Pumping in water and wastewater treatment applications is a critical, yet challenging, process. It is essential that wastewater pumping systems are effective and reliable to limit maintenance downtime, which can increase costs.
Airlift pumps are highly resistant to clogging, can be cleaned easily if needed, and are designed to suit any wastewater application. They have no moving parts, seals or electrical equipment, which makes them simple and reliable, with minimal operating and maintenance (O&M) costs and a long service life.
Conventional pumping systems typically feature mechanical equipment and can easily clog or be damaged depending on the management of grit and screenings. Pumps that become damaged or require significant maintenance downtime can compromise treatment objectives and result in increased O&M costs.
Airlift pumps are highly resistant to clogging and can be cleaned easily if needed. They have no moving parts, seals or electrical equipment, which makes them simple and reliable, with minimal operating and maintenance (O&M) costs and a long service life. No special housings or protection measures are required.
Airlift pumps are available in a range of sizes. They are designed to suit all applications and can fit into any wastewater pumping scheme where lifts of 4 to 5 ft (1.3 to 1.5 m) or less are required. They are ideal for pumping chemical floc, raw sewage, grit, primary sludge, return activated sludge, and mixed liquor.
Airlift pumps use low air pressure which is readily available throughout most diffused air wastewater treatment systems. The air used for pumping gives the benefit of additional oxygen transfer efficiency to the pumped liquid. Airlift pumps provide many other operational advantages over conventional pumping systems, such as:
- Minimum maintenance operation
- Installation simplicity
- Control simplicity
- Long Service Life (up to 20 years, which is the typical life of a wastewater treatment plant)
An airlift pump consists of a vertical educator pipe, partially submerged in the liquid to be pumped. Air is injected below the liquid surface. The air bubble mixes with the liquid, creating a regime inside the educator pipe which is less dense than the liquid feeding it. This produces an imbalanced of pressures between the densities of the outside and inside columns and the liquid causing the liquid outside the educator pipe to flow in, displacing the inside air/liquid up the educator tube and out the discharge. The action is similar to that of a chimney, where heat expansion of gases inside of chimney lowers their density to less than that of a column of air of equal height on the outside. The difference in weight causes the heavier outside air to push into the furnace and displace the gases up the chimney.
A plug valve in the airflow line controls the flow of the pumps. For automatic control, a solenoid is added to the air line. Motor starters, VFDs, sequencers, etc. are not required. The simple control schematics take advantage of a wide variety of conventional or solid-state circuitry.