Interactions between physical, chemical and biological processes in aquatic systems - impacts on receiving waters with different contents of treated wastewater

Two scenarios have be chosen within this PhD Thesis to describe the integrative key-significance of interactions between most relevant physical, chemical and biological processes in aquatic systems. These two case studies are used to illustrate and describe the importance of a detailed synthesis of biological, physical and chemical interactions in aquatic systems in order to provide relevant protection of water resources and to perform a sound water management. Methods are described to allow a detailed assessment of particular aspects within the complexity of the overall integration and therefore serve as a basis to determine the eventual necessity of proposed water management measures. Regarding the anthropogenic influence of treated wastewater on aquatic systems, one case study focuses on the interactions between emitted waters from a wastewater treatment plant and the resulting immission situation of its receiving water (The receiving water is quantitatively influenced by the treated wastewater by 95 %). This thesis proves that the effluent of wastewater treatment plants operated by best available technology meets the quality standards of running waters for the nutrients nitrogen and phosphorus, carbon-parameters, oxygen-regime and ecotoxicology. Within the second case study the focus is put on interactions between immissions and water usage. The general importance of biological phosphorus precipitation on the trophic situation of aquatic systems is described. Nevertheless, this generally known but within the field of applied limnology so far unrespected process of immobilization of phosphorus could be shown to represent a significant and major impact on phytoplannctotic development and eutrification. (author)