Development and commissioning of decision support tools for sewerage management.

Managing sewerage systems is a highly complex task due to the dynamic nature of the facilities. Their performance strongly depends on the know-how applied by the operators. In order to define optimal operational settings, two decision support tools based on mathematical models have been developed. Moreover, easy-to-use interfaces have been created as well, aiding operators who presumably do not have the necessary skills to use modelling software. The two developed programs simulate the behaviour of both wastewater treatment plants (WWTP) and sewer network systems, respectively. They have essentially the same structure, including raw data management and statistical analysis, a simulation layer using the application programming interface of the applied software and a layer responsible for the representation of the obtained results. Four user modes are provided in the two software including the simulation of historical data using the applied and novel operational settings, as well as modes concerning prediction of possible operation periods and updates. Concerning the WWTP software, it was successfully installed in Nantes (France) in June 2004. Moreover, the one managing sewer networks has been deployed in Saint-Malo (France) in January 2005. This paper presents the structure of the developed software and the first results obtained during the commissioning phase.

Test of the efficiency of three storm water quality models with a rich set of data.

The objective of this article is to test the efficiency of three different Storm Water Quality Model (SWQM) on the same data set (34 rain events, SS measurements) sampled on a 42 ha watershed in the center of Paris. The models have been calibrated at the scale of the rain event. Considering the mass of pollution calculated per event, the results on the models are satisfactory but that they are in the same order of magnitude as the simple hydraulic approach associated to a constant concentration. In a second time, the mass of pollutant at the outlet of the catchment at the global scale of the 34 events has been calculated. This approach shows that the simple hydraulic calculations gives better results than SWQM. Finally, the pollutographs are analysed, showing that storm water quality models are interesting tools to represent the shape of the pollutographs, and the dynamics of the phenomenon which can be useful in some projects for managers.

CSOs: tools for assessing their operation in our systems.

In recent years, regulations have been introduced under European legislation to govern wastewater discharge into natural environments, with particular provisions for combined sewer overflows. It has therefore become indispensable to control the hydraulic behaviour of these constructions. This article addresses the issue of 1D and 3D hydraulic modelling of CSOs. In the case of 1D modelling, a computational tool that is adapted to the hydraulic complexity of side weirs has been designed. For 3D modelling, the Fluent calculation code has been tested. The two modelling approaches have been validated by the data collected from the small-scale model in Obernai (French).

Optimisation of a large WWTP thanks to mathematical modelling.

Better controlling and optimising the plant's processes has become a priority for WWTP (Wastewater Treatment Plant) managers. The main objective of this project is to develop a simplified mathematical tool able to reproduce and anticipate the behaviour of the Tougas WWTP (Nantes, France). This tool is aimed to be used directly by the managers of the site. The mathematical WWTP model was created using the software WEST. This paper describes the studied site and the modelling results obtained during the stage of the model calibration and validation. The good simulation results have allowed to show that despite a first very simple description of the WWTP, the model was able to correctly predict the nitrogen composition (ammonia and nitrate) of the effluent and the daily sludge extraction. Then, a second more detailed configuration of the WWTP was implemented. It has allowed to independently study the behaviour of each of four biological trains. Once this first stage will be completely achieved, the remainder of the study will focus on the operational use of a simplified simulator with the purpose of optimising the Tougas WWTP operation.

Use of real time control modelling on the urban sewage system of Nancy.

Since 1991, European Legislation on the urban treatment of wastewater requires local authorities to take into account the treatment of polluted water transported by the sewerage system and this during dry and wet weather conditions. In the seventies, the urban Community of Grand Nancy constructed storage tanks in its sewerage system in order to prevent flooding and wish today to use them to reduce and control the pollution discharges into the receiving water. This action is a part of a European LIFE project 1996-2000. The main aim of this project was to assess the effectiveness of reducing pollution of one particular retention basin, the 12,000 m3 Gentilly tank. This one has two operating modes: protection against floods during heavy rain and reduction of pollutant overflows during lighter rain. To assess its effect on the pollutant discharge, the HYDROWORKS DM software and its Real Time Control Module have been used, calibrated and validated. As this study is still in progress, this paper describes the studied site and the modelling results under different weather conditions and shows that the mathematical model can be used to simulate the operation of the catchment area and its associated sewerage system realistically.

Long-term pollution simulation in combined sewer networks.

This paper presents results of long term pollution simulations on the example of the sewerage system of Grand-Couronne. This modelling work is part of a study where objective is to develop a method to define the reference flow of a WWTP. The model HYDROWORKS DM has been successfully validated in hydraulics and pollution for the sewer network, for long time simulations. A conceptual model has been built to model the pollution in the tank at the outlet of the combined system. One synthetic year of rain has been used to simulate the working of the "up stream system" of the WWTP (combined sewer + tank + separate sewer + pre-treatments) and has been successfully validated by measurements of the 1998-1999 year. If this paper is focused on the "up stream system", the SIMBA/SIMBAD WWTP model has been successfully calibrated and validated too, and the combination represents a fully validated "Integrated Model" for the sewerage system.

[Secretion pressure of human submandibular gland (author's transl)]. / Uber den Sekretionsdruck der Glandula submandibularis des Menschen.

The secretion pressure as well as the resistance of Glandula submandibularis towards retrograde instillation of water are determined electromanometrically. The results are compared with such measurements carried out by the same method in the parotid gland. The pressure behaviour of the submandibular gland corresponds with some quantitative differences to the behaviour of the parotid gland. The differences show the generally lower secretion power of submandibular gland. However there are no differences in the resistance against a retrograde instillation of water between submandibular and parotid gland. The connections of the observed and calculated parameters and clinical patterns are discussed.