How an Aeration Blower Sends Air Below the Water Surface
An aeration blower sends ambient air to diffusers near the bottom of a biological treatment tank. It must overcome water depth and the losses in the pipes and diffusers. The resulting bubbles provide an interface for oxygen to transfer into the water and support aerobic treatment.
Follow the air through the process
Pressure opens the underwater route
Air must overcome the water pressure at diffuser depth. Diffuser resistance and pipe losses add to that requirement. More water above the diffuser means a higher required delivery pressure.
A Roots blower moves trapped volumes
Two timed rotors turn in opposite directions. They carry pockets of air around the casing from inlet to outlet. The rotors keep a clearance; the air does not pass through their solid lobes.
Bubbles expose an air-water interface
Air leaves the diffuser openings as bubbles. Oxygen transfers from the bubbles into the water, where aerobic microorganisms use it. The bubbles are air; the blower does not manufacture pure oxygen.
Control useful oxygen delivery
Treatment load changes the required oxygen supply. Airflow control can respond to the plant oxygen target and measured dissolved oxygen. A turning blower alone does not prove the required oxygen transfer.
Airflow function
- Move air from above the tank to submerged diffusers.
- Supply pressure against hydrostatic and equipment resistance.
- Provide controllable air delivery within the process and blower limits.
What can change the result
- Increasing depth without allowing the required pressure.
- Fouled diffuser openings increase air-path resistance.
- Using motor-running status as a substitute for delivered air and dissolved oxygen measurements.
Start with the complete air path
Share your layout and the information you already have. Unknown values can be identified before a configuration is selected.
Match the fan to this air path
A Roots blower carries air pockets from inlet to outlet, while the tank and diffuser circuit determine the required delivery pressure. LONGWELL documents the LWSR family for wastewater aeration, making airflow and total pressure the starting points for selection.
Where it sits
Deliver air from above the tank to submerged diffusers against water depth and system losses.
Why consider this configuration
A Roots blower carries air pockets from inlet to outlet, while the tank and diffuser circuit determine the required delivery pressure. LONGWELL documents the LWSR family for wastewater aeration, making airflow and total pressure the starting points for selection.
Check the result in your equipment
Application questions
Does the blower make oxygen?
No. It moves ambient air. Oxygen must transfer across bubble surfaces into the water before the biological process can use it.
Does a deeper tank only need a longer pipe?
No. Additional depth also increases the hydrostatic pressure that the blower must overcome. Pipe and diffuser losses remain additional terms.
How should I specify the blower noise requirement?
Provide the site limit, measurement position and operating condition. The enclosure, inlet and outlet treatment, and complete package must be evaluated together.
Discuss diffuser aeration duty
Send the tank and diffuser layout or existing blower model. Include water depth, minimum and peak airflow, clean and fouled diffuser losses, pipe losses and inlet conditions.
A layout, installation photos or your existing model is enough to start the discussion.