The effluent from wastewater treatment plants contains a large amount of thermal energy that is currently not being utilized to its full potential. Wastewater heat is an ideal low-temperature heat source, which is characterized by year-round temperatures of generally over 10 °C. The heat can be used as renewable energy both at the wastewater treatment plant and also fed into a heating network. The use of wastewater heat in combination with modern heating networks is an option for climate-neutral heat generation with large heat pumps. In order to be able to tap the potential of wastewater heat utilization from the effluent of wastewater treatment plants as district heating in a targeted and efficient manner, it is necessary to identify and quantify the transferable heat output on a site-specific basis.

As part of his master's thesis, Lukas Höft evaluated the daily operating data of a total of four Hessian wastewater treatment plants of size classes 3 and 4 in detail for the period from 2019 to 2022 in order to determine their heat utilization potential over the course of the year. From this, location factors were developed that allow the results to be transferred to other wastewater treatment plants with little effort.

In many places, the potential for heat recovery from the effluent of wastewater treatment plants exceeds the plant's own requirements. This sustainable way of supplying heat can be an important building block for many Hessian municipalities to achieve climate neutrality and at the same time reduce anthropogenic thermal pollution of water bodies.

The jury judged the prizewinner's results to be very convincing and valuable. The work combines scientific standards with direct practical relevance in an outstanding way and fulfills the evaluation criterion "contribution to solving significant problems in engineering practice" very well. It also shows in an exemplary manner how the Faculty of Civil and Environmental Engineering generates concrete contributions to the use of renewable energies and thus also to the achievement of sustainability goals by closely linking university research, teaching and knowledge transfer.

The prize is sponsored by the Arbeitsgemeinschaft Stufenausbildung (Bau) Kassel - ASK and is endowed with a total of 3,000 euros. It is awarded in cooperation with the Faculty of Civil and Environmental Engineering at the University of Kassel once a year in a public ceremony to students of the faculty for outstanding final theses. The selection criterion is that the work to be awarded makes a contribution to solving significant problems in engineering practice, taking into account cost-effective planning, design and construction.

The North Hessian construction industry sponsorship prize continues the tradition of the KBB prize, which was first awarded 37 years ago. It is therefore the longest-standing prize for student theses at the University of Kassel.

Lukas Höft's Master's thesis was supervised by Prof. Tobias Morck (Department of Urban Water Management). Since completing his Master's degree, Lukas Höft has been working as a planning engineer at the Stade wastewater disposal company in the Hanseatic city of Stade (Lower Saxony).

The ceremony took place in the university's Gießhaus. For the first time, a new extension to the Gießhaus was also used for the event - in trial operation. In future, the 80 square meter hall will provide students with a quiet learning atmosphere and can also be used as a reception room for events.

The evening was hosted by Prof. David Laner, Dean of the Faculty of Civil and Environmental Engineering. The sponsorship award was presented by the two ASK board members Thilko Gerke and Dr. Burkhard Siebert. The keynote speech was given by Sascha Wiehager, Managing Director and Institute Director of BWI-Bau, Düsseldorf, on the topic of "European Green Deal - Effects on the construction value chain".

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