The activated sludge process consists of three channels. In operation, raw screened and degritted wastewater is fed to the outer channel. As the flow circulates, it passes through several aerated and anoxic zones. In the aerated zones, carbonaceous removal and nitrification occur. In the anoxic reaches between the aerobic zones, denitrification occurs. If the system is properly designed, anaerobic conditions can promote biological phosphorous removal.
The flow then passes through transfer ports to the middle, or “swing” channel. In periods of high loading, the dissolved oxygen concentration in the “swing” channel falls and the channel operates in the nitrification/denitrification mode of the outer channel. In periods of low load, the dissolved oxygen concentration in the “swing” channel increases and the channel serves to accelerate the aerobic processes. The flow then passes through another transfer port to the inner channel. The dissolved oxygen concentration in the inner channel is maintained at 2.0 mg/l or more to complete carbonaceous removal and nitrification.
COMPLETE NITRIFICATION/ DENITRIFICATION
The Fluidyne Jet MCR™ offers significant advantages compared to a similar system with surface aerators. The greatest process advantage is that our mixing pumps draw motive liquids (fully nitrified mixed liquor) from the inner channel and pump it back out to the outer channel at a rate that is approximately 3.0 times the design flow rate. This feature insures virtually complete denitrification. Surface aerated systems have no internal recycle and rely on simultaneous nitrification in the outer channel.