[0001]
　The present invention relates to a water treatment device.
Background technique
[0002]
　Desalination and seawater, as a technique for performing purification of industrial water, water treatment apparatus using a reverse osmosis membrane has been put to practical use. As a specific example, there is known a technique described in Patent Document 1. The film processing apparatus disclosed in Patent Document 1, each upstream stage side of the membrane module bank with a plurality of membrane modules, and a membrane module bank downstream stage, the raw water to the upstream stage side of the membrane module bank (the It has a pump for pumping the treated water), and.
[0003]
　However, in such devices, with respect to the proportion of fresh water that is recovered from the treatment water such as seawater (fresh water recovery ratio), in advance the target value is defined. When freshwater recovery is too high, the salt concentration in the concentrated water is a component of the fresh water is separated residual resulting in excessively increased. If the concentrated water of high salt concentrations were discharged into the environment, there is concern that environmental load increases. Therefore, if desalinate example seawater, freshwater recovery rate is set to about 25 to 40%.
[0004]
　Meanwhile, with the continuous operation of the device, if the performance of the reverse osmosis membrane is decreased, fresh water recovery ratio is relatively decreased. In this case, by increasing the supply pressure of the water to be treated for the reverse osmosis membrane, it is necessary to compensate for the decrease of the fresh water recovery. To increase the fresh water recovery ratio, by increasing the output of the pump, the supply pressure of the water to be treated for the reverse osmosis membrane is enhanced. By the pressure of the water to be treated is increased, the amount of fresh water that is separated in the reverse osmosis membrane is increased, fresh water recovery starts to rise.
CITATION
Patent Literature
[0005]
Patent Document 1: JP 2013-22544 JP
Summary of the Invention
Problems that the Invention is to Solve
[0006]
　However, with the fresh water recovery as described above is increased, the amount of concentrated water to be separated from the treated water is reduced. That is, in the apparatus described in Patent Document 1, the amount of concentrated water from the upstream stage side of the membrane module bank is supplied to the membrane module banks of the downstream stage is decreased. Furthermore, in the device using a reverse osmosis membrane, the lower limit value is set to the amount of concentrated water discharged from the one per element (flow rate). When the amount of the concentrated water is below the lower limit, problems such as scale deposits is caused by an increase in membrane surface concentration by concentration polarization at the membrane module, there is sufficient separation may not be performed enrichment. Accordingly, in the apparatus described in Patent Document 1, fresh water recovery becomes limited.
[0007]
　The present invention has been made in view of the above circumstances and aims to improve the fresh water recovery and utilization of the water treatment apparatus.
Means for Solving the Problems
[0008]
　The present invention employs the following means to solve the above problems.
　According to a first aspect of the present invention, the water treatment device is disposed in parallel with each other, of the treated water supplied from the upstream side as a reverse osmosis unit that performs processing of separating the primary concentrated water and freshwater a primary unit having a plurality of primary elements, by pumping the water to be treated from an upstream side of the primary unit, a pump for supplying該被treated water to the primary unit, the fewer than said primary element provided together is, are arranged in parallel with each other, and a secondary unit having a secondary element of the primary concentrated water as a reverse osmosis unit that performs processing of separating the secondary condensed water and fresh water, of the secondary concentrated water comprising part and the primary unit and a recirculation section for recirculating between the secondary unit.
[0009]
　In the water treatment apparatus as described above, by increasing the output of the pump, fresh water is recovered from the secondary unit ratio relative to the deposition of the water to be treated (freshwater recovery) increases. When fresh water recovery ratio increases, the amount of secondary concentrated water discharged from the per secondary element is reduced in the secondary unit.
　Here, the primary element, and a reverse osmosis membrane device, such as a secondary element, the lower limit value is set to the amount of concentrated water discharged. In the water treatment device, or a reflux portion, a portion of the secondary concentrated water can be refluxed between the primary unit and the secondary unit. Thus, even when increasing the fresh water recovery ratio, for each secondary element in the secondary unit, it is possible to obtain a concentrated water in an amount exceeding the lower limit of the above.
[0010]
　According to a second aspect of the present invention, the water treatment apparatus according to the first embodiment, the return portion, downstream of the secondary unit, and by connecting the upstream side of the secondary unit, a reflux line for the secondary concentrated water flows, is provided on the return line, and a reflux pump for pumping toward the secondary concentrated water flowing through the reflux line to the upstream side of the secondary unit, the it may be provided.
[0011]
　In the water treatment apparatus as described above, the pressure of the primary concentrated water on the upstream side of the secondary unit is higher than the pressure of the secondary concentrated water downstream of the secondary unit. Here, by providing the reflux pump as described above, it is possible to add a pressure to the secondary concentrated water in the return line. Thus, through the reflux line, it can be refluxed stably toward the secondary concentrated water to the upstream side of the secondary unit.
[0012]
　According to a third aspect of the present invention, the water treatment apparatus according to the first or second aspect, a portion of the water to be treated, from between said pump said primary unit, said primary unit it may include a bypass line for bypassing between the secondary unit.
[0013]
　According to the above-described configuration, when increasing the fresh water recovery ratio, i.e., even when the amount of the secondary concentrated water by the secondary unit is reduced, a portion of the water to be treated through the bypass line, primary without passing through the unit can be bypassed to the upstream side of the secondary unit (between the primary unit and secondary unit). Thus, a portion of the water to be treated, can lead to secondary unit as the primary concentrated water.
[0014]
　According to a fourth aspect of the present invention, the water treatment apparatus according to any one the above aspects, the water to be treated, the primary concentrated water, the secondary concentrated water, at least in one characteristic value of the fresh water comprising a measuring unit for measuring the Langelier saturation index obtained from the characteristic value, based on a comparison of the predetermined reference value, and a control unit for controlling the reflux of the secondary concentrated water by the recirculation section it may be.
[0015]
　According to a fifth aspect of the present invention, the water treatment apparatus according to the fourth embodiment, the characteristic value, the water to be treated, the primary concentrated water, the secondary concentrated water, at least one of the fresh water it is at a temperature, or electrical conductivity, wherein the control unit, the temperature, and may include a calculation unit for calculating the Langelier saturation index based on the electrical conductivity.
[0016]
　According to the above-described configuration, water to be treated, the primary concentrated water, secondary concentrated water, depending on in at least one quality of fresh water, it is possible to maximize the fresh water recovery ratio by the water treatment device. In particular, by providing the control unit and the measurement unit, by autonomously adjusting the performance of the water treatment device to changes in the water quality due to seasonal variations, it is possible to flexibly cope with the change.
Effect of the invention
[0017]
　According to the water treatment apparatus of the present invention, it is possible to improve the fresh water recovery and utilization.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018]
Is a system diagram showing a water treatment apparatus according to the first embodiment of FIG. 1 the present invention.
Is a system diagram showing a water treatment apparatus according to a second embodiment of the present invention; FIG.
3 is a system diagram showing a water treatment apparatus according to a modification of the present invention.
DESCRIPTION OF THE INVENTION
[0019]
First Embodiment
　For the first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the water treatment device 1 according to this embodiment, the intake line L1 treatment water SW flows, a pump P for pumping the downstream water to be treated SW from an upstream water intake line L1, a plurality reverse osmosis unit (primary element E1, the secondary element E2) in preparation primary unit U1 having, and a secondary unit U2, a connecting line Lc connecting these primary unit U1 and a secondary unit U2 to each other, the there. Furthermore, the water treatment device 1 has a portion of the secondary concentrated water CW2, a reflux unit 2 to recirculate between (on the connection line Lc) of the primary unit U1 and a secondary unit U2.
[0020]
　Intake line L1 is a flow path for guiding the treated water SW supplied from the outside to the water treatment device 1. On the upstream side of the intake line L1, for example, pre-processing unit (not shown) is provided. In the pretreatment device, it or oxidizing agent for suppressing the organisms contained in the sea water is attached to the apparatus, fine particles, addition of the agent for aggregating the colloid, and adjustment of pH is carried out. More specifically, such hypochlorite is preferably used as the oxidizing agent. Further, as the coagulant and an inorganic coagulant such as ferric chloride, polymer flocculants such as PAC are used. Suspension are agglomerated by these coagulants are removed by sand filter.
[0021]
　Thus, treated water SW that has been subjected to pretreatment, by a pump P provided on intake line L1, is pumped toward the downstream side medium said mounting water line L1 from the upstream side.
[0022]
　Primary unit U1, and the secondary unit U2 is a device for separating and concentrating by reverse osmosis treated water SW guided by the intake line L1. Primary unit U1 includes a plurality of primary elements E1 arranged in parallel with each other, a primary distribution line Ld1 for distributing the water to be treated SW in intake line L1 relative to the plurality of primary elements E1, emissions from the primary element E1 is primary concentrated water CW1, and freshwater (primary freshwater FW1) has primary catchment line Lg1 flowing respectively, and the primary freshwater line Lf1, the.
[0023]
　Primary Element E1 is a reverse osmosis membrane (RO membrane: Reverse Osmosis Membrane) such as a hollow fiber membrane or a spiral membrane is the reverse osmosis unit provided inside the. Each primary element E1 includes an exterior member called a vessel is provided with a reverse osmosis membrane arranged inside the vessel, mainly. Furthermore, the vessel, the primary inlet E11 connected to the distribution line, a primary catchment line Lg1, and primary freshwater line Lf1 primary condensing Mizuguchi respectively connected to E12, and primary freshwater collecting Mizuguchi E13, is provided It is.
[0024]
　Primary unit U1 is constituted by the primary element E1 is arranged in parallel with each other. In the present embodiment as an example, five primary elements E1 are arranged in parallel. More specifically, the downstream end of the intake line L1, a primary inlet E11 of each primary element E1 are connected to one another by the distribution lines. Furthermore, the primary condensing water line Lg1 includes a primary condensing Mizuguchi E12 of each of the primary elements E1, are connected to each other and the upstream end of the connecting line Lc (described later). Primary freshwater line Lf1 is a flow path for discharging and recovering separated fresh water to the outside in each primary element E1. Downstream of the primary freshwater line Lf1 is and tanks for storing the recovered fresh water, equipment is connected for applying a further filtration (both not shown). By being configured as described above, five primary elements E1 is at an parallel.
　Although only describes an example in which five secondary elements E2 provided in the present embodiment, the number of secondary element E2 is not limited to five, as long as more than the number of later-described secondary element E2 the may be four or less or may be six or more.
[0025]
　The secondary unit U2 is a configuration similar to that the primary unit U1, a device for further separation and concentration of the primary concentrated water CW1 generated by the primary unit U1. More specifically, the secondary unit U2 is partitioned with a plurality of secondary elements E2 arranged in parallel with one another, these for a plurality of secondary element E2, a primary concentrated water CW1 generated by the primary unit U1 a secondary distribution lines Ld2, secondary concentrated water CW2 discharged from the secondary element E2, and freshwater (secondary freshwater FW2) flows respectively secondary catchment line Lg2, and a secondary freshwater line Lf2, the It has.
[0026]
　Although the secondary element E2 is reverse osmosis membrane apparatus having the same structure as performance and Primary Element E1 above, distinguish these in the following description. The vessel of the secondary element E2, secondary and secondary inlet E21 connected to the dispensing line Ld2, secondary catchment line Lg2, and secondary freshwater line secondary convex respectively connected to Lf2 Mizuguchi E22 and, a secondary fresh water collection Mizuguchi E23, is provided.
[0027]
　In the present embodiment, since the three secondary element E2 is arranged in parallel with each other to form a secondary unit U2. The number of secondary element E2 in the secondary unit U2 is set smaller than the number of primary element E1 in the primary unit U1. In this embodiment, the secondary unit U2 will be described an example which is provided with three secondary elements E2, the number of secondary elements E2, to the extent less than said primary element E1 is a two may be, it may be four or more.
[0028]
　Connection lines Lc are connected with the downstream side of the primary unit U1, and a secondary unit U2. More specifically, the connection line Lc connects the downstream end of the respective primary catchment line Lg1 in the primary unit U1, the upstream end of each secondary distribution lines Ld2 in the secondary unit U2 to each other ing. Thus, the primary concentrated water CW1 generated by the primary unit U1, the primary condensing water line Lg1, connection lines Lc, and by distribution in the order of the secondary distribution lines Ld2, each secondary element E2 of the secondary unit U2 It is distributed. In the secondary element E2, by the primary concentrated water CW1 is further separation and concentration, fresh water and (secondary freshwater FW2), and the secondary concentrated water CW2 as a component of the residual except the secondary freshwater FW2 is generated It is. Fresh water is recovered through the secondary fresh water line Lf2. After secondary concentrated water CW2 is recovered through secondary catchment line Lg2, and is discharged to the outside via the post-processing by external equipment (not shown).
[0029]
　Further in the water treatment apparatus 1, a reflux portion 2 for recirculating a portion of the secondary concentrated water CW2 in a flow path between the primary unit U1 and the secondary unit U2 is provided in this embodiment. More specifically, the recirculation section 2 is branched from the secondary catchment line Lg2, and a reflux line Lc1 connected on said connection line Lc, reflux pump provided on the reflux line Lc1 and Pc, the recirculation valve V1 for switching the flow state of the reflux line Lc1, and a.
[0030]
　In other words, the reflux line Lc1 are connected to each other and a downstream side and the upstream side of the secondary unit U2. Here, the upstream side of the secondary unit U2, the pressure of the concentrated water (primary concentrated water CW1) is higher than the downstream side. Accordingly, the recirculation section 2 according to the present embodiment, by reflux pump Pc, are added the pressure toward the downstream side to the upstream side along the reflux line Lc1. Thus, a portion of the secondary concentrated water CW2 in the reflux line Lc1 is circulated toward the upstream side (on the connection line Lc) from the downstream side of the secondary unit U2 (upper secondary catchment line Lg2).
　Reflux valve V1 is, specifically, a valve device capable of adjusting the flow rate. That is, by adjusting the degree of opening of the recirculation valve V1, it is possible to adjust the amount of secondary concentrated water CW2 circulating medium reflux line Lc1.
[0031]
　Next, a configuration has been operating the water treatment apparatus 1, as described above.
　Under normal operating conditions, the reflux valve V1 in the recirculation section 2 above is closed. By driving the pump P in this state, the water to be treated SW is led to the primary unit U1 via the intake line L1. Treatment water SW pressurized by the pump P is passed through a high pressure state with respect to the reverse osmosis membrane of each primary element E1.
[0032]
　In the primary unit U1, reverse osmosis is carried out with respect to the treatment water SW in each primary element E1. Thus, in the primary element E1 includes a primary concentrated water CW1 salinity and the like in the treatment water SW is concentrated primary freshwater FW1 and a residual component excluding the primary concentrated water CW1 (fresh water) is generated . More specifically, among the water to be treated SW, the primary fresh water FW1 by fresh water component reaches the downstream through the reverse osmosis membrane. By primary freshwater FW1 is transmitted to the downstream side, the upstream side of the reverse osmosis membrane, salts contained in the treated water SW is concentrated. Thus, the primary concentrated water CW1 are generated at the upstream side of the reverse osmosis membrane. In the downstream side of the reverse osmosis membrane, a pressure of the primary freshwater FW1 is smaller than the pressure of the treated water SW.
[0033]
　Primary freshwater FW1 is recovered to the outside through the above-mentioned primary freshwater line Lf1. The primary concentrated water CW1, after collected in the primary catchment line Lg1, and flows into the secondary unit U2 on the downstream side via the connection line Lc. In the secondary unit U2, the primary concentrated water CW1 which has flowed through the connecting line Lc is respectively distributed to the secondary element E2 by secondary distribution lines Ld2.
[0034]
　Among the secondary element E2, similarly to the primary element E1, and concentrated freshwater isolation and salts from the primary concentrated water CW1 is performed. That is, as the fresh ingredients in the primary concentrated water CW1 secondary freshwater FW2, and a component of the residual secondary concentrated water CW2 except the secondary freshwater FW2 are generated.
[0035]
　Secondary freshwater FW2 is recovered to the outside by the secondary freshwater FW2 collecting water line. Secondary concentrated water CW2, after collected in the secondary catchment line Lg2, and is discharged into the outside environment. By the above operation is continuously performed, the water to be treated SW (seawater) is desalinated.
[0036]
　Incidentally, the water treatment device 1 as described above, the volume ratio of fresh water that is recovered from the treated water SW (freshwater recovery) in advance the target value is defined. For example, to desalinate seawater, freshwater recovery rate is set to about 25 to 40%. However, with the continuous operation of the device, if the performance of the reverse osmosis membrane is decreased, fresh water recovery is relatively lowered, which may fall below the target value of the. In this case, by increasing the output of the pump P, the supply pressure of the water to be treated SW for reverse osmosis membrane is enhanced. By the pressure of the water to be treated SW increases, the amount of fresh water that is separated in the reverse osmosis membrane is increased, fresh water recovery starts to rise.
[0037]
　On the other hand, with the fresh water recovery as described above is increased, the amount of secondary concentrated water CW2 is separated from treated water SW is reduced. Here, in the apparatus using a reverse osmosis membrane, the lower limit value is set to the amount of concentrated water discharged (flow rate). When the amount of the concentrated water is below the lower limit, problems such as scale deposits is caused by an increase in membrane surface concentration by concentration polarization at the membrane module, there is sufficient separation may not be performed enrichment.
[0038]
　Therefore, the water treatment apparatus 1 according to this embodiment, the upstream part of the secondary unit U2 of CW2 secondary concentrate by recirculation section 2 of the (more specifically, the primary unit U1 secondary unit U2 and refluxed to the connection on the line Lc) between. Thus, it is possible to relatively increase the amount of secondary concentrated water CW2 discharged from the secondary element E2 in the secondary unit U2. Therefore, the amount of secondary concentrated water CW2 discharged from each of the secondary element E2, may be greater than the lower limit.
[0039]
　Additionally, reflux of secondary concentrated water CW2 as described above, the driving of the reflux pump Pc, and can be easily carried out only by opening the recirculation valve V1. In particular, the valve device, such as the reflux valve V1 can be opened and closed in the water treatment apparatus 1 of the passing water (in operation). That is, in the water treatment apparatus 1 according to this embodiment, without stopping the operation, it is possible to recirculate a part of the secondary concentrated water CW2 upstream. Thus, it is possible to improve the freshwater recovery rate without lowering the operating rate of the water treatment apparatus 1.
[0040]
　In addition, the water treatment device 1 as described above, even when the amount of by increasing the fresh water recoveries primary concentrated water CW1 is reduced, thereby passed through all of the secondary element E2 in the secondary unit U2 be able to. In other words, if the amount of primary concentrated water CW1 is reduced, there is no need take action, including the unhandled detach a part of the secondary element E2 from the system. In general, the reverse osmosis unit to be processed impossible (secondary element E2), in order to protect the reverse osmosis membrane, it is necessary to fill the storage solution. However, with the above configuration, since the concentrated water to all of the secondary element E2 is passed through, it is possible to omit the equipment and steps for performing the filling and the like of the storage solution. Thus, it is possible to reduce the construction cost, and maintenance cost of the apparatus.
[0041]
[Second Embodiment]
　Next, a second embodiment of the present invention will be described with reference to FIG. Incidentally, the same reference numerals are given to configurations similar to the first embodiment described above, a detailed description thereof will be omitted.
　As shown in FIG. 2, the water treatment apparatus 1 according to this embodiment, in addition to the recirculation section 2 described above, the bypass portion 3 is provided. More specifically, the bypass portion 3, between the pump P and the primary unit U1 on intake line L1, and a bypass line Lb1 for connecting the primary unit U1 and the secondary unit U2, the bypass line Lb1 includes a bypass valve V2 provided in the above, the.
[0042]
　Such bypass line Lb1, a part of the components of the water to be treated SW is taken out of circulation medium intake line L1, without passing through the primary unit U1, is guided to the upstream side of the secondary unit U2. In other words, some components of the water to be treated SW taken out from intake line L1 is supplied to the secondary unit U2 as primary concentrated water CW1 (reduction).
[0043]
　According to the above configuration, it is possible to relatively increase the amount of primary concentrated water CW1 guided to the secondary element E2 in the secondary unit U2. Thus, the amount of secondary concentrated water CW2 discharged from each of the secondary element E2, may be larger than the lower limit of the amount of concentrated water determined for each secondary element E2.
[0044]
　Furthermore, removal of the water to be treated SW as described above, and the operation of the bypass can be easily performed only by opening the bypass valve V2. In particular, the valve device, such as the bypass valve V2 may be opened and closed in the water treatment apparatus 1 of the passing water (in operation). Therefore, the water treatment apparatus 1 according to this embodiment, without stopping the operation, a portion of the water to be treated SW can be bypassed toward the secondary unit U2. Thus, it is possible to improve the freshwater recovery rate without lowering the operating rate of the water treatment apparatus 1.
[0045]
　It has been described with reference to the drawings the embodiments of the present invention. However, the embodiments described above is only an example and can be variously modified without departing from the gist of the present invention.
[0046]
　For example, refluxing 2 in each embodiment described above, when operating the bypass section 3 may be performed by an operator's hand may be performed by the control unit shown in FIG. When using a control unit 4, on the intake line L1 described above, and on the connection line Lc, water (water to be treated SW in each line by providing a measuring unit 5, a primary concentrated water CW1, secondary concentrated water CW2, primary freshwater FW1, characteristic value of the secondary freshwater FW2) is measured. Based on these characteristic values, the control unit 4 recirculation section 2 (recirculation valve V1), controls the bypass unit 3 (opening and closing the bypass valve V2).
[0047]
　More specifically, as the measuring unit 5, the apparatus and capable to measure the electrical conductivity of the water, such as thermometer is appropriately used.
[0048]
　Control unit 4 includes an arithmetic unit 41 that calculates a characteristic value based on the value obtained by measurement by the measurement unit 5, a reflux portion 2 on the basis of the characteristic value calculated by the arithmetic unit 41, and the bypass section 3 a determination unit 42 operation necessity has recirculation valve V1 based on the determination of the determination unit 42, a signal generator 43 for instructing the opening of the bypass valve V2 as an electric signal.
[0049]
　When employing the above configuration, the measurement section 5, the electrical conductivity of the water, temperature, LSI (Langelier Saturation Index: Langeliar Saturation Index) continuously measuring the characteristic values ​​such as. Determining unit 42 in the control unit 4 performs with these characteristic values, the comparison with the reference value or reference range determined in advance. If it meets the reference value or reference range, the determination unit 42 determines that it is possible to raise the fresh water recovery ratio, opens the recirculation valve V1, the bypass valve V2.
[0050]
　Incidentally, definitive when using LSI as an index, the "if they meet the reference value or reference range", when LSI is smaller than the reference value (e.g., less than zero) it corresponds.
[0051]
　The determination of the increase in availability of fresh water recovery is usually performed to confirm the scale deposition presence of the element by LSI, but electrical conductivity, may be the same determination based on the temperature.
[0052]
　Values generally LSI, the electrical conductivity of the measured water, and on the values of the temperature. Furthermore, the electrical conductivity is determined by the dissolved salt concentration in the water (i.e., the concentration of salt dissolved in the ionic state as the electrolyte). Further, as the temperature of the water rises 1 ° C., the value of the LSI is generally 1.5 × 10 -2 increases.
[0053]
　Thus, the electrical conductivity by measuring unit 5, and after the temperature measured, the arithmetic unit 41 in the control unit 4, by carrying out calculation based on these characteristic values, it is also possible to adopt a configuration that calculates the LSI converted value is there. Even in this case, the determination unit 42 of the control unit 4, based on the LSI converted value, determines an increase availability of fresh water recovery.
[0054]
　According to such a configuration, depending on the quality of the water to be treated SW, the autonomously can be maximized freshwater recovery rates. In particular, the performance of the water treatment device 1 can correspond flexibly to changes in the water quality due to seasonal fluctuations.
[0055]
　In the case where both equipped with a reflux unit 2 and the bypass unit 3, it is desirable to define in advance priority for these devices. For example, if it is necessary to increase the fresh water recovery ratio, configuration is conceivable to first perform the reflux of the secondary concentrate CW2 by recirculation section 2 preferentially. In addition, the refluxing of the secondary concentrated water CW2, by the salt concentration at the inlet of the secondary unit U2 increases and the amount is relatively increased fresh water discharged from the primary unit U1 (permeate), permeate FLUX If is exceed the allowable value, by opening the bypass section 3 (bypass line Lb1) in addition, it is preferable to adopt a configuration for introducing the treatment water SW to the secondary unit U2.
Industrial Applicability
[0056]
　Water treatment device 1 described above, and according to the method of operating the water treatment apparatus 1, it is possible to improve the freshwater recovery and utilization.
DESCRIPTION OF SYMBOLS
[0057]
1 ... water treatment device 2 ... recirculation section 3 ... bypass section 4 ... control unit 41 ... computing unit 42 ... judging section 43 ... signal generator 5 ... measuring unit CW1 ... primary concentrated water CW2 ... secondary retentate E1 ... Primary Element E11 ... the primary inlet E12 ... the primary condensing Mizuguchi E13 ... the primary fresh water collection Mizuguchi E2 ... secondary element E21 ... secondary inlet E22 ... secondary collection Mizuguchi E23 ... secondary freshwater collection Mizuguchi FW1 ... the primary fresh water FW2 ... secondary freshwater L1 ... water intake line Lb1 ... bypass line Lc ... connection line Lc1 ... reflux line Ld1 ... primary distribution lines Ld2 ... secondary distribution lines Lf1 ... the primary fresh water line Lf2 ... secondary fresh water line Lg1 ... the primary condensing water line Lg2 ... secondary catchment line P ... pump Pc ... reflux pump SW ... treatment water U1 ... primary unit U2 ... second unit V1 ... recirculation valve V2 ... bypass valve

[Claim 1]
　Are arranged in parallel with each other, a primary unit having a plurality of primary elements of a reverse osmosis unit that performs processing of separating the treated water in the primary concentrate and fresh water supplied from the upstream side,
　the water to be treated the by pumping from the upstream side of the primary unit, a pump for supplying該被treated water to said primary unit,
　said with a small number are provided than the primary elements, are arranged in parallel with each other, the primary concentrated water two and a secondary unit having a secondary element of a reverse osmosis unit for performing a process for separating into the next retentate and fresh water,
　recirculating a part of the secondary concentrated water between the secondary unit and the primary unit , a reflux unit for
water treatment device comprising a.
[Claim 2]
　The return unit,
　downstream of the secondary unit, and by connecting the upstream side of the secondary unit, the reflux line of the secondary concentrated water flows,
　is provided on the return line, the reflux a reflux pump for pumping the secondary concentrated water which flows through the line toward the upstream side of the secondary unit,
the water treatment apparatus according to claim 1 comprising a.
[Claim 3]
　Wherein a portion of the water to be treated, from between said pump the primary unit, the water treatment apparatus according to claim 1 or 2 comprising a bypass line for bypassing between the primary unit and the secondary unit.
[Claim 4]
　The water to be treated, the primary concentrated water, the secondary concentrated water, and a measuring unit for measuring at least in one characteristic value of the fresh water,
　the Langelier saturation index obtained from the characteristic value, the reference value set in advance based on the comparison of a control unit for controlling the reflux of the secondary concentrated water by the recirculation section
water treatment apparatus according to any one of claims 1-3 comprising a.
[Claim 5]
　The characteristic value, the water to be treated, the primary concentrated water, the secondary concentrated water, at least in one temperature, or electrical conductivity of the fresh water,
　the control unit, the temperature and the electrical conductivity water treatment device according to claim 4 comprising a calculation unit for calculating the Langelier saturation index based.