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Arrangementer på Institut for Kemi og Biovidenskab

PhD Defense by Katie Kedwell

Katie Kedwell, Department of Chemistry and Bioscience will defend her thesis on: "Membrane Technology for Phosphorus Recovery from Wastewater”


06.06.2019 kl. 13.00 - 16.00



”Membrane Technology for Phosphorus Recovery from Wastewater”. 


Phosphorus is essential in many industries, particularly agriculture. However, phosphorus is a finite resource, and reserves are limited. Northern Europe has no phosphorus reserves, while Morocco has the World’s largest reserves of phosphate rock. Phosphorus has been used at an increasing rate, consequently, it is estimated that phosphorus reserves will be depleted within the next 200 years.

Phosphorus can be recovered from waste streams. The most promising of which is wastewater. During wastewater treatment phosphorus is removed by biological or chemical means. This means sewage sludge contains a high concentration of phosphorus. In some places sludge is spread on fields as a fertilizer. However, this raises issues surrounding odour, heavy metal contamination, and poor public opinion. Sludge can be incinerated and phosphorus recovered from the ashes, but the incineration process is energy intensive, and heavy metal contamination is sometimes still an issue.

The objective of this study is to increase the efficiency of struvite precipitation through concentrating digested sludge liquors (thus reducing the amount of magnesium additive) or through removal of phosphorus to a ‘clean’ stream, free of heavy metals or biological contamination. This can be achieved by using forward osmosis and selectrodialysis, respectively. An cost analysis of implementing forward osmosis and selectrodialysis at Aaby wastewater treatment plant  was then conducted to determine if either technology would be viable at full-scale.


  • Associate Professor Morten Lykkegaard Christensen, Dept. Chemistry and Bioscience, AAU, Denmark


  • Associate Professor Rudi P. Nielsen (Chairman), Dept. Chemistry and Bioscience, AAU, Denmark
  • Associate Professor Anders Bentien, Department of Engineering, Aarhus Universitet, Denmark
  • Assistant Professor Irena Petrinic,Laboratory of Water Biophysics and Membrane Pro- cesses, Faculty of Chemistry and Chemical Engineering, University of Maribor




Department of Chemistry and Bioscience, AAU, Section of Chemistry


Fredrik Bajers 7H, 9220 Aalborg Ø, room number: Auditorium