An efficient new aeration system has resulted in nearly $23,000 in annual energy savings to the Astoria (Ore.) Wastewater Treatment Facility. Besides giving the coastal town’s budget a boost, the new aeration system is doing a better job of processing wastewater to a level of purity that allows its discharge into the Columbia River.
The aerator upgrade was identified as an energy saving strategy through an energy efficiency study sponsored by Pacific Power. When Astoria decided to invest in the $341,000 system, they took advantage of a $100,000 incentive from the Energy Trust of Oregon, Inc., and a $224,000 loan from the Oregon Department of Energy to cover about 95% of the costs. The city expects to pay off the loan in approximately 10 years.
Before the new equipment was installed in October 2003, oxygen was mixed into the wastewater ponds with a 25-year-old mechanical aeration system that operated primarily on the surface.
The old system, which ran on 40 hp motors that operated constantly, used approximately 920,000 kWh of electricity each year. The new system is expected to use only 375,000 kWh thanks to more efficient motors that operate only when needed. When oxygen levels drop below the ideal point, sensors activate the aerators, and later shut them down when appropriate levels are achieved.
Mixing oxygen into the wastewater ponds creates the ideal environment for natural organisms to break down waste.
“We have a biological system that basically allows nature to do its work in a space that we define,” said Jon Garland, Astoria Water Treatment Facility plant operator. “The only chemical we add is chlorine for disinfection.”
“The system is not only more energy efficient, it’s also more production efficient,” added Mitch Mitchum, Astoria public works director. “It produces more aeration because it injects compressed air into the mixing. The old aerators were simply mechanical devices. This is a combination of a propeller device with injected air, which greatly increases the aeration efficiency. Our measurements indicate a much higher oxygen level now.”
Aeration Industries International, Inc., produced the system and provided technical assistance to Wadsworth Electric, which was the general contractor for the project. “The machines required a complete upgrading of the electrical plant that supplies the aerators,” said Mitchum. “Wadsworth did all that work with their local staff and did a great job working with Aeration Industries technicians to install the system.”
For information, phone 503/445-7603.
