A U.S. Patent Application for and”Airlift Perfusion Bioreactor for the Culture of Cells” was published by the Keck Graduate Institute on September 26th, 2019. The present invention is a bioreactor apparatus, comprising: a cell culture zone comprising a riser section and a downcomer section; a settling zone comprising an inclined gravity settler in fluid communication with the downcomer section, the inclined gravity settler being partitioned from the riser section; a gas injection inlet to the riser section; a liquid inlet to the cell culture zone; and a liquid outlet on the inclined gravity settler. Learn More