The VariOx™ jet aeration system is an aeration and mixing device used in numerous water and wastewater treatment applications. The jet aerator consists of an inner liquid nozzle and outer air nozzle. Liquid from the tank is recirculated through the inner nozzle at a high velocity. Concurrently, air is fed into the outer nozzle where it is combined with the high velocity liquid from the inner nozzle and discharged as a high energy plume. Air to the nozzles can be varied, or turned off, allowing the system to be used as both a mixing system and an aeration system.