Electromechanical diaphragm pumps deliver consistent flow
Problem
The City of Nampa (population 80,000) is the largest and fastest growing city in Canyon County, Idaho. The wastewater treatment plant, which also serves neighboring Caldwell, had been using lobe-style positive-displacement pumps to transfer thickened sludge from the primary clarifier underflow to further processing. With lobes rotating in close tolerance, these pumps experience wear and needed monthly maintenance.
Solution
MWH, a consulting company in Boise, worked with the city to select three ABEL EM 100 electromechanical diaphragm pumps, based on success at the Weber Wastewater Treatment Plant in Ogden, Utah and the Colorado Springs (Colo.) Wastewater Treatment Plant. Each pump has 250 gpm capacity and delivers consistent flow regardless of backpressure fluctuation. A grinder pump precedes each electric diaphragm pump.
Result
Maintenance downtime decreased, and reliability increased, yielding significant monthly savings. 412/741-3222; www.abelpumps.com.
Plant chooses upgraded plunger pump to replace 50-year-old model
Problem
In 1963, the Greater Chillicothe (Ill.) Sewer District purchased two Komline-Sanderson Model KSS-9-1 simplex 9-inch plunger pumps to transfer primary sludge to the anaerobic digester. Fifty years later, the district needed to replace one pump in a project to replace a digester cover.
Solution
Based on experience with the two pumps and two Model KS-11-1 plunger pumps purchased in 1993, the district, through Baxter & Woodman, specified the same Komline-Sanderson pump for an expected service life lasting decades. The pumps move 90 gpm of primary sludge at 3 to 5 percent solids to an anaerobic digester at discharge pressures of 30 feet total dynamic head for about 30 minutes a day. Since 1994, the district has purchased only $3,300 of routine spare parts for the pumps, amounting to a cost of 16 cents per day.
Result
The district is pleased with the parts and service department. David Day, plant superintendent, referred to the pumps as “indestructible.” 800/225-5457; www.komline.com.
Screw pumps solve high-lift pumping problem
Problem
The wastewater treatment plant in Willmar, Minn., needed a single-stage screw pump solution for 43.2 feet of lift. The plant team hoped to avoid using submersibles or two-stage screw pumps.
Solution
The plant installed three Landustrie open screw pumps from EPIC International in 2010. They pump 8,333 gpm. The pumps, 84 inches in diameter and 74 feet 6 inches long, have solid one-piece ductile cast-iron (not welded) upper and lower shafts and flanges and reinforced flight starts. They use fully self-aligning bearings and factory shot blasting and painting.
Result
The screw pumps solved the lift problem, and have run without incident since they were installed. 804/798-3939; www.epicintl.com.
High-capacity screw pumps used to convey mixed liquor to aeration tanks
Problem
CH2M HILL/Ambiotec Civil Engineering Group (a joint venture) won a contract to design and construct a major expansion for the Robindale Wastewater Treatment Plant in Brownsville, Texas. The facility needed to integrate the existing plant with the additions. New final clarifiers had to be installed at grade to reduce cost and address groundwater issues. This meant mixed liquor had to be pumped from the new aeration tanks to the clarifiers. Typical centrifugal pumps were not suitable because they would cause breakup of mixed liquor biological floc from the aeration tanks, hindering settling in the clarifiers.
Solution
Pro-Equipment Inc. supplied open screw pumps to handle mixed liquor transport to the clarifiers. Screw pumps were selected for their gentle hydraulics, limiting floc degradation. Four high-capacity pumps provide a lift of 18 feet at a maximum flow of 15,000 gpm per pump. Each pump is driven by a 100 hp motor through a high-reduction gear reducer to rotate at 40 rpm.
Result
The first two screw pumps were installed and successfully tested to verify capacity and one pump was placed in service. Installation of the two remaining pumps was pending. 262/513-8801; www.proequipment.com.
Automated bypass system increases efficiency and safety
Problem
A New York wastewater treatment plant needed yearlong treated water during construction. Factors including physical parameters, a small effluent pit, labor cost concerns and variable flow during stormwater surges dictated an automated system, responsive enough to manage the variable flow to scale pumping rates up and down on the fly as effluent and storm surges varied.
Solution
Rain for Rent developed a four-stage automated pumping system triggered by submersible transducers that measure the water level. As water levels in the pit changed, the electric DV400c 16-inch pumps were throttled up or down by variable-frequency drives (VFD) controlled by preprogrammed analog data reporting units (AnDRU Boxes). Treated water was bypassed from the pit and discharged.
Result
The automated system allowed construction on plant upgrades to proceed without interruption from increased effluent and stormwater during a 100-year storm event. 800/742-7246; www.rainforrent.com.