This is anaerobic sludge being mixed in a circular tank, using an eddy jet mixer. Eddy mixers are typically used in sludge storage tanks and anaerobic digestors. Usually, eddy mixers are used in systems with liquid levels between 5 and 30 feet.
This 5 million gallon flow equalization tank at a plant in Ohio is designed to treat storm wastewater. The tank has a sloped bottom and uses one submersible pump on the exterior of the tank. The jet mixer has four arms which are all supplied by one 90-HP pump.
The system can be operated with the liquid below the nozzles or up to the top liquid level of the tank, as long as the liquid level above the pump is greater than 3 feet. The system shows equal liquid level distribution throughout the tank.
This is a two-step activated sludge system treating wastewater in Houston, Texas. The first step uses five circular tanks to treat the concentrated waste. The second step (shown in this video) has seven rectangular tanks to further reduce the concentration of the influent wastewater using bidirectional jet aerators.
More air is used for the front end of the aeration tank, where the concentration is high. The rear end of the aeration tank is for maintaining dissolved oxygen, as well as treating the remaining load.
This aerobic digestor in Ohio is being mixed during start-up with clean water. Currently only the pump is in operation, showing the mixing action of the recirculation pump and the jet mixer with no aeration.