A container assembly includes a flexible bag having an interior surface bounding a chamber and an opposing exterior surface, the bag having a bottom end wall being comprised of a first sheet overlying a second sheet, the first sheet and the second sheet of the bottom end wall being welded together so as to form a first sparging area and a separated second sparging area that are both bounded between the first sheet and the second sheet, at least a portion of the first sheet overlying the first and second sparging areas being gas permeable.