RIAS

Resource-saving and integrated activated carbon production at wastewater treatment plants for the elimination of micro pollutants

Duration
01.11.2019 - 31.10.2022

In recent years, the elimination of trace substances from municipal wastewater has increasingly become a focus of public attention. Among the paths of entry of trace substances into the water cycle are in particular municipal sewage treatment plants, which can contribute to the reduction of emissions of trace substances into the aquatic environment by means of further process technologies that go beyond conventional sewage treatment. Besides oxidation with ozone, adsorption on activated carbon has proven to be a practicable process. Organic trace substances contained in the effluent of wastewater treatment plants can be removed by adsorption on activated carbon. Activated carbon is a highly polar substance that can be produced by activation of carbonized materials (typically: coconut, brown coal, hard coal, wood, etc.). However, activated carbon production, which takes place mainly in Asia, causes a very high environmental impact.

The objective of the RIAS project is to extract organic substances from raw wastewater by screening, to convert them into a resource-saving activated carbon (RAK) and to use them for the elimination of pollutants in municipal wastewater treatment plants. In this way, a raw material cycle that has not been considered so far could be closed in municipal sewage treatment plants.

For this purpose, RAK is produced from screenings by means of different processes and the adsorption capacity of RAK is tested in laboratory experiments as well as in semi-technical, continuous investigations. In the project idea presented here, the wastewater is mechanically pre-treated by wastewater screening (on an industrial scale). The screenings obtained by screening are firstly dewatered, then thermally treated by various thermochemical conversion processes (hydrothermal carbonisation or drying followed by pyrolysis) on a semi- and large-scale scale, pelletised or untreated pelletised and finally thermally activated. The RAK produced is characterized with respect to its performance for trace substance elimination and compared with conventional activated carbon to determine the most suitable process and the optimal process conditions for the production of RAK. Further investigations into the adsorption mechanism on the surface of the RAK will be undertaken beyond the scope of the project using gas sorption (physisorption and chemisorption) and in future collaboration with the company Anton Paar from Ostfildern. For a holistic evaluation, life cycle assessments of the produced RAK in comparison to conventional activated carbons will be established and evaluated and possible effects of the different processes on the clarification process and the operation of the wastewater treatment plant will be considered.

Project Homepage: www.projekt-rias.de