Jet Aeration Systems Explained

Aeration is a critical process of biological wastewater treatment, and it is used across municipalities and industries globally. Since its beginnings in 1985, Mixing Systems, Inc. has focused on delivering durable jet aeration systems, which produce fine bubbles via hydraulic shearing via concentric jet nozzles.

Mixing Systems, Inc.’s jet aeration systems are comprised of three major components:

1. Aeration manifolds located within the tank
2. Recirculation pumps that pull liquid (water) from the tank and hydraulically pump it back through the aeration manifolds at our designed operating levels
3. Blowers that provide air into the system

The water and air travel down separate lines within our aerators and meet within the double nozzle, concentric jets. Intense contacting and mixing of the two streams occurs in the high shear mixing chamber. The intimate contact between gas and liquid streams results in the formation of micron-size bubbles.

The mixed contents shoot out of the nozzles at a specified velocity depending on the particular application and flow in designed mixing patternsthat allow for continuous movement without any “dead zones” within the tank.

Example Videos Displaying Jet Aeration in Operation

• Activated Sludge Treatment

This tank is currently being filled using both directional and bidirectional aerators. The video demonstrates that the jet nozzles are installed level for equal air distribution.

This tank is part of a plant located in Canada, and is designed for activated sludge at low temperatures. This type of design is typically used in tanks with liquid levels between 15 and 35 feet.

• Equalization Tank

This storm holding tank at a plant in Ohio makes use of a jet mixer which creates a vacuum that entrains additional liquid between the inner and outer nozzles. The flow at the end of the flange shows the liquid being entrained between the inner and outer nozzles.

We made a video animation about entrainment: https://youtu.be/vfHPFcXnOWg

• Activated Sludge Treatment

Directional jet aerators during the installation process at a pulp mill in British Columbia, Canada. These aerators belong to an activated sludge system that uses in-ground tanks rather than building a concrete tank above ground.

• Activated Sludge Treatment

This video shows the backflush in an activated sludge tank. The system is being flushed using the airlift principle, which involves reversing the flow from the digestor through the jet nozzles, and out at the top of the tank. A strainer can be used to collect these solids, if necessary.

We have an animation video of this process: https://youtu.be/z-wzZFixq4Q

• Aeration

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.

• Activated Sludge Treatment

This tank is one of five that treats petrochemical and refinery wastewater in Houston, Texas. It has four directional jet aerators that mix the liquid in a counterclockwise motion. The plant collects wastewater from approximately fifty industries surrounding the plant.

The plant was initially constructed to aerate the wastewater using air, but was later converted to use pure oxygen. The conversion was intended for expansion purposes, as well as to reduce the volatile emissions being released into the atmosphere. By adding pure oxygen, the plant is able to increase capacity by 200-300%.

• Activated Sludge Treatment

This activated sludge plant uses a tank with a 105 foot diameter and 25 foot height. Intense mixing occurs within the tank, which can be mixed with or without aeration. Recirculation pumps provide the needed mixing energy for keeping the solids in suspension.

• Activated Sludge Treatment

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.

• Aeration

These directional jet aerators are in the process of being installed at the base of a tank. Support bases for the aerators are often anchored to the tank base (or, in the case of steel-bottom tanks, are welded to the tank base).

• Aeration

This tank (diameter: 180 feet, height: 33 feet) is mixed and aerated by six directional jet aerators, creating a circular flow pattern. This system is located at a pulp mill in British Columbia, Canada.

• Activated Sludge Treatment

A basin for this pulp and paper plant in Alberta, Canada had four directional mix jet aerators and three bidirectional mix jet aerators installed. The aerators were supplied by four 200 HP and three 125 HP vertical pumps, as well as two 800 HP centrifugal air blowers.

• Equalization Tank

This video demonstrates the process of mixing a holding tank in Ohio that collects wastewater during storm season. These tanks have sloped bottoms with jet mixers installed four feet from the bottom, with nozzles pointing downwards.

The system is designed to mix the tanks without air, but it has the capability to provide aeration in case issues arise with the odor in the tank (over the last twenty years, there has been no need to aerate the tank).

• Aerobic Digesters

This eddy jet mixer is shown during the start-up process. The mixer is located in a digestor tank and is designed to be operated as an anaerobic or aerobic digestor. Solids concentration can vary up to 4%.

• Activated Sludge Treatment

Several FRP (fiberglass reinforced plastic) jet aerators are thoroughly mixing and aerating the contents of this wastewater tank. The tank is part of a refinery located in Mexico.

• Activated Sludge Treatment

This tank belongs to an activated sludge system in operation at a pulp mill in Canada. The tank is being mixed with one bidirectional jet aerator. The system is designed for cold climates.

• Aerobic Digesters

This tank for an aerobic digester in Ohio is mixed and aerated by an eddy mix jet aerator. The system was initially designed to run as an aerobic digestor, and was later converted to run as a sludge storage tank. The pumps and blowers are located outside the tank, which is now completely enclosed to prevent air emissions into the atmosphere.

• Aerobic Digesters

This equalization tank treats beverage waste with a jet mixing and aeration system. Although the anaerobic tank is easily oxidized in 5-10 minutes, there is no need to use aeration (unless algae and other biological growth occurs). Mixing alone can be provided via recirculation pumps.

This tank is being mixed and aerated by four bidirectional jet aerators and three directional jet aerators. The tank is the size of several football fields, and is used for mixing pulp in a Canadian paper mill. This system in particular was specially designed to function at sub-zero temperatures.