The VariOx™ jet aeration system is an aeration and mixing device used in numerous water and wastewater treatment applications. Jet aeration combines many of the benefits and efficiencies of both mechanical and diffused air type systems. The jet aerator consists of an inner liquid nozzle and an outer air nozzle. Liquid from the basin is re-circulated through a jet motive pump and discharged through the inner liquid nozzle at a high velocity. Concurrently, air is fed into the outer air nozzle where it is mixed with the motive liquid and discharged as a high energy jet plume.
The cross flow of motive liquid through the air entering the outer nozzle creates a shearing action which generates a medium to fine air bubble. The air bubbles are entrained within the jet plume and discharged in a horizontal plane into the lower portions of the basin.
The jets can be operated with or without air being fed through the outer air nozzle. This provides the functionality of both a mixer and an aeration device. Air rates can also be varied through the outer nozzle which provides the ability to maintain a complete mix condition while adjusting air rates to satisfy process requirements.
The efficiency of the jet system is comparable to fine bubble diffuser systems. The main benefit is that, unlike membrane diffusers, the jets do not lose efficiency over time. Oxygen transfer efficiencies remain constant over the life of the equipment. This is a key advantage when considering both the long term operating cost and the operational sustainability since no scheduled down time for equipment replacement is required.
The motive liquid used to deliver oxygen provides a highly turbulent environment which results in a high alpha value, similar to mechanical type aerators. Alpha values of 0.85 are commonly used for typical municipal wastewater. The jets produce a medium to fine air bubble which is delivered in a high velocity horizontal flow pattern. This flow pattern provides a longer bubble residence time versus standard diffuser designs that create only a vertical path of air bubble travel.