Dumped Items

We have a storage room with allotted spaces for each apartment.  There is also  space in this room that is not alloted to anyone but collects mattresses, Tv’s and other items when tennants move out etc.

We have no way of knowing who these items belong to.  If we throw these items away in the council cleanup, could the owner sue us for the value of these items if they were storing them?  If we put out a notice to all residents giving notice of when we will be removing the items, is this within the law?  Are we ok to remove any items that are not stored within allotted spaces?