Jan 29, 2008

Oregon Facility Upgrade Saves Energy and Money

Roseburg Urban Sanitary Authority upgrade included a new air blower and air-diffuser system

Oregon’s Roseburg Urban Sanitary Authority (RUSA) is seeing better-than-expected cost savings from its recent municipal treatment facility upgrade, which included a new air blower and air-diffuser system for two wastewater basins, www.newsreviewinfo.com reported.

“We’re seeing a significant improvement in our electricity, even during the winter time, even though [the new system] is supposed to save money in the summer time,” Steve Witbeck, RUSA’s project manager, said.

The air-delivery system that was included in the $400,000 upgrade kick-starts waste-eating organisms into life during warm summer months by pushing more oxygen into wastewater through tiny air bubbles from the bottom of the basins, the website reported.

The overall function is similar to an aerator in a fish tank. “Except this is an $80,000 rock,” Witbeck said of the diffusers. The waste-eating organisms occur naturally.
“We just kind of cultivate them,” Witbeck said.

RUSA operates both aerator basins in the winter because the tiny bubbles the system produces allow the organisms the room they need to burst into action when they meet the effervescent water. Their old system used larger bubbles.

“This isn’t what it was designed to do, this is what we’re finding out we can do, in addition to that 10% that [the Oregon Energy Trust was] talking about we’d save in the summer time,” Witbeck said.

The Oregon Energy Trust uses taxes collected from utility payers to invest in efficient technologies and renewable resources. “They actually came in and did a full-blown audit of our facilities and identified ways we could save energy,” Witbeck said. “Some were marginal but obviously some were big.”

The new air blower uses less horsepower to do the same amount of work. “In the other system we could operate one basin and we had to throttle the blower back a little bit, but we were providing 1,100 cfm of air to one basin and it was costing us about 80 hp to do that,” Witbeck said. “We’re now feeding about 1,100 cfm of air to two basins and we’re only using 40 hp to do it.”

The new blower’s bearings ride on a cushion of air instead of grinding past each other, and require minimal maintenance, since regular oil changes and other work is no longer needed. For maintenance, the new blower’s pair of air filters has to be changed every four months. Its first maintenance check is scheduled 10 years after installment, and its lifespan is a minimal 20 years, the website reported. It is the first of its kind in an Oregon municipal facility, Witbeck said.

The Oregon Energy Trust proposed the design of the diffuser system and used grants to secure it and the new blower, according to the website. RUSA’s total cost for the entire project was $95,000. “If someone else had done it, it might’ve been a $500,000 or $600,000 project,” Witbeck said. With the initial savings from the new technology projected at $19,000 per year, RUSA expects to pay off its investment earlier than previously figured because of savings from cuts in electricity costs.
“When we put the system online, the week before we were averaging 7,000 kWh per day,” Witbeck said. Under the same circumstances, RUSA dropped to 6,000 kWh per day.