Impact of digestate hydrochar products on energy and nutrient recovery for WRRF- HydroEN-VEMM

This continuation of Hydroslam aims to evaluate the use case of digestate derived hydrochar products where hydrochar is applied in agriculture, mirroring sewage sludge digestate use, and process water is recirculated.

This is approached in three objectives:

•track pollutants (heavy metals, PAHs, PCBs, PFAS, Microplastics and Pharmaceuticals) through the HTC process,

•evaluate the comparative agronomic value of hydrochar through pot trials, and

•measure the response of recirculation of HTC products to anaerobic digestion.

The establishment of pot trials at MDU is already ongoing, and this research would provide imperative for the furtherance of this branch of research at MDU. Extending this research represents a cost-effective means of addressing important questions in sewage sludge management and value recovery at MDU and expanding the scope of the Hydroslam research project significantly.

Project objective

This knowledge from this project is important for developing the most effective circular waste management solutions in wastewater treatment facilities and advancing the water resource recovery. This will benefit VEMM as an alternative treatment for sewage sludge digestate and broaden the potential solutions investigated by MDU within the Hydroslam project. This research will also make progress in better understanding the potential environmental and economic benefits of circular organic waste management, as well as inform future research about the impacts of recirculation of HTC byproducts.We are planning to make a comprehensive analysis of micropollutants (PAHs, PCBs, PFAS, Microplastics and Pharmaceuticals) in the different streams (using already allocated funds) as well as of metal and nutrients. These analyses will not only improve the research quality but can also deliver Mälarenergi important and relevant insights regarding the behaviour of these micropollutants in their streams before and after HTC.Agricultural application is the dominant paradigm for sewage sludge treatment, therefore all VEMM partners stand to benefit from better understanding the performance of hydrochar as a potential substitute.