Integration of HTC in Wastewater treatment plants (IWas)
The primary purpose of the project is to increase the knowledge on the techno-economic impacts of integrating a hydrothermal carbonization process in a wastewater treatment plants as an alternative way to dispose and utilize sewage sludge.
Sewage sludge is a semi-solid residue produced in the treatment of wastewater. Sewage sludge is rich in organic matter with typically high levels of nutrients that should be brought back to the soils. However, there are several environmental and health risks of disposing sewage sludge directly into soils as it also contains heavy metals, antibiotics among other contaminants. In Sweden, only certified sewage sludge can be disposed in soils, but new and stricter regulations might ban this practice. As a result, novel routes to dispose sewage sludge, that can at the same time recover nutrients, is in high demand.
Hydrothermal carbonization (HTC), a thermochemical conversion process occurring at high pressure and in the presence of water, is seen by many as a promising process to dispose sewage sludge. In this process, sewage sludge is mainly converted into a solid carbonaceous material normally called hydrochar. A liquid by-product as well as a small amount of gas are also formed during the process.
The hydrochar can be used as filter material, as soil amender/fertilizer, as catalyst or in energy generation. The quantity and quality of the hydrochar depends, to a great extent, on the operation conditions, as for example temperature and pressure.
In this project, we will investigate the benefits of integrating an HTC in wastewater treatment plants as a process to dispose sewage sludge. We will investigate the best process conditions that can lead to the production of a hydrochar that can be used as filter material to remove metals in the wastewaters or to recover nutrients and energy. A lab scale HTC will be used to produce hydrochar from sewage sludge. The properties of the hydrochar will be investigated for each possible application. In this project, we will also investigate whether this integration will bring economic gains to the wastewater treatment plant.