KR101462565B1 - Monitoring method real-time fouling potential in Reverse Osmosis Process for Seawater Desalination and Desalination equipment having such monitoring function - Google Patents

Abstract

The present invention relates to a real-time membrane contamination potential monitoring apparatus and method for a seawater desalination reverse osmosis process for real-time monitoring of membrane contamination phenomena caused by various causes in a reverse osmosis process.

A real-time membrane contamination potential monitoring apparatus and method in a seawater desalination reverse osmosis process according to the present invention includes at least one of an influent storage tank, a high pressure pump, a reverse osmosis membrane module, a back pressure valve, an influent water flow sensor, an influent water temperature and conductivity measurement sensor, Condensate flow sensor, Concentrated water flow sensor, Small hollow ultrafiltration module, Pressure sensor, Decompression pump, Flow sensor, Turbidity measurement sensor, Data storage and processing computer, Analysis program, A chemical cleaning pump, and a cleaning chemical tank.

Reverse osmosis process, seawater desalination, membrane fouling, multi membrane fouling mechanism, membrane fouling potential

Description

TECHNICAL FIELD [0001] The present invention relates to a seawater desalination apparatus and a seawater desalination apparatus, and more particularly, to a seawater desalination and desalination apparatus having a real-

The present invention relates to a method for monitoring a real-time film contamination potential for a reverse osmosis membrane in a seawater desalination apparatus and a seawater desalination apparatus having such a function, and more particularly, to a desalination apparatus for desalination of seawater, A method for real-time monitoring of the progress of contamination in the field, and a desalination apparatus for seawater having such a function.

The reverse osmosis process has recently been attracting attention in various water treatment fields. In recent years, the application of reverse osmosis process has been expanding in the field of seawater desalination and sewage reuse. The seawater desalination market is currently estimated at 3 million tons / day and will grow to 6.2 million tons / day by 2015. In particular, the seawater desalination technology is a representative technology field that can solve the domestic water demand, provide alternative water resource securing technology, and pioneer the overseas market and create high value. In addition, seawater desalination technology has become a solution to providing alternative water resources for domestic water-scarce areas. In particular, it can reduce costs and improve environmental problems by replacing measures to secure water resources through controversial environmental issues. Therefore, domestic demand is expected to continue to increase in the future.

In addition to such seawater desalination, reverse osmosis is a highly sophisticated water treatment method in the fields of surface and groundwater treatment, industrial wastewater treatment and non-discharge reuse.

However, membrane contamination is an obstacle to the field application of this reverse osmosis process. Membrane fouling is a phenomenon that various foreign substances present in the influent water are deposited or adsorbed on the surface of the reverse osmosis membrane to reduce the water permeability of the reverse osmosis membrane. There are various kinds of foreign substances causing pollution such as floating particles, colloids, organic matters, microorganisms, and inorganic salts such as calcium salts. Therefore, it is difficult to anticipate the membrane contamination by these various contaminants in advance.

In general, the SDI (Silt Density Index) measurement method is widely used as a method for predicting the membrane contamination phenomenon in the reverse osmosis process and the nanofiltration process. SDI is used as a measure of the possibility of fouling in the membrane and measures the degree of contamination caused by suspended solids (SS) components using a 0.45 μm mesh filter. Measurement is made by flowing water at a pressure of 30 psid to a filter having a diameter of mm. At this time, the time (T0) required for the first 500 ml of water to flow is measured, and the time (T1) required for 500 ml of water to flow again after 15 minutes (T) do.

This SDI measurement is the most widely used method to predict membrane fouling trends of influent in current reverse osmosis and nanofiltration processes. In general, if the SDI is less than 3, the pollution is not severe. If the SDI is 5 or more, severe pollution may occur. However, there is a limitation in that the SDI measurement is not performed using the same phenomenon as that occurring in the reverse osmosis membrane (RO membrane). That is, SDI indirectly evaluates the possibility of membrane contamination by floating particles having a size of 0.45 μm or more, and can not evaluate the effect of colloid or organic matter having a size smaller than 0.45 μm. In the reverse osmosis process or nanofiltration process, it is operated in a crossflow mode. Therefore, the effect due to the surface characteristics of the membrane fouling material is important, and these can not be measured in the SDI. Therefore, it has been found in many studies that the SDI value differs from the actual operation result.

Therefore, a method such as MFI (Modified Fouling Index) is used as a method for supplementing SDI. However, since MFI and SDI use the same membrane basically, the membrane fouling substance which can be measured has the same limit. In order to overcome this problem, a method such as MFI-UF (Modified Fouling Index-Ultrafilter) or MFI-NF (Modified Fouling Index-Nanofilter) has been proposed. However, The film contamination tendency can not be well predicted.

In addition, since SDI and MFI can not be monitored in real time on site, it is difficult to apply it to automation system for reverse osmosis process. Therefore, there is a need for a method to directly monitor and control the membrane contamination phenomenon in actual process rather than SDI or MFI.

The present invention has been developed in order to meet the limitations and practical needs of the prior art as described above. Instead of measuring the membrane contamination potential by filtering the influent water through a filter as in the conventional SDI and MFI, And to make it possible to measure film contamination potential more precisely by using monitoring items that can be made.

A real-time membrane contamination potential monitoring apparatus and method in a seawater desalination reverse osmosis process according to the present invention includes at least one of an influent storage tank, a high pressure pump, a reverse osmosis membrane module, a back pressure valve, an influent water flow sensor, an influent water temperature and conductivity measurement sensor, And Conductivity Measurement Sensor, Processed Water Flow Sensor, Concentrated Water Pressure Sensor, Concentrated Water Flow Sensor, Small Hollow Ultrafiltration Module, Pressure Sensor, Decompression Pump, Flow Sensor, Turbidity Measurement Sensor, Data Storage and Processing Computer, Drug Cleaning A pump, and a cleaning agent tank.

In the meantime, the present invention provides an inflow water storage tank, a high pressure pump, a reverse osmosis module, a back pressure valve, an inflow water flow sensor, influent water temperature and conductivity measurement sensor, influent water pressure sensor, process water temperature and conductivity measurement sensor, A sensor for concentrated water flow, a small hollow fiber ultrafiltration module, a pressure sensor, a pressure reducing pump, a flow rate sensor, a turbidity measurement sensor, a computer for data storage and processing, an analysis program, a chemical cleaning pump, A device for measuring multiple membrane fouling indexes for predicting membrane fouling in reverse osmosis and nanofiltration processes is also provided. That is, a seawater desalination apparatus having a real-time film contamination potential monitoring function having the above-described structure is provided.

In the apparatus of the present invention as described above, the data storage and processing computer may further comprise at least one of an influent flow sensor, influent temperature and conductivity measurement sensor, influent pressure sensor, process water temperature and conductivity measurement sensor, process water flow sensor, The flow rate sensor, the flow rate sensor, and the turbidity measurement sensor, and may be configured to continuously receive data, calculate it as an analysis program, and notify the result of the calculation to the field driver, The product of the difference in pressure value measured from the water pressure sensor and the cross-sectional area of the membrane is divided by the average value of the flow values measured from the influent flow sensor and the concentrated water flow sensor and then corrected to the temperature measured by the influent water temperature and conductivity sensor It is also possible to have a configuration that monitors the blocking of the reverse osmosis membrane by dividing it by the viscosity of water The.

In addition, the analysis program of the multi-element membrane pollution index measuring apparatus for predicting the membrane contamination prediction of the reverse osmosis and nanofiltration process of the present invention includes an influent water flow sensor, influent water temperature and conductivity measurement sensor, process water temperature and conductivity sensor, The filtration resistance value of the cake formed in the reverse osmosis membrane may be calculated using the influent water temperature, influent conductivity, treated water temperature, treated water conductivity and concentrated water pressure value measured by the sensor and the concentrated water pressure sensor, respectively And the analysis program may automatically calculate the membrane fouling potential at intervals of 1 hour to 1 week. The small hollow fiber ultrafiltration module is immersed in an influent storage tank and filtered under reduced pressure. The filtration pressure And the filtrate flow rate is monitored and transmitted to the computer, Film can also be automatically determined by the potential contamination in the field.

In the apparatus for measuring a membrane contamination index for predicting membrane fouling in the reverse osmosis and nanofiltration process according to the present invention, the small hollow fiber ultrafiltration module is an external pressure hollow fiber membrane having a membrane area of 0.1 m ² or less and a pore size of 0.05 micrometer And the chemical cleaning pump and the cleaning chemical tank may be automatically operated by the film contamination potential calculated by the analysis program installed in the computer to clean the reverse osmosis membrane to control film contamination and blocking of the flow path.

In an apparatus for measuring a multi-membrane fouling index for predicting membrane fouling in the reverse osmosis and nanofiltration process, the analysis program uses the relative values of the three calculated membrane fouling potentials to determine the particulate matter in the reverse osmosis membrane process, Biofouling formation, and scale formation may be analyzed.

The characteristics of the multi-element membrane pollution index measuring apparatus for predicting membrane contamination of the reverse osmosis and nanofiltration process are also applied to the method of monitoring the real-time membrane contamination potential of the reverse osmosis membrane of the present invention and the seawater desalination apparatus having such a function.

As described above, the real-time membrane contamination potential monitoring apparatus and method in the seawater desalination reverse osmosis process according to the present invention are capable of monitoring the membrane contamination phenomenon caused by various causes in the reverse osmosis or nanofiltration process, It is possible to check for the diagnosis and pretreatment process. In addition, it is possible for a field driver to easily operate the seawater desalination reverse osmosis process, and the membrane cleaning cycle can be automatically determined according to membrane potential.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. Although the present invention has been described with reference to the embodiments shown in the drawings, it is to be understood that the present invention is not limited to the technical spirit and essential structure and operation of the present invention.

FIG. 1 is a schematic diagram showing a configuration of a reverse osmosis membrane type seawater desalination apparatus 100 according to the present invention having a real-time film contamination potential monitoring function.

As shown in the figure, the seawater desalination apparatus 100 according to the present invention includes an influent tank 10 containing seawater ("inflow water") introduced from the outside, and an influent tank 10 having a reverse osmosis membrane, And a reverse osmosis membrane module (12) for desalinating the influent water by reverse osmotic action when the water passes through the reverse osmosis membrane module. A high-pressure pump 11 may be provided between the inflow water tank 10 and the reverse osmosis membrane module 12 to supply seawater to the reverse osmosis membrane module 12. The reverse osmosis membrane module 12 having the reverse osmosis membrane and desalting the seawater by reverse osmosis is well known in the art, and the type and structure of the reverse osmosis membrane module 12 are not particularly limited.

The inflow water taken from the sea and subjected to the preprocessing process is transferred to the inflow water storage tank 10 and the turbidity measurement sensor 34 for measuring the turbidity of the influent water transferred to the inflow water storage tank 10 is provided to measure the turbidity of the influent water . The measured turbidity is transferred to the computer 40 and stored.

The inflow water storage tank 10 is provided with an ultrafiltration membrane module 30. Part of the inflow water stored in the inflow water storage tank 10 passes through the ultrafiltration membrane module 30 due to the pressure difference created by the decompression pump 32 The pressure P ₁ and the flow rate Q ₁ are measured by the pressure sensor 31 and the flow rate sensor 33 with respect to time so as to be sent to the computer 40 ).

The inflow water stored in the inflow water storage tank 10 is transferred to the reverse osmosis membrane module 12. Due to the pressure difference created by regulating the back pressure valve 13, some of the influent water passes through the reverse osmosis membrane and the remaining water does not pass through the reverse osmosis membrane, Concentrated water. The flow rate Q ₂ , the conductivity CD ₂ , the temperature T ₂ and the pressure P ₂ of the influent water transferred from the influent storage tank 10 to the reverse osmosis membrane module 12 are measured by the influent water flow rate sensor 20, And the conductivity measuring sensor 21, and the inflow water pressure sensor 22, respectively, and are recorded in the computer 40. The conductivity (CD ₃ ), the temperature (T ₃ ) and the flow rate (Q ₃ ) of the treated water passing through the reverse osmosis membrane are also measured by the treated water temperature and the conductivity measuring sensor 23 and the treated water flow rate sensor 24, (P ₄ ) and the flow rate (Q ₄ ) of the concentrated water that have not been passed through the reverse osmosis membrane and are recorded in the computer 40 are also measured by the concentrated water pressure sensor 25 and the concentrated water flow rate sensor 26, And is recorded in the computer 40. [

The analysis program installed in the computer 40 calculates the membrane contamination potential based on the sensor measurement data with respect to the influent water, the treated water, and the concentrated water.

The primary film contamination potential I ₁ for evaluating the influence of the particulate pollutants and colloidal contaminants contained in the influent water is calculated from the change in flow rate with time in the ultrafiltration membrane module 30 and the filtration time t The relationship between the slope S ₁ and the first film contamination potential I ₁ is calculated from the slope S ₁ by calculating the relationship between the filtration time / filtration volume / filtration volume t / The first film contamination potential I ₁ is calculated according to the relational expression ( ₁ ).

In the above Equation 1, I ₁ is the primary film contamination potential, μ is the viscosity coefficient, and A is the membrane area of the ultrafiltration membrane module. S ₁ is the slope value of the graph showing the relationship between the filtration time t and the filtration time / filtration volume t / V obtained from the change in the flow rate with time in the ultrafiltration membrane module 30. Specifically, A graph showing the relationship between the filtration time t and the filtration volume V, that is, the filtration time / filtration volume t / V and the filtration time t from the change in the flow rate with time in the module 30 When the value of the graph slope is obtained, the slope value is S ₁ .

The secondary membrane contamination potential (I ₂ ) for evaluating the membrane contamination of the reverse osmosis membrane between times t ₁ and t ₂ is obtained by the following equation ( ₂ ).

Wherein P ₄ is the pressure of the concentrated water is excluded can not pass through the reverse osmosis membrane (P ₄₎ and, CD ₃ is treated conductivity (CD ₃₎ of passing through the reverse osmosis membrane, T is the number of the temperature of the process, V is treated .

In the above equation (2), f (CD, T) is calculated by the following equation (3) and has units of Pa.

The third film contamination potential (I ₃ ) for evaluating the clogging of the reverse osmosis membrane between times t ₁ and t ₂ is obtained by the following equation (4).

Q ₂ is the flow rate Q ₂ of the influent water transferred from the influent storage tank 10 to the reverse osmosis membrane module 12 and Q ₄ is the flow rate Q ₄ of the concentrated water not passing through the reverse osmosis membrane, to be. P ₂ is the pressure of the inlet is conveyed to the reverse osmosis membrane module 12 from the incoming water storage tank (10) (P _2), and, P ₄ is the pressure (P ₄₎ of the number of excluded concentration can not pass through the reverse osmosis membrane.

The interval between t ₁ and t ₂ varies depending on the operating conditions of the reverse osmosis process, but it is generally preferred to be between 1 hour and 1 week.

Each of the primary, secondary, and tertiary film contamination potentials I ₁ , I ₃₂ , and I ₃ is automatically calculated according to the above equation using an analysis program installed in the computer 40 and notified to the field driver , The on-site operator can always monitor the progress of the contamination. If the film contamination potential value exceeds a set value, the computer 40 and the cleaning agent injection pump 50 are connected to allow the reverse osmosis membrane to be cleaned so that the membrane can be cleaned automatically. In the drawing, reference numeral 51 denotes a cleaning agent tank 51.

Also, by analyzing the tendency of the membrane contamination potential, it is possible to diagnose the operation situation of the reverse osmosis process and to determine the causes of membrane contamination and countermeasures.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall configuration diagram of a water treatment apparatus using a catalytic dynamic membrane according to the present invention. FIG.

Description of the Related Art

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10: Influent storage tank

11: High pressure pump

12: Reverse Osmosis Module

13: Backpressure valve

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20: Influent flow sensor

21: Influent water temperature and conductivity measuring sensor

22: Influent pressure sensor

23: Process water temperature and conductivity measurement sensor

24: Processed water flow sensor

25: Concentrated water pressure sensor

26: Concentrated water flow sensor

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30: Small Hollow Fiber Ultrafiltration Module

31: Pressure sensor

32: Pressure reducing pump

33: Flow sensor

34: Turbidity measuring sensor

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40: Computer for storing and processing data

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50: Cleaning agent injection

51: cleaning chemical tank

Claims (10)

An inflow water storage tank (10) containing inflow water flowing from the outside; A reverse osmosis membrane module (12) having a reverse osmosis membrane and desalinating the influent water by reverse osmosis when the influent water from the influent storage tank (10) is passed; An ultrafiltration membrane module (30) provided in the inflow water storage tank (10) to filter the inflow water stored in the inflow water storage tank (10) and return it to the inflow water storage tank (10); A pressure sensor 31 and a flow rate sensor 33 for measuring the pressure P ₁ and the flow rate Q ₁ of the influent water supplied to the inflow water storage tank 10 via the ultrafiltration membrane module 30; The flow rate Q ₂ of the influent water flowing from the inflow water storage tank 10 to the reverse osmosis membrane module 12, the conductivity CD ₂ of the inflow water, the temperature T _{2 of the} inflow water, and the pressure P _{2 of the} inflow water An inflow water flow sensor 20, an inflow water temperature and conductivity measurement sensor 21, and an inflow water pressure sensor 22, respectively; A treated water flow rate sensor 24 for measuring the flow rate Q ₃ of the treated water passed through the reverse osmosis membrane module 12, the conductivity (CD ₃ ) of the treated water and the temperature T _{3 of} the treated water, A water temperature and conductivity measuring sensor 23; A concentrated water pressure sensor 25 and a concentrated water flow rate sensor 26 for measuring the pressure P _{4 of the} concentrated water and the flow rate Q ₄ of the concentrated water without passing through the reverse osmosis membrane module 12; And a computer (40) for calculating film contamination potential using data transmitted from all the sensors; Wherein the membrane contamination state of the reverse osmosis membrane of the seawater desalination apparatus is monitored in real time in accordance with the membrane potential of the seawater desalination apparatus. The method according to claim 1, The computer 40 multiplies the product of the pressure difference measured by the influent pressure sensor 22 and the concentrated water pressure sensor 25 and the sectional area of the flow path of the membrane by the influent flow sensor 20 and the concentrated water flow sensor 26, and then divided by the viscosity of the water corrected to the temperature measured by the influent water temperature and the conductivity measuring sensor 21 to determine the membrane contamination potential, and the membrane contamination potential is used to determine the reverse osmosis Wherein the monitoring of the clogging of the membrane of the membrane is monitored. delete The method according to claim 1, The computer (40) is loaded with an analysis program (41); The analysis program 41 is a program for calculating the influent water flow rate measured by the influent flow sensor 20 and the influent water temperature and the temperature and the conductivity of the influent water measured by the conductivity measurement sensor 21, 23, the flow rate of the treated water measured by the treated water flow rate sensor 24, and the pressure value of the concentrated water measured by the concentrated water pressure sensor 25, And the filtration resistance value of the cake formed on the permeable membrane is calculated. The method according to claim 1, The computer (40) is loaded with an analysis program (41); Wherein the analyzing program (41) automatically calculates the membrane contamination potential at intervals of one hour to one week. The method according to claim 1, The ultrafiltration membrane module (30) is a small hollow fiber type filtration module; The ultrafiltration membrane module 30 is immersed in the inflow water storage tank 10 and is subjected to reduced pressure filtration and the filtration pressure and the filtered water flow rate are monitored using the pressure sensor 31 and the flow rate sensor 33 and transmitted to the computer 40 And the membrane contamination potential of the reverse osmosis membrane due to colloidal particles is automatically measured in the field. The seawater desalination apparatus has a real-time film contamination potential monitoring function for the reverse osmosis membrane. The method according to claim 1, The ultrafiltration membrane module (30) is a small hollow fiber type filtration module; Wherein the ultrafiltration membrane module (30) is an external pressure hollow fiber membrane having a membrane area of 0.1 m ² or less and has a pore size of 0.05 micrometer or less, and has a real-time film contamination potential monitoring function for a reverse osmosis membrane. The method according to claim 1, The chemical cleaning pump 50 and the cleaning chemical tank 51 are automatically operated by the film contamination potential calculated by the analysis program 41 installed in the computer 40 to clean the reverse osmosis membrane to prevent film contamination and blocking of the channel Wherein the control unit monitors the reverse osmosis membrane potential of the reverse osmosis membrane. delete A method for monitoring a real-time film contamination potential for a reverse osmosis membrane using a seawater desalination apparatus having a real-time film contamination potential monitoring function for a reverse osmosis membrane according to any one of claims 1, 2 or 4 to 8.

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