The cost of municipal sewage treatment – structure, origin, minimization – methods of fair cost comparison and allocation

Cost comparison in the field of wastewater treatment is a difficult task, particularly concerning sewages charges in different countries. German wastewater management is, for one thing, known to be very efficient, yet, for another, comparatively costly on an international scale. In this context, the marginal conditions typically prevailing in the field of sewage treatment in Germany should be mentioned: dense population and industrialization with high export-oriented production rates, high-profile purification requirements enforced by law. To establish a valid cost comparison, it is necessary to include both the investment and the operating expenses within the scope of the overall annual costs. The major factors impacting the different cost types are represented. Only if these factors are taken into account and quantified, will cost comparison be fair and lead to useful results. Ten hints for cost minimization are given to serve as a guideline for successful and responsable cost reduction. Cost transparency is the prerequisite for the possibility to develop saving potentials while simultaneously securing the social and political acceptance of the charges levied, and to compare the different plants with one another. Experience from Ruhrverband, a water management association for an entire catchment area, being responsible for planning, building and operation of 94 wastewater treatment plants and other plants for water quantity and water quality management, is reported.