If you are the proud owner of a garden and you had acquired a tree with its clod, you can always try to replant it in your little green paradise. You can certainly dig it up next year to let it know again the joys of decorations and the tickling of garlands.
Otherwise, you will get rid of its pot and all its decorations before placing it on your sidewalk on the days of harvesting green waste (1 time per week according to the calendar specific to your municipality). This is valid for the entire territory of the Brussels region. You can leave the brace. For artificial trees, it will however go to the container park, it is indeed considered a bulky household.
Each year Bruxelles Propreté reports harvesting between 170 and 200 tonnes of Christmas trees ... the natural trees are then crushed at the Forest recycling center.