Slashing Power Costs Through Precise DO Control  

Power usage has always been the single greatest consumable expense for most wastewater treatment plants, and costs per kW continue to climb significantly nationwide. For activated sludge plants, this means that gaining tighter dissolved oxygen (DO) control in aeration is becoming increasingly essential — not only for meeting strict treatment requirements but for achieving and maintaining cost-efficient power usage.

Gainesville, Florida
LDO Slashes Power Costs in Gainesville

By switching from membrane-based DO probes to Hach's LDO probe technology to attain more precise aeration control, operators at Gainesville Regional Utilities' (GRU) two wastewater treatment plants reduced the cost of power consumed by more than $23 per million gallons of treated flow — a total estimated power savings of more than $123,000 per year.

Hach DO application

"Adding Hach DO probes has been
one of the wisest investments we've
made," says James Hope, Director
of Water Reclamation Facilities for
Gainesville Regional Utilities.

"The tighter aeration control, made possible by adding the Hach LDO probes, has not only reduced our energy consumption significantly, but also our labor and maintenance costs," says James Hope, GRU's Director of Water Reclamation Facilities. "For example, we saved about $20,000 per year just in reduced probe maintenance and calibration costs alone, compared to when we used membrane-based DO probes."

GRU is a community-owned, multi-service utility in Gainesville, Florida, and operates the 14 MGD Kanapaha Water Reclamation Facility and the 9 MGD Main Street Wastewater Plant. Hach LDO probes were first installed in the Main Street Plant's two 1.3 million gallon aerobic digesters, replacing membrane-based probes that had required frequent cleaning and constant calibration, as well as entire instrument replacement about every two months. After initial experience showed the Hach LDO probes required far less operator attention than the membrane-based probes, GRU installed the new probes in the three aeration basins serving the Main Street Plant and also in two basins at its Kanapaha Water Reclamation Facility. And since then, additional LDO probes have been installed to further reduce aeration costs at both facilities.

Operators found the LDO probes provide more significantly stable and accurate DO measurements than the membrane-type probes, primarily due to the elimination of measurement drift caused by fouling. The accuracy and dependability of the new probes gave operators sufficient confidence to initiate automated aeration control using the probe's on-line DO measurements.

"Adding the Hach DO probes has been one of wisest investments we've made," Hope says, "and it's brought us numerous benefits. With the costs for electricity going up higher and higher, I don't want to think about what our power costs would be if we hadn't taken these proactive measures." The utility has saved more than $123,000 per year in power costs due to precise aeration control at its plants.

Find out more about Hach's Advanced LDO® Process Dissolved Oxygen Probe.