Benchmarking--an approach to efficiency enhancement in planning, construction and operation of wastewater treatment plants.

In the following paper the technique of benchmarking was transferred to the field of wastewater treatment. The method was developed within a pilot project, in which 4 wastewater treatment plants (WVTP) (size category: 10,000-100,000 p. e.) of the Emschergenossenschaft/Lippeverband and the Aggerverband were involved. Meanwhile this method is applied to more than 100 WWTP. Specific technical and economic parameters were determined for the whole treatment plant and afterwards assigned to the different treatment steps. With these numbers differences between the examined plants and the respective benchmarks were visible. On the basis of the following cause analysis a schedule could be developed containing at first measures, which could be translated into action immediately. The less obvious reasons for differences between individual numbers required a deeper cause analysis. Because of external influences not all the plants can reach the benchmarks.