KR102013255B1 - Seawater Desalination Plant and Control Method for the same - Google Patents

Abstract

The present invention relates to a seawater desalination plant and a control method thereof, which specify the water quality index of seawater based on particles, colloids, and proteins, thereby optimizing the pretreatment method to improve membrane fouling reliability and to optimize the operation. The seawater desalination plant according to the present invention includes a water intake process unit for taking in seawater, a pretreatment process unit for pretreatment of raw water taken from the water intake process unit to remove particles, colloids, and organic matters, and pretreated water at the pretreatment process unit And a control unit for controlling a reverse osmosis process unit for removing salt from the pre-treatment process unit and / or a reverse osmosis process unit for the reverse osmosis process unit, wherein the control unit includes a Particle-Membrane Fouling Index (P-MFI) of the raw water. ), Colloid-Membrane Fouling Index (C-MFI), and protein concentration, and P-MFI, C-MFI, and protein of the treated water It is possible to control the pre-processing step and / or the reverse osmosis process, on the basis of Fig. According to the present invention, it not only provides a control method capable of minimizing reverse osmosis membrane contamination, but also has an effect of predicting and controlling the time of washing and replacing the reverse osmosis membrane.

Description

Seawater Desalination Plant and Control Method for the same}

The present invention relates to a seawater desalination plant for desalination of seawater using a reverse osmosis process, and more particularly, to specify the water quality index of seawater based on particles, colloids, and proteins, and to optimize the pretreatment method accordingly, thereby relieving reverse osmosis membrane contamination. The present invention relates to a seawater desalination plant and a method of controlling the same, to improve the quality of the plant and achieve optimization of operation.

Since 2000, water capacity has increased rapidly in agriculture, urban use, and industrial use all over the world. As a result, water shortage is intensifying worldwide. In 2025, 3 billion people are expected to face water shortages, especially in the Middle East and Africa.

Since most of the world's water resources exist as seawater, desalination of seawater is regarded as a powerful alternative to solve the water shortage problem by making seawater, an infinite water resource, available as freshwater.

Various substances such as sodium, magnesium, and chlorine ions are dissolved in seawater, and high concentrations of substances dissolved in seawater must be removed in order to be drinkable. For desalination to remove salt from water, evaporation method and membrane separation method are commonly used. The evaporation method uses a phase change between liquid and gas, which heats seawater to make water vapor, and then condenses the water back into water. In the membrane separation method, reverse osmosis (RO) process is used to obtain fresh water by applying pressure to a semi-permeable membrane that passes through water but does not pass through salt. Most widely used.

A seawater desalination plant using a reverse osmosis process generally comprises a water intake process, a pretreatment process, a reverse osmosis process, and a posttreatment process. Currently, a seawater desalination plant has various problems.

The water quality performance factors for the design / operation of seawater desalination plants are mostly borrowed from the general water treatment field, thereby limiting the increase in plant efficiency. In addition, although the SDI (silt density index) index is used as the water quality standard of the inflow process of the seawater desalination plant unit, excessive membrane contamination used in the reverse osmosis process may occur even if the water quality standard is satisfied.

Even though the characteristics of raw water are similar in season and region, design issues continue to occur due to different combinations and capacity calculations of the optimal pretreatment process. Due to this lack of performance diagnosis and prediction and the resulting operating conditions are difficult to change.

Various water quality performance factors have been proposed for the purpose of improving these problems, but require expensive analytical equipment and analysis personnel, low linkage with plant operation factors, and lack of integrated consideration in terms of plant operation rather than individual factors. Therefore, there are still limitations that are difficult to be used as field operation factors.

An object of the present invention is to present a water quality index indicating the characteristics of the water quality for the operation of seawater desalination plant, and to propose a method for controlling seawater desalination plant operation using the same and a seawater desalination plant using the same.

Seawater desalination plant according to the present invention for achieving the above object is a pre-treatment process unit for pretreating raw water taken from the water intake process unit, seawater intake process unit to remove particles, colloid, and organic matter, the pretreatment ball And a control unit for controlling a reverse osmosis process unit for removing salt from the treated water pre-treated by the government and a pre-treatment process of the pretreatment process unit and / or a reverse osmosis process of the reverse osmosis process unit, wherein the control unit is a P-MFI of the raw water. The pretreatment process and / or the reverse osmosis based on Particle-Membrane Fouling Index (C-MFI), Colloid-Membrane Fouling Index (C-MFI), and protein concentration, and P-MFI, C-MFI, and protein concentration of the treated water. The throwing process can be controlled.

In particular, the pretreatment process unit may include a resolved air floatation (DAF) process, and may include at least one of an ultrafiltration (UF) process and a dual media filtration (DMF) process.

The controller may determine whether to perform the DAF process based on the P-MFI of the raw water, and at least one of the UF process and the DMF process based on P-MFI, C-MFI, and protein concentration of the treated water. It is possible to set the filtration rate of, and to set the amount of flocculant to be injected into the raw water based on the C-MFI of the raw water or the treated water.

In particular, the control unit may set the amount of flocculant to be injected into the raw water in proportion to the C-MFI of the raw water or may set the amount of flocculant to be injected into the raw water in inverse proportion to the C-MFI of the treated water. A set amount of flocculant may be injected into raw water flowing into the DAF process and / or raw water flowing into at least one of the UF process and the DMF process.

In addition, the controller may determine the amount of oxidant to be injected into the treated water treated by the pretreatment process unit based on the protein concentration of the raw water, and based on the P-MFI, C-MFI, and protein concentration of the treated water. The degree of fouling of the reverse osmosis membrane used in the reverse osmosis process unit can be predicted, and the cleaning timing and / or exchange time of the reverse osmosis membrane can be controlled based on the prediction.

The control device used in the seawater desalination plant for desalination of seawater using the water intake process, the pretreatment process, and the reverse osmosis process according to the present invention for achieving the above object is the raw water and the pretreatment process withdrawal of seawater in the intake process MFI measuring unit for measuring Particle-Membrane Fouling Index (P-MFI) and Colloid-Membrane Fouling Index (C-MFI) of the treated water, the protein measuring unit for measuring the protein concentration of the raw water and the treated water and the It may include a control unit for controlling the process of the seawater desalination plant based on P-MFI, C-MFI, and protein concentration of the raw water and the treated water.

Particularly, when subdividing the control unit, the control unit sets the amount of flocculant to be injected into the raw water in order to aggregate the colloid included in the raw water based on the C-MFI of the seawater and / or the C-MFI of the treated water. Included in the pretreatment process of the seawater desalination plant based on the flocculant control unit, DAF control unit for determining whether to perform the DAF process based on the P-MFI of the raw water, C-MFI, P-MFI, and protein concentration of the treated water A filtration controller for determining the filtration rate of the filtered filtration process, and an oxidant controller for determining the amount of oxidant to be injected into the treated water based on the protein concentration of the raw water, and in addition, C-MFI of the treated water. Predict the fouling degree of the reverse osmosis membrane used in the reverse osmosis process of seawater desalination plant based on the concentration of P, MFI, and protein, and the reverse osmosis membrane based on the above prediction. The reverse osmosis control unit for setting the washing time and / or replacement time of the may be further included.

In particular, the coagulant control unit may set the amount of coagulant injected into the raw water in proportion to the C-MFI of the raw water, and may set the amount of coagulant injected into the raw water in inverse proportion to the C-MFI of the treated water. A set amount of flocculant may be injected into the raw water flowing into the DAF process and / or raw water flowing into the filtration process.

Process control method of the seawater desalination plant according to the present invention for achieving the above object is Particle-Membrane Fouling Index (P-MFI), Colloid-Membrane Fouling Index (C-MFI), and protein concentration of raw water received seawater Obtaining the P-MFI, C-MFI and protein concentrations of the treated water after the pretreatment process, controlling whether to perform the DAF process based on the P-MFI of the raw water, Determining the amount of coagulant to be injected into the raw water based on C-MFI and / or C-MFI of the treated water, determining the amount of oxidant to be injected into the treated water based on the protein concentration of the raw water,

And determining the filtration rate of the filtration process based on the P-MFI, C-MFI, and protein concentrations of the treated water, in addition to the P-MFI, C-MFI, and protein concentrations of the treated water. Predicting the reverse osmosis membrane fouling used in the reverse osmosis process and setting the cleaning time and / or replacement time of the reverse osmosis membrane based on the prediction.

And determining the amount of flocculant to be injected into the raw water based on the C-MFI of the raw water and / or the C-MFI of the treated water to determine the amount of flocculant to be injected into the raw water in proportion to the C-MFI of the raw water. Or determining the amount of flocculant to be injected into the raw water in inverse proportion to the C-MFI of the treated water.

According to the present invention, there is an effect of minimizing membrane contamination based on water quality index based on particle, colloid, protein concentration.

In addition, according to the present invention has the effect of having the efficiency of the process by evaluating the water quality of the raw water and the treated water flowing into the reverse osmosis process with the same water quality index.

In addition, according to the present invention, by developing new water quality performance factors, and using them to evaluate the characteristics of raw water, there is an effect of presenting a method for evaluating the water quality performance for each unit pretreatment process and a method for calculating the pretreatment capacity according to the raw water characteristics.

1 is a view showing a process of seawater desalination plant using a general reverse osmosis process.
2 illustrates a seawater desalination plant including control logic in accordance with one embodiment of the present invention.
3 is a view showing a seawater desalination plant control apparatus according to an embodiment of the present invention.
Figure 4 shows a method of controlling the desalination process in the control unit 400 of the seawater desalination plant according to an embodiment of the present invention.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and like reference numerals designate like elements throughout the specification.

Throughout the specification, when a part is "connected" to another part, this includes not only "directly connected" but also "electrically connected" with another element in between. . In addition, when a part is said to "include" a certain component, this means that it may further include other components, except to exclude other components unless otherwise stated.

When a portion is referred to as being "above" another portion, it may be just above the other portion or may be accompanied by another portion in between. In contrast, when a part is mentioned as "directly above" another part, no other part is involved between them.

Terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited to these. These terms are only used to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, the first portion, component, region, layer or section described below may be referred to as the second portion, component, region, layer or section without departing from the scope of the invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an,” and “the” include plural forms as well, unless the phrases clearly indicate the opposite. As used herein, the meaning of "comprising" embodies a particular characteristic, region, integer, step, operation, element and / or component, and the presence of other characteristics, region, integer, step, operation, element and / or component It does not exclude the addition.

Terms indicating relative space such as "below" and "above" may be used to more easily explain the relationship of one part to another part shown in the drawings. These terms are intended to include other meanings or operations of the device in use with the meanings intended in the figures. For example, if the device in the figure is reversed, any parts described as being "below" of the other parts are described as being "above" the other parts. Thus, the exemplary term "below" encompasses both up and down directions. The device can be rotated 90 degrees or at other angles, the terms representing relative space being interpreted accordingly.

Unless defined otherwise, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Commonly defined terms used are additionally interpreted to have a meaning consistent with the related technical literature and the presently disclosed contents, and are not interpreted in an ideal or very formal sense unless defined.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

1 is a view showing a process of seawater desalination plant using a general reverse osmosis process.

Referring to FIG. 1, the seawater desalination plant may include a water intake process 10, a pretreatment process 20, a reverse osmosis process 30, and a post treatment process 40. In addition, there may be a wastewater treatment facility that treats wastewater generated during seawater treatment.

Intake process 10 is a process of taking in seawater which is raw water for desalination. In order to reduce the load of the pre-treatment process 200, it is necessary to take clean seawater as much as possible, and to obtain high quality raw water, it is necessary to take deep sea water with a depth of 60 m or more, or to set up a well in the groundwater aquifer. galleries) and the like. The withdrawn raw water may be introduced into the pretreatment process 20 through a device such as a filter or a disk filter to remove sand and the like.

The pretreatment process 20 is a process for removing suspended solids, inorganic compounds, organic pollutants, etc., which may cause contamination or damage to the reverse osmosis membrane. Floating solids include colloids and particulate matter, and inorganic compounds include ions, manganese, calcium carbonate, calcium sulfate, and silicon dioxide. Organic pollutants include organic matter and microorganisms in seawater. The pre-treatment process that is currently applied universally may be to use a conventional process, such as agglomeration, sedimentation, filtration, etc., which is traditionally applied to water purification treatment, and to use a membrane filtration process using a membrane such as a microfiltration membrane or an ultrafiltration membrane. Membrane filtration process requires less space than conventional process, but generates a lot of waste water and requires the use of chemicals for membrane cleaning.

The pretreatment process 20 should select an appropriate pretreatment process according to the size of the treatment and the surrounding conditions such as raw water quality, and should be configured to meet the inflow water quality conditions (turbidity and / or SDI) allowed by the reverse osmosis process 300. do. In general, in the pretreatment step 20, it is necessary to treat so that the turbidity is 0.5 and SDI 3 or less. In addition, in the pretreatment process 20, acidification and antiscalants may be added to the reverse osmosis membrane to remove salts such as carbonate and calcium sulfate, which cause scale.

The pretreatment process 20 may also perform treatment for organic materials and microorganisms. The fouling of the reverse osmosis membrane, that is, the contaminants attached to the membrane and the membrane clogging, is mainly caused by organic substances and microorganisms. The organic substances are removed by coagulation, precipitation, filtration, and disinfection in the pretreatment process (20). Oxidants may be used to remove microorganisms or UV disinfection may be performed.

The reverse osmosis process 30 may remove salt from the seawater introduced through the pretreatment process 20 using a reverse osmosis membrane. Reverse osmosis membranes are generally made of organic synthetic materials and consist of a composite membrane coated with a membrane skin layer on a porous support layer.

The post-treatment process 40 may appropriately treat the water from which the salt is removed by the reverse osmosis process 30 to suit the end use purpose. When used as drinking water, it should be treated to have no taste or smell, to be corrosive, and to be properly disinfected. That is, in the post-treatment process 40, gas such as carbon dioxide and oxygen dissolved in water may be removed, the alkalinity and pH may be adjusted, and disinfection may be performed to prevent the regeneration of microorganisms.

In such a seawater desalination plant, the pretreatment process 20 uses turbidity of raw water (sea water), Total Suspended Solid (TSS), and / or Total Organic Carbon (TOC) as the water quality index, and based on these water quality indexes, the pretreatment process The configuration, capacity and operation of 20 can be designed. On the other hand, the reverse osmosis process 30 generally designs operating conditions based on the Si Den Density Index (SDI).

However, the SDI used here is used as a measure of the possibility of fouling in the separator. A typical SDI measurement method is 47 mm in diameter. Water is flowed through a 0.45um filter at 30psid to measure the degree of contamination caused by suspended solids. At this time, the time taken for the first 500ml of water is measured, and after 15 minutes, the time taken for 500ml of physical flow is measured again, and the ratio of these two hours is defined as the SDI value. SDI measurement is a widely used method to predict the tendency of membrane contamination of influent in current reverse osmosis process. In general, fouling is not severe when SDI is less than 3 and severe fouling can be expected when it is above 5 . However, this SDI measurement method is only a method of indirectly evaluating the possibility of membrane contamination by suspended particles having a size of 0.45um or more. Therefore, SDI cannot evaluate the influence of colloids or organic substances having a size of less than 0.45um. Also, although TOC is generally used as an indicator for analyzing reverse osmosis fouling by organic substances, TOC values include all types of organic substances, including all organic substances having low correlation with reverse osmosis membrane fouling. Correlation with the ring is lowered and membrane fouling cannot be accurately predicted. As an example, the water quality index of the treated water treated by the pretreatment process 200 is respectively less than 4 SDI, turbidity is less than 0.01, the TOC is 1 ~ 3ppm (case 1) and SDI is 3 In two plants with similar water quality indices of less than 0.01, turbidity less than 0.01, and TOCs of 1 to 3 ppm (case 2), the number of reverse osmosis membrane washes (Clean In Place; Less than two times a year Case 2 shows a significant difference of more than 12 times a year. The percentage of reverse osmosis membranes replaced every year is also 12% in Case 1 and 19% in Case 2, which is currently in seawater desalination plants. Water quality indices such as TOC and SDI are not correlated with fouling of reverse osmosis membranes.

As another example, organic matter may be adsorbed on the reverse osmosis membrane surface or accelerate the growth of microorganisms, thereby reducing the water permeability of the membrane. It can be easily classified into (Humic) organic matter and Protein (organic) organic matter. Humic series organics cause reverse osmosis membrane fouling by adsorption, have negative charge and have hydrophobic properties. On the other hand, protein-based organics cause reverse osmosis membrane fouling by adsorption or biodegradation and are amphoteric and hydrophilic. In general, protein-based organics are larger than humic-based organics, which can cause more reverse osmosis membrane fouling, and the rate of removal in the pretreatment process 200 is 10-50% for the humic series and less than 10% for the protein series. It is enough. Therefore, it can be seen that the protein-based organic matter has more correlation with the reverse osmosis membrane fouling than the TOC is used to measure the overall organic matter.

Based on the above analysis results, the present invention uses MFI (Membrane Fouling Index) and protein as design criteria for the configuration and operation of the pretreatment process 200. Particularly in the case of MFI, P-MFI (Particle-MFI) representing the concentration of particles and C-MFI (Colloid-MFI) representing the concentration of colloids are used.

2 illustrates a seawater desalination plant including control logic in accordance with one embodiment of the present invention.

,

, 및

는 각각 전처리 공정(200)을 거친 처리수의 P-MFI, C-MFI, 및 단백질 농도를 나타내고,

,

, 및

는 각각 취수 공정(100)에 의해 취수된 원수의 P-MFI, C-MFI, 및 단백질 농도를 나타낸다. 즉, 본원 발명에서 제시하는 제어 로직은 P-MFI, C-MFI, 및 단백질 농도를 기초로 전처리 공정(200) 및 역삼투 공정(300)을 제어할 수 있다.2, a seawater desalination plant according to an embodiment of the present invention may include a water intake process 100, a pretreatment process 200, a reverse osmosis process 300, and a controller 400. Here, the water intake process 100, the pretreatment process 200, the reverse osmosis process 300 may perform the same function as the conventional process described above. On the other hand, the control unit 400, unlike the conventional process, the control logic (410 to 460) based on the concentration of the P-MFI, the index indicating the concentration of the particles, the C-MFI indicating the concentration of the colloid, and protein-based organic matter Using the pretreatment process 200 and the reverse osmosis process 300 can be controlled. In Figure 2

,

, And

Represents the P-MFI, C-MFI, and protein concentrations of the treated water which have passed through the pretreatment process 200, respectively.

,

, And

Represents the P-MFI, C-MFI, and protein concentrations of the raw water withdrawn by the intake process 100, respectively. That is, the control logic proposed in the present invention may control the pretreatment process 200 and the reverse osmosis process 300 based on the P-MFI, C-MFI, and protein concentration.

The pretreatment process 200 may include a DAF process 210 and an UF process 220 or a DMF process 230 as shown in FIG. 2.

The DAF (Dissolved Air Flotation) process 210 generates a large amount of fine air bubbles and then removes contaminants using the same. The minimum size of the microbubbles generated in the DAF process 210 is about 30 μm, and particles smaller in size may not be effectively removed in the DAF process 210. Therefore, in order to secure the efficiency of the DAF process 210, a coagulant such as iron chloride (FeCl 3) may be added to agglomerate very small particles such as colloids to grow into flocs of sufficient size.

UF (Ultrafiltration) process 220 is for separating substances in raw water by using a semipermeable membrane, which does not pass through suspensions, colloids, and high molecular organics, and allows water, salts, and low molecular organics to pass through colloids and polymers. Can be used to remove organics.

Dual Media Filteration (DMF) process 230 is a process that can remove proteins, particles, contaminants, etc. using a porous carrier such as sand, gravel, anthracite.

The pretreatment process 200 may include at least one of the UF process 220 and the DMF process 230.

The control unit 400 controls P-MFI, C-MFI, and protein concentration and / or P-MFI, C-MFI, and protein of the raw water withdrawn by the intake process 100 and / or the pretreatment process 200. Based on the concentration, control of each process of the pretreatment process 200, coagulant injection, oxidant injection, reverse osmosis membrane fouling prediction and control may be performed.

)을 바탕으로 설정하고나 또는 전처리 공정(200)을 모두 거친 처리수의 C-MFI 값(

)을 바탕으로 설정될 수 있다. 즉 일 실시 예로서 취수된 원수의 C-MFI 값에 비례하여 주입하는 응집제의 양을 증가시킬 수 있다. 또 다른 일 실시 예로서 처리수의 C-MFI 값에 비례하여 주입하는 응집제의 양을 증가시킬 수 있다. 즉, 원수의 콜로이드 또는 처리수의 콜로이드의 양이 많을수록 더 많이 응집을 시켜야하기 때문에 그에 비례하여 주입하는 응집제의 양을 설정할 수 있다.The controller 400 may control the amount of flocculant injected into the raw water flowing into the DAF process 210 or the treated water after the DAF process 210 to increase the size of the fine particles such as colloid. The amount of flocculant injected at this time is the C-MFI value of the raw water taken by the intake process 100 (

C-MFI value of the treated water which is set based on or passed through the pretreatment process 200 (

) Can be set based on That is, in one embodiment, the amount of flocculant to be injected may be increased in proportion to the C-MFI value of the raw water taken. As another example, the amount of flocculant injected may be increased in proportion to the C-MFI value of the treated water. That is, since the more colloid of raw water or the colloid of treated water is required to aggregate, the amount of flocculant to be injected can be set in proportion.

)이 기설정된 값보다 작은 경우에는 DAF 공정(210)을 수행하지 않고, 이후의 공정을 통해 원수에 포함된 입자를 제거할 수 있도록 할 수 있다. 원수의 P-MFI 값이 기설정된 값보다 큰 경우에는 DAF 공정(210)을 수행하도록 설정할 수 있다.The controller 400 may also determine whether to perform the DAF process 210 itself or not. Since the DAF process 210 is a process for removing large particles, the DAF process 210 may not be performed when the amount of particles included in the raw water taken in the intake process 100 is small. That is, as an example, the P-MFI value of the raw water (

) Is smaller than the predetermined value, it is possible to remove the particles contained in the raw water through the subsequent process without performing the DAF process (210). When the P-MFI value of the raw water is larger than the predetermined value, the DAF process 210 may be set to be performed.

The controller 400 may control the filtering rate of the UF process 220 and / or the DMF process 230. In general, a faster filtration rate reduces the amount of protein and / or particles removed and a slower filtration rate increases the amount of protein and / or particles removed. Therefore, the filtration rate may be determined based on P-MFI, C-MFI, and protein concentrations of the treated water that has passed through the pretreatment process 200. That is, the filtration rate may be determined so that P-MFI, C-MFI, and protein concentration of the treated water required in the reverse osmosis process 300 may be minimized in order to minimize fouling of the reverse osmosis membrane. In this case, the P-MFI, C-MFI, and protein concentrations of the treated water may be repeatedly measured, and the filtration rate may be changed based on the results.

)를 바탕으로 주입하는 산화제의 양을 결정할 수 있다. 일 실시 예로서 원수의 단백질 농도가 높을수록 주입하는 산화제의 양을 크게할 수 있다.In addition, the controller 400 may determine the amount of the oxidant to be injected to remove the microorganisms contained in the treated water. The oxidizing agent may be chlorine, chlorine dioxide, chloramine, and the like, but chlorine disinfection is generally used, and the control unit 400 controls the protein concentration of raw water taken in the intake process 100.

) Can determine the amount of oxidant to be injected. As an example, the higher the protein concentration of raw water, the greater the amount of oxidant to be injected.

The control unit 400 predicts the fouling degree of the reverse osmosis membrane used in the reverse osmosis process 300 based on the P-MFI, C-MFI, and protein concentration of the treated water that has passed through the pretreatment process 200, and based on the reverse osmosis membrane It is possible to control the wash cycle or timing of, or the replacement cycle or timing.

3 is a view showing a seawater desalination plant control apparatus according to an embodiment of the present invention.

The control device illustrated in FIG. 3 may be used as the controller 400 of FIG. 2.

Referring to FIG. 3, the control apparatus includes an MFI measuring unit 410, a protein measuring unit 420, and a control unit 430, and the control unit 430 includes a coagulant control unit 431, a DAF control unit 432, and an oxidant control unit. 433, a filtration control unit 434, and a reverse osmosis control unit 435.

The MFI measuring unit 410 measures P-MFI (Particle-Membrane Fouling Index) and C-MFI (Colloid-Membrane Fouling Index) of the seawater taken in the intake process 100 and the treated water that has passed through the pre-treatment process 200. For example, MMAS (Multiple Membrane Array System), which can measure P-MFI and C-MFI by sequentially evaluating particles and colloids contained in raw or treated water using two membranes Can be used.

The protein measuring unit 420 may measure protein concentrations of the seawater and the treated water. The protein measuring unit 420 may distinguish between humic-based organic substances and proteins included in seawater or treated water by using Fluorescence Excitation-Emission Matrix (FEEM). Based on this, the concentration of the protein can be measured.

The controller 430 performs a process of the seawater desalination plant based on the concentrations of P-MFI, C-MFI, and protein of the seawater and the treated water measured by the MFI measuring unit 410 and the protein measuring unit 420. In more detail, the coagulant control unit 431, the DAF control unit 432, the oxidant control unit 433, the filtration control unit 434, and the reverse osmosis control unit 435 may be included.

The coagulant control unit 431 may set the amount of coagulant injected into the seawater. Since the DAF process and / or the filtration process included in the pretreatment process may remove particles, colloids or proteins of a predetermined size or more, a colloid such as a colloid may be used. Fine particles need to be agglomerated with a flocculant to increase their size. Thus, the coagulant control unit 431 may set the amount of the coagulant injected into the seawater in order to aggregate the colloids contained in the seawater based on the C-MFI of the seawater showing the concentration of the colloid and / or the C-MFI of the treated water.

The DAF controller 432 may determine whether to perform the DAF process based on the P-MFI of the seawater. Since the DAF process requires considerable power to operate, the DAF process may not be performed when the P-MFI is lower than or equal to a predetermined value in order to reduce power consumption, and the DAF process may be controlled to be performed only by a predetermined value or higher.

The filtration control unit 434 may determine the filtration rate of the filtration process included in the pretreatment process of the seawater desalination plant based on the C-MFI, P-MFI, and protein concentration of the treated water. The filtration process may be an UF process and / or a DMF process and the faster the filtration rate, the smaller the amount of particles or protein removed.

The oxidant controller 433 may determine the amount of the oxidant to be injected into the treated water based on the protein concentration of the seawater. The oxidizing agent is used to remove microorganisms that may cause fouling on the reverse osmosis membrane. A high protein concentration may indicate that there are many microorganisms in the treated water. Accordingly, the oxidant control unit 433 may control the amount of the oxidant injected into the treated water in proportion to the seawater protein concentration.

The reverse osmosis control unit 435 predicts the fouling degree of the reverse osmosis membrane used in the reverse osmosis process of the seawater desalination plant based on the C-MFI, P-MFI, and protein concentration of the treated water, and based on the prediction, The timing of cleaning and / or replacement can be set. Reverse osmosis membranes may have a high degree of fouling as the C-MFI, P-MFI, and protein concentrations of the treated water are increased, and thus, it is necessary to reduce the timing of washing or to replace the reverse osmosis membrane.

Figure 4 shows a method of controlling the desalination process in the control unit 400 of the seawater desalination plant according to an embodiment of the present invention.

Referring to FIG. 4, the control unit 400 obtains P-MFI, C-MFI, and protein concentrations of raw water taken in the intake process 100 and treated water after the pretreatment process 200 for control (S100, S200). )can do. In this case, an initial control value for the pretreatment process 200 of the controller 400 may be temporarily set based on past process data. The controller 400 determines whether to perform (on) or not (off) the DAF process 210 based on the P-MFI of the raw water (S300), and based on the C-MFI of the raw or treated water. The amount of flocculant to be injected may be determined (S400), and the amount of oxidant to be injected may be determined based on the protein concentration of raw water (S500). The filtration rate of the UF process 220 and / or the DMF process 230 may be determined based on the concentration of P-MFI, C-MFI, and protein of the treated water (S600).

In addition, the control unit 400 predicts the filing of the reverse osmosis membrane used in the reverse osmosis process 300 based on P-MFI, C-MFI, and protein concentration of the treated water (S700), and based on the prediction, The timing of cleaning and / or replacement may be controlled (S800).

The P-MFI, C-MFI, and protein concentrations of the present invention are used instead of the turbidity, SDI, and TOC, which are parameters indicating the state of raw water used in the conventional seawater desalination plant. You will be able to control.

In addition, based on P-MFI, C-MFI, and protein concentrations, the capacity to be treated in each process can be determined and the desalination plant can be designed accordingly. As an example, a desalination plant can be designed by measuring P-MFI and / or C-MFI of raw water and determining the treatment performance of the DMF process 230 or UF process 220 as a function of the measured values. In addition, when selecting a specific product, for example, when selecting DAF equipment for the DAF process 210, the DAF process 210 is supplied based on the C-MFI value of the treated water by supplying the same raw water to the products of various companies. Equipment can be selected.

As described above, the present invention measures the water quality index based on the particle, colloid, and protein concentrations, and uses the same to control the seawater desalination plant, thereby minimizing reverse osmosis membrane contamination and predicting and controlling the timing of washing and replacing the reverse osmosis membrane. Has the effect.

Those skilled in the art to which the present invention pertains may understand that the present invention may be embodied in other specific forms without changing the technical spirit or essential features, and thus, the embodiments described above are exemplary in all respects and are not intended to be limiting. Should be. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. .

10, 100: intake process
20, 200: pretreatment process
30, 300 reverse osmosis process
40: aftertreatment process
400: control unit

Claims (21)

As seawater desalination plant,
Water intake process unit for taking in sea water;
A pretreatment process unit which pre-treat the raw water collected by the intake process unit to remove particles, colloids, and organic substances;
A reverse osmosis process unit for removing salt from the treated water pretreated in the pretreatment process unit; And
A control unit for controlling a pretreatment step of the pretreatment step and / or a reverse osmosis step of the reverse osmosis step;
The controller is based on the Particle-Membrane Fouling Index (P-MFI), Colloid-Membrane Fouling Index (C-MFI), and protein concentration of the raw water, and P-MFI, C-MFI, and protein concentration of the treated water. Controlling the pretreatment process and / or the reverse osmosis process, wherein P-MFI is an index corresponding to the concentration of particles contained in the raw water or the treated water, and C-MFI is applied to the raw water or the treated water. Is an index corresponding to the concentration of colloids included,
The pretreatment process unit,
A DAF (Dissolved Air Flotation) process, and
At least one of an UF (UltraFiltration) process and a DMF (Dual Media Filtration) process,
The control unit,
Determining whether to perform the DAF process of the pretreatment process based on the P-MFI of the raw water,
Setting the filtration rate of at least one of the UF process and the DMF process based on P-MFI, C-MFI, and protein concentrations of the treated water,
Setting the amount of flocculant to be injected into the raw water based on the C-MFI of the raw water or the treated water,
Determining the amount of the oxidizing agent to be injected into the treated water treated in the pretreatment step based on the protein concentration of the raw water,
Seawater desalination plant. delete delete delete delete The method of claim 1,
The control unit,
Setting the amount of flocculant to be injected into the raw water in proportion to the C-MFI of the raw water,
Seawater desalination plant. The method of claim 1,
The control unit,
Setting the amount of flocculant to be injected into the raw water in inverse proportion to the C-MFI of the treated water,
Seawater desalination plant. The method of claim 1,
The control unit,
Injecting the flocculant into raw water introduced into the DAF process and / or raw water introduced into at least one of the UF process and the DMF process,
Seawater desalination plant. delete The method of claim 1,
The control unit,
Predicting the fouling degree of the reverse osmosis membrane used in the reverse osmosis process unit based on the P-MFI, C-MFI, and protein concentration of the treated water,
Seawater desalination plant. The method of claim 10,
The control unit,
Controlling the timing of cleaning and / or replacement of the reverse osmosis membrane based on the prediction,
Seawater desalination plant. A control device used in a seawater desalination plant for desalination of seawater using a water intake process, a pretreatment process, and a reverse osmosis process,
Particle-Membrane Fouling Index (P-MFI) and Colloid-Membrane Fouling Index (C-MFI) of raw water from which seawater is collected in the intake process and the treated water that has undergone the pretreatment process, wherein P-MFI is the seawater or the treatment An MFI measuring unit measuring an index corresponding to a concentration of particles included in water, and a C-MFI indicating an index corresponding to a concentration of colloid included in the seawater or the treated water;
Protein measuring unit for measuring the protein concentration of the raw water and the treated water; And
And a controller for controlling a process of a seawater desalination plant based on P-MFI, C-MFI, and protein concentrations of the raw water and the treated water.
The control unit,
A coagulant control unit for setting the amount of coagulant injected into the raw water to agglomerate colloid included in the raw water based on the C-MFI of the raw water and / or the C-MFI of the treated water;
A DAF controller for determining whether to perform a DAF process based on the raw water P-MFI;
A filtration control unit for determining a filtration rate of a filtration process included in a pretreatment process of a seawater desalination plant based on C-MFI, P-MFI, and protein concentrations of the treated water; And
An oxidant control unit for determining the amount of the oxidant to be injected into the treated water based on the protein concentration of the raw water,
Control device used in seawater desalination plant. delete The method of claim 12,
The control unit,
Predict the fouling degree of the reverse osmosis membrane used in the reverse osmosis process of the seawater desalination plant based on the C-MFI, P-MFI, and protein concentration of the treated water, and based on the prediction, the timing and / or exchange of the reverse osmosis membrane Further comprising: a reverse osmosis control unit for setting the time,
Control device used in seawater desalination plant. The method of claim 12,
The flocculant control unit,
Setting an amount of flocculant to be injected into the raw water in proportion to the C-MFI of the raw water,
Control device used in seawater desalination plant. The method of claim 12,
The flocculant control unit,
Setting the amount of flocculant to be injected into the raw water in inverse proportion to the C-MFI of the treated water,
Control device used in seawater desalination plant. The method of claim 12,
The flocculant control unit,
Injecting the flocculant into the raw water flowing into the DAF process and / or raw water flowing into the filtration process,
Control device used in seawater desalination plant. As a process control method of seawater desalination plant,
Particle-Membrane Fouling Index (P-MFI), Colloid-Membrane Fouling Index (C-MFI), and Protein Concentration of Raw Water Received by Seawater, wherein P-MFI is an index corresponding to the concentration of particles contained in the raw water C-MFI is an index corresponding to the concentration of colloid (Colloid) contained in the raw water;
Obtaining P-MFI, C-MFI and protein concentrations of the treated water after the pretreatment process;
Controlling whether to perform a DAF process based on the raw water P-MFI;
Determining an amount of flocculant to be injected into the raw water based on the C-MFI of the raw water and / or the C-MFI of the treated water;
Determining an amount of an oxidant to be injected into the treated water based on the protein concentration of the raw water;
Determining the filtration rate of the filtration process based on the P-MFI, C-MFI, and protein concentrations of the treated water; And
Predicting reverse osmosis membrane fouling used in reverse osmosis process based on P-MFI, C-MFI, and protein concentration of the treated water,
Process control method of seawater desalination plant. The method of claim 18,
Setting a timing for cleaning and / or replacing the reverse osmosis membrane based on the prediction;
Process control method of seawater desalination plant. The method of claim 18,
Determining the amount of flocculant to be injected into the raw water based on the C-MFI of the raw water and / or the C-MFI of the treated water
Determining an amount of flocculant to be injected into the raw water in proportion to the C-MFI of the raw water;
Process control method of seawater desalination plant. The method of claim 18,
Determining the amount of flocculant to be injected into the raw water based on the C-MFI of the raw water and / or the C-MFI of the treated water
Determining an amount of flocculant to be injected into the raw water in inverse proportion to the C-MFI of the treated water;
Process control method of seawater desalination plant.

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