In Gravenhorst, a district of Hörstel in North Rhine-Westphalia, a modern mine water treatment plant is currently under construction. Now an important milestone in the project has been reached: mechanical completion.
The building construction, civil engineering structures and installation of all central components are scheduled to be successfully completed by the end of August 2025. This includes aggregates, chemical containers, pumps, measuring points as well as all mechanical and EMSR technology (electrical, measurement, control and regulation technology). The technical building equipment - including fire alarm systems, lighting, safety lighting, ventilation and sanitary installations - will be completed in the coming weeks.
Mine water treatment at former mining site
The mine water treatment plant is a technical facility for treating mine water from former mines. The aim is to purify the polluted water and then discharge it into the natural water cycle. At the location of Ibbenbüren - the northernmost hard coal mine in Germany - coal was extracted until 2018. Following the decommissioning of the mine operated by RAG Aktiengesellschaft, planning began for the deconstruction process and the implementation of long-term water management measures. The Dresden-based company Umwelt- und Ingenieurtechnik GmbH Dresden (UIT) was commissioned with the planning and construction of the required water treatment facility.
Function checks and commissioning can start
Function tests and commissioning of the plant will begin this summer - first in dry conditions, then followed by wet conditions. During the trial phase, mine water from the so-called West Field of the former mine will be used. Upon successful completion of this testing phase, the plant will be transitioned into regular continuous operation. In doing so, it will make an important contribution to the sustainable management of mine water in Gravenhorst as well as to the protection of surrounding water bodies.
Complex Multi-Stage Water Treatment Process
The treatment of mine water takes place in several consecutive process stages. The water is first directed to the treatment facility through a tunnel approximately 7.4 km long, where it initially arrives at the pump house.
There, it is coarsely cleaned using a straining system and is then pumped into the first treatment stage - the neutralization basin. In this step, sulfate is precipitated with the aid of lime milk, and the iron contained in the water is oxidized through aeration. The pre-treated water then flows toward the thickeners, where solids are separated from the water in a sedimentation stage.
The sedimented solids are pumped out of the thickeners and transferred to landfill ponds, provided sufficient capacity is available. If this is no longer possible, a pre-planned sludge treatment facility will be constructed on site, where the liquid sludge can be dewatered and subsequently disposed of.
The pre-treated water then passes through the post-sedimentation basin, which is divided into two sections. The extended retention time allows additional solids to settle. Afterwards, the water flows through a demanganization stage and into the drainage basin. Here, further processing steps are carried out, including pH adjustment. After this final stage, the treated mine water is carefully monitored and environmentally soundly discharged into the natural water cycle.
Experienced plant engineering company from Dresden implements major project
The Dresden-based plant engineering and construction company Umwelt- und Ingenieurtechnik GmbH Dresden (UIT) was commissioned to construct the facility. Since its founding in 1990, the company has been active in plant engineering and possesses extensive experience in the design and construction of mine water treatment plants, Chemical-physical treatment plants, biogas testing plants and pilot plants.
As part of this project, UIT initially conducted feasibility studies and conceptual pre-assessments. Building on these, the company took on the role of general contractor (GU) for the plant design, developed the 3D construction plans and was responsible for coordinating and supervising the facility’s construction. UIT managed all craftsman and partner companies involved in the project. The company is part of the General Atomics Europe Group, which was also actively involved in project management and organizational implementation.
