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Idaho Department of Environmental Quality

Innovative, energy-efficient upgrades to Jerome wastewater treatment plant will save the city $635,000 a year

May 7, 2019

By DEQ Grants and Loans Program

Upgrades to the City of Jerome Wastewater Treatment Plant will save the city almost 10,311,646 kW-hr and $635,000 per year. The energy savings is equal to the total annual power needs of over 800 homes or the annual lighting needs of 8,000 residences, and looking at it in a different way, the energy savings is almost equal to one half of the repayment for the city’s $22.2 million project loan.

The upgrades were made possible with a low-interest loan from the Idaho Department of Environmental Quality State Revolving Fund (SRF). The SRF loan process emphasizes reductions to operations and maintenance costs, and through an investigation required by the SRF’s Green Project Reserve Program, it was revealed that upgrading the Jerome Water Reclamation Facility would provide significant savings.  

The savings came from the installation of energy-efficient options the city chose to fund in lieu of more energy-intensive alternatives. The substantial cost savings from reduced energy bills will rapidly offset the initial cost difference of the ‘green’ components.

Instead of additional aerobic digesters, the city chose to construct anaerobic digestion facilities, reducing sludge treatment power demand by approximately 98%. Unlike aerobic digestion, anaerobic digestion requires power only for mixing because natural gas and biogas from the process are used to heat the contents of the tanks. Anaerobically digested sludge is also easier to dewater, resulting in lower chemical costs; in addition the decreased volume of biosolids for disposal reduces hauling costs.

The city’s consultants also recommended aeration basin capacity and efficiency be upgraded with fine bubble diffusers, a dissolved oxygen control system, and high speed turbo blowers with Variable Speed Drives. Using this combination, along with the installation of intermediate clarifiers that reduce the aeration demand in the aeration basins, the city reduces aeration power demand by approximately 84%.

Additional cost-effective ‘green’ improvements identified by the design consultants included energy-efficient LED lighting.

By providing these energy-efficient and innovative upgrades, the city of Jerome can expect many more years of continued cost savings.

Digestors under construction


Intermediate Clarifier


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