KR20170099201A

KR20170099201A - Prediction Method for Organic-Fouling of Membrane

Info

Publication number: KR20170099201A
Application number: KR1020160021285A
Authority: KR
Inventors: 신광희; 황수현; 박병구; 최현성
Original assignee: 두산중공업 주식회사
Priority date: 2016-02-23
Filing date: 2016-02-23
Publication date: 2017-08-31
Also published as: KR101795910B1

Abstract

The present invention relates to a method of predicting organic fouling of a membrane, in which membrane fouling can be accurately, rapidly, and conveniently predicted by establishing an indicator having a high correlation with organic fouling of the membrane. Specifically, the present invention provides a method of predicting organic fouling of a membrane, comprising: a step of classifying organic matters into groups; a step of analyzing a degree to which each of the organic groups, classified according to the step of classifying organic matters into groups, is accumulated on the membrane; and a step of establishing an indicator predictive of membrane fouling based on the degree to which each of the organic groups is accumulated on the membrane, which has been analyzed in the step of analyzing a degree to which each of the organic groups is accumulated on the membrane.

Description

{Prediction Method for Organic Fouling of Membrane}

The present invention relates to a method for predicting organic film fouling, and more particularly, to a method for predicting organic film fouling which can accurately, quickly, and easily predict membrane fouling by setting an index highly correlated with organic film fouling .

Membrane filtration technology is a separation process that can almost completely separate and remove substances to be treated in the raw water and the wastewater according to the pore size and surface charge of the membrane. Membrane is a porous membrane with a lot of pores. It can separate organic pollutants, inorganic contaminants, parasites, bacteria, etc. contained in water. Therefore, the membrane filtration technology is recognized as one of effective technologies for water / wastewater treatment and sewage (wastewater) reprocessing in terms of the efficiency of removal of pollutants such as organic / inorganic pollutants, organic substances in the effluent of waste water (EfOM) come.

In addition, the water treatment using the membrane has advantages in that the amount of chemicals such as coagulant used is smaller than that of other filtration processes, and the area required can be reduced, which is widely used in the overall water treatment field.

The most important thing in the membrane is how much physical strength and how much good quality membrane permeate can be obtained. However, there is a problem that the membrane process causes fouling depending on use, thereby deteriorating the performance of the membrane. Fouling is a phenomenon that various foreign substances present in the influent water are deposited or adsorbed on the surface of the membrane to reduce the water permeability of the membrane. Examples of the foreign matter causing the membrane contamination include floating particles, colloids, organic matter, microorganisms, And inorganic salts such as calcium salts. Membrane contamination is affected by electrostatic interactions (repulsion or attraction) or hydrophobic interactions, depending on the hydrodynamic element, membrane properties, and chemical properties of the contaminants, such as the size of the contaminants, Interaction between contaminants also affects the diffusion coefficient of contaminants from the membrane surface. As a result, there is a problem that the operability of the overall facility deteriorates and the cost increases.

Therefore, it is very important to predict membrane fouling, but it is very difficult to predict the membrane fouling phenomenon in advance because the materials causing the membrane fouling are very diverse as described above.

Studies on membrane fouling phenomena to date have been focused on filtration experiments, analysis of contaminated membranes, and assessment of membrane fouling by existing membrane fouling indexes (e.g., sludge density index). These existing studies require much time to analyze and limit the quantification of pollution level.

Accordingly, SDI (Silt Density Index) measurement method has been developed as a method for predicting membrane contamination phenomenon generally in reverse osmosis or nanofiltration process. SDI is used as a measure of the possibility of fouling in the membrane. According to the SDI measurement method, the degree of contamination caused by the SS (Suspended Solid) component is measured by flowing water at a pressure of 30 psid to a filter having a diameter of 47 mm and 0.45 탆. At this time, the time (T0) required for the first 500 ml of water to flow is measured. Then, after 15 minutes (T), the time required for 500 ml of water to flow again (T1) is measured, and the ratio of these two times is used as a scale.

SDI measurements are the most widely used method for predicting membrane contamination trends of influent in current reverse osmosis or nanofiltration processes. In general, if the SDI is less than 3, the pollution is not severe. If the SDI is 5 or more, severe contamination may occur. That is, the SDI measurement method is a method for indirectly evaluating the possibility of film contamination by floating particles having a size of 0.45 탆 or more. Therefore, SDI can not evaluate the effect of colloid or organic matter having a size of less than 0.45 μm.

In general, TOC (Total Organic Carbon) is used as a method for analyzing membrane fouling due to organic substances. However, the TOC value includes all kinds of organic substances and organic substances having low correlation with membrane contamination, Corrosion is not highly correlated and precise membrane contamination can not be predicted.

Also, there is a problem in that it is not suitable for use as an indicator in a field plant because expensive analytical equipments and specialized manpower are required to analyze substances causing organic film contamination.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for predicting membrane fouling which can accurately and quickly predict membrane fouling by setting an indicator having high correlation with organic membrane fouling have.

According to an aspect of the present invention, there is provided a method of analyzing an organic material, the method comprising: classifying organic substances into groups; analyzing a film accumulation degree of each organic substance group classified by grouping the organic substances into groups; Determining an indicator of membrane fouling predicting based on the film deposition degree of each organic matter group analyzed by the analyzing step.

The step of classifying the organic substances into groups may be performed based on fluorescence analysis data and TOC (Total Organic Carbon) analysis data.

The step of classifying the organic substances into groups is classified into two organic groups of Humic type and three organic groups of Protein type.

The step of analyzing the film accumulation degree may be performed by analyzing the concentrations of the organic matter groups in the influent water and the effluent in the membrane process.

The step of setting the indicator is characterized by setting the concentration of the organic substance group having the highest film accumulation degree analyzed by the step of analyzing the film accumulation degree as an indicator.

The step of setting the indicator is characterized by combining the concentrations of a plurality of organic substance groups having a high degree of accumulation of the film analyzed by the step of analyzing the film accumulation degree as indicators.

The step of setting the indicator is characterized by setting the sum of the concentrations of the plurality of organic substance groups having a high film accumulation degree analyzed by the step of analyzing the film accumulation degree as an index.

Wherein the coefficient of concentration of each organic substance group in the sum of the concentrations of the plurality of organic substance groups is set differently according to the film accumulation degree.

In addition, when the indicator is set by the step of setting the indicator, it may further include setting a range of the indicator according to the degree of membrane contamination so as to predict the possibility of contamination of the organic membrane in each membrane process.

The step of setting the range of the indicator is characterized by taking into account the rate of increase of the differential pressure in the membrane process.

The method may further include the step of predicting membrane contamination in each membrane process using the index set by the step of setting the index.

The step of predicting the membrane fouling is characterized by deriving the numerical value of the indicator set by the step of setting the indicator in each membrane process and predicting membrane fouling according to the derived range of the numerical value.

And a numerical value of the indicator is derived by classifying the organic matter into groups.

The method may further include determining a drug injection schedule based on the degree of the predicted membrane fouling according to the step of predicting the membrane fouling.

The step of determining the drug injection schedule may include injecting the drug intermittently when the degree of the predicted film contamination is low according to the step of predicting the film contamination, , And when the degree of predicted film contamination is high, it is determined to inject the chemicals continuously.

According to the method of predicting the organic film contamination of the present invention, organic matter can be classified into groups based on fluorescence analysis data and TOC (Total Organic Carbon) analysis data, so that quantitative analysis as well as qualitative analysis can be performed.

In addition, based on the film accumulation degree of each organic substance group, an indicator of film fouling prediction having a high correlation with the organic film fouling is set, and the film fouling is predicted using the indicator.

In addition, it is possible to predict film fouling easily and quickly because expensive analytical equipment and professional manpower are not needed for prediction analysis of membrane fouling.

Further, by determining the drug injection schedule based on the predicted degree of film contamination according to the step of predicting the membrane contamination, the drug cost can be minimized and the membrane contamination can be effectively controlled.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a step-by-step method for predicting organic film contamination according to an embodiment of the present invention; FIG.
2 is a schematic view showing a fluorescence analysis method.
FIG. 3 is a graph showing an analysis result using the fluorescence analysis method of FIG. 2 in one embodiment.
Figures 4A-4E are graphs of organics groups sorted in one embodiment.

Hereinafter, a preferred embodiment of a method for predicting organic film contamination according to the present invention will be described with reference to FIGS. 1 to 4E.

It is to be understood that both the foregoing description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention, and are not intended to limit the scope of the invention. But are merely illustrative of the elements recited in the claims.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification. Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

FIG. 1 is a schematic view showing a method of predicting organic film contamination according to an embodiment of the present invention, FIG. 2 is a schematic view showing a fluorescence analysis method, FIG. 3 is a graph showing an analysis result using the fluorescence analysis method of FIG. And FIGS. 4A to 4E are graphs of organic compounds classified in one embodiment.

First, a method for predicting organic film contamination according to an embodiment of the present invention will be described step by step with reference to FIG.

The method of predicting organic film contamination according to the present invention includes a step S100 of classifying organic substances into groups, a step S200 of analyzing the film accumulation degree of each organic substance group, a step S300 of setting an indicator of film contamination prediction, A step S400 of setting the range of the indicator according to the degree of the membrane fouling, a step S500 of predicting the membrane fouling, and a step S600 of determining the drug injection schedule.

Membrane processes cause fouling and degrade the performance of membranes. The organic matter present in the influent of the membrane process adsorbs on the surface of the membrane or accelerates the growth of the microorganisms (Bio-fouling), thereby reducing the water permeability of the membrane.

Organic materials can be classified into groups of similar properties in terms of polarity, charge, size, etc. (S100: classification of organic materials into groups). Organic materials can be classified by various methods, but they can be based on fluorescence analysis data and TOC (Total Organic Carbon) analysis data in this embodiment. The Fluorescence Excitation Emission Matrix (FEEM) is for qualitative analysis, and the TOC analysis is for quantitative analysis.

As shown in FIG. 2, the fluorescence analysis method may include a method of stimulating a light source to a sample to be analyzed and analyzing a light source emitted from the sample. In fluorescence analysis, each organic material exhibits inherent fluorescence absorption and emission wavelengths, and it is possible to provide comprehensive information on organic matter. Also, because of its high sensitivity, it is possible to measure even a trace amount of organic matter.

FIG. 3 shows an analysis result using the fluorescence analysis method in one embodiment, and is shown in a graph according to fluorescence excitation and divergence wavelength (Emission).

Based on fluorescence analysis data and TOC analysis data, organics can be classified into groups, which can be achieved by various methods, but are preferably classified through statistical analysis. The parafac tool can be used as a statistical analysis method, and organic materials having similar characteristics can be classified and quantified by group based on the analysis data through matlab coding or the like.

4A to 4E, according to the position and shape of the graph according to the fluorescence excitation and the emission wavelength, two organic groups of humic type and a protein Protein) group, and we will explain this by reference. The three organic groups of the C1, C2, and Protein groups are defined as C3, C4, and C5 groups, respectively, in the two organic groups of the humic system. The organic group of the humic system is contaminated by adsorption, has a negative charge, and has a hydrophobic property. On the other hand, the protein-based organic material group is an amphoteric substance and has a hydrophilic property, causing membrane contamination by adsorption or biodegradation. Generally, the organic materials of the protein series are larger than the organic materials of the humic type.

Next, the possibility of membrane contamination is analyzed for each group of organic substances classified (S200: step of analyzing the film accumulation degree). The possibility of membrane contamination can be analyzed by using the degree of accumulation of organic matter in the membrane, and the concentration of each organic substance group in the influent water flowing into the membrane process and the effluent flowing out can be analyzed for a predetermined time.

For example, the concentration of each organic substance group in the influent can be measured, the concentration of each organic substance group in the effluent can be measured, and the degree of accumulation in the membrane can be determined using Mass Balance for each organic substance group. That is, if the concentration in the influent water is the same as the concentration in the effluent or the concentration in the influent water is slightly higher than the concentration in the effluent, it is not likely to accumulate in the membrane and the possibility of membrane contamination is low. It is considered that there is a high probability of membrane contamination because the degree of accumulation in the membrane is high. Also, even if the concentration in the influent water is lower than the concentration in the effluent due to the error, it should be considered that the possibility of contamination of the membrane is low because it is not accumulated in the membrane.

In addition, the step of analyzing the film accumulation degree (S200) may be analyzed for a predetermined period of time, so that even when the film processing conditions of each season and region are somewhat different, the average film accumulation can be analyzed.

Next, an index of the film fouling prediction is set based on the film accumulation degree of each organic substance group analyzed by the step of analyzing the film accumulation degree (S200) (S300: step of setting an indicator of membrane fouling prediction) .

The index of membrane fouling prediction can be determined based on the concentration of one organic substance group or the concentration of a plurality of organic substance groups having a high film accumulation degree based on the film accumulation degree of each organic substance group analyzed, The correlation is high, and membrane contamination can be predicted according to the value of the indicator.

In one embodiment, the index of the film fouling prediction may be set to the concentration of the organic substance group having the highest film accumulation degree analyzed by the step S200 of analyzing the film accumulation degree.

Further, according to another applicable embodiment, the index of film fouling prediction may be calculated by summing the concentrations of a plurality of organic material groups having relatively high film accumulation degrees analyzed by the step S200 of analyzing the film accumulation degree Can be set. However, the present invention is not limited thereto, and it is possible that the concentration of a plurality of organic substance groups having a high degree of film accumulation is combined. Further, the coefficient of the concentration of each organic substance group in the sum of the concentrations of the plurality of organic substance groups may be set differently according to the film accumulation degree. It is preferable to set the coefficient multiplied to the concentration of the organic substance group to be analyzed with the highest degree of film accumulation to maximize the effect on the indicator. As described above, the film accumulation degree is relatively high according to the film accumulation degree, and the coefficient is set to a large value to make the influence on the indicator large. The relatively low film accumulation degree can reduce the influence on the indicator by setting the coefficient to be small. This makes it possible to set more accurate indices and accurately predict film fouling.

As a result of analyzing the degree of film accumulation in the present embodiment, it was found that among the five organic substances classified in the above, the C4 accumulation degree is the highest, the accumulation degree of the C1 and C3 groups is relatively high, The film accumulation degree is low and there is almost no possibility of contamination of membrane.

At this time, in one embodiment, the indicator can be set to the concentration of the organic C4 group having the highest film accumulation degree.

In other applicable embodiments, the sum of the concentrations of a plurality of groups of organic substances, that is, C1, C3, and C4 groups having a relatively high degree of film accumulation (C1 + C3 + C4) can be set. At this time, the index (C1 + C3 + 6C4) can be set by setting the coefficient of the concentration of the organic substance C4 group analyzed to have the highest degree of film accumulation to be large.

If an index capable of predicting membrane fouling is set in accordance with the setting of the indicator (S300) as described above, the range of the indicator according to the degree of membrane fouling can be predicted so as to predict the degree of possibility of organic membrane fouling in each membrane process (S400: setting the range of the indicator). For example, in this embodiment, when the index is defined as the sum of the concentrations C1 + C3 + 6C4 of the plurality of organic substance groups C1, C3, and C4 having high film accumulation degrees, The probability of film contamination is low when 3? C1 + C3 + 6C4? 6, and the possibility of film contamination is high when 6? C1 + C3 + 6C4 <3 Can be set.

At this time, the degree of membrane contamination is highly correlated with the differential pressure (DELTA DP) indicating the difference in pressure before and after membrane permeation of the membrane in the membrane process, and the greater the degree of membrane contamination, the greater the differential pressure. Therefore, it is preferable to consider the rate of increase of the differential pressure of the membrane process when setting the range of the indicator capable of predicting the degree of possibility of membrane contamination.

Since the indicator for predicting the membrane contamination is set, the membrane contamination can be predicted using the set index (S500: step for predicting membrane contamination). To do this, the concentration of each organics group in the influent water is measured in a membrane process to predict membrane contamination. It is also possible to measure only the concentration of the organic substance group necessary for calculating the numerical value of the preset index. At this time, the concentration of each organic substance group may be measured by a step S100 of classifying the organic substances into groups, that is, by fluorescence analysis and TOC analysis. Next, the numerical value of the predetermined indicator can be derived using the concentration of each organic substance group measured, and the degree of possibility of contamination of the membrane can be predicted according to the derived indicator.

Next, the drug injection schedule may be determined based on the predicted degree of film contamination according to the step S500 of predicting the membrane fouling (S600: step of determining the drug injection schedule).

The organic matter present in the influent water of the membrane process is adsorbed on the membrane surface or accelerates the growth of the microorganisms (bio-fouling), and a medicine such as a sterilizing agent is injected to control the organic matter. At this time, it is important to determine the injection timing and concentration of the drug according to the organic matter concentration of the influent water in order to reduce the cost of the drug.

According to the present embodiment, when the degree of predicted film fouling is low according to the step S500 of predicting the film fouling, no chemical is injected. When the predicted degree of film fouling is intermediate, the chemical is intermittently injected, When the predicted degree of film contamination is high, the drug injection schedule can be determined so that the drug is continuously injected. For example, in one embodiment, when the numerical value of the index derived by the step S500 of predicting the film contamination is 3? C1 + C3 + 6C4 < 6, It can be injected intermittently for 6 hours.

Therefore, if the chemical injection timing and the injection cycle are determined based on the index value of the film fouling prediction as described above, the drug cost can be minimized and the film contamination can be effectively controlled.

The present invention is not limited to the above-described specific embodiment and description, and various changes and modifications may be made by those skilled in the art without departing from the scope of the present invention as claimed in the claims. And such modifications are within the scope of protection of the present invention.

Claims

Classifying the organic substances into groups;
Analyzing a film accumulation degree of each organic substance group classified by grouping the organic substances into groups; And
Setting an indicator of membrane fouling predicting based on a film deposition degree of each organic matter group analyzed by analyzing the film deposition degree;
Wherein the organic film is contaminated.

The method according to claim 1,
The method of claim 1, wherein the grouping of the organics is performed based on fluorescence analysis data and TOC (Total Organic Carbon) analysis data.

3. The method of claim 2,
Wherein the step of classifying the organic substances into groups is classified into two organic groups of Humic type and three organic groups of Protein type.

The method according to claim 1,
Wherein analyzing the film accumulation degree comprises analyzing the concentration of each organic substance group in the influent water and the effluent in the membrane process.

The method according to claim 1,
Wherein the setting of the indicator sets the concentration of the organic substance group having the highest film accumulation degree analyzed by the step of analyzing the film accumulation degree as an indicator.

The method according to claim 1,
Wherein the setting of the indicator is performed by combining the concentrations of a plurality of organic substance groups having a high film accumulation degree analyzed by the step of analyzing the film accumulation degree as an indicator.

The method according to claim 6,
Wherein the setting of the indicator sets the sum of the concentrations of the plurality of organic substance groups having a high film accumulation degree analyzed by the step of analyzing the film accumulation degree as an indicator.

8. The method of claim 7,
Wherein the coefficient of concentration of each organic substance group in the sum of the concentrations of the plurality of organic substance groups is set differently according to the film accumulation degree.

The method according to claim 1,
Setting a range of an indicator according to the degree of film contamination so that the probability of organic film contamination in each membrane process can be predicted when the indicator is set by setting the indicator;
Further comprising the steps of:

10. The method of claim 9,
Wherein the step of setting the range of the indicator is set in consideration of the rate of increase of the differential pressure in the membrane process.

10. The method of claim 9,
Predicting membrane fouling in each membrane process using an indicator set by setting the indicator;
Further comprising the steps of:

12. The method of claim 11,
Wherein the step of predicting membrane fouling includes deriving numerical values of the indicator set by the step of setting the indicator in each membrane process and predicting membrane fouling according to the range of the derived numerical value Way.

13. The method of claim 12,
Wherein the numerical value of the indicator is derived by classifying the organic matter into groups.

12. The method of claim 11,
Determining a drug injection schedule based on the predicted degree of membrane contamination according to the step of predicting membrane fouling;
Further comprising the steps of:

15. The method of claim 14,
The step of determining the drug injection schedule may include injecting the drug intermittently when the degree of the predicted film contamination is low according to the step of predicting the film contamination, , And when the predicted degree of film contamination is high, it is determined to continuously inject the chemical.