European plants use pumps to reduce foam

Problem: Two wastewater treatment plants in Brussels, Belgium, faced issues with sludge circulation in the decanting basins. Previously installed pumps were creating too much foam, leading to sludge particles floating near and on the surface. Because the sludge was not settling into the basins as expected, the extraction process was not effective and the pumps were using more energy than anticipated.

Solution: Six Cornell 18NHFL self-priming pumps were installed to pump sludge from lower to higher tanks. They are driven by 90 kW electric motors and are controlled by variable-frequency drives that operate between 400 and 600 rpm. The maximum hydraulic efficiency of the pumps is 87.3 percent.

Result: The pumps helped remove excess air from the sludge before it was pumped into the upper tanks and came in contact with surface mixers. The dry/vacuum-priming pumps with Redi-Prime system helped remove air bubbles trapped in the water. They have worked effectively since 2011. 503/653-0330; www.cornellpump.com.

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Ultrasound flow monitor deployed in pump station

Problem: In a two-pump station, Thames Water wanted to monitor station performance and check the condition and efficiency of each pump. The usual approach would be to install a magflow-type meter. However, that would have required groundwork, including the building of a separate chamber next to the existing pumping station to house extra piping and the meter.

Solution: The company used a Flow Pulse unit from Pulsar Process Measurement. Completely noninvasive, it is installed using a simple band and silicon pad to make close contact with the pipe; it can be positioned close to pipe bends or flanges. It fires an ultrasound pulse from a high-output ceramic crystal through the pipe wall and analyzes the flow using Refracted Spread Spectrum Analysis (RSSA), which consolidates the real-flow information from the mass of signals coming from the particles, bubbles, turbulence, vortices and eddies within the flowing liquid.

Result: Thames Water benefited from the unit’s rapid deployment at cost savings over the magflow meter. 850/279-4882; www.pulsar-pm.com. 

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Town increases efficiency with retrofit wastewater pumps

Problem: The Town of Harleyville, S.C., was looking to upgrade its aging lift stations to increase efficiency, lower utility costs and reduce pump maintenance. The town’s six 25-year-old lift stations each suffered from frequent clogging, expensive maintenance and repair, and large monthly utility bills related to extended pump runtimes.

Solution: Working with global engineering consultant URS Corporation and Carolina Pumpworks, the town began by retrofitting one lift station with Grundfos SLV wastewater pumps. The improvement was dramatic and led to upgrades at two additional lift stations. The three duplex lift stations each have two 5.5 hp, 1,750 rpm three-phase pumps that alternate operation according to the station’s level control system, which offers system redundancy and added capacity during high-flow events. SuperVortex impellers ensure that solids up to 3 inches in diameter pass freely.

Result: The additional pump capacity combined with the pumps’ reliability saved the town 35 percent in utility costs and $25,000 in maintenance costs per year. The stations cut runtime by roughly 80 percent and peak pump operation fell from an average of 18 to 3.5 hours per day. 800/921-7867; http://us.grundfos.com.

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Alternative power runs remote pump station

Problem: The City of Princeton, Ill., undertook an excess flow storage project to alleviate system surcharging and sewer backups by providing extended combined sewer overflow storage and controlled influent flow to the wastewater treatment plant. The site selected to construct the lagoon was remote. While it was desirable for its ample acreage and hydraulic profile, it created significant financial challenges in extending three-phase electrical power and generator fuel to the site.

Solution: Precision Systems and Smith & Loveless jointly developed a solar/propane-powered hybrid pump station with SCADA monitoring and control, eliminating the need for utility-based three-phase power and natural gas. The solar component, which powers the system controls and SCADA, is always in standby and ready to engage the propane-fueled generator to power the pumps for as long as necessary to drain the lagoon back to the collections system. The SCADA system provides real-time indication monitoring of lagoon level, pump operation and battery conditions for the control system and standby generator. It maintains itself in a charged state for operation during overflow events.

Result: The solution has reduced system surcharging while providing ample storage and a creative means to control and transport the lagoon contents without using utility power. Precision Systems: 708/891-4300; www.precision-systems.com / Smith & Loveless Inc.: 800/898-9122; www.smithandloveless.com.

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New system simplifies pumping system communication

Problem: HTM Sales implements SCADA systems to interconnect pumping stations. Initially the company used radio pairs that required multiple antennas. Due to the configuration of these radio pairs, sometimes it was necessary to install more than one system. A second iteration used multipoint-to-point radios that eliminated multiple antennas, but the solution was complicated by the use of hop-keys. HTM wanted a simpler solution.

Solution: For an installation in McCook, Neb., HTM used power supplies, surge protection and Radioline modules from Phoenix Contact. Radioline can function as a master, slave or repeater, avoiding the need to stock additional modules. It can download the network settings to all spokes from the master and can communicate point-to-point and point-to-multipoint.

Result: The Type 3 surge protection for power supplies and proper coaxial surge protection for antennas increased uptime. By properly protecting the system, HTM stopped losing wireless modules to transient strikes. HTM no longer has to keep track of the hop-keys necessary for programming each site/radio. This solution increased uptime, simplified inventory and eased implementation. 800/888-7388; www.phoenixcontact.com.

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High-capacity screw pumps used to convey mixed liquor to clarifiers

Problem: CH2M HILL/Ambiotec Civil Engineering Group won a contract to design and construct an expansion for the Robindale Wastewater Treatment Plant in Brownsville, Texas. The facility needed to integrate the existing plant with the additions, including final clarifiers to be installed at grade to reduce cost and address groundwater issues. This meant mixed liquor had to be pumped from the aeration tanks to the clarifiers. 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 supplied open screw pumps to handle mixed-liquor transport to the clarifiers. The pumps have 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 is driven by a 100 hp motor through a high-reduction gear reducer to rotate at 40 rpm.

Result: The four screw pumps have been operating successfully to convey mixed liquor to the clarifiers since the fall of 2013. 262/513-8801; www.proequipment.com.

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Variable-frequency drive and rigid-shaft motor reduce maintenance, energy costs

Problem: The well system in Osceola, Ark., experienced frequent motor, drive and pump failures, resulting in $85,000 per year in maintenance costs. The system, installed in May 1975, was composed of two vertical, six-stage turbine-style pumps coupled to 250 hp hollow-shaft motors through an eddy- current drive.

Solution: Technicians replaced the eddy-current drive and hollow-shaft motors with a variable-frequency drive and rigid-shaft motor from WEG Electric Corp. The system reduces vibration and slippage and is controlled with pump speed rather than a control valve. The solid-shaft motor has two points of efficiency and precision-alignment capability. The variable-frequency drive eliminates the component between motor and pump, reducing the overall height of installation.

Result: The system saves the utility an average of 390,540 kWh which, combined with a decrease of $30,000 in annual maintenance costs, saves $61,000 per year. 800/275-4934; www.weg.net.

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Hydraulic trash pumps meet grit-processing demands

Problem: The Carpinteria (Calif.) Sanitary District was using a towable 4-inch self-priming trash pump to dewater its water-and-grit slurry in a half-full 290,000-gallon wastewater tank. One day when the dewatering was scheduled, the pump stopped working as it could not handle the high concentration of grit.

Solution: A representative from Stanley Hydraulic Tools demonstrated the TP08 4-inch hydraulic trash pump with a HP28 twin-power unit. The pump can move 800 gpm and up to 4-inch solids. During the demonstration, the unit pumped the slurry to a conveyer belt, which then pressed the last water from the grit. The grit was then placed in a separate storage compartment for processing to be sold as fertilizer.

Result: The HP28 was run from 7 a.m. to noon with few breaks in operation. To remove the grit, the power unit was turned off to add more water to the mixture. Otherwise it ran for a majority of the five-hour period. The slurry mixture was pumped with ease. 503/659-5660; www.stanleyhydraulic.com.