Synopsis

The City of Newark was seeking relief from excessive electric bills through significant updates. It’s Licking River WWTP on the east side of the city completed installation of new, highly efficient EDI FlexAir Pro® MiniPanel bubble diffusers in its three aeration basins, WAS tanks, and a post-aeration tank. Total project cost was $1,875,875 of which $370,630 went for the diffuser equipment and installation. Funding for the project included a gridSMART grant from AEP Ohio that could be used to cover energy-saving expenditures. A stipulation of the grant was that expenditures must show a seven-year return on investment, which only the diffusers could demonstrate. Newark’s new diffusers have not only improved critical plant processes but saves nearly $14,000 per month in electricity fees while creating excess capacity that allows more plant loading, including acceptance of trucked waste streams that generate new and unexpected revenues.

Project Background & Challenges

The City of Newark is in the second phase of its Long-Term Control Plan to optimize interactivity between its four plants and provide EPA-compliant, reliable service at reasonable rates. Priorities for this project were replacement of 25-year-old existing equipment that was reaching the end of its service life, and significantly improving process efficiencies to reduce operating costs. Electricity powering the large, aging motors on the blowers that aerate the activated sludge was the WWTP’s greatest single operating expense.

The EDI Solution

An initial two-month study confirmed the project was worth pursuing on a cost/benefit basis, followed by an engineering study to determine what primary considerations should be for new equipment.

“We originally only intended to replace our two aging blowers with new, high efficiency units,” recalls Darin Wise, the plant’s superintendent. “We hadn’t really thought it necessary to also replace the diffusers. But our research showed we could save more money in the long run by combining new, highly efficient diffusers with the new blowers. So we decided to do the whole project.”

Upgraded System Performance

It was expected that the majority of electric savings would come from replacing the old blowers. What wasn’t anticipated was how much annual savings, and new revenue streams could actually be generated by pairing the new blowers with EDI FlexAir Pro® Panel Diffusers.

“These EDI diffusers are just so much more efficient,” enthuses Wise. “Putting air in the water has associated costs, and now our transfer efficiency and bubble efficiency is better. The Panel diffuser creates more and smaller bubbles, which also rise slower in the tank to allow more contact time with bacteria. Our air requirements have dropped significantly – sometimes to a third of what they were.”

The unexpected boost in efficiency allowed 100% treatment to be accomplished in just 2 of 3 dedicated basins. This freed up the third basin to treat trucked-in industrial waste and septage, generating new disposal fee revenues of $83,000 from January 1, 2014, to February 24, 2014. This third basic now represents pure profit, and the plant makes some margin on high BOD/high ammonia flows through their efficient new aeration basin.

Wise is very pleased with the amount of savings and profit his new blower/EDI Panel diffuser pairing is generating. “We initially had to spend extra on electric to allow for more air use to treat additional loading, but our electric bill till dropped significantly, between $12,000-$14,000 a month. We’re installing another blower/diffuser combination now,” he explains. “We’ll depend on it as a redundant system.”

These improvements are projected to save $168,000 per year in electrical usage and, as of March 31, the plant has already taken in an extra $153,000 in loading fees this year.