It was intended to return with the International Gothenburg Symposia every other time to the birthplace of these events, Gothenburg in Sweden. But instead the 8th symposium has been invited to be organized and held in Prague, i. e. in the midst of Central and Eastern Europe a region now keen on intensified environmental control. This attests that the symposia have attained such standing in the interna tional world of operators, designers, officers and researchers in water treatment technology that their presence in various parts of the world has been requested. And this ever growing significance, in short the success of this conference series, stems form the fact that the symposia offer a unique platform for the exchange of ideas and experiences on all aspects of water and wastewater treatment between administrators, engineers and scientists. The content of this book, i. e. the schedule of the symposium lectures, results for the most part from a vast response to an international call for papers. Many excellent contributions are included in this volume but at the same time many outstanding ones could not be included for lack of time and space. The total sum of these contributions document again the development in the field, both in terms of new technological (and other) developments as well as public and administrative acceptance and approval of solutions offered.