KR102080849B1 - Method for improving performance of pressure retarded osmosis process - Google Patents

Abstract

The present invention relates to a method for improving the performance of the pressure delayed osmosis membrane, the method for improving the performance of the pressure delayed osmosis process of the present invention does not cause a decrease in permeation flow rate by chlorhexidine gluconate, and does not cause damage to the separator . In addition, at low concentrations, the formation of biofilms may be inhibited, and at high concentrations, biofilms may be destroyed to remove the biofilms, thereby increasing permeate flow rate, thereby being useful for improving the performance of the pressure delayed osmosis process.

Description

METHOD FOR IMPROVING PERFORMANCE OF PRESSURE RETARDED OSMOSIS PROCESS}

The present invention relates to a method for improving the performance of a pressure delayed osmosis process.

The pressure delay osmosis process utilizes the osmotic pressure difference between the induction solution and the inflow solution to produce sustainable renewable energy that converts the increased flow rate generated by the movement of water in the inflow water through the separation membrane into the induction solution through a turbine or energy recovery device. It is a process. In the pressure delay osmosis process, a membrane is used between the two solutions in order to take advantage of the osmotic pressure difference between the inflow solution and the induction solution.

The pressure delayed osmosis membrane is an asymmetric membrane composed of an active layer and an active layer, and the support layer is in contact with the inflow solution, and the active layer is in contact with the induction solution. At this time, the active layer of the pressure delayed osmosis membrane is a polyamide of a dense structure, it is difficult to penetrate microorganisms through the active layer. On the other hand, the support layer is made of polysulfone and nonwoven fabric, and the support layer surface has many gaps and has a porous structure therein, so that microorganisms can easily penetrate and attach.

In particular, the biofilm formed inside the support layer remains between the gaps even if separated from the surface of the support layer to reduce the permeate flow rate. That is, the biofilm formed on the pressure delayed osmosis membrane causes economic losses such as a decrease in permeate flow rate, an increase in cleaning cost due to an increase in the number of cleaning cycles, and a replacement cost of the pressure delayed osmosis membrane due to a decrease in performance.

On the other hand, the biofilm formed by the microorganism is difficult to remove because it is strongly attached to the surface. In addition, when living in an environment in which microorganisms are attached, sterilization and disinfection are difficult because they have much stronger resistance to harsh environments (pH, temperature, depletion of nutrients) and attack of antibiotics, compared to floating life. In addition, since microorganisms can benefit from various benefits as a result of the formation of such biofilms, they are present in the form of biofilms in most natural and industrial environments.

The microorganisms that form the biofilm are covered with a polymeric material called extracellular polymeric substance (EPS). Therefore, the biofilm is a collection of microorganisms in which microorganisms such as bacteria, yeast and mold are attached to the skin, oral cavity, or tooth or facility pipe and storage tank of the human body under specific conditions. It can also serve as a habitat for microorganisms, accelerating the growth of bacteria.

On the other hand, it has been confirmed that halogen oxide can be used to remove the biofilm formed in the reverse osmosis membrane. In this regard, Korean Patent Laid-Open Publication No. 10-2005-0083674 discloses a method of removing biofilm on a separator and killing bacteria using a combined type of oxidized halogen biocide which slowly releases halogen. However, the oxidizing fungicide injected into the influent in order to kill the microorganisms in the pressure delay osmosis process and remove the biofilm, reacts with the polyamide layer to cause physicochemical damage.

KR 10-2005-0083674 A

In order to improve the performance of the pressure delayed osmosis process, the present inventors have completed the present invention by treating chlorhexidine gluconate at a specific concentration to remove the biofilm formed in the separator and confirming that the decreased permeate flow rate is increased.

The present invention includes a step of adding a cationic fungicide to an influent solution in a pressure delay osmosis process using a difference in osmotic pressure between an induction solution having a high salinity concentration in contact with an active layer of a membrane and an influent solution having a low salt concentration in contact with a support layer of a separator. It provides a method for improving the performance of the pressure delay osmosis process.

In another aspect, the present invention is the first pressure exchange device and the second pressure exchange device to increase the pressure by receiving the sea water, the production of the filtered water salt is filtered through the reverse osmosis membrane by receiving the high pressure seawater, the concentrated brine is the second SWRO facility for delivering to the pressure exchange device, the first PRO facility to receive the concentrated brine discharged from the second pressure exchange device as PRO brine, receiving the PRO raw water from the outside to perform the pressure delay osmosis process, and the first 1. A seawater desalination system using pressure delayed osmosis technology comprising a second PRO facility in which a pressure delayed osmosis process is performed by receiving PRO brine discharged from a PRO facility, the method comprising adding a cationic fungicide to the PRO raw water. It provides a method to improve the performance of seawater desalination system using pressure delay osmosis technology.

The method for improving the performance of the pressure delayed osmosis process of the present invention does not cause a decrease in permeate flow rate due to chlorhexidine gluconate, and does not cause damage to the separator. In addition, at low concentrations, the formation of biofilms may be inhibited, and at high concentrations, biofilms may be destroyed to remove the biofilms, thereby increasing permeate flow rate, thereby being useful for improving the performance of the pressure delayed osmosis process.

1 is a block diagram showing a seawater desalination system using a pressure delay osmosis process.
FIG. 2A is a diagram showing the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) by treating Gram-positive bacteria ( S. aureus ) with chlorhexidine gluconate.
2b is a diagram showing the minimum inhibitory concentration and the minimum bactericidal concentration by treating gram negative bacteria ( P. aeruginosa ) with chlorhexidine gluconate.
3a is a diagram comparing the amount of biofilm formed by Gram-positive bacteria according to chlorhexidine gluconate concentration.
Figure 3b is a measure of the amount of biofilm formed by gram negative bacteria according to the chlorhexidine gluconate concentration.
Figure 4a is a diagram confirming the biofilm formed in the support layer of the membrane after immersing the membrane in the microbial medium for one day (live microorganisms are represented by green fluorescence, dead microorganisms are represented by red fluorescence).
Figure 4b is a view confirming the biofilm formed on the separator after flowing the microbial medium without chlorhexidine gluconate for 24 hours to the support layer of the biofilm formed membrane.
Figure 4c is a view confirming the biofilm formed on the separator after flowing a microbial medium added with chlorhexidine gluconate at a concentration of 0.8 ppm to the support layer of the biofilm formed membrane for 24 hours.
Figure 4d is a view confirming the biofilm formed in the separator after flowing the microbial medium added with chlorhexidine gluconate at a concentration of 8 ppm to the support layer of the biofilm formed membrane for 24 hours.
5 is a view of measuring the microbial amount and thickness of the biofilm formed in the separator of Figures 4a to 4d.
6 is a view confirming the damage of the separator by chlorhexidine gluconate treatment through ATR-FTIR.
Figure 7a is a graph showing the growth curve of P. aeruginosa according to the concentration of chlorhexidine gluconate during 24 hours operation of the pressure delay osmosis process apparatus.
Figure 7b is a standard flow rate (J _w ) with the increase in the cumulative permeation (L / m ² ) of the pressure delay osmosis process according to the concentration of chlorhexidine gluconate / J _o ).

Hereinafter, the present invention will be described in detail.

The present invention includes a step of adding a cationic fungicide to an influent solution in a pressure delay osmosis process using a difference in osmotic pressure between an induction solution having a high salinity concentration in contact with an active layer of a membrane and an influent solution having a low salt concentration in contact with a support layer of a separator. It provides a method for improving the performance of the pressure delay osmosis process.

The pressure delay osmosis process is a sustainable renewable energy that converts the increased flow rate generated by the water in the inflow water toward the induction solution through the membrane using the osmotic pressure difference between the induction solution and the inflow solution into energy through a turbine or an energy recovery device. Production process.

As used herein, the term "pressure delayed osmosis membrane" refers to an asymmetric separation membrane composed of an active layer and a support layer. Based on the pressure delay osmosis membrane, the induction solution is in contact with the active layer of the membrane, the influent solution is in contact with the support layer of the membrane. The separation membrane may be a pressure delayed osmosis membrane including a polyamide-based active layer.

The active layer is formed on the porous support, it may be composed of polyamide. Specifically, it may be formed by the polymerization of an amine compound and an acyl halide compound, wherein the amine compound is not limited thereto, for example, m-phenylenediamine, p-phenylenediamine, 1,3, 6-benzenetriamine, 4-chloro-1,3-phenylenediamine, 6-chloro-1,3-phenylenediamine, 3-chloro-1,4-phenylenediamine or mixtures thereof. In addition, the acyl halide compound is an aromatic compound having 2 to 3 carboxylic acid halides, but is not limited thereto, for example, trimezoyl chloride, isophthaloyl chloride, terephthaloyl chloride or a mixture thereof. It is preferable. At this time, the active layer is allowed to pass through the water molecules, such as salt does not pass.

The support layer may be formed of a coating layer of a polymer material on a nonwoven fabric, and the polymer material may include, for example, polysulfone, polyethersulfone, polycarbonate, polyethylene oxide, polyimide, polyetherimide, polyetherketone , Polypropylene, polymethylpentene, polymethyl chloride and polyvinylidene fluoride may be used, but is not necessarily limited thereto. Among these, it is preferable to use polysulfone.

In addition, the cationic fungicide may be any one selected from sodium benzoate, distearyldimonium chloride and chlorhexidine gluconate.

As used herein, the term "chlorhexidine gluconate" refers to a cationic fungicide with bactericidal power used for sterilization of medical devices, mouthwashes, toothpastes, and cosmetic additives.

The chlorhexidine gluconate may be added to the inflow solution in contact with the support layer of the separator to act on microorganisms that inhabit the outer surface and the inner gap of the support layer. In addition, chlorhexidine gluconate does not pass through the active layer of the separator. In an embodiment of the present invention, the chlorhexidine gluconate was used at a concentration of 0.1 ppm to 8 ppm, which is a specific concentration that does not reduce the permeate flow rate while removing the biofilm formed on the support layer of the separator. In this case, when chlorhexidine gluconate is added to the influent solution at a high concentration, the permeate flow rate can be reduced (FIG. 7B). Thus, chlorhexidine gluconate can be added at 0.1 ppm to 8 ppm, 0.3 ppm to 5 ppm or 0.5 ppm to 1 ppm.

In addition, the chlorhexidine gluconate may be added to the inflow solution intermittently or continuously to inhibit the growth of microorganisms, thereby suppressing the formation of biofilm, reducing the cleaning cost of the separator, and improving the performance of the separator. In one embodiment of the present invention it was confirmed that the addition of the chlorhexidine gluconate to 0.8 ppm to suppress the formation of the biofilm, it was confirmed that the permeate flow rate does not decrease with the addition of chlorhexidine gluconate.

The influent solution may be, but is not limited to, primary sewage treatment water, secondary sewage treatment water, tertiary sewage treatment water, brine water, ground water or surface water.

The present invention is the first pressure exchange device and the second pressure exchange device to increase the pressure by receiving the sea water, the production of the filtered water salt is filtered through the reverse osmosis membrane by receiving the high pressure seawater, concentrated brine is the second pressure exchange SWRO facility to transfer to the device, the first PRO equipment receiving the concentrated brine discharged from the second pressure exchange device as PRO brine, the PRO raw water from the outside to perform a pressure delay osmosis process, and the first PRO In a seawater desalination system using a pressure delayed osmosis technique comprising a second PRO equipment receiving pressure brine discharged from a facility and performing a pressure delayed osmosis process, a pressure delay comprising adding a cationic fungicide to the PRO raw water. It provides a method for improving the performance of the seawater desalination system process using osmosis technology.

The term "PRO" used in the present invention is an abbreviation of Pressure Retarded Osmosis and is called pressure delayed osmosis, and is increased by the inflow of water through the separation membrane through the separation membrane using the osmotic pressure difference between the induction solution and the inflow solution. A sustainable renewable energy production process that converts flow rates into energy through turbines or energy recovery devices.

The term "SWRO" used in the present invention is an abbreviation of Seawater Desalination Reverse Osmosis, and means a seawater desalination technology of reverse osmosis, which is a technique of producing fresh water by applying pressure higher than osmotic pressure to seawater using a reverse osmosis membrane.

The seawater desalination system using the pressure delay osmosis technology, referring to FIG. 1, the high-pressure concentrated brine 10 in which the generated water 9 is filtered and concentrated in the SWRO facility 170 is transferred to the second pressure exchange device 140. Inflow is to transmit pressure to the fourth brine (5). The concentrated brine 10 depressurized while transferring the pressure from the second pressure exchange device 140 to the fourth brine 5 may be pressurized to a predetermined pressure by a third pressure regulator 180 such as a booster pump BP. have. The concentrated brine 10 pressurized by the third pressure controller 180 is introduced into the PRO facility 190 including the PRO membrane for the osmosis process as a high salinity induction solution, and is used in the pressure delayed osmosis process, so the PRO brine It was named (11).

Also available as PRO raw water 12 may be any one or more of primary sewage treatment water, secondary sewage treatment water, tertiary sewage treatment water, brackish water, ground water and surface water. In this case, the PRO raw water 12 may be supplied to the PRO facility 190 after being pretreated with water quality, quantity, pressure, and volume flow rate appropriate for the pressure delayed osmosis process.

The pre-processed PRO raw water 12 is supplied to the PRO facility 190 as a supply solution, and the induction solution and the feed solution introduced into the PRO facility 190 meet with each other across the PRO membrane in the PRO facility 190. At this time, water flows from the feed solution into the draw solution by the salinity difference between the draw solution and the feed solution, and the flow rate of the draw solution increases.

The extracted water exiting from the PRO raw water 12 through the PRO membrane in the PRO plant 190 has a very low salinity, and the mixed casts free energy is generated by the salinity difference between the two solutions while mixing with the PRO brine 11, The pressure of the PRO brine 11 is maintained by the mixed cast free energy thus generated.

The PRO produced water 13 discharged from the PRO plant 190 increases in volume flow rate while maintaining the pressure relative to the PRO brine 11. The PRO production water 13 is discharged from the PRO facility 190 and then flows into the first pressure exchange device 130 and transmits pressure to the first brine 2 to pressurize the first brine 2. After transferring the pressure to the first brine 2, the PRO production water 13 is lowered in pressure, and may be subjected to a separate treatment or process after being discharged from the first pressure exchange device 130.

Meanwhile, the PRO raw water 12 loses the extracted water while undergoing a pressure delay osmosis process at the PRO facility 190, and the concentrated brackish water is transported to an external storage tank or the like as the PRO concentrated water 14 or stored. It may be utilized through a separate post treatment or process.

The cationic fungicide may be any one selected from sodium benzoate, distearyldimonium chloride and chlorhexidine gluconate. The chlorhexidine gluconate may be added at a concentration of 0.8 ppm to 8 ppm.

Cationic fungicide in the seawater desalination system process using the pressure delay osmosis technology can be administered to PRO raw water (12). Specifically, chlorhexidine gluconate at position 12 in FIG. 1 may be flowed with influent for about 30 minutes per day by intermittent infusion during osmotic backwashing at a concentration of 0.8 ppm to 8 ppm.

The present inventors measured the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) by adding chlorhexidine gluconate to gram positive bacteria S. aureus and gram negative bacteria P. aeruginosa (FIG. 2A and FIG. 2B).

In addition, the microbial amount of the biofilm according to the chlorhexidine gluconate concentration was measured (Figs. 3a and 3b).

By setting a specific concentration section based on the chlorhexidine gluconate concentration, the chlorhexidine gluconate was treated in the separator to confirm the inhibition and removal ability of the biofilm formation (FIGS. 4A to 5).

In addition, it was confirmed that chlorhexidine gluconate does not damage the pressure delayed osmosis membrane (Fig. 6).

In addition, while operating the pressure delay osmosis process equipment, it was confirmed that the standard flow rate increased with the addition of chlorhexidine gluconate specific concentration (Fig. 7b).

Therefore, the method for improving the performance of the pressure delayed osmosis membrane of the present invention is useful for improving the performance of the pressure delayed osmosis process by adding chlorhexidine gluconate to the inflow solution to recover the permeate flow rate through biofilm removal and suppressing the formation of the biofilm. Can be used.

Hereinafter, the present invention will be described in detail by way of examples. However, the following examples are only for illustrating the present invention, and the present invention is not limited to the following examples.

Experimental Example  One. Cationic  Confirmation of biofilm formation inhibition of fungicides

Experimental Example  1.1. Chlorhexidine Gluconate  Confirmation of minimum inhibitory concentration and minimum killing concentration of Gram-positive and negative bacteria according to the concentration

Gram-positive bacteria (S. aureus) and Gram-negative bacteria (P. aeruginosa) in TSB (Tryptic soy broth) medium were incubated for one day in an incubator at 37 ° C. The next day, the cells were resuspended in fresh TSB medium so that the concentration of microorganisms was 10 ⁷ CFU / mL. 200 μl of TSB medium containing microorganisms was added to a 96-well plate. Chlorhexidine gluconate was added to each well to a concentration of 62.5, 31.3, 15.6, 7.8, 3.9, 2.0, 1.0, 0.5, 0.2 or 0 μg / ml. Thereafter, the cells were cultured in an incubator at 37 ° C. for 24 hours.

The minimum inhibitory concentration (MIC) of a microorganism is the minimum concentration at which no growth of a particular microorganism occurs in a given environment, and the minimum killing concentration (MBC) is the minimum concentration required to kill a specific microorganism. 100 μl was taken in order of concentration in which the growth of microorganisms did not occur, and each plated in TSA (Tryptic soy agar). Then, TSA was further incubated for 24 hours in an incubator at 37 ℃ temperature. After 24 hours, the concentration at which the colonies of microorganisms were not produced was chosen as the minimum killing concentration.

The results of measuring the minimum inhibitory concentration and the minimum killing concentration of Gram-positive bacteria ( S. aureus ) according to the chlorhexidine gluconate concentration are shown in FIG. 2A.

As a result, the minimum inhibitory concentration and the minimum killing concentration of chlorhexidine gluconate against Gram-positive bacteria S. aureus were measured to be less than 1.0 ppm (FIG. 2A).

In addition, the results of measuring the minimum inhibitory concentration and the minimum killing concentration of Gram-negative bacteria ( P. aeruginosa ) according to the chlorhexidine gluconate concentration are shown in FIG. 2B.

As a result, the minimum inhibitory concentration of chlorhexidine gluconate against Gram-negative bacteria P. aeruginosa was determined to be less than 7.8 ppm, and the minimum killing concentration was less than 15.6 ppm (FIG. 2B).

Experimental Example  1.2. Chlorhexidine Gluconate  Inhibition of biofilm formation according to concentration Confirm

The pretreatment process as described in Experimental Example 1.1. Gram-positive bacteria (S. aureus) and Gram-negative bacteria (P. aeruginosa) in TSB (Tryptic soy broth) medium were incubated for one day in an incubator at 37 ° C. The next day, the cells were resuspended in fresh TSB medium so that the concentration of microorganisms was 10 ⁷ CFU / mL. 200 μl of TSB medium containing microorganisms was added to a 96-well plate. Chlorhexidine gluconate was added to each well to a concentration of 62.5, 31.3, 15.6, 7.8, 3.9, 2.0, 1.0, 0.5, 0.2 or 0 μg / ml. Thereafter, the cells were cultured in an incubator at 37 ° C. for 24 hours.

All TSB medium of the cultured 96-well-plate was removed and washed twice with PBS (Phosphate buffer saline) solution to remove unattached microorganisms and residual medium. 200 μl of 0.1% (v / v) crystal violet was added and then stained in the dark for 15 minutes. After washing twice with ultrapure water (DI water), ethanol was added to elute the attached dye solution. Absorbance at 545 nm wavelength was measured on a UV spectrophotometer.

As a result, in the case of Gram-positive bacteria, it was confirmed that biofilm formation was suppressed at a chlorhexidine gluconate concentration of 1.0 ppm or more. In addition, it was confirmed that biofilm formation was inhibited at the concentration of chlorhexidine gluconate of 3.9 ppm or more for gram negative bacteria.

It was confirmed that the addition of a low concentration of chlorhexidine gluconate inhibits the formation of biofilm by inhibiting growth without killing the microorganisms (FIGS. 3A and 3B).

Experimental Example  1.3. In the separator Chlorhexidine Gluconate  Confirmation of biofilm removal effect by concentration

In order to adhere with the microorganism, the pressure delay osmosis membrane was attached by attaching double-sided tape to the slide glass so that the support layer of the pressure delay osmosis membrane faced upward. P. aeruginosa, incubated in a 37 ° C. incubator for 1 day, was added to a petri dish in a solution diluted 1:20 with fresh TSB medium. The slide glass with the pressure delay osmosis membrane was attached to a medium containing microorganisms and cultured in an incubator at 37 ° C. for one day.

Thereafter, a pressure delayed osmosis membrane was placed in each medium of the Drip flow biofilm reactor. Chlorhexidine gluconate was added to TSB medium at a concentration of 0 ppm, 0.8 ppm or 8 ppm and each medium was flowed into a drip flow biofilm reactor at a flow rate of 0.3 ml / min. After 24 hours, the surface of each pressure delayed osmosis membrane was washed twice with PBS and dyed for 15 minutes by treatment with Live / Dead Cell Double Staining dye solution. In order to remove the unattached dye solution, the surface of the pressure delayed osmosis membrane was washed with ultrapure water. Three-dimensional images were obtained using a confocal laser scanning microscope (CLSM).

As a result, the biofilm was formed on the surface of the pressure-delayed osmotic membrane support layer when the microbial culture medium without chlorhexidine gluconate was injected for one day (Fig. 4a). In the case of injecting the microbial culture without treatment with chlorhexidine gluconate, many biofilms were formed, and the microorganisms fluoresce green in general and were mostly alive (FIG. 4B). On the other hand, when the microbial culture solution to which 0.8 ppm of chlorhexidine gluconate was added, the whole was red in fluorescence (FIG. 4C). This means that most of the microorganisms have died. In addition, when the microbial culture solution to which 8 ppm of glohexidin gluconate was added was injected, most of the biofilm was removed from the surface of the support layer (FIG. 4D).

Experimental Example  1.4. Chlorhexidine Gluconate  Confirmation of biomass and biofilm thickness according to concentration

The pressure delayed osmosis membrane treated with chlorhexidine gluconate by concentration in Experimental Example 1.3 was measured biomass and Biofilm thickness of the three-dimensional biofilm image using comstat software of ImageJ.

As a result, when the microbial culture medium without any treatment was injected into the support layer of the biofilm formed membrane, the microbial amount and the biofilm thickness increased.

On the other hand, when a microbial culture solution containing 0.8 ppm of chlorhexidine gluconate was injected, the microorganisms were killed and the thickness of the biofilm no longer increased. Therefore, it was confirmed that the addition of low concentration chlorhexidine gluconate inhibits the formation of the biofilm.

In addition, when a microbial culture solution containing 8 ppm of chlorhexidine gluconate was injected, the biofilm thickness was 6.0 µm, which was thinner than that of the conventional biofilm. Therefore, it was confirmed that the biofilm is removed when the high concentration of chlorhexidine gluconate is added (FIG. 5).

Experimental Example  2. Chlorhexidine Gluconate  Confirmation of damage of membrane by treatment

The pressure delayed osmosis membrane was soaked in ultrapure water, 5% (v / v) chlorine, 5% (v / v) chlorhexidine gluconate solutions for 1 hour. Thereafter, the pressure delayed osmosis membrane was washed three times with ultrapure water. The pressure delayed osmosis membrane was dried for one day using a vacuum desiccator. The active layer of the dried pressure delayed osmosis membrane was analyzed using an ATR-FTIR analyzer. The absorbance was measured by setting the resolution to 1 cm ^-1 and the measurement range from 1200 cm ^-1 to 1800 cm ^{- 1} .

6 shows the results of confirming whether the separator is damaged by chlorhexidine gluconate treatment. A is the active layer surface of the membrane treated with 5% (v / v) chlorhexidine gluconate, B is the active layer surface of the membrane treated with 5% (v / v) chlorine, and C is the ATR- surface of the active layer of the membrane treated with nothing. It was measured by an attenuated total reflectance-fourier transform infrared (FTIR) spectrometer.

Dotted lines shown in FIG. 6 are peaks indicating the chemical structures involved in polyamide bonds. Peak of 1542cm ^-1 represents an amide bond of the surface structure by NH, NC bond, peak of 1609cm ^-1; means a bond structure between the polymer C = C bonds. The peak of 1665 cm ⁻¹ is an amide bond structure of C═O and CN.

As a result, the peaks of 1542, 1609 and 1665 cm ⁻¹ disappeared from the surface of the active layer of the membrane treated with 5% (v / v) chlorine of B by the oxidizing fungicide. This confirmed that the surface polyamide was damaged by reacting with chlorine. It was confirmed that the surface of the active layer of the separation membrane of A and C was not damaged, and from the results of A, chlorhexidine gluconate was confirmed to be compatible with the separation membrane even at high concentrations (FIG. 6).

Example  One. Chlorhexidine Gluconate  According to addition Pressure delay osmosis  See changes in process efficiency

A laboratory scale pressure delay osmosis process apparatus was used. In order to stabilize the pressure delay osmosis membrane, the operation was performed using ultrapure water for 2 hours before the pressure delay osmosis process equipment was operated, and the artificial influent and artificial reverse osmosis concentrate were injected and operated. The operation was performed for 24 hours, and the operating temperature was maintained at 25 ± 0.5 ° C. Synthetic sewage was used as the influent used in the pressure delay osmosis process, and the induced solution was artificially prepared with reverse osmosis concentrate. The injection concentration of chlorhexidine gluconate in the influent was 0 ppm, 0.8 ppm, 4 ppm or 8 ppm, respectively, and the experimental results for the flow rate were automatically entered into the data storage computer.

The change in the standard flow rate of the pressure delayed osmosis process according to the chlorhexidine gluconate concentration is shown in FIG. 7b.

As a result, when the microorganism and chlorhexidine gluconate were not added to the inflow solution, it was confirmed that the permeate flow rate of the initial separation membrane was maintained. In addition, when only the microorganisms are treated in the influent solution, it was confirmed that the permeate flow rate decreased by about 40% compared to the initial permeate flow rate.

On the other hand, when chlorhexidine gluconate was added at a concentration of 0.8 ppm to the influx solution treated with the microorganism, it was confirmed that the permeate flow rate was maintained similar to the initial permeate flow rate. In addition, the addition of chlorhexidine gluconate at a concentration of 8 ppm to the influx solution treated with microorganisms showed a lower permeate flow rate than the addition of 0.8 ppm of chlorhexidine gluconate. This is a decrease in permeation flow caused by chlorhexidine gluconate remaining inside the support layer.

Therefore, a specific concentration interval of 0.8 ppm to 8 ppm was confirmed in which the recovery amount for the permeation rate decrease by the biofilm is greater than the decrease in the permeate flow rate by chlorhexidine gluconate (FIG. 7B).

1 ': desalination system 110: DAF facility
120: UF plant 130: first pressure exchange device
140: second pressure exchange device 150: first pressure control device
160: second pressure regulator 170: SWRO facilities
180: third pressure regulator 190: PRO equipment
192: 1st PRO facility 194: 2nd PRO facility

Claims (8)

In a pressure delayed osmotic process using a difference in osmotic pressure between a high salinity induction solution in contact with an active layer of a membrane and a low salinity inflow solution in contact with a support layer of a separator, chlorhexidine gluconate is added to the inflow solution at a concentration of 0.5 ppm to 1 ppm. By inhibiting the formation of the biofilm in the support layer of the membrane, the method of improving the performance of the pressure delay osmosis process. The method of claim 1,
The active layer is made of a polyamide, a method for improving the performance of the pressure delay osmosis process. The method of claim 2,
Wherein said polyamide is formed by the polymerization of an amine compound and an acyl halide compound. The method of claim 3, wherein
The amine compound is m-phenylenediamine, p-phenylenediamine, 1,3,6-benzenetriamine, 4-chloro-1,3-phenylenediamine, 6-chloro-1,3-phenylenediamine and It is one or a mixture thereof selected from the group consisting of 3-chloro-1,4-phenylene diamine, a method for improving the performance of the pressure delay osmosis process. The method of claim 3, wherein
The acyl halide compound is one or a mixture thereof selected from the group consisting of trimezoyl chloride, isophthaloyl chloride and terephthaloyl chloride, the method of improving the performance of the pressure delay osmosis process. The method of claim 1,
The support layer is one selected from the group consisting of polysulfone, polyethersulfone, polycarbonate, polyethylene oxide, polyimide, polyetherimide, polyetherketone, polypropylene, polymethylpentene, polymethyl chloride and polyvinylidene fluoride That is, how to improve the performance of the pressure delay osmosis process. The method of claim 1,
The addition of the chlorhexidine gluconate improves the performance of the pressure delayed osmosis process, which suppresses the increase of the biofilm formed in the support layer of the separator not to exceed 12.1 ± 0.4 μm after the process when the thickness of the biofilm initially is 10.1 ± 1.8 μm. How to. A first pressure exchange device and a second pressure exchange device for raising pressure by receiving sea water;
SWRO facility for receiving the pressure-increasing seawater to produce the product water filtered the salt through the reverse osmosis membrane, and deliver the concentrated brine to the second pressure exchange device;
A first PRO facility in which the concentrated brine discharged from the second pressure exchange device is supplied as brine of a pressure delayed osmosis (PRO), and is supplied with PRO raw water from the outside to perform a pressure delayed osmosis process; And
In the seawater desalination system using a pressure delayed osmosis technology comprising a second PRO equipment is subjected to a pressure delay osmosis process by receiving the PRO brine discharged from the first PRO equipment,
Using chlorhexidine gluconate at a concentration of 0.5 ppm to 1 ppm to the PRO raw water to inhibit the formation of biofilm in the PRO membranes in the first PRO facility and the second PRO facility. How to improve the performance of desalination systems.

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