March 1993

C. Judson King, UC Berkeley (Panel Chair)

Edward L. Cussler, University of Minnesota

William Eykamp, Consultant

George E. Keller II, Union Carbide Corporation

H.S. Muralidhara, Cargill Research

Milton E. Wadsworth, University of Utah


The objective of this study was to survey technological activity in separations in Japan, and to compare this activity with that in the United States. For this purpose, the six-person panel and accompanying support personnel spent a week in Japan, visiting one or more sites at seven corporations, five government laboratories, and six universities.

The panel's full report describing our findings is organized as follows:

  1. this Executive Summary;
  2. an introduction and analysis of major issues (Chapter 1);
  3. individual chapters delving into particular areas of separations -- separation and purification of gases, water purification, separations of several other sorts involving liquids, hydrometallurgical separations, ion-exchange membrane technology, dewatering and crystallization (Chapters 2-7); and
  4. descriptions of the panel's various site visits (Appendices B-F).

A succinct presentation of the JTEC panel's conclusions regarding the relative status and trends of Japanese and U.S. technology and support structure is given in Table 23. Japan is strong and highly competitive in several areas of separations. For the most part, this position has not been achieved by invention or creative new departures. Instead, it comes from careful selection of the most effective technology available on the world market, followed by diligent implementation, evolutionary advances, strong emphasis on management and control of quality, and effective use of corporate experience. This thrust has been greatly aided by the fact that Japan until recently, in contrast with the United States, has had a steadily expanding economy and growing production, which have provided the opportunity for installation of new capacity with the latest technology.


Table 23

is the JTEC panel's effort to categorize the relative strengths of separations technology in Japan and the United States. The table is divided into various methods of separation, and also by categories of research, development and implementation for each method. Following the entries for various methods of separation, the panel addresses certain cross-cutting aspects of research, development and implementation (Table 24).


The panel observed a number of distinctive characteristics of the Japanese situation (Chapter 1 of the full report). Since it has essentially no indigenous energy resources, Japan seeks avenues toward energy independence. Energy costs are high, and there is a strong drive for energy conservation. Energy costs and restricted land area both promote reuse and recycling. In many other areas Japan seeks self-sufficiency; production of salt (NaCl) is an example. Cultural viewpoints and the peculiar nature of the Japanese labor market sometimes bring about specialized approaches. Thrusts in separations technology often support areas of Japanese industrial strength, notably in the electronics industry. Conversely, approaches to meeting separations needs often utilize Japanese strengths, such as instrumentation and photovoltaic technology.

The drive for energy conservation has been particularly apparent in the Japanese paper industry, as is presented and analyzed in more detail in Chapter 7 of the full report. Environmental concerns are ascendant in Japan, and much is happening in the area of pollution abatement. However, the issue appears to be addressed much less through formal legal regulation, and more through government coordination and influence upon industry, than is the case in the United States.

Japan Compared to U.S. by Types of Separation

(See Key)
[table 23]


Japanese universities utilize the "koza" system, where for a particular area a professor is assisted by junior faculty members. This structure enables organized and efficient usage of resources, but would seemingly suppress the development of junior faculty as independent investigators. Research in Japanese universities focuses on derivative advances and supporting information, more than upon creativity and progress toward new scientific understanding. Research facilities in Japanese universities tend to be in very poor condition and crowded. There are major problems of safety and housekeeping, in comparison with the norm in U.S. universities. Research instrumentation is abundant and strong.

General Aspects

(See Key)
[table 24]


Corporate activity seems to be relatively more diversified in Japan than in the United States. An example is Kobe Steel, Ltd., which has followed a thread of high-pressure technology that has led the company into a number of very different areas of application.


Membrane Separations

Japan has national technological thrusts, involving government, industry, government laboratories, and universities. The thrusts most closely connected with separations have been the Aqua Renaissance Project, which deals with water purification, and Project Sunshine and Project Moonlight, which deal with energy independence and related issues. Membrane technologies have been emphasized in these thrusts.

Many of the membrane-based separations activities in Japan have come about through these national initiatives. Membrane separation is an area of Japanese strength, where Japan has about 25 percent of the world market. Membranes are far more prominent among the mix of separation technologies in Japan than in the rest of the world. Here again the Japanese position is not attained through entirely new approaches, but through perceptive selection of available technology, evolutionary improvements, and emphasis upon quality.

The emphasis upon membrane separation technologies in Japan seems to result in large measure from definition of priorities at the government level. The panel can only surmise about the reasons for choosing this emphasis. Synthetic membranes are an area where Japan is already successful and derives considerable economic benefit. Membrane separation may also be regarded as an area where the most opportunities are available for advances. In that sense, the Japanese may regard membrane separations as a less mature technology than do the United States and the rest of the world. Membrane technologies do serve the needs of the strong Japanese electronics industry. For example, membranes are useful in ultrapurification of water (Chapter 3 of the full report); however, this is an area where U.S. companies (e.g., Millipore) have most of the market. Membrane separations may be regarded in Japan as an effective path for energy conservation and/or technological independence. Developments in membrane technology can lead to advances in technology for batteries, analytical instrumentations and medical applications, notably diagnostics.

Global Environment

Another interesting national thrust pertains to global environmental issues, notably global warming and depletion of the stratospheric ozone layer. Japan has proposed an international plan called "The New Earth 21 (Action Plan for the 21st Century)." The large, main research facility for the Research Institute of Innovative Technology for the Earth (RITE) will be completed in the Kansai Science City in the summer of 1993. One of the areas being given the most emphasis in this initiative is fixation and utilization technology for carbon dioxide (CO2). As typically described, this involves use of membrane separations to remove and recover CO2 from the flue gases of fossil-fuel power plants, with conversion of the recovered carbon dioxide to large-scale chemical products such as methanol. This endeavor raises several very fundamental issues concerning feasibility: (1) the very large volume of CO2 that would have to be recovered to make a difference in the global environment; (2) whether a CO2-benign source of hydrogen for conversion to chemicals can be achieved; and, (3) whether the uses of recovered CO2 would themselves return CO2 to the atmosphere. Therefore the true economic basis for the New Earth 21 initiative is questionable.


The following more detailed comparisons are drawn from the individual chapters of the full report.

Separation and Purification of Gases

Japanese development of technology in gas separations has in general trailed that in other parts of the world, but the commercialized technology in a number of cases may be roughly equivalent to that found elsewhere (Chapter 2). Membrane technology for large-scale, selective recovery of carbon dioxide is receiving attention in connection with the RITE global-warming initiative. However, there is surprisingly little research on membrane technology for other gas separations, especially when the overall Japanese emphasis on membrane separations technology is taken into account. Several small-scale, specialized applications are being developed in connection with the needs of the electronics industry.

Water Purification

Membrane technology for water purification in Japan is largely conventional, but two applications are pushing the limits of current technology -- water for the nuclear industry and water for the production of microelectronic chips (Chapter 3). Approximately 1,000 liters of ultrapurified water are used per wafer in the chip manufacturing industry. The purity required is related to the minuscule dimensions of features on the chips. Contaminants of concern include bacteria, particles, organic matter and dissolved oxygen. Highly sequential purification trains are utilized, with extensive and repeated use of membrane separations and ion exchange. Interestingly, the needs of the Japanese electronics industry are met by vendors of pre-packaged water-purification assemblies, while in the U.S. the tendency is for individual chip manufacturers to assemble their own water-purification plants. The two approaches seem to achieve roughly equivalent results. The water-purification needs for next- and future-generation chips require substantial advances beyond current technology.

Also related to water purification, but on a larger and coarser scale, the panel found that there has apparently been a decision in Japan to replace chlorine with ozone for municipal water treatment. The use of ozone is generally considered to be more expensive and less proven for general use, but it does avoid the formation of trace levels of chlorinated organics.

Separations with Liquids

Much of the research and development activity in Japan for other separations involving liquids focuses on membranes (Chapter 4). Pervaporation, a method of vaporizing a liquid mixture selectively through a membrane, is receiving attention for ethanol-water separation, as it is elsewhere in the world. There is also attention to use of this technique for separation of isopropanol and water (an electronics industry need) and for separations of trace organics from water. There is also work on absorption of nitrogen and sulfur oxides (NOx and SOx) from power-plant flue gases and on supercritical fluid extraction, largely for oils and other substances that serve specific Japanese food and flavor needs. Finally, there are several efforts directed toward "chiral" separations, that is, separations of mixtures of optically active isomers.

Hydrometallurgical Separations

There are numerous instances of metals refining and separations in Japan, with substantial and diverse accompanying research (Chapter 5). Emphasis is on smelting and refining, rather than recovery from the ore, since Japan imports most of its metals as concentrates. As in other areas, processes are based upon conventional technology, but a high degree of improvement has been achieved. Equipment is more modern than in the U.S. because Japanese industry has been able to add substantial capacity in recent years. Over the past four decades there has been a major decline in U.S. zinc production. Meanwhile, Japan has become the world's third largest producer of zinc.

There has been a significant amount of research on the fundamentals of leaching, solvent extraction, ion exchange, and chemical and electrochemical reduction. University research in this field is generally of high quality but mainly theoretical.

Ion-Exchange Membrane Technology

Japan has over forty years of experience in the development and manufacture of ion-exchange membranes; much of the development has evolved in the context of producing salt from seawater by means of electrodialysis (Chapter 6). Japan is a world leader in this area, with a broad spectrum of membranes for sale and internal use, with a main theme of environmental applications. Advances are being made in spacer materials and adhesives for membrane modules. Other innovations are in implementation of ion-exchange membranes in tubular geometries (ED CORE, Tokuyama Soda -- see Chapter 6), replacing the conventional flat-sheet geometry, and in bipolar, "water-splitting" membrane technology.

Dewatering (Pulp and Paper Industry)

Japan ranks second and third in world production of paper and pulp, respectively, behind the U.S. in both cases. Over the past two decades Japan has achieved very large reductions in the amount of purchased energy needed for the paper industry -- about a factor of two for the industry as a whole (Chapter 7). For the most part, these savings have not resulted from innovative technology, although the addition of new capacity utilizing newer and more efficient technology has been one factor. Other factors include extensive use of recycle, obtaining a higher concentration of black liquid (separations) within the plants, use of high-pressure and therefore high-temperature boilers, and conversion to continuous digesters.


The most striking technological innovation that the panel found was Kobe Steel's pressure-driven crystallizer, used for separations of organics (Chapter 7). This advance follows from Kobe's practice over the years of using its high-pressure expertise to branch into different areas of application. Increasing pressure, an instantly transmitted thermodynamic parameter, to a great enough extent can bring about solidification in a controlled way, and subsequent reduction and/or cycling of pressure brings about controlled melting that can cause formation of more perfect, and therefore purer and easily separable crystals.

Published: March 1994; WTEC Hyper-Librarian