Field equipment for separation of heavy metals from organic sludge retrieved from sea/lake beds

Important results from the project

The project has, in line with its objective, tested the two proposed purification methods. In extensive tests on a small scale, one of the methods showed considerably more potential than the other. This method was therefore chosen for large-scale testing and demonstration. The project has met the goal to construct a simple and robust full-scale system for separation of metals from sediments. The project has also involved a number of municipalities and county administrative boards in the project and demonstrated the system to them. See the attached project report for more information.

Expected long term effects

The bioleaching method has enabled a reduction of metals of up to 80 %. The method also retains phosphorus and nitrogen in the sediment. Performed cultivation tests show that the sediment has good properties as a fertilizer, in line with commercial fertilizers. There has been a strong interest in the method among involved farmers. The method for eliminating metals from sediment makes it possible to use material from lakes with higher metal content as fertilizer, which in turn increases the ability to restore these eutrophic lakes by dredging.

Approach and implementation

The work has followed the project plan. Extensive testing was first conducted on a small scale, and the process was optimized. Then, a scaled up concept system was constructed. It enabled us to test the process under conditions similar to those in the field. Finally, a full-scale system was built and tested. The project deviates from the plan in one aspect. Only one of the two methods was scaled up and tested at full-scale. Since the bioleaching method showed significantly more potential during the initial small-scale tests, Teknikmarknad chose to focus the later efforts on this method.