The purpose of the project was to evaluate membrane distillation as an alternative separation technology for different water purification applications. Membrane distillation (MD) is a unit operation that uses water repellent (hydrophobic) membranes as a barrier for contaminated water. The driving force for the process is the vapor pressure over the membrane achieved by applying temperature differences between a warm and a cold side. The process takes place at temperatures below 100 °C and at ambient pressure. Pilot studies were performed at Hammarby Sjöstadsverk to test the separation of pharmaceutical residues from municipal wastewater after biological treatment as well as final treatment of flue gas condensate. In both cases, most target compounds were separated to a very high degree, often more than 90 %. The project also included energy studies that showed some potential for energy optimisation of the current equipment and provided input for energy efficient set-up, e.g. by using waste heat such as the return flow from district heating. Varying results for the single modules also indicated optimisation potential. The project was performed in cooperation between IVL Swedish Environmental Research Institute, Xzero AB as technology provider, and KTH (Royal institute of technology) for energy studies