The development of the integrated control of sewage network and wastewater treatment plant has progressed during the last decade. Nevertheless, an operational implementation of the concepts for huge, complex systems has hardly been realised. That was an obvious reason to initiate the project "Integrated Sewage Management (ISM)". The ISM project aimed at the development of strategies for an integrated management of the Berlin sewage system consisting of sewer networks (both, combined and separate system), pump stations, pressure mains and wwtp. For these purposes a numerical model of the collection system has been built up. Those catchments have been chosen that have a significant quantity of wastewater and are connected to at least one of the three main wastewater treatment plants of Berlin (Ruhleben, Waßmannsdorf and Schönerlinde). To enable an evaluation of total emissions it was necessary to incorporate not only catchment area and collection system but also the wwtp into the model. Furthermore, the Berlin specific transport of wastewater through pressure mains had to be considered. Both, advective pollutant transport and the limiting pressure situation had to be taken into account. An integrated model of collection system, pressure mains and wwtp has been set up for the catchment of wwtp Ruhleben for the study of a global control concept. Those processes that were of particular importance for the control concepts or had a significant influence on the criteria (derived from the objectives) had to be simulated adequately. Hence, for the Berlin model the main attention was paid to an accurate reproduction of in-pipe storage activation and the transport of wastewater through the pressure pipes. A sufficient set of data was available to model the system structure. For process parameter estimation the necessary information was taken from the operational SCADA system. Some gaps in the data could be closed by additional measurement campaigns (Bln VII, 2001; Bln X, 2002; Heiligensee, 2003). For modelling the collection system the dynamic flow routing model InfoWorks CS of Wallingford Software Limited has been chosen due to its user-friendliness (window navigation, GIS) and comprehensiveness (pollutant load calculation, long-time simulation, spatial rainfall distribution, rtc module). A suitable approach to the simulation of the Berlin pressure mains was found to be based on EPANET 2 of the U.S. Environmental Protection Agency. The software SIMBA® 5 of ifak System GmbH has been used to simulate the dynamic treatment processes. For the activated sludge conversion part the Activated Sludge Model No. 1 (ASM 1) has been used. The three models have been coupled in sequence on the basis of simple input and output files. Further on, in the framework of three sub studies the ISM model has been applied to operational questions. The applicability of the ISM model for the assessment of the impact of the NPA control on the wwtp was tested. NPA stands for “new pump automatic (Neue Pumpen Automatik)” and signifies a control concept that is implemented in the framework of the LISA project (BWB). The inflow to wwtp Schönerlinde has been simulated for one rain event and the NPA control of the pump stations could be simulated well on the basis of the InfoWorks rtc module. Furthermore, the ISM model has been applied to evaluate a concept for a level dependant real-time control (Pegelgesteuerte Förderstromregelung) of sewage pump stations. The idea of the concept was to build an easy function that allowed continuously varying the pumpage and implicitly managing available inline storage capacities within the trunk sewers. The objective was to smooth the delivery towards the treatment plant to avoid peak loads. The evaluation showed that it is possible to manage available inline storage volume by applying the control function. But only if there is an adequate retention volume of around 60.0 m³/ha Aimp or more a significant improvement of the flow characteristic towards the wwtp is possible. Consequently, in Berlin only two catchments have the potential for the introduced control concept (Charlottenburg III und Ruhleben). Finally, the effects and the benefit from global pump station control in comparison to local control have been studied on the basis of the integrated model. The assessment of the Berlin drainage system that was carried out before arrived at the conclusion that there is a high potential for the control of the total system. The positive rating can partly be ascribed to the high storage volume that can be activated within the trunk sewers and the high number of pump stations that are used as actuators. However, this potential is already used by locally controlling the pump stations and storing sewage in the collectors. The potential of a global control of sewage pump stations arises from the non-uniform distribution of rainfall and the non-uniform distribution of storage volumes over the system. Those conditions usually lead to a non-uniform utilisation of storage capacities and further on to sewer overflows that cannot be balanced by local control. A look on the simulated total emissions showed that concerning discharged quantities the load from the wwtp is highly dominant, since most of the time (under dry weather conditions) wwtp effluents are the only impact on the receiving water. Furthermore, the global control concept only works during rain situation and does not have an influence on dry weather effluents. Consequently, the influence of global control on yearly total emissions is marginal. Nevertheless, it could be shown that global control can avoid peak load situations at the inflow to the wwtp and consequently reduce peak loads in the effluent. The control concepts had a significant influence on the emissions from combined sewer overflows. The reduction of sewer overflows plays a prominent role since they present a highly dynamic impact on the water body. The simulations showed that on average during periods of cso 2.5 t COD/h enter the receiving water. Compared to that load the continuous impact from the wwtp effluent was only 0.4 t COD/h. Moreover, due to the high fraction of biodegradable organic substrate the impact from combined sewer overflows is of special relevance. In contrary to the refractory COD from wwtp effluents, 60 % of the COD from combined sewer overflows are biodegradable leading to extreme oxygen depletion within the receiving water. It could be shown that under current conditions at the wwtp (rain weather capacity of wwtp Ruhleben = 6700 l/s) a local control (= local automation) of the pump stations has an adverse effect on the performance of the sewage system. In contrary to an optimum coordination of the pump stations local control leads to an overloading of the wwtp and an increase of emissions from combined sewer overflows by 9 % (volume), 15 % (COD) and 20 % (TKN). Due to that reason the current operation provides for manual interventions in case of rain events to coordinate the delivery of the pump stations. This necessity will persist under the LISA automation. Assuming a future upgrade of wwtp Ruhleben and an increase in rain weather capacity up to 7650 l/s, global pump station control will result in cso emissions that are 19 % (volume), 20 % (COD) and 25 % (TKN) below that under local control (= local automation). The major deliverable of the ISM project is the model for the Berlin collection system (18 combined and 29 separate sewer systems that are connected to the three main wastewater treatment plants Ruhleben, Waßmannsdorf and Schönerlinde). The further application and maintenance of the sewer model will take place at BWB, department NA-G. The scope of studies that will be supported by the model covers operational planning as well as general, conceptual and investment planning (storage optimisation, problem of parasite water). Concerning the implementation of the global control concept that has been developed in the framework of the ISM project first tests shall be carried out in 2006 and 2007. Therefore, the follow-up project EVA (Entscheidungshilfesystem zur Verbundsteuerung von Abwasserpumpwerken / Decision support system for global control of sewage pump stations) was planned at KWB to enable support and a further cooperation between KWB and BWB. The algorithm has to be adapted to the operational and technical boundary conditions and a detailed practical planning in terms of control engineering has to be carried out. The main prerequisite for an implementation of the introduced control concept is the technical ability of the pump stations to increase delivery beyond the value of 2 * Qd,16. Simultaneously, an authorisation is necessary to introduce a flexible regulation of the pump station’s rain weather delivery off the value of 2 * Qd,16 as demanded nowadays by the Berlin water authority. If the necessary data is available (usually given by the existing scada system of BWB) and if the used pumps can be controlled according to the above-stated technical requirements, thestudied control concept can be implemented without any further constructional investment.

Schroeder, K. , Mannel, R. , Pawlowsky-Reusing, E. , Broll, J. (2005): Integrated Simulation of the Berlin Sewage System and Evaluation of a global Real-time Control Concept.

p 8 In: 10th International Conference on Urban Drainage 2005. Kopenhagen, Dänemark. 21. - 26.8.2005


The paper presents the build-up of a model for the integrated simulation of the sewage system of Berlin, Germany, focusing on the catchment of the wastewater treatment plant Ruhleben. The Ruhleben catchment, draining 185 km² and a population of 1.38 million inhabitants is characterised by its high portion of combined sewerage. The model comprises the collection system, pump stations, pressurised mains and the wastewater treatment plant. Hydraulic and quality processes are taken into account. A preliminary assessment of the sewage system and the analysis of historical operational data showed a high potential concerning global real-time control of the pump stations. Three different global control scenarios have been studied on the basis of a long time simulation over 50 days and compared with a local control regime. The results show that the coordinated operation leads to a reduction of total emissions. Main improvements can be achieved concerning the discharges from combined sewer overflows. These improvements are of major significance due to the high hazard potential of combined sewer overflows.

Mannel, R. , Pawlowsky-Reusing, E. (2003): Erfahrungen mit neuronalen Netzen für Simulationen des Kanalnetzes.

p 13 In: ATV-DVWK und VDI/VDE Gemeinschaftstagung "Mess- und Regelungstechnik in abwassertechnischen Anlagen". Wuppertal. 25. - 26.11.2003

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