Identification of water quality changes in a water system – limitations and perspectives

From the abstraction point and the entrance of water in a Water System (WS) till its discharge back to the environment, water passes through a number of treatments and uses that directly affect its quality. The water quality changes several times while the water returning to the environment at a discharge point into the sea, a lake or a river has poorer quality compared to the water entering the system. All the parts of a WS should be integrated into one single model to assess the performance of the overall system for the development of design and control strategies assisting in its sustainable and cost effective management. Available models for the individual components have to be employed in order to develop the integrated tool. Problems that arise from this methodology are the increased data requirements together with incompatibility of state variables, processes and parameters used in different approaches. For improved control and performance of a WS that includes the water treatment and waste water treatment processes a good knowledge of water quality at each part of the system is required. Preliminary analysis of the available data shows an increase of the values in a number of quality parameters between the water source till the water treatment facility. Key-Words: Water-quality modelling, water-quality processes, Athens Water System