Eliminating Lift Station Grease

Large-bubble mixing devices help a Rhode Island sewer authority eliminate many lift station cleanings and reduce odor complaints

Eliminating Lift Station Grease

A before photo shows the effectiveness of the mixing device offered by C3ND Environmental Consulting, based on technology from Pulsed Hydraulics.

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Flat topography in the Rhode Island city of Warwick requires multiple lift stations and force mains to deliver wastewater for treatment.

Some of the city’s 49 lift stations experienced grease buildup that ultimately restricted flow in force mains and created odors in residential neighborhoods. The Warwick Sewer Authority tried chemical treatments with limited success.

Then three years ago, staff members learned about a mixing device offered by C3ND Environmental Consulting, based on technology from Pulsed Hydraulics.

After a successful trial at one of the most problematic lift stations, the authority purchased the unit; it has since added eight more. “We had usually cleaned that pump station twice a year,” says Joe Colicchio, senior collection inspector. “We haven’t cleaned it in two years. There is no grease buildup, and there are no issues downstream in the sewer mains.”

MAINTENANCE HEADACHES

Before installing the mixers, the Warwick team faced substantial labor and expense for lift station cleaning, according to Mike Bedard, superintendent. Some stations needed cleaning two or more times per year. Cleanings meant hiring a combination vacuum-jetter truck and often performing a confined-space entry. A single cleaning event costs as much as $5,000.

The mixing system, a PHi-CA (Constant Air), is a simple device that uses the upward surge of large bubbles from the bottom of the lift station wet wells to mix the contents. The mixing action keeps grease from coming out of solution and solidifying, Colicchio says. 

The device consists of a 1 hp linear air pump, stainless steel couplings and clamps, 50 feet of air hose, and an 8-inch stainless steel bubble-forming plate that sits just above the suction side of the lift station pumps.  

The hose directs air to the bubble-forming plate, which then ejects bubbles several inches in diameter. As these bubbles rise to the surface, they keep grease as well as rags and other debris in motion so that the pumps can push them out in a controlled manner. The bubbles also break up grease mats that otherwise would form on the surface.  

GIVING IT A TRY

The technology was first tested at a 1 mgd lift station in a residential neighborhood where grease had been a persistent problem. The Warwick team installed a full-scale unit inside the station. Improvement was evident “right off the bat,” says Colicchio. “Previously, grease would start forming days after we cleaned the wet well. Now it just doesn’t form.”

Bedard says PHi-CA units will be added to all the bigger pump stations. “We’re also looking at smaller problematic wet wells. We’re not done. If our field people see issues at a given lift station, we will make the investment.” He notes that odor complaints have dropped dramatically in neighborhoods where the mixers have been deployed. 

Installation is simple and takes less than an hour, Colicchio says. Maintenance consists of removing and cleaning two filters on the air pump, which operates quietly and is suitable for outdoor or indoor applications. 

Steve Buckley, director of business development with C3ND, says that in addition to pump stations the mixers have been used in locations such as primary clarifier scum pits, sludge holding tanks, equalization basins and aerobic digesters. Warwick now has 13 mixers installed.

“The Warwick team has been going to every pump station where they have a problem with grease and other buildup of debris and putting mixers in,” Buckley says. “They have saved hundreds of hours of labor and thousands of dollars by not having to clean the wet wells. 

“Warwick is a very well-run authority. Bedard and Colicchio have been champions of this mixer, along with Chuck Labbe, director of maintenance and operation. They are a very professional staff and furnish reliable, high-quality services for the city and its environment. They believed in the product. C3ND has supported them and will continue to do so.”



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