A container assembly includes a flexible bag having an interior surface bounding a chamber and an opposing exterior surface, the bag having a top end wall, a bottom end wall, and an encircling sidewall extending therebetween, the bottom end wall including a first polymeric sheet overlying a second polymeric sheet. A first weld line welds the first polymeric sheet to the second polymeric sheet, the first weld line bounding a first sparging area formed between the first polymeric sheet and the second polymeric sheet. A plurality of first perforations are formed through a portion of the first polymeric sheet that overlies the first sparging area so that gas can pass from the first sparging area, through the first perforations and into the chamber of the bag.