Described herein is aerobic granular sludge gravity-driven membrane system, methods of making and using thereof are described. The aerobic granular sludge (AGS) integrated with a gravity-driven membrane (GDM) filtration system is an energy efficient wastewater treatment system that takes advantage of AGS reactor systems integrated with gravity-driven membrane system to reduce membrane fouling and produce microbiologically and chemically safe water. The AGS-GDM system includes at least an AGS reactor tank containing raw wastewater and granular sludge and a membrane tank including one or more gravity-driven membrane(s).