R.D.Schuiling Faculty of Earth Sciences, Utrecht University, P.O. Box 80.021, 3508 TA Utrecht, the Netherlands 1998 - 350 pages Abstract Geochemical engineering makes use of optimized geochemical processes for the solution of environmental problems. It has developed in a few years from a collection of unrelated scientific and technological incidents into a coherent concept about how and where we can improve our geo-environment. All solutions to problems of pollution are based on neutralization/breakdown, concentration, dilution, isolation or immobilization, which serve to eliminate the pollutant, make it more manageable, or prevent its entry into the mobile phase, usually water, from which it can affect the biosphere. All of these solutions have their counterpart in nature, where many examples are found of high concentrations of potentially harmful substances. A major prerequisite of geochemical engineering solutions is that they should be compatible with the natural evolution of the system in its geo-environment. The advantages of this approach are that we can devise low-cost technologies (nature does most of the hard work itself), interfere least with nature, and quite often end up with useful by-products. Disadvantages are that technologies based on natural geochemical processes tend to be slow. The application of geochemical engineering concepts requires a better understanding of our environment and its ongoing processes than is necessary for a "classical" technology. In most environmental technologies the conditions are externally imposed on the system to be treated, and the natural evolution of the system is eliminated, or at best neglected. The concept of seeking a closer conformity with nature is paralleled in other disciplines like agriculture or the medical sector, where we see a similar evolution in the direction of techniques that are more in harmony with nature. Geochemical engineering brings many advantages, particularly in developing countries, or in countries where the state of the economy does not permit the introduction of expensive high-tech environmental technologies. So far most of the applications of geochemical engineering concepts so far have focussed on solutions to environmental problems, but there are a number of cases where the environmental issue is more indirect, as e.g. in civil engineering. Geochemical engineering may be practised on large, almost global scale, down to that of individual minerals, in accordance with the fact that geochemical processes also act on vastly different scales. An overview will be given of some of the problems that are being studied.
Keywords: Geochemical engineering, environmental technology, neutralization, concentration, dilution, isolation, immobilization, geodiversity
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