FIG. 10 has concentrated water on the downstream side of the connection point between the concentrated water piping unit 41 and the raw water piping unit 61 at the point where the concentrated water piping unit 41 and the raw water piping unit 21 are connected. The piping part 41 is provided with a discharge amount adjusting mechanism 62 for adjusting the amount of concentrated water discharged out of the system, and the salt concentration measured by the salt concentration measuring mechanism 33 or returned to the raw water. 7 and 8 in that the signal transmission mechanism 5 is arranged so that the discharge amount adjusting mechanism 62 can control the discharge amount of the concentrated water outside the system based on the salt concentration result of the mixed water with the concentrate. It is comprised similarly to the water treatment apparatus shown.

Further, in the point that the concentrated water amount adjusting mechanism 42 using the constant flow valve for controlling the flow rate of the concentrated water to a constant amount is provided upstream from the connection point with the reflux pipe unit 61, FIG. The configuration is the same as in FIG.
On the other hand, in the water treatment apparatus shown in FIG. 7, FIG. 8, etc., all have given examples of a constant flow valve etc. as the treated water quantification mechanism 32 provided in the treated water piping part 31, The water treatment apparatus shown in FIGS. 9 and 10 includes a flow meter 32a provided in the treated water piping section 31 as the treated water quantification mechanism 32, and the rotation of the raw water transport pump 22 based on the measured value of the flow meter 32a. It differs from the water treatment apparatus shown in FIGS. 7 and 8 in that an inverter 32b for changing the number and these control lines 32c (hereinafter also referred to as “treated water quantification control line 32c”) are provided.

  That is, the water treatment apparatus shown in FIGS. 9 and 10 is configured to be able to control the water pressure inside the supply water chamber 13, and for example, deposits are generated on the reverse osmosis membrane or membrane separation is performed. When the water permeation performance of the reverse osmosis membrane fluctuates due to a change in the temperature of the water introduced into the module, the water pressure of the concentrated water inside the supply water chamber 13 is fluctuated according to the fluctuation, and a certain amount It is comprised so that treated water may be obtained.

  For this reason, the water treatment method using the water treatment apparatus shown in FIGS. 9 and 10 treats wastewater having a large variation in water quality such as the content of components and water temperature that generate deposits on the reverse osmosis membrane. It can be said that this is a suitable water treatment method.

In addition to the examples described with reference to FIGS. 1 to 10, various types of control and facility operation methods in a conventionally known water treatment method can be employed.
In addition, the water treatment using the cleaning wastewater in the metal smelting factory as an example has been described above. However, for example, water treatment such as seawater desalination is also within the intended scope of the present invention, and the water treatment of the present invention. According to the method and the water treatment apparatus, it is possible to obtain an effect that water having a certain level of water quality can be stably obtained even in desalination of seawater.

The schematic block diagram which shows the water treatment apparatus used for one Embodiment. The schematic block diagram which shows the water treatment apparatus used for other embodiment. The schematic block diagram which shows the water treatment apparatus used for other embodiment. The schematic block diagram which shows the water treatment apparatus used for other embodiment. The schematic block diagram which shows the water treatment apparatus used for other embodiment. The schematic block diagram which shows the water treatment apparatus used for other embodiment. The schematic block diagram which shows the water treatment apparatus used for other embodiment. The schematic block diagram which shows the water treatment apparatus used for other embodiment. The schematic block diagram which shows the water treatment apparatus used for other embodiment. The schematic block diagram which shows the water treatment apparatus used for other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Membrane separation module 2 Raw water transport mechanism 3 Treated water transport mechanism 4 Concentrated water transport mechanism 5 Signal transmission mechanism 6 Concentrated water recirculation mechanism 11 Housing 12 Reverse osmosis membrane 13 Supply water chamber 14 Permeate water chamber 21 Raw water piping section 22 Raw water transport pump 31 treated water piping section 32 treated water quantification mechanism 32a flow meter 32b inverter 32c control line (treated water quantification control line)
33 Salt concentration measuring mechanism 41 Concentrated water piping section 42 Concentrated water amount adjusting mechanism 51 Inverter 61 Reflux piping section 62 Discharge amount adjusting mechanism 63 Reflux water quantifying mechanism

Claims (2)

By introducing raw water containing salts into a membrane separation module in which a reverse osmosis membrane is used, the reverse is applied to treated water having a lower salt concentration than the raw water and concentrated water having a higher salt concentration than the raw water. By separating the raw water continuously into the membrane separation module, the concentrated water is continuously discharged from the membrane separation module, and the treated water is continuously discharged from the membrane separation module. A water treatment method,
The amount of salts that permeate the reverse osmosis membrane is set to an electric amount of the raw water so that the outflow amount from the membrane separation module of the treated water is controlled to be constant and the salt concentration of the treated water can be controlled to a predetermined value or less. determined by conductivity, characterized in that to suppress the increase in the amount of salts that the transmittance by increasing the flow rate of the raw water when the amount of salts that passes through the reverse osmosis membrane obtained from the electric conductivity is increased Water treatment method. A membrane separation module using a reverse osmosis membrane is provided, and raw water containing salts is flowed into the membrane separation module, and the treated water has a lower salt concentration than the raw water, and the salt concentration is lower than the raw water. The concentrated water is separated into high concentrated water by the reverse osmosis membrane, and the raw water is continuously flowed into the membrane separation module, whereby the concentrated water is continuously discharged from the membrane separation module, and the treated water Is a water treatment device continuously discharged from the membrane separation module,
A control mechanism for controlling the amount of outflow from the membrane separation module of the treated water constant, and the concentration of the treated water salt by changing the amount of the raw water inflow according to the amount of the salt permeating the reverse osmosis membrane A control mechanism for controlling the concentration of the salt of the treated water to a predetermined value or less, and the control mechanism for controlling the concentration of the salt of the treated water to be equal to or less than the predetermined value, An electrical conductivity meter for measuring the amount of salt that permeates the reverse osmosis membrane by the electrical conductivity meter to increase the inflow of the raw water and It is comprised so that the increase in quantity may be suppressed, The water treatment apparatus characterized by the above-mentioned .

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