**2. Analysis of patents and articles on water treatment membranes**

Treatment and the reusing of wastewater are mainly based on the activated sludge process. In the activated sludge process, the amount of generated sludge is large, the treatment cost is high, and it is vulnerable to impacts such as biological oxygen demand (BOD) overload and toxicity, and problems such as sludge bulking occur. However, the membrane bioreactor (MBR) does not need to regulate the amount of microorganisms in the reactor and does not cause the sludge expansion phenomenon. In addition, it has excellent durability against load generated in the operation such as impact, toxicity, and organic load. It is expected that the technology of the MBR process will increase gradually because of the advantages of this separation membrane process [25, 26]. In most of the domestic large and medium-sized water purification facilities, using river water or lake water as a water source, problems occur periodically. However, the conventional water treatment methods such as coagulation, sedimentation, filtration, and disinfection processes are inferior in taste and odor. There is a limit in effectively controlling harmful organic substances and the like. In order to overcome the limitations of this conventional treatment method, microfiltration or ultrafiltration using a membrane has been shown to be a breakthrough technology that can replace the existing rapid sand filtration system because it completely removes turbidity and pathogenic microorganisms. In addition, it can easily combine with the existing unit-altitude water treatment process such as ozone-activated carbon to optimize the process configuration suitable for the characteristics of raw water and water quality, and it is more

compact and easier to maintain than the existing water treatment method [27, 28].

consumption, and reducing maintenance costs [29, 30].

206 Desalination and Water Treatment

Techniques for converting seawater to fresh water include conventional coagulation, coagulation, sedimentation, single- or two-phase granular filtration, dissolved air flotation, and lowpressure membrane filtration techniques using microfiltration or ultrafiltration membranes. Conventional pretreatment processes are generally used in seawater desalination, but it is difficult to completely remove float or colloidal particles, which makes it difficult to supply water in a stable manner. However, when the membrane is pretreated, it has the advantage of reducing the cost required in the desalination process, such as increasing the permeation flow rate, reducing the washing cycle, reducing the use of washing chemicals, reducing energy

A membrane electrode assembly (MEA), which is one of the most important components among the separation membranes used in the ion exchange process, includes a proton exchange membrane fuel cell (PEMFC). The membrane consists of two electrodes, cathode and anode, which determine the performance of the fuel cell [31–33]. Currently, the most widely used hydrogen ion exchange membranes are produced by DuPont's nafion® as well as Dow Chemical, 3 M, and others. The perfluorinated proton exchange membrane has been applied to most commercial fuel cell devices due to its high chemical/mechanical stability and excellent hydrogen ion transfer ability. However, since the production process requires high temperature/high pressure conditions, the production cost has increased. The limitation is that it has a pollution problem, and there is a problem that performance is reduced at high temperature due to low glass transition temperature [34, 35]. Therefore, research on the production of a hydrocarbon-based proton exchange membrane having a relatively high manufacturing cost

and high thermal stability has been actively pursued as an alternative thereto [36–39].

In this review, the water treatment membranes are divided into wastewater treatment membranes, water treatment membranes, seawater desalination membranes, and ion exchange membrane separators. Through analysis of domestic and foreign patent information and In this chapter, we show all patents and papers for water treatment membranes. In the past 20 years (1995–2014), we have divided membranes for wastewater treatment, separation membranes for water treatment, and seawater desalination membrane trends. In evaluating the competitiveness of patent technology, patents filed after 2015 are analyzed only as valid patents before 2015 except for the fact that they were undisclosed. The patent database of WIPS was used for the analysis of the patent. The patent data were searched through the keyword search and the secondary classification was performed using the library method for noise and pattern removal. Finally, a final classification was carried out by experts in each field. The patent activity index (PAI), the patent intensity index (PII), the patent market-power index (PII), the patent market power index (PMI), and patent citation index (PCI) were the categories. These terms can be defined as follows. Patent activity is defined as the absolute number of patent applications based on the number of public/patent publications issued by the Patent Office. Patent concentration refers to providing information about the technological innovation activities that a country concentrates on relative to other countries. The patent market power refers to the use of patents as an indicator of the patentability of patents when the number of family patents is large, because patents are applied only when they are in commercial profit or for technology competition in the relevant country. Finally, patent impact is the measure of the impact of the patent on future patents, and the US patent with patent information for the patents is targeted [40–43].

The number of patent applications has been evaluated in the 10 countries, including Korea, the USA, Japan, China, and Europe, which are the major developing countries, for patent technology competitiveness. A total of 4629 patent applications were searched. 1144 patents were related to separation membranes for wastewater treatment, 734 patents related to water treatment membranes, 668 patents related to seawater desalination membranes, and 2083 patents related to membranes for ion exchange processes. **Figure 4** shows the patent application trends by technology in the last 20 years.

The thesis has been published in the past 20 years (1997–2016), and it has been evaluated for technical competitiveness. 13,506 papers are related to the separation membrane for wastewater treatment, 7958 papers are related to the separation membrane for water treatment, 9524 papers related to separation membrane for desalination, and 16,254 papers related to separation membrane for an ion exchange process. **Figure 5** shows the trend of publications by technology in the past 20 years. The database used to analyze the technological competitiveness of the paper is the Scopus paper retrieval system, which collects information by category and country and uses the Bibliometric Activity Index (BAI), Bibliometric Citation Index (BCI), and Bibliometric Intensity Index (BII). These terms can be defined as follows. The thesis activity is the number of absolute dissertations, which shows the corresponding country for the technology divided by the total number of countries. The impact of a paper is defined as an index that provides information that can be compared with other countries in terms of the quality of the paper. Finally, the thesis density can be defined as an index that provides information on the

**2.1. Evaluation of patent technology competitiveness of water treatment membranes**

patent market power, and patent influence by country.

Kingdom; IT, Italy; NL, Netherlands; CN, China.

**Table 2.** An analysis table about PAI, PII, PMI, and PCI by each country.

\*

**Figure 6.** Top countries with the highest number of patent application.

As a result of analyzing the number of applications for separation membrane-related patents, the following results were obtained: Japan (2093 cases), Korea (1134 cases), the USA (585 cases), Canada (135 cases), Germany (97 cases), France (49 cases), Italy (35 cases), the Netherlands (33 cases), and China (31 cases). As for the patent activities, Japan was overwhelmingly ranked high (0.49), followed by Korea (0.27), the USA (0.14), Canada (0.03), and Germany (0.02). **Table 2** and **Figure 7** show the patents' utilization rate, patent concentration,

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In terms of the degree of patent concentration in each country, Japan tends to concentrate most on water treatment membranes (1.20), Korea on wastewater treatment membranes (1.72), and the USA on ion exchange membranes (1.13)—1.37, 1.39, 1.32, and 1.86 for Canada, Germany, the United Kingdom, and Italy, respectively, for the ion exchange membrane, 1.25 for the wastewater treatment membrane for France and 1.77 and 1.25 for the water treatment membranes. As a result of analyzing the number of family patents of separation membrane-related patents, the following results were obtained: Japan (5651 cases), the USA (3328 cases), Korea (1743 cases),

**Index of evaluation KR\* JP US CA DE FR GB IT NL CN** PAI\*\* 0.27 0.49 0.14 0.03 0.02 0.01 0.01 0.01 0.01 0.01 PII 4.46 3.92 3.76 3.42 3.13 3.59 3.91 2.76 3.85 3.98 PMI 0.46 0.81 1.71 2.02 2.64 2.66 3.12 3.49 2.06 1.23 PCI 0.51 0.50 1.18 1.87 0.67 0.51 1.02 2.40 0.66 0.14

ISO code: KR, Korea; JP, Japan; US, United States of America; CA, Canada; DE, Germany; FR, France; GB, United

\*\*PAI: Patent Activity Index, PII: Patent Intensity Index, PMI: Patent Market-power Index, PCI: Patent Citation Index.

**Figure 4.** Patent applications 1996–2016 in membrane related technology.

**Figure 5.** Papers publications 1996–2016 in membrane related technology.

relative concentration of a technological innovation activity in a given technology sector relative to other countries in terms of the number of relative papers published. Major countries participating in the analysis of information are the top 13 countries such as Korea, the USA, Japan, China, and Europe (**Figure 6**).

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**Figure 6.** Top countries with the highest number of patent application.

#### **2.1. Evaluation of patent technology competitiveness of water treatment membranes**

As a result of analyzing the number of applications for separation membrane-related patents, the following results were obtained: Japan (2093 cases), Korea (1134 cases), the USA (585 cases), Canada (135 cases), Germany (97 cases), France (49 cases), Italy (35 cases), the Netherlands (33 cases), and China (31 cases). As for the patent activities, Japan was overwhelmingly ranked high (0.49), followed by Korea (0.27), the USA (0.14), Canada (0.03), and Germany (0.02). **Table 2** and **Figure 7** show the patents' utilization rate, patent concentration, patent market power, and patent influence by country.

In terms of the degree of patent concentration in each country, Japan tends to concentrate most on water treatment membranes (1.20), Korea on wastewater treatment membranes (1.72), and the USA on ion exchange membranes (1.13)—1.37, 1.39, 1.32, and 1.86 for Canada, Germany, the United Kingdom, and Italy, respectively, for the ion exchange membrane, 1.25 for the wastewater treatment membrane for France and 1.77 and 1.25 for the water treatment membranes.

As a result of analyzing the number of family patents of separation membrane-related patents, the following results were obtained: Japan (5651 cases), the USA (3328 cases), Korea (1743 cases),


\* ISO code: KR, Korea; JP, Japan; US, United States of America; CA, Canada; DE, Germany; FR, France; GB, United Kingdom; IT, Italy; NL, Netherlands; CN, China.

\*\*PAI: Patent Activity Index, PII: Patent Intensity Index, PMI: Patent Market-power Index, PCI: Patent Citation Index.

**Table 2.** An analysis table about PAI, PII, PMI, and PCI by each country.

relative concentration of a technological innovation activity in a given technology sector relative to other countries in terms of the number of relative papers published. Major countries participating in the analysis of information are the top 13 countries such as Korea, the USA,

Japan, China, and Europe (**Figure 6**).

**Figure 4.** Patent applications 1996–2016 in membrane related technology.

208 Desalination and Water Treatment

**Figure 5.** Papers publications 1996–2016 in membrane related technology.

efficacy, and patent concentration tended to be concentrated on wastewater treatment

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As a result of analyzing the number of published papers related to membranes, the results obtained were as follows: the USA (11,435), China (9235), Japan (3183), Korea (3013), Germany (3005), Canada (2370), the United Kingdom (2312), Spain (2296), Australia (2260), Italy (1710), and the Netherlands (1422). Therefore, in the activity of the thesis, the USA (0.24) was the highest, followed by China (0.20), Japan (0.07), Korea (0.06), and Germany (0.06). **Table 3** and **Figure 9** show the activities of each country, the influence of the thesis, and the concentration of the thesis. As a result, the total number of citations for the membrane-related papers was found to be 351,996 in the US, 125,276 in China, 84,777 in Japan, 69,354 in Japan, 66,727 in the UK, 66,492 in Canada, (66,239), Australia (61,057), Korea (60,156), Netherlands (43,128), Spain (41,663), Italy (41,281) and India (40,121), Followed by the United States (0.31), China (0.11), Germany (0.08),

According to the concentration of each country, the USA tends to concentrate the most in the ion exchange process membrane (1.15), China in the wastewater treatment membrane (1.36), and Korea in the seawater desalination membrane (1.19). China, Spain, and Italy are the most

**KR\* JP US CA DE FR GB IT NL CN IN CA ES**

BAI\*\* 0.06 0.07 0.24 0.05 0.06 0.05 0.05 0.04 0.03 0.2 0.05 0.05 0.05 BCI 4.03 3.8 4.02 3.91 4.04 3.99 3.98 3.95 4.21 3.94 4.02 3.91 4.06 BII 0.05 0.06 0.31 0.06 0.08 0.06 0.06 0.04 0.04 0.11 0.04 0.06 0.04

ISO code: KR, Korea; JP, Japan; US, United States of America; CA, Canada; DE, Germany; FR, France; GB, United

**2.2. Evaluation of technology competitiveness of water treatment membranes**

membrane (1.72) (**Figure 8**).

Japan / France / Canada / Britain (0.6).

**Figure 8.** Top countries with the highest number of paper publications.

Kingdom; IT, Italy; NL, Netherlands; CN, China; IN, India; CA, Canada; ES, Spain.

**Table 3.** An analysis table about BAI, BII, and BCI by each country.

\*\*BAI: Bibliometric Activity Index, BCI: Bibliometric Citation Index, BII: Bibliometric Intensity Index.

**Index of evaluation**

\*

**Figure 7.** An analysis graph about PAI, PII, PMI, and PCI by each country.

Canada (910 cases), Germany (852 cases), France (426 cases), Italy (407 cases), the Netherlands (226 cases), and China (127 cases). (11.63), Britain (10.39), France (8.86), Germany (8.78), Netherlands (6.85), Canada (6.74), the United States (5.69) and China (4.10), Japan (2.70), and Korea (1.54). The results of this study are as follows: Italy (3.49), Britain (3.12), France (2.66), Germany (2.64), the Netherlands (2.06), Canada (2.02), the USA (1.71) (0.81), followed by Korea (0.46).

As a result, the total number of patents for separator-related patents was derived from the USA (4238 cases), Canada (1537 cases), Japan (979 cases), Germany (267 cases), Italy (163 cases), France (101 cases), the Netherlands (96 cases), and China (11 cases). The number of registered patents related to membranes was 271 in the USA, 147 in Japan, 62 in Canada, 30 in Germany, 26 in Korea, 15 in France, 12 in the UK, (31.86), Canada (24.79), the United States (15.64), and the United States (15.64), followed by the United States), Britain (13.58), Germany (8.90), Netherlands (8.73), Korea and France (6.73), Japan (6.66) and China (1.83). The results of this study are as follows: Italy (2.40), Canada (1.87), the USA (1.18), the UK (1.02), Germany (0.67), the Netherlands (0.66), Korea and France (0.51), and China (0.14). Among them, Korea ranked 2nd place in patent activity, 10th place in patent market power, and 7th place in patent efficacy, and patent concentration tended to be concentrated on wastewater treatment membrane (1.72) (**Figure 8**).

#### **2.2. Evaluation of technology competitiveness of water treatment membranes**

As a result of analyzing the number of published papers related to membranes, the results obtained were as follows: the USA (11,435), China (9235), Japan (3183), Korea (3013), Germany (3005), Canada (2370), the United Kingdom (2312), Spain (2296), Australia (2260), Italy (1710), and the Netherlands (1422). Therefore, in the activity of the thesis, the USA (0.24) was the highest, followed by China (0.20), Japan (0.07), Korea (0.06), and Germany (0.06). **Table 3** and **Figure 9** show the activities of each country, the influence of the thesis, and the concentration of the thesis.

As a result, the total number of citations for the membrane-related papers was found to be 351,996 in the US, 125,276 in China, 84,777 in Japan, 69,354 in Japan, 66,727 in the UK, 66,492 in Canada, (66,239), Australia (61,057), Korea (60,156), Netherlands (43,128), Spain (41,663), Italy (41,281) and India (40,121), Followed by the United States (0.31), China (0.11), Germany (0.08), Japan / France / Canada / Britain (0.6).

According to the concentration of each country, the USA tends to concentrate the most in the ion exchange process membrane (1.15), China in the wastewater treatment membrane (1.36), and Korea in the seawater desalination membrane (1.19). China, Spain, and Italy are the most

**Figure 8.** Top countries with the highest number of paper publications.

**Figure 7.** An analysis graph about PAI, PII, PMI, and PCI by each country.

210 Desalination and Water Treatment

Canada (910 cases), Germany (852 cases), France (426 cases), Italy (407 cases), the Netherlands (226 cases), and China (127 cases). (11.63), Britain (10.39), France (8.86), Germany (8.78), Netherlands (6.85), Canada (6.74), the United States (5.69) and China (4.10), Japan (2.70), and Korea (1.54). The results of this study are as follows: Italy (3.49), Britain (3.12), France (2.66), Germany (2.64), the

As a result, the total number of patents for separator-related patents was derived from the USA (4238 cases), Canada (1537 cases), Japan (979 cases), Germany (267 cases), Italy (163 cases), France (101 cases), the Netherlands (96 cases), and China (11 cases). The number of registered patents related to membranes was 271 in the USA, 147 in Japan, 62 in Canada, 30 in Germany, 26 in Korea, 15 in France, 12 in the UK, (31.86), Canada (24.79), the United States (15.64), and the United States (15.64), followed by the United States), Britain (13.58), Germany (8.90), Netherlands (8.73), Korea and France (6.73), Japan (6.66) and China (1.83). The results of this study are as follows: Italy (2.40), Canada (1.87), the USA (1.18), the UK (1.02), Germany (0.67), the Netherlands (0.66), Korea and France (0.51), and China (0.14). Among them, Korea ranked 2nd place in patent activity, 10th place in patent market power, and 7th place in patent

Netherlands (2.06), Canada (2.02), the USA (1.71) (0.81), followed by Korea (0.46).


\* ISO code: KR, Korea; JP, Japan; US, United States of America; CA, Canada; DE, Germany; FR, France; GB, United Kingdom; IT, Italy; NL, Netherlands; CN, China; IN, India; CA, Canada; ES, Spain.

\*\*BAI: Bibliometric Activity Index, BCI: Bibliometric Citation Index, BII: Bibliometric Intensity Index.

**Table 3.** An analysis table about BAI, BII, and BCI by each country.

important for separating membranes for wastewater treatment, Germany for water treatment membranes, Korea, India, the UK, Australia, and the Netherlands for seawater desalination membranes, USA, Japan, And the researcher.

**3.1. Top applicant and posting office of separation membranes for wastewater** 

Japan is the main applicant of the separation membranes for wastewater treatment. In Korea, the rankings are gradually increasing over time. (Korea Institute of Science and Technology, Korea Advanced Institute of Science and Technology, Woongjin Chemical), 4 (Korea Institute of Science and Technology), 2 (Korea Institute of Science and Technology, Phylos, Sinopec, and Samsung C & T). Among them, Korea Institute of Science and Technology (KIST) ranked eighth place (4 cases) in two sections, third place (7 cases) in three sections, and first place (9 cases) in four

**Figure 11.** Comparison of total number of papers publications of global company in field of different membrane

**Figure 10.** Comparison of total number of patent applications of global company in field of different membrane

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**treatment**

technology between the periods 2006 and 2016.

technology between the periods 2006 and 2016.

sections.
