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Technology, Oil-Free Air Compressors

Screw Blowers versus Centrifugal Air Compressors in Wastewater Treatment


In the wastewater treatment process, millions of bacteria feed on organic waste, breaking it down into carbon dioxide, nitrogen and water. Because these bacteria require oxygen as part of this process, large quantities of air are blown into aeration tanks. As a critical function that is in operation 24 hours a day, seven days a week, blowers can represent up to 70 percent of the total electricity costs for industrial wastewater treatment plants.

Depending on the amount of wastewater requiring treatment and the specific needs of the plant, a wastewater treatment facility may consider a variety of blowers and air compressors for their applications. The following examples outline specific results from two wastewater treatment plants that recently outfitted their facilities with either screw blowers or centrifugal air compressors.

Plant Incorporates Two ZS Screw Blowers to Increase Efficiency

  • Challenge – This particular wastewater treatment plant processes 3 million cubic meters of sewage water every year and sixty percent is industrial sewage water from nearby meat processing facilities. This water results in above-average quantities of phosphate that can be a challenge for a facility to handle. All of the process equipment must also work together to detect the pollution level of the water and respond accordingly.
  • Solution – The plant tested how two Atlas Copco ZS 55+ oil-free screw blowers with variable speed drive would work with two blowers from another manufacturer to supply compressed air between 1,500-3,500 cubic meters per hour with a target excess pressure of 500 mbar to a maximum of 600 mbar.
  • Results – The ZS screw blowers increased efficiency by 10 percent, compared to the facility’s other machines. Plus, the easy installation means the machines were up and running quickly and the compact design makes routine maintenance a breeze. With its integrated VSD and controller, the machine is easily linked to the process control system and provides the exact amount of oxygen needed to treat the wastewater.

Deep Sedimentation Tanks Require High-Pressure Compressed Air

  • Challenge – The tanks at this particular wastewater treatment plant are 10 meters high with a water depth of 8.5 meters. Normal tanks are usually four to five meters deep, meaning this plant needed large quantities of high-pressure compressed air to process the wastewater. However, the energy-intensive process of blowing air through diaphragm tube aerators was accounting for 40 percent of the plant’s entire power consumption.
  • Solution – The previous compressed air installation featured five aging single-stage screw compressors that required a complete overhaul at a great cost. Centrifugal compressors with magnetic bearings were deemed the most efficient upgrade for the specific application, providing the high pressure air required for the deep sedimentation tanks.
  • Results – The plant installed three ZB 130 oil-free centrifugal air compressors with variable speed drive to work in tandem with two of the older single-stage screw compressors. The plant is now saving nearly $20,000 each year on maintenance, energy and resources due to the upgraded equipment.

Is Your Facility in Need of an Upgrade?

Let us show you how much you can save by replacing inefficient technology with the latest energy-efficient air compressors and blowers. Contact us or leave a comment below to get started.

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