Valve positioner provides boost to effluent quality

Problem: An Illinois wastewater treatment plant needed to improve valve position on each of its three drainage doors, then send the information to an Emerson Process Delta V plant control system for monitoring. Because each door had different opening characteristics, plant personnel had to be able to modify the analog output signal for each unit. To complicate matters, the valve actuator housings were small and located in challenging environments.

Solution: The plant purchased field-programmable Kinax 2W2 Angular Position Transmitters from Absolute Process Instruments. Each transmitter is 1.95 inches in diameter and 1.1 inches deep, small enough to be installed in the actuator housings. They use relative capacitive sensing technology and create no drag on the valve gearing.

Result: The transmitters gave the plant an accurate and repeatable linear 4-20 mA signal for the valve position that was easily interfaced with the plant’s control system. This allowed the operators to accurately control the drainage doors for better flow control, resulting in improved effluent quality. 800/942-0315; www.api-usa.com.

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Drive technology keeps water flowing

Problem: The Public Utilities in Mooresville, North Carolina, needed to control a new water plant’s 800 hp pumps. The system needed to prevent the higher-power pumps from overpowering an older facility.

Solution: The plant worked with Eaton to design and install an adjustable-frequency drive (AFD) system. A compact integrated control gear solution close-coupled the new drive with the plant’s existing Eaton Ampgard medium-voltage motor control. By integrating its SC9000 encapsulated powerpole (EP) AFD and motor control with a bus connection, the new drive was installed without moving cables and equipment. The design kept the AFD in one room with no modifications and tied it back to the plant’s existing communications system.

Result: The system controlled water flow, enabled a lower speed and made it possible to use new and old treatment plants for increased capacity and redundancy. “As a representative responsible to the citizens of Mooresville, we wanted to find a way to implement the equipment we had on hand,” says Barry McKinnon, Public Utilities director. “Eaton’s AFD drive solution has performed with no problems, helping us ensure water treatment services for our customers.” 877/386-2273; www.eaton.com.

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Pumps tackle large bypass project, allowing infrastructure upgrades

Problem: The 54-inch concrete sanitary sewer line in Greenwich, Connecticut, was being attacked by hydrogen sulfide and deteriorating. After a condition assessment, it was determined that the critical pipe should be rehabilitated as soon as possible.

Solution: To complete the rehab without disturbing daily operations, a 40.9 mgd temporary bypass system diverted the flow from three areas of town to the wastewater treatment plant. The town rented 20 diesel-drive pumps (Godwin, a Xylem brand) and 11,000 feet of 18-inch HDPE pipe. The sewer bypass flowed out of five separate suction locations and was set up to handle low and high flows. The pumps automatically turned on or shut off as flow varied. An additional pump was placed at each location for backup. Two factory-trained mechanics were on site 24/7 with service vehicles fully stocked with parts.

Result: The engineers helped guide the process from start to finish. The 35-day installation process went off without a hitch, as did the eight-week bypass while the sewer line was rehabilitated. 877/959-9881; www.xylem.com/dewatering.

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Piston pumps enable plant to increase amount of biosolids handled

Problem: After two major expansions, the City of Glens Falls (New York) Wastewater Treatment Plant staff decided to supplement its solids with outside waste and opened a receiving facility. Today, the plant accepts a broad range of materials. However, the benefits were moot without the ability to effectively incinerate what was collected.

Solution: By upsizing to a larger pair of Schwing Bioset piston pumps, the plant increased pumping capability to deal with increased biosolids handling. The pumps take cake dewatered to 24 to 26 percent solids and pump it for incineration, where a 32-ton load (an 18-wheel trailer full) can be reduced to 100 pounds of ash.

Result: The long-term performance of the pumps has helped the plant remain viable in serving the city and surrounding areas. 715/247-3433; www.schwingbioset.com.

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New valve configurations help maintain water pressure at plant

Problem: Patoka Lake, Indiana, nearly doubled its water treatment plant’s capability with a complex network of pipes, booster pumping stations, elevated tanks and reservoirs. To keep water flowing smoothly, the plant needed different control valve solutions to maintain the pressure in each district-metered area.

Solution: Two bypass pump control valves from Singer Valve were put between the pump discharge and check valve to prevent surges when starting the pumps and increase the pipeline flow. Two 12-inch flow-metering valves with internal drop check were installed downstream of the pumps to prevent reverse flow and eliminate a downstream check valve. Coupled with a multi-process control panel, these valves can measure and control the flow, making it possible to program varying flow setpoints during the day. Finally, a 24-inch control valve partnered with an EPC-4XF control panel and X156 position transmitter for valve position indication handles additional flows to multiple water plants equally.

Result: The right valves for each application and the ability to tweak each valve with various backup features and remote control options gave Patoka Lake the flexibility to manage water distribution effectively. The upgrades allow the city to grow and welcome new residents with reliable water flow. 604/594-5404; www.singervalve.com.

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Water plant replaces chemical feed system with efficient upgrade

Problem: The Coastside County Water District (CCWD) in northern California provides treated water to the scenic town of Half Moon Bay and several unincorporated communities in the area. The system is served by two treatment plants, the Nunes Water Treatment Plant (4.5 mgd) and Denniston Creek Water Treatment Plant (1 mgd), and water is distributed through about 100 miles of transmission and distribution pipe. Part of a plan to modernize and upgrade water treatment capabilities focused on the elimination of 1-ton chlorine gas cylinders at Nunes and 150-pound pressurized gas cylinders at Denniston.  Aside from the obvious improvements in operator and community safety, the cost savings related to the risk management plan and emergency scrubber maintenance made sense.

Solution: CCWD ultimately chose the Process Solutions Microclor OSHG system from UGSI Solutions for both plants, with Denniston installing a 40-pound-per-day system first and Nunes utilizing a 100-pound-per-day system about a year later.

Result: Both systems have performed according to spec, with minimal maintenance needed. 858/218-3745; www.ugsicorp.com.