JP2012170848A - Water treatment system and method for injecting flocculant therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment system which can highly accurately control a flocculant injection rate and can impede the generation of fouling and to provide a method for injecting a flocculant therefor.SOLUTION: The water treatment system comprises pretreatment apparatuses 3 and 11, a reverse osmosis membrane module 6, a flocculant injection apparatus 10 which injects a flocculant into seawater fed into the pretreatment apparatuses, a water quality analyzer 32 which measures the TEP amount and other water quality items of seawater at a position downward of the pretreatment apparatuses, a recording apparatus 23 which records a water quality analysis result being a combination of at least two water quality items, correlation derivation means 21-23 which derive the TEP vs. flocculant injection rate correlation, the other water qualities vs. flocculant injection rate correlation, and the correlation between at least two water quality items, and a flocculant injection rate control means 20 which selects the initial value of a suitable flocculant injection rate from past actual data, determines a flocculant injection rate by using the water quality measurements results and a plurality of the correlations, and controls the flocculant injection apparatus so as to attain the determined flocculant injection rate.

Description

  The present invention relates to a water treatment system that filters brackish water, seawater, groundwater or landfill leachate, industrial wastewater, and the like containing solutes such as ions and salts with a reverse osmosis membrane module and a coagulant injection method thereof.

  Membrane filtration is known as a method for obtaining domestic water, industrial water, and agricultural water from brackish water, seawater, groundwater or landfill leachate, industrial wastewater and the like containing solutes such as ions and salts. There is a method using a reverse osmosis membrane as one of the membrane filtration methods. A reverse osmosis membrane (RO membrane) is a membrane that does not allow impurities other than water, such as ions and salts, to pass through water. Water and solutes are separated by applying a pressure higher than the osmotic pressure according to the solute concentration. To separate.

  As a water treatment system using such a reverse osmosis membrane module, for example, in a seawater desalination system, before seawater is desalted through a reverse osmosis membrane module, turbidity, algae, microorganisms, etc. contained in the taken seawater are suspended. A flocculant is injected to remove turbid substances to form flocs to facilitate removal, followed by pretreatment such as sand filtration and membrane filtration. In addition to sand filtration, membrane filtration such as microfiltration membranes (MF membranes) and ultrafiltration membranes (UF membranes), which are membrane modules, is used for this pretreatment.

  Conventionally, as the control system for the flocculant injection rate, many have calculated the flocculant injection rate from a physical and chemical viewpoint. For example, in membrane filtration processing of seawater, There is also a problem from a biological point of view that biological dirt and fouling occur on the membrane surface due to dissolved organic matter, microorganisms, particularly highly viscous organic matter released by microorganisms, and inorganic ions.

  The quality of the water to be treated is subject to time and seasonal variations, as well as geographical differences, and the fouling factors are affected by these factors, so that the appropriate flocculant injection rate varies accordingly. Among the fouling, those that significantly reduce the filterability are irreversible dirt, and it is important to suppress the generation.

  As a means to suppress fouling, grasp the amount of substances that cause fouling in the target water to be treated, and determine membrane filtration operating conditions and filter membranes according to the risk of fouling formation. Various methods for controlling the cleaning conditions have been proposed.

  For example, Patent Document 1 proposes a method of installing an aggregation monitoring device, measuring the turbidity or chromaticity of a collected sample, and controlling the injection amount of the flocculant according to the measured value. Patent Document 2 proposes a method of obtaining a flocculant injection rate from the correlation between the turbidity of raw water and the flocculant injection rate and controlling the amount of the flocculant injected based on the obtained injection rate. Furthermore, in Patent Document 3, the coagulant injection rate is corrected according to the deviation from the set value of the residual coagulant main component concentration from the residual coagulant main component concentration in the treated water containing flocs after the flocculant injection. A method has been proposed.

JP-A-5-146608 JP 2007-029851 A JP 2010-137115 A

  However, none of the above-described prior arts has absolutely fewer process condition items for determining the flocculant injection rate, and in particular, the prior art does not consider any biological factors as process condition items. In other words, it is inadequate to control the injection rate with high accuracy. Biological factors have a great influence on the water treatment process, and it becomes difficult to obtain a stable treated water quality when the water quality of the treated water fluctuates daily or seasonally. A fouling that clogs the pretreatment system and the reverse osmosis membrane module in the subsequent stage occurs, and it becomes difficult to continue the operation, which may lead to a decrease in operating rate.

  The present invention has been made to solve the above problems, and provides a water treatment system capable of controlling the flocculant injection rate with high accuracy and effectively preventing fouling, and a flocculant injection method thereof. The purpose is to do.

  In the present invention, turbidity, SDI, MFI in the treated water and the treated water that has been pretreated in order to adapt to the problems from the physical and chemical viewpoints in consideration of the biological factors described above. , TOC, E260, TEP (Transparent Exopolymer Particle: hereinafter referred to as TEP) amount, Chlorophyll a amount, Phytoplankton number, Fluorescence intensity, etc. By measuring the membrane differential pressure in consideration of the suppression of the increase in the differential pressure of the reverse osmosis membrane, and calculating the coagulant injection rate from the relationship set in advance in at least two or more combinations from these results Optimize.

  Furthermore, the quality of the water to be treated has time and seasonal variations, and further geographical differences, and the appropriate coagulant injection rate varies accordingly, so that the water temperature, salt concentration, The water quality index can be corrected in consideration of pH and alkalinity.

  The present invention newly adds consideration from the above-mentioned biological viewpoint, and includes the following means for solving the above problems.

  The water treatment system according to the present invention includes a pretreatment device that filters solute-containing water to remove foreign substances, a reverse osmosis membrane module that separates and removes solute by membrane filtration of the pretreated solute-containing water, A flocculant injection device for injecting and adding a flocculant to the solute-containing water supplied to the treatment device; and the amount of transparent extracellular polymer particles of the solute-containing water at the downstream side of the pretreatment device and at least one other A first water quality analyzer for measuring each of the water quality measurement items, a recording device for recording a water quality analysis measurement result obtained by combining at least two water quality measurement items obtained from the water quality analysis device, and the transparent cell A correlation between the amount of the outer polymer particles and the injection rate of the flocculant, a correlation between the other water chamber measurement item and the injection rate of the flocculant, and the at least two or more water qualities. Correlation between measurement items A relational expression deriving means for deriving each of the relational expressions, an initial value of an appropriate flocculant injection rate from past performance data, and an injection of the flocculant from the selected initial value, and further from the recording device Using the called water quality analysis measurement result and the correlation expression derived by the relational expression deriving means, a coagulant injection rate is obtained, and the coagulant injection device is controlled to obtain the obtained coagulant injection rate. And a flocculant injection rate control means.

  The important terms in the present specification are respectively defined below.

  Solute-containing water refers to brackish water, seawater, groundwater, landfill leachate, industrial wastewater containing solutes such as ions and salts. In particular, it refers to seawater and brackish water that contain a large amount of inorganic components such as ions and salts as solutes.

  Transparent extracellular polymer particles are transparent exopolymer particles (abbreviated as TEP), and are substances that cause a so-called slimy substance that is sticky on the surface of an object. TEP is one of the causative agents of fouling that not only adheres to the surface of the membrane, but also clogs the micropores, significantly reducing the filterability of the membrane and causing irreversible clogging. TEP is a substance generated for various reasons. From the biological viewpoint, TEP is composed of transparent extracellular polymer particles emitted from living cells and transparent extracellular polymer particles emitted from dead cells. Inclusive.

  The Silt Density Index is the Silt Density Index (abbreviated as SDI), which is one of the water quality indicators defined by ASTM D4189.

  The modified fouling index is a modified fouling index (abbreviated as MFI), which is a semi-quantitative water quality index that indicates how much fouling occurs in the membrane by the liquid to be subjected to membrane filtration. Incidentally, the fouling index is defined in JIS K3802.

  Total organic carbon is Total Organic Carbon (abbreviated as TOC), which is a water quality indicator that indicates the total amount of organic matter that can be oxidized in water as the amount of carbon. TOC is one of the water quality indicators that can replace the previous BOD and COD.

  The ultraviolet absorbance is one of water quality indicators indicating the degree of light absorption when water is irradiated with ultraviolet light having a wavelength of 260 nm, and is expressed by E260. By the way, E260 is an index that shows how much organic substances with double bonds are contained in water.

1 is a configuration block diagram showing a water treatment system according to a first embodiment of the present invention. The block diagram which shows the water treatment system which concerns on the 2nd Embodiment of this invention. The block diagram which shows the water treatment system which concerns on the 3rd Embodiment of this invention. The block diagram which shows the water treatment system which concerns on the 4th Embodiment of this invention. The block diagram which shows the water treatment system which concerns on the 5th Embodiment of this invention. The block diagram which shows the water treatment system which concerns on the 6th Embodiment of this invention. The block diagram which shows the water treatment system which concerns on the 7th Embodiment of this invention. The block diagram which shows the water treatment system which concerns on the 8th Embodiment of this invention. The characteristic diagram used when selecting the flocculant injection rate in the method of this invention. The characteristic diagram used when selecting the flocculant injection rate in the method of this invention. The characteristic diagram used when selecting the flocculant injection rate in the conventional method. The flowchart for implementing the method of this invention. The characteristic line figure for demonstrating the selection procedure of the coagulant injection rate in the method of this invention. The characteristic line figure for demonstrating the selection procedure of the coagulant injection rate in the method of this invention.

  As a result of intensive studies on the relationship between the process conditions in the operation of the water treatment system and the water quality items related to biological factors, the present inventors are not a single substance that causes membrane fouling in treated water. It was found that a plurality of substances interacted to form fouling. Furthermore, the present inventors have analyzed the water quality items related to biological factors of the treated water in detail, and combined the at least two or more of the water quality items of various biological factors to optimize the flocculant injection rate. I found out that I would like to make it easier.

  The present invention has been made based on such knowledge, and preferred embodiments thereof will be described below.

  (1) A water treatment system according to an embodiment of the present invention includes a pretreatment device (3, 11) for removing foreign substances by filtering solute-containing water, and membrane-filtering the pretreated solute-containing water to remove the solute. A reverse osmosis membrane module (6) for separation and removal, a flocculant injection device (10) for injecting and adding a flocculant to the solute-containing water supplied to the pretreatment device, and a downstream side of the pretreatment device A first water quality analyzer (32) for measuring the amount of transparent extracellular polymer particles of solute-containing water and at least one other water quality measurement item, and at least two or more obtained from the water quality analyzer A recording device (23) for recording water quality analysis measurement results combining water quality measurement items, a correlation equation between the amount of the transparent extracellular polymer particles and the injection rate of the flocculant, and the other water quality measurement items And the coagulant injection rate, Select a relational expression deriving means (21-23) for deriving a correlation expression between at least two water quality measurement items, and an appropriate initial value of the coagulant injection rate from past performance data. Then, the injection of the flocculant is started from the selected initial value, and further, the flocculant injection rate is obtained using the water quality analysis measurement result called from the recording device and the correlation formula derived by the relational expression deriving means. And a flocculant injection rate control means (20) for controlling the flocculant injection device so as to obtain the obtained flocculant injection rate.

  In this embodiment, it is possible to optimize the flocculant injection rate by analyzing water quality measurement items related to biological factors of solute-containing water and combining at least two of these results.

  Here, considering only the two water quality measurement items and considering the priority of the combination, the combination of TEP and turbidity is the most preferable, the combination of TEP and MFI is the next most preferable, and TEP and E260 are combined. The combination with is next preferred. Of course, if three or four or more water quality measurement items are combined, the flocculant injection rate can be controlled with higher accuracy.

  (2) In the above (1), the pretreatment device is a sand filtration device having a sand filtration layer, and the amount of the transparent extracellular polymer particles of solute-containing water and at least one in the upstream side of the pretreatment device. It is preferable to further have a second water quality analyzer that measures other water quality measurement items.

  According to this embodiment, foreign substances contained in the solute-containing water, for example, insoluble solids such as sand particles and fibers, can be quickly and reliably removed by the sand filtration layer, and the load on the downstream equipment and devices is reduced. In addition, the life of the RO membrane of the reverse osmosis membrane device is extended.

  Further, according to the present embodiment, the water quality measurement item on the upstream side of the pretreatment device can be measured and analyzed using the second water quality analyzer, and the flocculant injection rate can be controlled with higher accuracy. .

  (3) In (1) above, the water quality analysis result obtained by the first water quality analyzer is set as a control target value, the set control target value is recorded in the recording device, and the recorded control target value is Called from the recording device, the called control target value is sent to the flocculant injection rate control means, the flocculant injection rate control means is used to determine the flocculant injection rate using the control target value, and the obtained flocculant injection It is preferable to further have a feedback control means for feedback-controlling the flocculant injection device so as to achieve a rate.

  According to the present embodiment, feedback control of the flocculant injection rate by the feedback control means has an advantage that the optimization time of the flocculant injection rate from the initial value to the optimum value is shortened.

  (4) In (2), the water quality analysis result obtained by the second water quality analyzer is set as a control target value, the set control target value is recorded in the recording device, and the recorded control target value is Called from the recording device, the called control target value is sent to the flocculant injection rate control means, the flocculant injection rate control means is used to determine the flocculant injection rate using the control target value, and the obtained flocculant injection It is preferable to further have a feedback control means for feedback-controlling the flocculant injection device so as to achieve a rate.

  Also in the present embodiment, as in (3) above, the feedback control of the flocculant injection rate by the feedback control means shortens the optimization time of the flocculant injection rate from the initial value to the optimum value. There are advantages.

  Furthermore, according to the present embodiment, not only the water quality measurement items on the downstream side of the pretreatment apparatus but also the water quality measurement items on the upstream side contribute to the optimization of the coagulant injection rate. The injection rate can be feedback controlled with higher accuracy.

  (5) In the above (1), it is preferable to use a membrane filtration device having a filtration membrane as the pretreatment device. As the membrane filtration device of this embodiment, a microfiltration membrane (MF membrane) or an ultrafiltration membrane (UF membrane) can be used.

  According to the present embodiment, when the filtration function is reduced due to clogging or the like, the reduced filtration membrane can be easily replaced, so that the maintenance inspection time is shorter than the sand filtration device, and the maintenance inspection cost is reduced. Is reduced.

  (6) In the above (5), a second water quality analyzer that measures the amount of transparent extracellular polymer particles of solute-containing water and at least one other water quality measurement item on the upstream side of the pretreatment device, respectively. It is preferable to further have.

  According to this embodiment, it is possible to measure and analyze the water quality measurement items on the upstream side of the pretreatment device using the second water quality analyzer, and to control the flocculant injection rate with higher accuracy.

  (7) In (5), the water quality analysis result obtained by the first water quality analyzer is set as a control target value, the set control target value is recorded in the recording device, and the recorded control target value is Called from the recording device, the called control target value is sent to the flocculant injection rate control means, the flocculant injection rate control means is used to determine the flocculant injection rate using the control target value, and the obtained flocculant injection It is preferable to further have a feedback control means for feedback-controlling the flocculant injection device so as to achieve a rate.

  According to the present embodiment, feedback control of the flocculant injection rate by the feedback control means has an advantage that the optimization time of the flocculant injection rate from the initial value to the optimum value is shortened.

  (8) In (6), the water quality analysis result obtained by the second water quality analyzer is set as a control target value, the set control target value is recorded in the recording device, and the recorded control target value is Called from the recording device, the called control target value is sent to the flocculant injection rate control means, the flocculant injection rate control means is used to determine the flocculant injection rate using the control target value, and the obtained flocculant injection It is preferable to further have a feedback control means for feedback-controlling the flocculant injection device so as to achieve a rate.

  According to the present embodiment, not only the water quality measurement items on the downstream side of the pretreatment apparatus but also the water quality measurement items on the upstream side contribute to the optimization of the coagulant injection rate. Feedback control can be performed.

  (9) In any one of the above (1) to (8), means for measuring the continuous water quality of the solute-containing water and the state of the plant respectively on the upstream side and the downstream side of the pretreatment device, and the flocculant injection An event occurs such as a means for automatically changing the rate, a means for judging the quality of the treatment, and at the start of injection of the flocculant injection device, when the water quality fluctuates, and / or when the plant conditions are changed. In this case, it is preferable to further include an arithmetic unit that obtains an appropriate injection rate.

  According to the present embodiment, the coagulant injection rate can be controlled to the optimum value to the same extent as under manned monitoring even under unattended monitoring without an operator.

  (10) In any of the above (1) to (9), the other water quality measurement items are turbidity, silt density index (SDI), modified fouling index (MFI), total organic carbon (TOC) Preferably, it is one or more selected from the group consisting of an amount, ultraviolet absorbance (E260), chlorophyll a amount, phytoplankton number, and fluorescence intensity.

  In the present embodiment, attention is paid to turbidity, SDI, MFI, TOC, E260, chlorophyll a amount, phytoplankton number, and fluorescence intensity from a biological viewpoint as water quality measurement items other than TEP, and at least one of these is selected. The optimum value of the flocculant injection rate can be obtained by calculation using a combination of the two measurement results and the TEP amount measurement result and the correlation equation.

  The most preferable combination of water quality measurement items is a combination of TEP and turbidity, the next preferable is a combination of TEP and E260, and the next preferable is a combination of TEP and MFI.

  (11) The flocculant injection method of the water treatment system according to the embodiment of the present invention includes (a) filtering solute-containing water by a pretreatment device to remove foreign matters, and (b) pretreated solute-containing water. (C) the amount of transparent extracellular polymer particles of solute-containing water and at least one other water quality measurement item on the downstream side of the pretreatment device; (D) Record the water quality analysis measurement result combining at least two measured water quality measurement items in a recording device, and (e) the amount of the transparent extracellular polymer particles and the injection rate of the flocculant A correlation formula between the other water chamber measurement item and the injection rate of the flocculant, and a correlation formula between the at least two water quality measurement items. (F) Appropriate from past performance data The initial value of the flocculant injection rate is selected, the flocculant injection is started from the selected initial value, and the flocculant injection rate is calculated using the water quality analysis measurement result and the correlation equation called from the recording device. And the amount of the flocculant injected into the solute-containing water supplied to the pretreatment device is controlled so that the calculated flocculant injection rate is obtained.

  In this embodiment, it is possible to optimize the flocculant injection rate by analyzing water quality measurement items related to biological factors of solute-containing water and combining at least two of these results.

  Hereinafter, an example of a seawater desalination plant system will be described as an example of various preferred modes for carrying out the present invention with reference to the accompanying drawings.

(First embodiment)
First, a water treatment system 1 according to a first embodiment will be described with reference to FIG.

  The water treatment system 1 of the present embodiment includes a raw water tank 2, a supply pump P1, a flow meter 31, a sand filtration device 3 as a pretreatment device, a first treatment tank arranged in series in order from the upstream side along a piping line. The water quality analyzer 32, the adjustment water tank 4, the water pump P2, the security filter 5, the high pressure pump P3, the reverse osmosis membrane module 6, and the treated water tank 7 are provided. Furthermore, the water treatment system 1 has a flocculant injection device 10 as a peripheral device, and the flocculant is injected into the upstream line L2 immediately before the inlet of the sand filtration device 3.

  The water treatment system 1 includes a control system 20 provided in a control room of a management building located away from the site site. The control system 20 includes a CPU 21 as a flocculant injection rate control means, an input / output interface 22 that forms part of the configuration of a relational expression derivation means, and a database 23 as a recording device. The control system 20 keeps equipment and devices on the site site under constant monitoring, and the overall process in the water treatment system is controlled in an integrated manner.

  The raw water tank 2 is a tank that stores seawater pumped up by a pump (not shown) through a piping line L1 drawn into the sea.

  The sand filtration device 3 is connected to the raw water tank 2 via a supply line L2 to which a pump P1 and a flow meter 31 are attached. The sand filtration device 3 has a sand filtration layer for filtering and removing foreign matters (solid matter, etc.) contained in seawater sent from the raw water tank 2, and burdens on the downstream devices 4, 5, 6. It functions as a pre-processing device for reducing the problem.

  The flow meter 31 measures the flow rate of the seawater flowing through the line L2, and sends a flow rate detection signal S1 to the input / output interface 22 in the input unit of the control system 20.

  A line L10 from the flocculant injection device 10 is connected to the line L2 between the raw water tank 2 and the sand filtration device 3, and the flocculant is injected into the seawater immediately before being supplied to the sand filtration device 3. ing. The injection control of the flocculant will be described later.

  The first water quality analyzer 32 has a function of measuring and analyzing the quality of seawater. In this embodiment, the two water quality measurement items TEP and turbidity are measured, and the signal S2 is controlled by the control system. The data is sent to 20 input / output interfaces 22.

  The adjustment water tank 4 has a function of temporarily storing the pretreated water sent from the sand filtration device 3 via the line L3 and precipitating the suspended substance by the action of the flocculant. The outlet of the adjusted water tank 4 is connected to the safety filter 5 via a line L4, and the supernatant water is sent from the adjusted water tank 4 to the safety filter 5 by the water pump P2.

  A safety filter 5 is installed between the water pump P2 and the high-pressure pump P3, and in order to prevent clogging of the membrane of the reverse osmosis membrane module 6, turbidity having a certain particle size is removed. ing. The outlet of the safety filter 5 is connected to the reverse osmosis membrane module 6 via the high pressure line L5 so that high pressure seawater of about 6 MPa is applied from the safety filter 5 to the RO membrane in the reverse osmosis membrane module 6 by the high pressure pump P3. It has become.

  The primary side of the reverse osmosis membrane module 6 communicates with the pressure recovery line L62, and high-pressure concentrated seawater (brine) is discharged from the reverse osmosis membrane module 6 through the line L62 and sent to a pressure recovery device (not shown). ing. Moreover, the secondary side of the reverse osmosis membrane module 6 communicates with the treated water discharge line L61, and treated water (fresh water) is sent to the treated water tank 7 through the line L61.

  The treated water tank 7 is a tank for temporarily storing treated water (fresh water) that has permeated through the RO membrane, and the outlet feeds water to a device or apparatus in a later process (not shown) via the water feed line L7. .

  Next, the operation of this embodiment will be described.

  Seawater is supplied to the sand filtration device 3 by the supply pump P <b> 1 to perform pretreatment, and is temporarily stored in the adjustment water tank 4. Thereafter, seawater in the adjustment water tank 4 is fed to the high pressure pump P3 by the water pump P2, and the high pressure pump P3 boosts the seawater to a high pressure state (about 6 MPa) and feeds it to the reverse osmosis membrane module 6. The safety filter 5 removes turbidity or the like having a certain particle size in order to suppress clogging of the membrane of the reverse osmosis membrane module 6.

  The reverse osmosis membrane module 6 removes solutes such as ions and salts contained in the raw water, is stored in the treated water tank 7, and is supplied to another reverse osmosis membrane module (not shown) in order to obtain better water quality. Sometimes. The solute removed by the reverse osmosis membrane module 6 is drained as concentrated water. Since this concentrated water is high pressure, from the viewpoint of energy recovery, many methods are used that are sent to the power recovery device and used (not shown).

  A first water quality analysis device 32 is installed in a line between the sand filtration device 3 as a pretreatment device and the adjustment tank 4 in order to perform water quality analysis of seawater after the pretreatment system. In the present embodiment, since the flocculant injection rate control is optimized by combining two or more water quality analysis results, the first water quality analysis device 32 is provided with a plurality of water quality analysis devices according to the application. May be. The water quality analyzer 32 measures regularly at a predetermined cycle, and also performs measurement when a certain event occurs.

  The control system 20 controls the coagulant injection rate from the pretreated water quality result after the pretreatment from the first water quality analyzer 32. For example, from the two results of the water quality item x and the water quality item y, When obtaining the optimum coagulant injection rate K, first, the optimum value of each water quality item is extracted. For example, in the water quality item x, the optimum flocculant injection rate is shown in FIG. 12, and when a certain event occurs, an appropriate flocculant such as the previous value is obtained along the method (storage means) as shown in FIG. Injection is performed with the injection rate set as an initial value. Thereafter, the injection rate is automatically increased by n times at regular intervals, a characteristic curve f (Kx) of the water quality item x is created and added to the recording device. In f (Kx) at that time, the flocculant injection rate at which dX / dKx = 0 is extracted, and this is set as the optimum flocculant injection rate of the water quality item x. However, when the flocculant injection rate continues to decrease as shown in FIG. 14, the optimum value is set when the threshold value is reached. Furthermore, also in the water quality item y, the optimal flocculant injection rate in the water quality item y is obtained by the above procedure. Thus, after the optimum coagulant injection rates are determined as Kx (water quality item x) and Ky (water quality item y), for example, a new Kz is obtained from a relationship such as the following equation (1).

Kz = a · Kx + b · Ky (1)
a: weighting factor for water quality item x, b: weighting factor for water quality item y where a + b = 1.

  If there are more than two water quality items, use the following equation (2) instead of equation (1) to select an arbitrary n and determine the optimal flocculant injection rate considering the results of n water quality items Extract.

K = w1 · K1 + w2 · K2 + ... + wn · Kn (2)
A flocculant injection device 10 is installed in a line L10 between the supply pump P1 and the sand filtration device 3. The flocculant injection device 10 incorporates a flow rate adjustment valve whose operation is controlled by the control system 20.

  The water quality analysis of the water to be treated is performed by the water quality analyzer 32, and the result is controlled by the control system 20. The flocculant injection rate is calculated by the above procedure, the injection rate is extracted, and the flow rate measured by the flow meter 31. Accordingly, an injection amount of the flocculant is injected from the flocculant injection device 10.

  In the present invention, the optimum value of the target value is searched using the water quality analyzer 32 after the pretreatment system, similarly to the operator's thought pattern.

  In the water treatment system 1 using the reverse osmosis membrane module 6, for example, before the seawater is desalted through the reverse osmosis membrane module, suspended substances such as turbidity, algae, and microorganisms contained in the taken seawater are removed. In order to remove, after the flocculant is injected, the sand filtration device 3 is used for pretreatment.

  In the present embodiment, the first water quality analysis device 32 analyzes the water quality of the seawater downstream from the pretreatment device, controls the result in the control system 20, calculates the coagulant injection rate according to the above procedure, and calculates the injection rate. The flocculant is injected by the flocculant injection device 10 according to the flow rate measured by the flow meter 31.

  The effect of this embodiment will be described.

  In the water treatment system 1 of the present embodiment, water quality analysis of seawater as solute-containing water is performed, and control is performed in combination with at least two of the results, thereby providing more reliable control and water quality analysis of seawater. Therefore, it is not limited to a specific water quality and can be applied widely, and can be adapted to water quality fluctuations due to weather, geographical differences, etc., so that the coagulant injection rate can be optimized.

  In this embodiment, it is possible to determine the appropriateness of the injected flocculant injection rate by calculating the flocculant injection rate by water quality analysis of the water to be treated after the pretreatment system, and the injected flocculant injection rate is If it is not appropriate, a more precise coagulant injection rate can be calculated by deriving a relational expression between the water quality item being measured and the injection rate, and extracting a new optimal injection rate, enabling cost reduction. Become.

  Compared to the case where the coagulant injection rate is selected based on one water quality analysis result as shown in FIG. 11, at least two water quality analysis results are adopted as shown in FIGS. 9 and 10, and each water quality result is weighted. By adding a coefficient and calculating from the previously set relationship as described above, it is possible to prevent more serious problems such as drug overdose, cost increase, and biological growth. For example, as shown in FIG. 9, when there are two water quality analysis items A and B (severity of the problem, priority: B> A), the coagulant injection rate is the optimum value X of the water quality item A and the optimum of the water quality item B. From the value Y, the optimum coagulant injection rate Z is calculated from a preset relationship. According to this example, the flocculant injection rate increases, but by taking into account the value of the water quality item B, which is a more serious problem, in order to suppress other problems in the water treatment facility, overall, cost reduction, etc. Connected. Furthermore, in the case shown in FIG. 10, the flocculant injection rate can be reduced.

  In this embodiment, the flocculant injection rate is also controlled from a biological viewpoint such as TEP, phytoplankton, and chlorophyll a, which is considered to be one of the factors of fouling. Costs can be reduced because problems such as loss are taken into consideration.

(Second Embodiment)
A water treatment system according to the second embodiment will be described with reference to FIG. In addition, description of the part which this embodiment overlaps with said embodiment is abbreviate | omitted.

  The water treatment system 1 </ b> A of the present embodiment is different in that a second water quality analyzer 33 is newly installed in a line L <b> 2 between the sand filtration system 3 and the flow meter 31. Similar to the first water quality analyzer 32, the second water quality analyzer 33 measures two water quality measurement items, TEP and turbidity.

  The operation of this embodiment will be described.

  The control system 20A controls the coagulant injection rate based on the water quality results of the water to be treated from the upstream water quality analyzer 33 and the downstream water quality analyzer 32. For example, the control system 20A includes a water quality item x and a water quality item y. When obtaining the optimum coagulant injection rate K from the two results, first, the optimum value of each water quality item in the treated water before the pretreatment system is extracted. For example, in the water quality item x, when an event occurs as shown in FIG. 12, the optimal flocculant injection rate is set as an initial value along the storage means as shown in FIG. inject. Thereafter, the injection rate is automatically increased by n times at regular intervals, a characteristic curve f (Kx) of the water quality item x is created and added to the recording device. In f (Kx) at that time, the flocculant injection rate at which dX / dKx = 0 is extracted, and this is set as the optimum flocculant injection rate of the water quality item x. However, when the flocculant injection rate continues to decrease as shown in FIG. 14, the optimum value is set when the threshold value provided is reached. Furthermore, also in the water quality item y, the optimal flocculant injection rate in the water quality item y is obtained by the above procedure. In this way, after the optimum coagulant injection rate is determined as Kx (water quality item x) and Ky (water quality item y), a new Kz is obtained from a relationship such as equation (1).

Kz = a · Kx + b · Ky (1)
a: weighting factor for water quality item x, b: weighting factor for water quality item y where a + b = 1.

  When there are more than two water quality items, the formula (1) becomes the formula (2), and arbitrary n pieces are selected, and the optimum coagulant injection rate is extracted in consideration of the n water quality item results.

K = w1 · K1 + w2 · K2 + ... + wn · Kn (2)
In the present embodiment, the optimum value of the target value is searched using the water quality analysis device 32 after the pretreatment system, similarly to the operator's thought pattern.

  In a water treatment system using a reverse osmosis membrane module, for example, before desalting seawater through a reverse osmosis membrane module, suspended substances such as turbidity, algae, and microorganisms contained in the taken seawater are removed. Therefore, after inject | pouring a flocculant, it pre-processes using a sand filtration system.

  In the present embodiment, the second water quality analyzer 33 analyzes the water quality of the solute-containing water upstream of the pretreatment device 3 to set an initial value, and the first water quality analysis device 32 sets the downstream of the pretreatment device 3. The water quality analysis of the solute-containing water is performed on the side, the result is controlled in the control system 20, the coagulant injection rate is calculated by the above procedure, the injection rate is extracted, and the aggregation is performed according to the flow rate measured by the flow meter 31. An injection amount of the flocculant is injected by the agent injection device 10.

  The effect of this embodiment will be described.

  In the water treatment system 1A of the present embodiment, water quality analysis of the upstream and downstream seawater of the pretreatment device is performed, and by controlling the combination of at least two results, more reliable control and Become. In addition, by analyzing the quality of the water to be treated before the pretreatment system, it is not limited to a specific water quality, so it can be applied widely and can be adapted to water quality fluctuations due to weather and geographical differences. It is possible to optimize the rate.

  In this embodiment, it is possible to determine the appropriateness of the injected flocculant injection rate by performing a water quality analysis of the seawater downstream of the pretreatment device. If the injected flocculant injection rate is not appropriate, measurement is performed. Since the relational expression between the water quality item and the injection rate can be derived and a new optimum injection rate can be extracted, the cost can be reduced. In addition, water quality analysis of the seawater upstream from the pretreatment device is performed, and the initial value is set closer to the optimum coagulant injection rate at that time by setting the initial value based on the analysis result and pre-recorded storage means. Since it can be set, the time required to extract the optimum value of the injection rate can be shortened and the amount of injection to be shaken can be reduced, which can further contribute to cost reduction.

  Compared to the case where the coagulant injection rate is selected based on one water quality analysis result as shown in FIG. 11, at least two water quality analysis results are adopted as shown in FIGS. By assigning a weighting factor and calculating from a preset relationship such as Equation 1, more serious problems such as drug overdose, cost increase and biological growth can be prevented. For example, as shown in FIG. 9, when there are two water quality analysis items A1 and B1 (severity of the problem, priority: B1> A1), the coagulant injection rate is the optimum value X of the water quality item A1 and the optimum of the water quality item B1. From the value Y, the optimum coagulant injection rate Z is calculated from a preset relationship. According to this example, the flocculant injection rate increases, but by taking into account the value of the water quality item B1, which is a more serious problem, in order to suppress other problems in the water treatment facility, overall, cost reduction, etc. Connected. Furthermore, in the case shown in FIG. 10, the flocculant injection rate can be reduced.

  Next, a coagulant injection control method for optimally controlling the coagulant injection rate using the above-described water treatment system will be described with reference to FIG.

  Regardless of whether the control room of the management building is manned or unmanned, the water treatment system is constantly monitored by a monitoring device. In such a constantly monitored water treatment system, the control system 20 determines whether any event has occurred in the water treatment system (step K1).

  If it is determined that some event has occurred in the water treatment system, it is next determined whether or not there is a water quality analyzer A (second water quality analyzer) (step K2). Here, an event that occurs in the water treatment system is a sudden change in process conditions such as a rapid rise in the temperature of seawater taken in due to the inflow of warm current.

  When it is determined that the water quality analyzer A is present, an initial value is set based on the water quality analysis result of the seawater, and the flocculant is injected into the seawater before being pretreated by the pretreatment device 3 at the flocculant injection rate according to the initial value. Start (step K3).

  When it is determined that there is no water quality analyzer A, the injection of the flocculant is started with the optimum flocculant injection rate for the same month as the initial value from the past performance data (step K4).

  Next, the analysis result after the injection of the flocculant is recorded in the recording means (step K5).

The flocculant injection rate is changed to a value different from the initial value, and the flocculant is injected (step K6). For example, the flocculant injection rate is changed in the direction of decreasing the flocculant from the initial value. After the flocculant injection, the analysis result of the water quality measurement item of seawater is recorded in the recording means (step K7).

  Next, it is determined whether or not the rate of change of the characteristic curve f (k) corresponding to the correlation equation between the water quality measurement item and the flocculant injection rate increases (step K8).

  When it is determined that the change rate of the characteristic curve f (k) is increased, the flocculant is injected by changing the flocculant injection rate in the direction of increasing from the initial value (step K9).

  Next, the analysis result after injecting the flocculant is recorded in the recording means (step K10).

  The flocculant injection rate is further changed in the same direction as the previous change of the flocculant injection rate (step K11). That is, the flocculant is injected into the seawater by further changing the flocculant injection rate from the initial value.

  It is determined whether or not the rate of change of the characteristic curve f (k) corresponding to the correlation equation between the water quality measurement item and the flocculant injection rate increases (step K12).

  When it is determined that the rate of change of the characteristic curve f (k) increases, the coagulant injection rate at which dX / dK = 0 is set as the optimum coagulant injection rate of the water quality item X (step K13). Thereafter, the respective flocculant injection rates for at least two water quality items are determined, and an optimum flocculant injection rate is newly determined from them. The analysis result of the water quality measurement item of the seawater after the injection of the flocculant is recorded in the recording means (step K15).

  If it is determined that the rate of change of the characteristic curve f (k) does not increase, it is next determined whether or not the rate of change of the characteristic curve f (k) has reached the threshold shown in FIG. 14 (step K14). This threshold value serves as a criterion for determining the control target value, and is a value set with reference to past performance data.

  When it is determined that the rate of change of the characteristic curve f (k) has reached the threshold, the threshold is set as the optimum flocculant injection rate for the water quality item X (step K16). Thereafter, the respective flocculant injection rates for at least two water quality items are determined, and an optimum flocculant injection rate is newly determined from them. The analysis result of the water quality measurement item of the seawater after the injection of the flocculant is recorded in the recording means (step K17).

  According to this embodiment, since the flocculant injection rate is also controlled from a biochemical point of view such as TEP, phytoplankton, and chlorophyll a, which are considered to be one of the factors of fouling, clogging of membranes and in piping Costs can be reduced because problems such as pressure loss are taken into consideration.

(Third embodiment)
A water treatment system according to a third embodiment will be described with reference to FIG. In addition, description of the part which this embodiment overlaps with said embodiment is abbreviate | omitted.

  The water treatment system 1B of the present embodiment is different in that a feedback control circuit 24 that functions as feedback control means is newly provided in the control system 20B.

  The first water quality analyzer 32 has a function of measuring and analyzing the quality of seawater, and in this embodiment, two water quality measurement items TEP and E260 are measured.

  The operation of this embodiment will be described.

  The control system 20B controls the flocculant injection rate based on the water quality result of the seawater downstream from the pretreatment device from the first water quality analyzer 32. For example, the control system 20B includes two water quality items x and water quality item y. When obtaining the optimum coagulant injection rate K from the results, first, the optimum value of each water quality item is extracted. For example, in the water quality item x, the optimum flocculant injection rate is as shown in FIG. 12, and when there is a recording means as shown in FIG. 13 when a certain event occurs, the flocculant injection rate is set along the recording means. Set and inject flocculant. On the other hand, when there is no storage means, an appropriate flocculant injection rate such as the previous value is set as an initial value for injection. Thereafter, the injection rate is automatically increased by n times at regular intervals, a characteristic curve f (Kx) of the water quality item x is created and added to the recording device. In f (Kx) at that time, the flocculant injection rate at which dX / dKx = 0 is extracted, and this is set as the optimum flocculant injection rate of the water quality item x. However, when the flocculant injection rate continues to decrease as shown in FIG. 14, the optimum value is set when the threshold value provided is reached. Furthermore, also in the water quality item y, the optimal flocculant injection rate in the water quality item y is obtained by the above procedure. In this way, after the optimum coagulant injection rate is determined as Kx (water quality item x) and Ky (water quality item y), a new Kz is obtained from a relationship such as equation (1). With this Kz as a target value, the pretreated water quality items x and y are corrected by feedback control to control the coagulant injection rate.

Kz = a · Kx + b · Ky (1)
a: weighting factor for water quality item x, b: weighting factor for water quality item y where a + b = 1.

  When there are more than two water quality items, the formula (1) becomes the formula (2), and arbitrary n pieces are selected, and the optimum coagulant injection rate is extracted in consideration of the n water quality item results.

K = w1 · K1 + w2 · K2 + ... + wn · Kn (2)
In the present embodiment, the optimum value of the target value is searched using the first water quality analysis device 32 on the downstream side of the pretreatment device, similarly to the operator's thought pattern.

  In a water treatment system using a reverse osmosis membrane module, for example, before desalting seawater through a reverse osmosis membrane module, suspended substances such as turbidity, algae, and microorganisms contained in the taken seawater are removed. Therefore, after inject | pouring a flocculant, it pre-processes using a sand filtration system.

  In the present embodiment, the first water quality analyzer 32 performs water quality analysis on the downstream side of the pretreatment device, the result is controlled by the control system 20B, the coagulant injection rate is calculated by the above procedure, and the injection rate is extracted. Then, feedback control is performed using this value as a target value to correct the injection rate, and the coagulant injection apparatus 10 injects an injection amount of the coagulant according to the flow rate measured by the flow meter 31.

  The effect of this embodiment will be described.

  In the water treatment system 1B of the present embodiment, water quality analysis of seawater downstream of the pretreatment device is performed and control is performed by combining at least two of the results, and more reliable control is performed, and the extracted injection rate By performing feedback control, the injection rate can be corrected and kept constant.

  In this embodiment, it is possible to determine the appropriateness of the injected flocculant injection rate by calculating the flocculant injection rate by analyzing the quality of seawater downstream of the pretreatment device, and the injected flocculant injection rate is If it is not appropriate, a more precise coagulant injection rate can be calculated by deriving a relational expression between the water quality item being measured and the injection rate, and extracting a new optimal injection rate, enabling cost reduction. Become.

  Compared to the case where the coagulant injection rate is selected based on one water quality analysis result as shown in FIG. 11, at least two water quality analysis results are adopted as shown in FIGS. By assigning a weighting factor and calculating from the previously set relationship as described above, it is possible to prevent more serious problems such as drug overdose, cost increase, and biological growth. For example, as shown in FIG. 9, when there are two water quality analysis items A1 and B1 (severity of the problem, priority: B1> A1), the coagulant injection rate is the optimum value X of the water quality item A1 and the optimum of the water quality item B1. From the value Y, the optimum coagulant injection rate Z is calculated from a preset relationship. According to this example, the flocculant injection rate increases, but by taking into account the value of the water quality item B1, which is a more serious problem, in order to suppress other problems in the water treatment facility, overall, cost reduction, etc. Connected. Furthermore, in the case shown in FIG. 10, the flocculant injection rate can be reduced.

  According to the present embodiment, the flocculant injection rate is controlled also from a biological viewpoint such as TEP, E260, phytoplankton, chlorophyll a, which is considered to be one of the factors of fouling. Costs can be reduced because problems such as clogging and pressure loss in piping are taken into consideration.

(Fourth embodiment)
A water treatment system according to a fourth embodiment will be described with reference to FIG. In addition, description of the part which this embodiment overlaps with said embodiment is abbreviate | omitted.

  In the water treatment system 1C of the present embodiment, a second water quality analyzer 33 is newly installed in the line L2 between the sand filter 3 and the flow meter 31, and functions as a feedback control means in the control system 20C. The difference is that a feedback control circuit 24 is provided.

  The second water quality analyzer 33 has a function of measuring and analyzing the quality of seawater, and in this embodiment, two water quality measurement items TEP and MFI are measured. Similarly, the first water quality analyzer 32 measures two water quality measurement items TEP and MFI.

  The operation of this embodiment will be described.

  The fourth embodiment differs from the second embodiment in that feedback control means 24 is newly installed and the injection rate extracted by the coagulant injection rate calculation means is corrected by feedback control.

  The effect of this embodiment will be described.

  In the water treatment system 1C of the present embodiment, water quality analysis of seawater is performed on the upstream side and the downstream side of the pretreatment device, respectively, and at least two or more of the results are combined and controlled, thereby enabling more reliable control It becomes. In addition, by analyzing the water quality of the seawater upstream of the pretreatment device, it is not limited to a specific water quality, so it can be applied to a wide range and can be adapted to water quality fluctuations due to weather and geographical differences. It is possible to optimize the injection rate.

  In this embodiment, it is possible to determine the appropriateness of the injected flocculant injection rate by performing a water quality analysis on the downstream side of the pretreatment device, and when the injected flocculant injection rate is not appropriate, measurement is performed. Since the relational expression between the water quality item and the injection rate can be derived and a new optimum injection rate can be extracted, the cost can be reduced. Also, water quality analysis of the seawater upstream of the pretreatment device is performed, and the initial value is set closer to the optimum coagulant injection rate at that time by setting the initial value based on the analysis result and pre-recorded storage means. Since it can be set, the time required to extract the optimum value of the injection rate can be shortened and the amount of injection to be shaken can be reduced, which can further contribute to cost reduction. The optimum flocculant injection rate thus extracted can be corrected by feedback control and kept constant.

  Compared to the case where the coagulant injection rate is selected based on one water quality analysis result as shown in FIG. 11, at least two water quality analysis results are adopted as shown in FIGS. By assigning a weighting factor and calculating from a preset relationship such as Equation 1, more serious problems such as drug overdose, cost increase and biological growth can be prevented. For example, as shown in FIG. 9, when there are two water quality analysis items A1 and B1 (severity of the problem, priority: B1> A1), the coagulant injection rate is the optimum value X of the water quality item A1 and the optimum of the water quality item B1. From the value Y, the optimum coagulant injection rate Z is calculated from a preset relationship. According to this example, the flocculant injection rate increases, but by taking into account the value of the water quality item B1, which is a more serious problem, in order to suppress other problems in the water treatment facility, overall, cost reduction, etc. Connected. Furthermore, in the case shown in FIG. 10, the flocculant injection rate can be reduced.

  The present invention controls the flocculant injection rate from the viewpoint of biochemistry such as TEP, MFI, phytoplankton, and chlorophyll a, which is considered to be one of the factors of fouling. In consideration of problems such as pressure loss, the cost can be reduced.

(Fifth embodiment)
A water treatment system according to a fifth embodiment will be described with reference to FIG. In addition, description of the part which this embodiment overlaps with said embodiment is abbreviate | omitted.

  The water treatment system 1D of this embodiment is different in that a membrane filtration device 11 is installed as a pretreatment device instead of the sand filtration device of the first embodiment. As a filtration membrane of the membrane filtration device 11, a microfiltration membrane (MF membrane) or an ultrafiltration membrane (UF membrane) can be used.

  The operation of this embodiment will be described.

  In a water treatment system using a reverse osmosis membrane module, for example, before desalting seawater through a reverse osmosis membrane module, suspended substances such as turbidity, algae, and microorganisms contained in the taken seawater are removed. Therefore, after injecting the flocculant, the membrane filtration device 11 is used for pretreatment.

  Sea water quality varies with time, seasons, and geographical differences, and the appropriate coagulant injection rate varies accordingly. Therefore, the water quality items in the above description (means for solving the problems) are necessary. In addition, the water quality index can be corrected in consideration of the reverse pressure osmosis membrane in the latter stage and the increase in the differential pressure of the membrane of the membrane filtration device 11 as the pretreatment.

  The effect of this embodiment will be described.

  In the water treatment system 1D of the present embodiment, by performing a water quality analysis of seawater and controlling the combination of at least two of the results, it becomes more reliable control, and by performing a water quality analysis of the treated water, Since it is not limited to a specific water quality, it can be widely applied and can be adapted to fluctuations in water quality due to weather, geographical differences, etc., so that it is possible to optimize the flocculant injection rate.

  In this embodiment, it is possible to determine the appropriateness of the injected flocculant injection rate by calculating the flocculant injection rate by analyzing the quality of seawater downstream of the pretreatment device, and the injected flocculant injection rate is If it is not appropriate, a more precise coagulant injection rate can be calculated by deriving a relational expression between the water quality item being measured and the injection rate, and extracting a new optimal injection rate, enabling cost reduction. Become.

  Compared to the case where the coagulant injection rate is selected based on one water quality analysis result as shown in FIG. 11, at least two water quality analysis results are adopted as shown in FIGS. 9 and 10, and each water quality result is weighted. By adding a coefficient and performing calculation based on the relationship set in advance as described above, it is possible to prevent more serious problems such as drug overdose, cost increase, and biological growth. For example, as shown in FIG. 9, when there are two water quality analysis items A1 and B1 (severity of the problem, priority: B1> A1), the coagulant injection rate is the optimum value X of the water quality item A1 and the optimum of the water quality item B1. From the value Y, the optimum coagulant injection rate Z is calculated from a preset relationship. According to this example, the flocculant injection rate increases, but by taking into account the value of the water quality item B1, which is a more serious problem, in order to suppress other problems in the water treatment facility, overall, cost reduction, etc. Connected. Furthermore, in the case shown in FIG. 10, the flocculant injection rate can be reduced.

  Since the present invention controls the flocculant injection rate from the biological viewpoint such as TEP, phytoplankton, and chlorophyll a, which is considered to be one of the factors of fouling, membrane clogging and pressure loss in piping Therefore, cost reduction can be realized.

(Sixth embodiment)
A water treatment system according to a sixth embodiment will be described with reference to FIG. In addition, description of the part which this embodiment overlaps with said embodiment is abbreviate | omitted.

  In the water treatment system 1E of the present embodiment, the membrane filtration device 11 is installed as a pretreatment device instead of the sand filtration device, and the second water quality analysis device is installed in the line L2 between the membrane filtration device 11 and the flow meter 31. The difference is that 33 is newly installed.

  The operation of this embodiment will be described.

  Sea water quality varies with time, seasons, and geographical differences, and the appropriate coagulant injection rate varies accordingly. Therefore, the water quality items in the above description (means for solving the problems) are necessary. In addition, the water quality index can be corrected in consideration of the increase in the differential pressure of the reverse osmosis membrane in the latter stage and the membrane of the membrane filtration system as the pretreatment.

  The effect of this embodiment will be described.

  In the water treatment system 1E of the present embodiment, the water quality analysis of the upstream and downstream seawaters of the pretreatment device is performed, and the control is performed with a combination of at least two results, thereby providing more reliable control. It becomes. In addition, by analyzing the water quality of the seawater upstream of the pretreatment device, it is not limited to a specific water quality, so it can be applied to a wide range and can be adapted to water quality fluctuations due to weather and geographical differences. It is possible to optimize the injection rate.

  In this embodiment, it is possible to determine the appropriateness of the injected flocculant injection rate by performing a water quality analysis of the seawater downstream of the pretreatment device. If the injected flocculant injection rate is not appropriate, measurement is performed. Since the relational expression between the water quality item and the injection rate can be derived and a new optimum injection rate can be extracted, the cost can be reduced. Also, water quality analysis of the seawater upstream of the pretreatment device is performed, and the initial value is set closer to the optimum coagulant injection rate at that time by setting the initial value based on the analysis result and pre-recorded storage means. Since it can be set, the time required to extract the optimum value of the injection rate can be shortened and the amount of injection to be shaken can be reduced, which can further contribute to cost reduction.

  Compared to the case where the coagulant injection rate is selected based on one water quality analysis result as shown in FIG. 11, at least two water quality analysis results are adopted as shown in FIGS. 9 and 10, and each water quality result is weighted. By adding a coefficient and calculating from a preset relationship such as equation (1), it is possible to prevent more serious problems such as drug overdose, cost increase, and biological growth. . For example, as shown in FIG. 9, when there are two water quality analysis items A1 and B1 (severity of the problem, priority: B1> A1), the coagulant injection rate is the optimum value X of the water quality item A1 and the optimum of the water quality item B1. From the value Y, the optimum coagulant injection rate Z is calculated from a preset relationship. According to this example, the flocculant injection rate increases, but by taking into account the value of the water quality item B1, which is a more serious problem, in order to suppress other problems in the water treatment facility, overall, cost reduction, etc. Connected. Furthermore, in the case shown in FIG. 10, the flocculant injection rate can be reduced.

  In this embodiment, the flocculant injection rate is also controlled from a biochemical viewpoint such as TEP, phytoplankton, and chlorophyll a, which is considered to be one of the factors of fouling. Costs can be reduced because problems such as loss are taken into consideration.

(Seventh embodiment)
A water treatment system according to a seventh embodiment will be described with reference to FIG. In addition, description of the part which this embodiment overlaps with said embodiment is abbreviate | omitted.

  The water treatment system 1F of this embodiment is different in that a membrane filtration device 11 is installed as a pretreatment device instead of a sand filtration device, and a feedback control circuit 24 that functions as a feedback control means is provided in the control system 20C. .

  The operation of this embodiment will be described.

  The seventh embodiment is different from the third embodiment in that the sand filtration system 3 is changed to a membrane filtration device 11.

  Sea water quality varies with time, seasons, and geographical differences, and the appropriate coagulant injection rate varies accordingly. Therefore, the water quality items in the above description (means for solving the problems) are necessary. In addition, it is also possible to correct the water quality index in consideration of the increase in the differential pressure of the membrane of the reverse osmosis membrane in the latter stage and the membrane filtration device 11 as the pretreatment device.

  The effect of this embodiment will be described.

  In the water treatment system 1F of the present embodiment, water quality analysis of seawater downstream of the pretreatment device is performed, and the control is performed with more reliability by combining at least two of the results, and the extracted injection The injection rate can be corrected and kept constant by feedback control of the rate.

  In the present invention, it is possible to determine the appropriateness of the injected flocculant injection rate by calculating the flocculant injection rate by analyzing the water quality of seawater downstream of the pretreatment device, and the injected flocculant injection rate is appropriate. If not, the relationship between the water quality item being measured and the injection rate can be derived, and a new optimum injection rate can be extracted to calculate a stricter flocculant injection rate, thereby reducing costs. .

  Compared to the case where the coagulant injection rate is selected based on one water quality analysis result as shown in FIG. 11, at least two water quality analysis results are adopted as shown in FIGS. 9 and 10, and each water quality result is weighted. By adding a coefficient and calculating from the previously set relationship as described above, it is possible to prevent more serious problems such as drug overdose, cost increase, and biological growth. For example, as shown in FIG. 9, when there are two water quality analysis items A1 and B1 (severity of the problem, priority: B1> A1), the coagulant injection rate is the optimum value X of the water quality item A1 and the optimum of the water quality item B1. From the value Y, the optimum coagulant injection rate Z is calculated from a preset relationship. According to this example, the flocculant injection rate increases, but by taking into account the value of the water quality item B1, which is a more serious problem, in order to suppress other problems in the water treatment facility, overall, cost reduction, etc. Connected. Furthermore, in the case shown in FIG. 10, the flocculant injection rate can be reduced.

  In this embodiment, the flocculant injection rate is also controlled from a biological viewpoint such as TEP, phytoplankton, and chlorophyll a, which is considered to be one of the factors of fouling. Costs can be reduced because problems such as loss are taken into consideration.

(Eighth embodiment)
A water treatment system according to the eighth embodiment will be described with reference to FIG. In addition, description of the part which this embodiment overlaps with said embodiment is abbreviate | omitted.

  In the water treatment system 1G of the present embodiment, a membrane filtration device 11 is installed as a pretreatment device instead of a sand filtration device, and a second water quality analysis device is installed in a line L2 between the membrane filtration device 11 and the flow meter 31. The difference is that 33 is newly installed and a feedback control circuit 24 that functions as feedback control means is provided in the control system 20G.

  The operation of this embodiment will be described.

  The eighth embodiment is different from the fifth embodiment in that the sand filtration system 3 is changed to a membrane filtration device 11.

  Sea water quality varies with time, seasons, and geographical differences, and the appropriate coagulant injection rate varies accordingly. Therefore, the water quality items in the above description (means for solving the problems) are necessary. In addition, the water quality index can be corrected in consideration of the increase in the differential pressure of the reverse osmosis membrane in the latter stage and the membrane of the membrane filtration system as the pretreatment.

  The effect of this embodiment will be described.

  In the water treatment system 1G of the present embodiment, more reliable control is performed by performing water quality analysis on the upstream and downstream seawaters of the pretreatment device and controlling the results by combining at least two of the results. It becomes. In addition, by analyzing the water quality of the seawater upstream of the pretreatment device, it is not limited to a specific water quality, so it can be applied to a wide range and can be adapted to water quality fluctuations due to weather and geographical differences. It is possible to optimize the injection rate.

  In this embodiment, it is possible to determine the appropriateness of the injected flocculant injection rate by performing a water quality analysis of the seawater downstream of the pretreatment device. If the injected flocculant injection rate is not appropriate, measurement is performed. Since the relational expression between the water quality item and the injection rate can be derived and a new optimum injection rate can be extracted, the cost can be reduced. Also, water quality analysis of the seawater upstream of the pretreatment device is performed, and the initial value is set closer to the optimum coagulant injection rate at that time by setting the initial value based on the analysis result and pre-recorded storage means. Since it can be set, the time required to extract the optimum value of the injection rate can be shortened and the amount of injection to be shaken can be reduced, which can further contribute to cost reduction. The optimum flocculant injection rate thus extracted can be corrected by feedback control and kept constant.

  Compared to the case where the coagulant injection rate is selected based on one water quality analysis result as shown in FIG. 11, at least two water quality analysis results are adopted as shown in FIGS. 9 and 10, and each water quality result is weighted. By adding a coefficient and calculating from a preset relationship such as equation (1), it is possible to prevent more serious problems such as drug overdose, cost increase, and biological growth. . For example, as shown in FIG. 9, when there are two water quality analysis items A1 and B1 (severity of the problem, priority: B1> A1), the coagulant injection rate is the optimum value X of the water quality item A1 and the optimum of the water quality item B1. From the value Y, the optimum coagulant injection rate Z is calculated from a preset relationship. According to this example, the flocculant injection rate increases, but by taking into account the value of the water quality item B1, which is a more serious problem, in order to suppress other problems in the water treatment facility, overall, cost reduction, etc. Connected. Furthermore, in the case shown in FIG. 10, the flocculant injection rate can be reduced.

  In this embodiment, the flocculant injection rate is also controlled from a biochemical viewpoint such as TEP, phytoplankton, and chlorophyll a, which is considered to be one of the factors of fouling. Costs can be reduced because problems such as loss are taken into consideration.

  As described above, according to the present invention, the turbidity of treated water, SDI, MFI, TOC, E260, TEP amount from a biological viewpoint, chlorophyll a amount, phytoplankton number, fluorescence intensity, etc. are analyzed, respectively. By combining the results of combining at least two of these water quality results, it is possible to optimize the flocculant injection rate. In particular, by adding biological factors to the water quality item, more optimal flocculant injection is possible. The rate can be calculated.

1, 1A-1G ... Water treatment system,
2 ... Raw water tank, 3 ... Pretreatment device (sand filtration tank), 4 ... Adjusted water tank, 5 ... Security filter,
6 ... reverse osmosis membrane module (RO membrane module), 7 ... treated water tank,
10 ... flocculant injection device,
11 ... Pretreatment device (filtration membrane module, MF membrane module or UF membrane module),
20, 20A, 20B, 20C, 20D, 20E, 20F, 20G ... control system,
21 ... CPU (flocculating agent injection rate control means, relational expression derivation means),
22: Input / output interface (relational expression deriving means),
23 ... Database (recording device, relational expression deriving means),
24 ... feedback control circuit (feedback control means, relational expression derivation means),
31 ... Flow meter,
32. 1st water quality analyzer (downstream water quality analyzer),
33 ... 2nd water quality analyzer (upstream water quality analyzer),
P1, P2 ... pump, P3 ... pump, L1-L7, L10 ... line,
S1 to S4: Signals.

Claims (11)

A pretreatment device for removing foreign substances by filtering solute-containing water;
A reverse osmosis membrane module that separates and removes the solute by membrane filtration of the pretreated solute-containing water;
A flocculant injection device for injecting and adding the flocculant to the solute-containing water supplied to the pretreatment device;
A first water quality analyzer for measuring the amount of transparent extracellular polymer particles of solute-containing water and at least one other water quality measurement item on the downstream side of the pretreatment device,
A recording device for recording a water quality analysis measurement result obtained by combining at least two water quality measurement items obtained from the water quality analysis device;
A correlation equation between the amount of the transparent extracellular polymer particles and the injection rate of the flocculant, and a correlation equation between the other water chamber measurement item and the injection rate of the flocculant, and the at least two Relational expression deriving means for deriving correlation expressions between the above water quality measurement items,
By selecting an appropriate initial value of the flocculant injection rate from the past performance data, starting the injection of the flocculant from the selected initial value, and further by the water quality analysis measurement result called from the recording device and the relational expression derivation means A coagulant injection rate control means for determining the coagulant injection rate using the derived correlation formula and controlling the coagulant injection device so as to obtain the determined coagulant injection rate;
A water treatment system comprising: The pretreatment device is a sand filtration device having a sand filtration layer;
The apparatus further comprises a second water quality analyzer that measures the amount of transparent extracellular polymer particles of solute-containing water and at least one other water quality measurement item upstream of the pretreatment device. Item 1. A water treatment system according to item 1. The water quality analysis result obtained by the first water quality analyzer is set as a control target value, the set control target value is recorded in the recording device, the recorded control target value is called from the recording device, and the called control The target value is sent to the flocculant injection rate control means, the flocculant injection rate control means is used to determine the flocculant injection rate using the control target value, and the flocculant injection is performed so that the obtained flocculant injection rate is obtained. The water treatment system according to claim 1, further comprising feedback control means for feedback-controlling the apparatus. The water quality analysis result obtained by the second water quality analyzer is set as a control target value, the set control target value is recorded in the recording device, the recorded control target value is called from the recording device, and the called control The target value is sent to the flocculant injection rate control means, the flocculant injection rate control means is used to determine the flocculant injection rate using the control target value, and the flocculant injection is performed so that the obtained flocculant injection rate is obtained. The water treatment system according to claim 2, further comprising feedback control means for feedback-controlling the apparatus. The water treatment system according to claim 1, wherein the pretreatment device is a membrane filtration device having a filtration membrane. The apparatus further comprises a second water quality analyzer that measures the amount of transparent extracellular polymer particles of solute-containing water and at least one other water quality measurement item upstream of the pretreatment device. Item 6. A water treatment system according to item 5. The water quality analysis result obtained by the first water quality analyzer is set as a control target value, the set control target value is recorded in the recording device, the recorded control target value is called from the recording device, and the called control The target value is sent to the flocculant injection rate control means, the flocculant injection rate control means is used to determine the flocculant injection rate using the control target value, and the flocculant injection is performed so that the obtained flocculant injection rate is obtained. 6. The water treatment system according to claim 5, further comprising feedback control means for performing feedback control of the apparatus. The water quality analysis result obtained by the second water quality analyzer is set as a control target value, the set control target value is recorded in the recording device, the recorded control target value is called from the recording device, and the called control The target value is sent to the flocculant injection rate control means, the flocculant injection rate control means is used to determine the flocculant injection rate using the control target value, and the flocculant injection is performed so that the obtained flocculant injection rate is obtained. The water treatment system according to claim 6, further comprising feedback control means for feedback-controlling the apparatus. Means for measuring the continuous water quality of the solute-containing water and the state of the plant respectively on the upstream side and the downstream side of the pretreatment device;
Means for automatically changing the coagulant injection rate;
Means for determining the quality of the process;
An arithmetic unit for obtaining an appropriate injection rate when an event occurs such as when the injection of the flocculant injection device starts, when the water quality changes, and / or when the conditions of the plant are changed;
The water treatment system according to claim 1, further comprising: The other water quality measurement items are turbidity, silt density index (SDI), modified fouling index (MFI), total organic carbon (TOC) content, ultraviolet absorbance (E260), chlorophyll a content, phytoplankton number, The water treatment system according to claim 1, wherein the water treatment system is one or two or more selected from the group consisting of fluorescence intensity. (A) The solute-containing water is filtered by a pretreatment device to remove foreign matters,
(B) The pretreated solute-containing water is subjected to membrane filtration with a reverse osmosis membrane module to separate and remove the solute,
(C) Measure the amount of transparent extracellular polymer particles of solute-containing water and at least one other water quality measurement item on the downstream side of the pretreatment device,
(D) Record a water quality analysis measurement result combining at least two measured water quality measurement items in a recording device;
(E) a correlation equation between the amount of the transparent extracellular polymer particles and the injection rate of the flocculant, a correlation equation between the other water quality measurement item and the injection rate of the flocculant, and at least the above Deriving correlation expressions between two or more water quality measurement items,
(F) selecting an appropriate initial value of the flocculant injection rate from past performance data, starting the injection of the flocculant from the selected initial value, and further correlating the water quality analysis measurement result called from the recording device The amount of the flocculant injected with respect to the solute-containing water supplied to the pretreatment device is controlled so as to obtain the obtained flocculant injection rate using the formula.
A flocculant injection method for a water treatment system.

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