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Degree project on measures at wastewater treatment plant

Published: 9 September 2021

Oskar Bäck, who studied the master programme Natural Resources Engineering at Luleå University of Technology, has now completed his student thesis project. He carried out the study on behalf of Roslagsvatten AB. The aim of the work was to contribute knowledge so that the flotation process at Margretelund's wastewater treatment plant can be improved

One aim of the study was to make a historical analysis of the function and efficiency of the flotation process regarding the separation of suspended material from wastewater. Subsequently, a full-scale pilot study was carried out on Margretelund's wastewater treatment plant's flotation process with the aim of optimizing the process and finding an operating method that allows higher flows without impaired separation of suspended material.

The experiments were performed by varying two operating parameters - degree of recirculation of dispersion water and surface load. Suspended material was measured in both incoming and outgoing water to estimate the degree of separation and concentrations. The surface load was found to have the clearest effect on the content of outgoing suspended material. As the surface load increased, it gave a clear increase in suspended matter in outgoing water. The results also showed that the degree of recirculation of the dispersion water has a potential effect. Outgoing concentration of suspended material could be reduced if the recycling rate was increased.

After completing his studies, Oskar Bäck will start working at Roslagsvatten AB as a process engineer. He will continue with further studies on the flotation process and have responsibility for a number of smaller treatment plants in Roslagen.

Daniel Zetterström, Roslagsvatten AB was the external supervisor for Oskar Bäck. Supervisor from LTU was Inga Herrmann and examiner Annelie Hedström, also from LTU.

Inga Herrmann

Inga Herrmann, Associate Professor

Phone: +46 (0)920 492528
Organisation: Urban Water Engineering, Architecture and Water, Department of Civil, Environmental and Natural Resources Engineering
Annelie Hedström

Annelie Hedström, Professor

Phone: +46 (0)920 492309
Organisation: Urban Water Engineering, Architecture and Water, Department of Civil, Environmental and Natural Resources Engineering