Freeport, Maine, plant saves money and energy with hybrid blowers

In 2010, engineering firm Woodard & Curran conducted an energy analysis at the Freeport (Maine) Wastewater Treatment Facility. The plant was consuming more than 8.9 kBtu per gallon of wastewater treated, which is double the national average. While an outdated oil heating system contributed, the plant’s multistage centrifugal aeration blowers accounted for 80 percent of electricity consumption. 

The .44 mgd facility has an average daily flow of .25 mgd. However, the plant’s existing blowers were delivering a larger volume of air, particularly during the slower winter season.

Following the 2010 energy assessment, the plant went through extensive upgrades. The aging multistage blowers were replaced with two Aerzen Delta Hybrid blowers, which achieve power savings comparable to turbo blowers while retaining the advantages of a positive displacement blower. 

In addition to accommodating seasonal fluctuations, the blowers had to meet the plant’s mixing energy requirements and physical limitations, which included combined aeration basins and clarifiers in a package design. The treatment units were also converted from an airlift pump system to an electric pump system, reducing air requirement and providing better return-activated sludge flow control. 

The hybrid blowers went online in December 2011, with one blower handling the plant’s aeration requirements and a second blower installed for redundancy. Before the upgrade, the facility’s electricity use was between 110,000 and 120,000 kWh per month. With the upgrades, energy consumption dropped to less than 40,000 kWh per month. At full load, the old centrifugal blower consumed about 62,240 kWh per month, compared to 50,560 kWh per month for the new hybrid blower. 

Aerzen USA provides positive displacement blowers, turbo blowers, screw compressors and vacuum pumps for the wastewater industry. 

610/380-0244 •


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