You can dispose of sanitary towels and nappies at the sorting stations (milieuperrons). Note that the containers are not available at every sorting station but are scattered around the whole city. These containers are locked so you will have to register for access to these containers through the municipality. For registering you will need your milieupas. After registration, your milieupas is activated for four years of access to the disposal containers. When you throw your sanitary towels or nappies away, make sure they are in the indicated 25 litre bags. You can get these for free at the service stations of supermarkets (same place where you can buy the red general waste bags).
You can find more information on the locations and details about the disposal of incontinence products and nappies from the municipality website.