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Two new digesters, a post-thickener and a powerhouse went into operation at Wastewater Treatment Plant Mergelstetten in Heidenheim on 15 July 2021. Together with the City of Herbrechtingen and the municipalities of Gerstetten, Steinheim and Nattheim, the City of Heidenheim has invested six million euros in this project over the past two years. The sewage sludge from the municipalities involved will be treated in the wastewater treatment plant in Mergelstetten. The new technology will enable more digester gas to be extracted from sewage sludge in future, thus increasing the plant's own electricity and heat generation. The methane gas produced from the sludge digestion process is used in the two CHP units to generate thermal and electrical energy. The heat is used to heat the digesters and the operating buildings; the electricity flows into the treatment plant for its own use. The two digesters, each with a volume of 1,400 cubic metres, replace the previous sewage sludge treatment facilities, but can work in independent as well as combined operation. As a partner in a consortium, DAHLEM was commissioned with the planning of the engineering structures (Service Phases 1-4).

Even if there are no visible electrical installation works on the construction site of Pumping Station Oberhausen yet, the electrotechnical equipment ist making bis steps forward. At the factory acceptance test in Finland, two out of the 10 frequency converters of the "small" and "large" sewage pumps were successfully tested and approved by the manufacturer as the first components of the powerful drivelines. These are frequency converters with a nominal voltage of 690 V and a rated current of 1.180 A, respectively 1.700 A, which corresponds to a rated output of 900, respectively 1.250 kW. The high demand on the network repercussions with limit specifications to the harmonic, inter-harmonic and, for the first time, also to the supra-harmonic currents, required the frequency converters to install active line filters and correspondingly large-sized line reactors. These are, like the actual power electronics of the frequency converter, cooled by water. Each frequency converter consists of 5 control cabinets, with each frequency converter being approx. 3 m wide. Helmut Mangelmann heads the Electrical Engineering Department at DAHLEM and works in the team of the design consortium (Planungs-ARGE) of Pumping Station Oberhausen: "We have planned and built quite a lot in the field of electrical engineering, but these dimensions go far beyond the previous performance levels. In the low voltage sector, they are at the limits of what is technically possible in terms of circuit and transmission technology."

The government grant decision, which the Environment Minister Franz Unterseller (left) handed over to Lord Mayor Fritz Kuhn (middle) and City Director Wolfgang Schanz (right), Head of the Civil Engineering Department, on 3rd September on the spot, was the starting signal for the expansion of the main sewage treatment plant Stuttgart-Mühlhausen with a fourth treatment stage. The main sewage treatment plant Stuttgart-Mühlhausen, built in 1916 as one of the first sewage treatment plants in Germany, is operated by Stadtentwässerung Stuttgart (SES) and should count to the most modern ones in the Federal Republic by 2028. Due to the complexity and the considerable investment, the expansion will take place in three construction phases. In the first phase, powder activated carbon silos and dosing stations will be set up at the Biology North and South as well as an energy control centre will be built. The federal state of Baden-Württemberg supports this project with just under 3 million EUR. With the construction of the treatment stage for the elimination of trace substances, the City of Stuttgart is making a significant contribution to water protection in the federal state. Dipl.-Ing. Mathias Kleffmann, process expert at DAHLEM and project manager of the design consortium, is pleased. "It's great that we can now start with the direct dosing on a large-scale and implement the new process technology on a industrial scale." 

By means of holistic optimization, Waste Water Treatment Plant Aachen-Soers has succeeded in reducing the enormous energy demand of the recovery by around 55 per cent. Together with DAHLEM, the Wasserverband Eifel Rur planned the modernization of the oxygen supply of the aeration tanks. The design was implemented at the beginning of the year, followed by the commissioning of the blower station mid-year. The RWTH Aachen accompanies the project scientifically. DAHLEM supported the process design, which was modeled in a 3D-planning and accompanied the award procedure. The enclosed article about the project provides detailed information about the modernization of the plant. The waste water treatment plant is also referred to as a nationwide model Enterprise.
Article, "Water & Waste Water Technology” magazine, July 2019

There was much enthusiasm at an unusual design meeting on the extension of WWTP Kleve-Salmorth, which is soon to be launched as a thermo-compact plant: plant manager Michael Offenberg and his team from the Kleve-based environmental operations were able to see how it felt in the new buildings of the waste water treatment plant. Is there enough space between the plant parts? Can one move well in between? Are there any missing components, etc. With the help of VR glasses, Torsten Wach, who is in charge of the project coordination, guided the participants through the building model, which was projected directly onto a screen. It made it possible for all involved to point out errors or changes and to rectify them before the start of construction. WWTP Kleve-Salmorth is regarded as a flagship project for innovative sewage sludge treatment and meets the requirements of the new Sewage Sludge Ordinance for Waste Water Treatment Plants to reclaim phosphorus from municipal sewage sludge in the future. Thus in the long run, the supply of this nutrient, which is central to all organism, shall be ensured. DAHLEM provides the design services, from the initial conceptual design to the award, including construction supervision.

The Rhine-Main area is booming and with the increase in population, the demand for potable water is also rising. It is the second dry summer in a row. However, the amount of water needed is not the problem, its distribution is, say the experts at the Hessen Water company. The company intends to build a reduntant potable water transport pipeline west of Darmstadt. The length of the planned steel pipeline with a diameter of DN 1000 will be about 17.4 km from Riedstadt-Wolfskehlen to Gernsheim-Allmendfeld (waterworks). This also includes a connection to the Eschollbrücken waterworks and a booster station to be built there. The route is partly located in potable water protection areas, crosses a Natura 2000 site and often finds itseld in areas with high groundwater levels. For the approval of the potable water transport pipeline, Hessen Water will apply for a planning approval procedure with public participation at the Darmstadt Regional Council. DAHLEM, as part of a joint venture, provides the technical engineering services for the planning of the construction measure (design, approval and implementation planning as well as preparation and participation in the contract award procedures).

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Large excavation of 95.000 tons of earth was necessary to move the former, dead straight and musty-smelling Köttelbecke into the new stream bed in the Pelkum field. Freed from dirty water, the renaturated border stream between Bottrop and Gladbeck now meanders cleanly through the reed-covered landscape. The measure is part of the Emscher Renaturation Generation Project and was celebrated on 18.09.2019 with Lord Mayor Bernd Tischler, City of Bottrop, Mayor Ulrich Roland, City of Gladbeck and the board members of the Emschergenossenschaft Prof. Dr. Uli Paetzel and Dr. Emanuel Grün. Emschergenossenschaft is investing a total of around five billion Euro in the generation project. In this way, the association is making a contribution to urban development and climate protection, said Paetzel. The enlarged water surface helps cool off heat islands and becomes a biotope for strengthening biodiversity. DAHLEM was commissioned with the construction planning for the conversion of the water body up to the involvement in the contract award.