This task will be implemented on year 3 of the project. As it is very likely that by-products resulting from the hydrometallurgical treatment will have very different characteristics than primary slags, a second set of pot experiments will be performed, using those secondary waste. The same experimental setup than in task 5.1 will be implemented. This will answer the issue of the suitability of secondary waste for plant growth as well as the promoting effect of “Arbuscular Mycorrhizal Fungi” (AMF) on this kind of substrate.