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).
Heavy rainfall and urban flash floods will pose major challenges to our society in the future. In cooperation with the environmental office of the City of Frankfurt a.M., DAHLEM developed heavy rain hazard maps, which were created as part of an overall concept for protection against heavy rain and are now available online in the geodata portal. Dipl.-Ing. Tim Schneider, employee of the Darmstadt office, managed the concept. He has been a DWA-certified specialist planner for heavy rainfall prevention since 2019 and has been working intensively at DAHLEM on the topics of heavy rainfall and urban flash floods since 2010. He sees protection against heavy rainfall as a joint municipal task and was particularly pleased about the publication: "The fact that the heavy rain hazard maps produced by DAHLEM are available online to all citizens is an important step in the context of climate change adaptation. The environmental agency has done a very good job with the publication of the maps. In addition to the main results of the analysis, plenty of further information on related topics is also available."
In 2017, the design for the construction of the fully biological wastewater treatment plant Peja in Kosovo started. After more than 2.5 years of construction, the plant has been put into operation. With a treatment plant capacity of 81,000 population equivalents, it is one of the first wastewater treatment plants in Kosovo. An anaerobic-mesophilic digester stabilises the sewage sludge obtained and the plant's own power supply is provided by several CHP units using sewage gas. In addition to domestic wastewater treatment, the connection of a supraregional brewery is planned. Wastewater Treatment Plant Peja is one of the first steps to improve the wastewater infrastructure in Kosovo. Wastewater from residential areas usually ends up untreated in surface waters. While area-wide sewerage systems for wastewater discharge are largely in place in urban areas, the country lacks municipal and industrial wastewater treatment plants. The "Wastewater Management South-West Kosovo IV" programme aims to improve wastewater disposal and treatment in several cities, especially with regard to sustainable protection of natural water resources and improvement of the living conditions of the population. The programme provides for extensive wastewater disposal measures for the city of Peja, financed by KfW, SECO and local own funds from the city administration and the Republic of Kosovo. The total construction costs of the measures in the City of Peja amount to around €20 million. They include the construction of a main collector to transport the wastewater to the treatment plant site 6 km away, another collector to connect the southern city areas, stormwater overflows and a fully biological treatment plant. The municipal waste management company RWC HIDRODRINI JSC commissioned DAHLEM with the design, functional call for tender and construction supervision of the wastewater treatment plant as well as the transport collectors.
It was a historic moment when Pumping Station Oberhausen was commissioned on Friday, 20 August 2021, in the presence of the North Rhine-Westphalian Prime Minister Armin Laschet. For it is only with the start-up of the enormous pumps with a delivery rate of up to 16,000 l/s that the approx. 60 km long Emscher underground sewer (AKE) between Dortmund and Dinslaken also takes on its function of transporting wastewater. Previously, the Emscher served as the "cesspool of the Ruhr" for over 170 years and was long considered the dirtiest river in Germany. The project of the century to renaturalise the Emscher took many years and was completed on time. For the realisation of Pumping Station Oberhausen alone, more than ten years of planning and construction are behind the parties involved, in addition to, for example, Emschergenossenschaft‘s various planning offices, experts, construction companies and approval authorities. Emschergenossenschaft commissioned DAHLEM with the design of the almost 50-metre deep pumping station of Pumping Station Oberhausen, which also sets architectural standards in the part above ground. In addition to the design, DAHLEM, as part of a joint venture, was responsible also for the construction supervision of the complex process, control, energy and machine technology.
At Chausseestraße in Berlin-Mitte, the construction of an approximately 17,000 m3 underground stormwater overflow basin, designed by DAHLEM on behalf of Berliner Wasserbetriebe, has begun. The basin is intended to temporarily store stormwater during heavy rainfall in order to sustainably relieve the sewage system and the Spree River. It is part of Berlin's large-scale storage programme and "disappears" completely under the square on the banks of Süd-Panke. Apart from the operations building, which is architecturally adapted to the neighbouring wastewater pumping station, only a striking steel chimney rises 30 meters above the ground. If the basin is completely flooded within 30 minutes by heavy rain, the exhaust air escapes through this chimney high above the rooftops of Berlin. Currently, a circular diaphragm wall - double excavation pit, with a depth of around 30 m, is being built on the construction site in the immediate vicinity of the headquarters of the Federal Intelligence Service. The completion of the stormwater overflow basin, including the operations building, is scheduled for 2026.
New technology for the environmentally friendly wastewater treatment is now to be installed: By the end of 2022, the Eifel-Rur Water Association is investing around 4,00 million Euros in the conversion of four secondary settling tanks at Wastewater Treatment Plant Aachen-Soers in order to effectively relieve the polluted water load. The ozonation plant has already been built and, as the largest in Europe, integrated into the existing wastewater treatment system. The wastewater treatment plant has been treating the wastewater of the city of Aachen since 1913 and is dimensioned for 458,300 population equivalents. By 2022, four secondary settling tanks will be upgraded step by step with new stainless steel central structures and height-adjustable inlet structures. The DN 700 return sludge pipes will be replaced by new stainless steel pipes. The optimization of the secondary clarification system is expected to increase the capacity by approx. 20%. A joint venture with DAHLEM as lead company has been commissioned with the project and specialist planning. The state of NRW is funding both the large-scale technical implementation and the accompanying research on the entire project of the wastewater treatment plant.
IIt is almost completed - the new construction of Mörscher Wald Waterworks, for which the ground-breaking ceremony took place in November 2018. The waterworks will be completely rebuilt according to the latest technical standards and will be put into operation on schedule, in 2021. The new building for the 70-year-old plant is constructed on a directly adjacent plot of land. Once the new plant is commissioned, the existing one will be completely dismantled and the area will be reforested. In the future, the new waterworks will ensure the vital potable water supply for the city of Karlsruhe and the surrounding communities. Investigations of the potable water demand up to 2040 showed that due to climate change and the predicted population growth, a capacity of 60.000 m³/d, respectively 3.000 m³/h, will have to be provided in the future as maximum capacity for raw water pumping and treatment. The architectural design of the building provides for a harmonious integration into the forest environment. As a partner in a joint venture, DAHLEM has been commissioned with the design of the engineering structures, the building interior space and the outdoor facilities. A BIM-oriented 3D model was created for the building design.
It is almost cojmpleted - the reconstruction of Katernberger Bach: On a length of approx. 1,1 kilometers the stream receives new space next to the old waterway. Furthermore, the stream will run openly for 1,2 kilometers. Construction started in 2019. Since the 1960s, it has been flowing through the Katernberg district of Essen mostly with pipes. The opening up of the stream and the separation of clean and polluted water as well as the renaturation of blocked waterways should improve the stream ecologically. The redesign is part of the Century Project for the ecological improvement of the Emscher system between Dortmund and Dinslaken, which started in the 1990s. By means of subsidence, the pure water produced in the upper reaches will be pumped via a new pure water pumping station to the planned disclosure section. In addition to the hydraulic engineering planning, bottom slides, fords and bridges will be constructed and several culverts will be implemented. In addition to the ecological improvement measures, experience stations will be built to make the water accessible and thus integrate it into the life of the district. The Emscher River Association (Emschergenossenschaft) commissioned DAHLEM with the project planning, structural design, technical equipment and site management for the reconstruction of the watercourse.
It is a high-tech facility where everything is just about right. With outstanding architecture, a clearly defined purpose and state-of-the-art technology inside, its new digesters are, therefore, characteristic of Würzburg wastewater treatment plant. In the future, 4,500 tonnes of sewage sludge will be produced each year, with an almost tripled annual capacity of 10,000 cubic metres. This means more digester gas and more power generation. 4.2 million kWh of additional electricity can now be produced to be consumed directly on site. As a result of this measure, the CO2 balance improves enormously and the odour nuisance is also reduced. A focal point of the electrical engineering was the integration of the generated energy with the Mainfranken network in line with the Renewable Energy Sources Act. Specifically, the lightning protection system was a considerable planning challenge. Here, it was necessary to, on the one hand, adapt the components of the new digesters and, on the other, to protect their design membrane and the potentially explosive areas against lightning strikes. DAHLEM was responsible for the electrotechnical planning for all service phases.
At MARK 51º7, the former Opel factory site in Bochum, an industrial, technology and knowledge campus is currently being built that will fulfil the requirements of future work environments, supporting a work/life blend. With development at an advanced stage and the infrastructure almost entirely complete, the ambitious plan for the location is increasingly becoming a reality.For the development of the sewer and road construction, DAHLEM, as part of a joint venture, supervised the implementation of the gigantic and complex construction site. The design and construction supervision for the stormwater retention basin, with a volume of 6,500 m³ for protection in cases of heavy rain, has already been completed. The site was awarded the polis Award 2019 in its category as "Best urban surface recycling, MARK 51°7 - successful reactivation in eastern Bochum".
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