Flow through aerobic granular sludge system and method

A flow through aerobic granular sludge (AGS) system for treating wastewater comprising:

• a multi-pass flow through reactor comprising a first pass, a second pass downstream of the first pass, and a third pass downstream of the second pass, wherein each of the first pass, the second pass, and the third pass comprises an adsorption zone, an unaerated zone downstream of the adsorption zone, and an aerated zone downstream of the unaerated zone, and wherein at least the adsorption zone of the first pass includes AGS granules;
• a selector zone located downstream of the third pass, the selector zone configured to remove the AGS granules from the wastewater;
• and a return AGS pumping system in communication with the selector zone, the return AGS pumping system configured to transport the AGS granules removed from the wastewater in the selector zone to the adsorption zone of at least one of the following:
• the first pass, the second pass, the third pass, or any combination thereof, wherein the multi-pass flow through reactor is configured such that, at all stages of operation, the wastewater and AGS granules flow continuously and sequentially from the first pass to the second pass and from the second pass to the third pass.