Dexter Utility District, Dexter, ME
The Dexter Utility District retained Tata & Howard to evaluate their existing wastewater treatment facility and to provide wastewater treatment facility design. Tata & Howard recommended a phased approach to upgrade the facility in order to reduce the initial impact on the sewer user rates. The first phase of the improvements combined improvements which would improve the reliability and obtain energy savings with cleaning and disposing of sludge for the first time from their 25 year old facility. This approach allowed for a grant loan financing package to be utilized. The first phase facility upgrade included replacing a leaking single air header main with two individual air headers, replacing course bubble diffusers with fine bubble membrane diffusers, replacing three 25 year old blowers with new blowers with variable speed drives. The speed of the new blowers is controlled by a PID loop using dissolved oxygen analyzers, to maintain optimum treatment and minimize energy consumption. These improvements have reduced the energy consumption at the wastewater treatment facility by more than 50 percent.