Case Study: City of Gig Harbor – Gig Harbor Wastewater Treatment Plant

High energy and maintenance costs, inflexible operating range and high noise levels

Gig Harbor WWTP replaced its positive displacement blowers with APG-Neuros turbo blowers, reducing its energy
consumption, increasing its operational flexibility, creating a pleasant working environment and saving thousands of dollars
thanks to its small foot print.

The aeration blowers were one of the multiple upgrades implemented in the City of Gig Harbor WWTP to expand its capacity. The city’s “WWTP Improvements- Engineering Report” by H.R. Esvelt Engineering, revised June 2003, recommended improvements to address concerns of high energy and maintenance costs, operation challenges, and growing aeration demands.

Challenge
Gig Harbor WWTP had four positive displacement (P.D.) blowers aerating both of their digesters and aeration basins; three 100 HP and one 60 HP. The blowers were very loud and did not provide a flexible operating range to meet various plant flows. After an oil leak from one of the facility’s four P.D. blowers led to a fire, plant management knew they needed to look into technologies that provide a safer and cleaner working environment, as well as operational advantages.

Solution
In 2007, APG-Neuros installed a demo NX100 high speed turbo blower to provide air to the plant’s digester. Replacing the non-operational P.D. blower proved to be an easy switch as the APG-Neuros blower is a ‘plug and play’ unit; it required no special foundation and no external connections outside of the enclosure. If not for the NX series turbo blower, the plant would have had to spend thousands of dollars to increase the footprint of the blower building to house the additional blowers they required to meet the air demand.

The plant staff monitored the operation and performance of the blower for about three months; the NX100 blower proved to be reliable, quiet and simple to operate, convincing staff that the APG-Neuros Turbo Blower was the right technology for their operation. After the demonstration period of the blower has ended, they kept the NX100 for the digester airflow requirements, and retrofitted the remaining three PD blowers with two NX75 for their aeration basin and two NX50 blowers for a smaller aeration basin.

Positive Results
Today, the NX100s and one NX75 are satisfying the majority of the plant’s annual flows. The current blower capacity will meet the needs of their Phase 2 expansion that is currently in design, with a treatment capacity of 2.4 MGD. The ability to turndown is contributing to significant monthly savings from energy savings which can be used towards other plant improvements.