For the latest in water-treatment technology and energy conservation, look no further than the effervescence.

At the Roseburg Urban Sanitary Authority, tiny air bubbles riffle through sewer effluent for earlier-than-expected cost savings.

“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.

Last December, the municipal treatment facility completed a $400,000 upgrade that included a new air blower and air-diffuser system for two wastewater basins. The air-delivery system kick-starts waste-eating organisms into life during warmer months by pushing more oxygen into wastewater, blowing tiny air bubbles from the bottom of the basins.

The overall function is akin to an aerator disguised within a fish tank’s landscape.

“Except this is an $80,000 rock,” Steve Witbeck, RUSA’s project manager, said of the diffusers. “Little bubbles are more efficient than big bubbles.”

The bugs are naturally occurring organisms.

“We just kind of cultivate them,” Witbeck said.

Before the new diffusers, RUSA relied on coarse-bubble action in the basins, roiled by water delivered through pipes stemming from the bottom. The air was pushed by a 200-horsepower blower.

The wastewater is first introduced to the bugs in a holding tank. When it’s cold, the bugs aren’t as active.

During the winter, however, the coarse-bubble delivery system focused on one basin at a time. The old system passed the water through the first bio-tank many times to collect as many waste-eating bugs as possible before sending it to the coarse-bubble basin because the first tank was more effective.

Tiny bubbles changed that.

Witbeck said the bugs need more room to operate when it’s cold. Because fewer of them collect in the water on the first pass through the initial tank, they have all the room they need to burst into action when they meet the effervescent water. So RUSA operates both aerator basins in the winter.

“This isn’t what it was designed to do, this is what we’re finding out we can do, in addition to that 10 percent that they were talking about we’d save in the summer time,” Witbeck said.

‘They’ being the Oregon Energy Trust, dedicated to changing how Oregonians produce and use energy by investing in efficient technologies and renewable resources with taxes collected from utility payers.

“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.”

Bigger than the 931 diffusers dispersing air in each basin is the new air blower, the Audi of municipal facility machines which uses a lot 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 (cubic feet per minute) of air to one basin and it was costing us about 80 horsepower to do that,” Witbeck said. “We’re now feeding about 1,100 cfm of air to two basins and we’re only using 40 horsepower to do it.”

Even better, the new blower’s bearings actually ride on a cushion of air — designed by aeronautical engineering — instead of grinding past each other, and require minimal maintenance. Regular oil changes and other work that required several man-hours are no longer needed.

For maintenance, the new blower has a pair of air filters that cost $160 that have to be changed every four months. Its first maintenance check is scheduled 10 years after installment.

And it’s the first of its kind in an Oregon municipal facility, Witbeck said. It’s lifespan is a minimal 20 years.

The Oregon Energy Trust proposed the design of the diffuser system, securing it and the new blower, mainly through grants.

The total cost to RUSA 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.

Elaine Prause, industrial program manager at Oregon Energy Trust, said if a municipal or private business is interested in energy-saving technologies, they can contact Energy Trust for information on cost incentives and schedule an audit.

“We’ll go and do the studies to find opportunities” for them, Prause said.

With the initial savings from the new technology projected at $19,000 per year, RUSA expects to pay off its investment earlier than the five years previously figured. The savings come in cuts to electricity costs.

“When we put the system online, the week before we were averaging 7,000 kilowatt hours per day,” Witbeck said.

Under the same circumstances, RUSA dropped to 6,000 kWh per day.

RUSA’s annual electricity budget is about $180,000.



• You can reach reporter Adam Pearson at 957-4213 or by e-mail at apearson@newsreview.info.