An old adage warns that if the only tool available is a hammer, then every problem will look like a nail. However, when it comes to chopper pumps, Landia customers have been finding a variety of uses for this tool. From Arkansas to Utah, and a myriad other locations across America, operators continue to find innovative solutions to problems with the help of Landia chopper pumps. The following two case studies illustrate just a few of these solutions currently in use in the field.
CASE STUDY 1: PROTECTIVE CHOPPER PUMP CUTS GREASE
At the Benton Utilities Wastewater Treatment Plant near Little Rock, Arkansas, a tough new Landia EradiGator chopper pump is ensuring that grease and scum are continuously churned up to prevent other smaller pumps in the process from blocking.
The recirculating chopper pump was supplied with a custom-built bracket to fit into the bottom of a square tapered scum pit at Benton, where the scum pit receives skimmed-off wastewater from the plant’s clarifiers.
“We’re really using the Landia chopper pump more as a mixer so that a layer of scum can’t build up and block the existing smaller pumps we have on our rail system,” notes Jonathan Buff, manager of Benton Utilities Wastewater Treatment Plant, comments. “Either way, it’s very effective.”
Landia’s EradiGator chopper pumps are widely used in lift stations and scum pits for mixing and macerating debris and grease, in order to prevent clogging of pumps and piping.
“Previously, we did experience problems with blocked pumps, especially because we are working with just a 3-inch line,” adds Buff. “But the Landia chopper pump keeps everything churned up and on the move, with no problems for our existing units, which can now send the mixed scum to our digesters with no breakdowns or downtime.”
CASE STUDY 2:MIXER AND PUMP RETROFIT FOR BIOREACTORS
The newly expanded wastewater treatment facility in American Fork, Utah, where Landia has completed a successful pump and mixer retrofit
At the newly expanded 30 million gallons (113.5 million liters) daily wastewater treatment facility in American Fork, Utah, Landia has completed a successful pump and mixer retrofit that has transformed eight existing oxidation ditches into new high-rate activated sludge bioreactors with biological nutrient removal, solids dewatering, and UV disinfection.
A total of forty-eight Landia submersible mixers and sixteen Landia axial flow pumps are achieving complete mixing and nitrate recycling in a new activated sludge process at the site run by the Timpanogos Special Service District, close to Utah Lake, which serves ten cities in the region.
Working in close conjunction with leading Utah and Idaho engineering firm Bowen Collins and Associates, Inc. to select long-lasting equipment that would give optimum performance, mixers from Landia now mix the sludge in the anaerobic and anoxic tanks, while internal Landia recycle pumps send nitrified mixed liquor from the aeration basin onto the anoxic tanks.
Operating at low propeller speed, each Landia mixer is equipped with large surface area propeller blades to ensure gentle treatment of the activated sludge.
The axial flow pumps operate on variable frequency drives, by which each pump’s flow rate is optimized for the required Nitrate recycle rate.
“The move to bioreactors has been a learning experience for us, with a great deal of hard work put in to achieve the required mixing and recirculation,” says Ed Yates, maintenance coordinator for Timpanogos Special Service District. “Landia’s pumps and mixers are performing well and the support we’ve been given by the company to help get the equipment up and running to our satisfaction has been exemplary.”
The $77 million project, which also features a new headworks and influent pump station, has increased the capacity of the treatment plant from 18.3 million gallons (69.3 million liters) daily to 30 million gallons (113.5 million liters) daily.
Over the past twenty-five years, Landia has installed thousands of mixers and axial flow pumps in U.S. wastewater treatment plants for mixing and pumping of activated sludge.
About the Author
MODERN PUMPING TODAY, August 2014
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