Josef Winter, Claudia Gallert, Universität Karlsruhe, Germany Hans-Joachim Jördening, Technische Universität Braunschweig, Deutschland

The growing awareness of environmental problems, caused especially by the predominate use of fossil resources in connection with pure chemical pathways of production, has led the focus on those alternatives, which sounds environmentally more friendly. Here, biotechnology has the chance to influence and improve the quality of the environment and production standards by:

- introduction of renewable instead of fossil raw materials

- controlled production of very specific biocatalysts for the

- development of new and environmentally improved production technologies with less purified substrates and generation of fewer by-products

- bioproducts as non-toxic matters, mostly recyclable.

Some impressive studies on industrial applications of biotechnology are published in two OECD reports, which summarized, that biotechnology has the potential of a reduction of operational and/or capital cost for the realization of more sustainable processes (OECD1, OECD2). However, until today the sustainability of technical processes is more the exception than the rule and therefore so-called "End-of-Pipe"-technologies are absolutely necessary for the treatment of production residues.

In 1972 the Club of Rome published its study "Limits of Growth" and prognosted an upcoming shortage of energy and primary resources as a consequence of exponential growth of population and industry (Meadows et al. 1972). Although the quantitative prognoses of Dennis Meadows and his research team have not been fulfilled, the qualitative statements are today well accepted. Aside of a shortage of resources for production of commodities the limits for an ecologically and economically compatible disposal of production residues and stabilized wastes have to be more and more taken into consideration. The limits for disposal of solid and liquid pollutants in soil and water or of waste gases in the atmosphere are a major issue, since soil, water and air are no longer able to absorb/adsorb these emissions without negative consequences for ecology and life in general. The ultimate oxidation product of organic residues by incineration or - more smooth - by biological respiration in aquatic or terrestric environment led to a significant increase of the carbon diox ide content of the atmosphere in the last centuries and thus influences the overall climate. This increase is abundantly attributed to combustion of fossil fuels by traffic and of fossil fuels and coal for industrial production processes and house heating. Increasing concentrations of carbon dioxide in the atmosphere from incineration of fossil energy sources and from decomposition of organic matter are the main reason for the greenhouse effect.

Whereas the pollution of soil with waste compounds and subsequently with their (bio)conversion products generally remains a locally restricted, national problem, as long as evaporation of volatile compounds into the air or solubilization of solids in rain or groundwater can be prevented, emissions into water or the atmosphere are spreading rapidly and soon reach an international dimension. A disturbance of the equilibrium of the natural cycles of carbon, nitrogen, phosphate, sulfur or halogen compounds causes an ecological imbalance and endangers nature. In the Brundt-land-report "Our common future" (Hauff 1987) a discussion was started about "sustainable development". The practical realization of this concept was suggested at the "Conference on Environment and Development" of the United Nations in Rio de Janeiro in 1992 and enforced as an action programme in the so-called Agenda 21. A sustainable development to maintain the basis for future generations is contra-indicated by exploitation of non-regenerative energy and material resources and a shortening of life cycles (e.g. in information technologies).

A life cycle assessment is required to reduce or at least to bring to everybodies attention the flood of waste material. By the obligate demand for recycling of waste components, which is fixed in European Council Directive 91/156/EEC and e.g. translated to the German waste law (KrW/AbfG 1996), production and the use of commodities should minimize the amount of wastes. The practicability of this approach must be demonstrated in industrialized countries and then should be adopted by less developed or developing countries.

Environmental biotechnology initially started with wastewater treatment in urban areas at the turn of the 19/20th century (Hartmann 1999) and has been extended among others to soil remediation, off gas purification, surface and groundwater cleaning, industrial wastewater purification, deposition techniques of wastes in sanitary landfills and composting of bioorganic residues, mainly in the second half of the 20 century.

The available processes for the protection of the terrestric and aquatic environment were summarized in the first edition of "Biotechnology" still in one volume. Some ten years later in the second edition of "Biotechnology" the development in the above mentioned environmental compartments was updated and decribed by experts in the field from Europe and the United States of America. Although the description was kept very stringent, the above mentioned areas of environmental processes finally were issued in 3 volumes. Volume 11a of "Biotechnology" was subtitled "Environmental Processes I - Wastewater Treatment" (edited in 1999) and was devoted to general aspects and the process development for carbon, nitrogen and phosphate removal during wastewater treatment and anaerobic sludge stabilization. Volume 11b of "Biotechnology" was subtitled "Environmental Processes II - Soil Decontamination" (edited in 2000) and summarized microbial aspects and the pro cesses that were applied for soil (bio-)remediation and Volume 11c, subtitled "Environmental Processes III - Solid Waste and Waste Gas Treatment, Preparation of Drinking water" (edited in 2000) covered general aspects, microbiology and processes for solid waste treatment, waste gas purification and potable water preparation.

The new book "Environmental Biotechnology" covers what we think the most relevant topics of the previous volumes 11a, b and c of "Biotechnology" in a comprehensive form. The invited authors were given the opportunity to update their contributions when a significant progress was achieved in their field in recent years. For instance, although many alternatives were existing in the past for domestic sewage treatment to remove nitrogenous compounds, the development of new biological processes for nitrogen removal in the laboratory and in pilot scale-dimension was reported recently. These processes work with a minimized requirement for an additional carbon source. Although these processes are not yet widely applicated in praxi, they are investigated in detail in pilot- or demonstration-scale in single wastewater treatment plants. The results seem to be promissing and might get importance in the future.

The authors and the editors of the new book hope that the presented comprehensive overview on processes of environmental biotechnology for liquid, solid and gaseous waste treatment will help students and professional experts to obtain a fast fundamental information and an overview over the biological background and general process alternatives. This might then be a useful basis or starting point to tackle a specific process in more detail.

Josef Winter, Claudia Gallert, Hans-Joachim Jordening Karlsruhe and Braunschweig, September 2004

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