Energy Management And Sustainability

Energy Management And Sustainability
Oil-free screw blowers provide compressed air to process effluent

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Oil-free screw blowers provide compressed air to process effluent

Problem: Operators of the wastewater treatment plant in Versmold, Germany, sought an updated energy source to process effluent. The 2.2 mgd plant treats 60 percent high-strength wastewater from meat processors containing above-average quantities of phosphate. The treatment and measurement technology, process controls and compressed air technology had to quickly measure the influent contents and respond accordingly.

Solution: Two Atlas Copco ZS 55+ oil-free screw blowers with variable-speed drives supply energy-efficient compressed air to process effluent. Nitrification and denitrification take place simultaneously in two aeration tanks. The aerobic  process is first supplied with oxygen via the plate aerators. During the subsequent anaerobic phase, the tank contents are mixed together.

Result: The plant has cut energy costs by 10 percent. The two blowers supply compressed air at about 900 to 2,100 cfm. The volume of flow is automatically adjusted to the exact air demand using the variable-speed drives. “The blowers are compact, and it is not necessary to make many modifications,” says plant manager Khosrow Ghobadi. “The machines are simply linked to the process control system, which we did without any problems.” 866/546-3588;

Submersible shredding pumps solve clogging issues

Problem: Regency in the Forest, a 400-unit, upscale adult-living apartment complex north of The Woodlands, Texas, uses a lift station to move raw sewage and runoff for the final processing. The lift station has two non-clog pumps in a duplex setup. When the pumps stopped working soon after their installation, service personnel found them clogged with fishing line, burlap bags and other debris. The crew repaired the pumps and reinstalled them, only to be called back weekly for several months for the same failures. Someone apparently was dumping things into a manhole on the property.

Solution: Pumps of Houston replaced the non-clog pumps with two 5 hp SK 37C electric submersible pumps from BJM Pumps. They have a tungsten carbide shredding impeller. Shredded pieces pass through the pump and into the wastewater stream.

Result: The pumps have worked almost flawlessly. One pump jammed when it could not digest an entire prom dress and several yards of thick nylon rope. Otherwise, both pumps have run without failure. 877/256-7867;

Heat exchangers used to overcome dimensional restrictions and increase energy production

Problem: Cory Environmental’s plant in Weston-super-Mare, United Kingdom, burns biogas from anaerobic digesters to reduce energy costs and improve efficiency and uses biosolids as fertilizer. Three heat exchangers were required for digester heating, waste pasteurization and heating of a fat tank. The available footprint was small.

Solution: HRS Heat Exchangers designed and built three units mounted on a common boxed stainless steel frame. The units have stainless steel cladding over the frame and connections for each unit protruding from the cladding. The corrugated tube design helped keep the footprint to a minimum. The high turbulence and increased heat transfer rate significantly reduced the footprint.

Result: The compact solution fit the site and helped with pipe work connections. 623/915-4328;

Grinder eliminates wipes problem

Problem: In 2012, the Santa Margarita Water District in California saw a change in the influent at its reclaimed water facility. Disposable wipes were degrading pump performance, requiring all four pumps to run continuously, instead of cycling two pumps at a time. When the pumps could no longer keep up, the plant staff had to derag them by hand, forcing a plant shutdown about every four weeks for two hours and exposing workers to potential injuries from sharps in the rag balls. The labor and the loss of an acre-foot of reclaimed water per month cost $15,000 per year.

Solution: The facility upgraded its Channel Monster from JWC Environmental to a new perforated drum configuration designed to combat wipes and other materials. The upgraded drums are made of durable perforated metal that better traps wipes and forces them into the cutter stack, essentially eliminating clogs.

Result: Since the upgrade, the district has had zero pump clogging issues and has returned to using two pumps at a time. Energy costs decreased by $78,000 per year and manual pump clean-out was eliminated. 800/331-2277;

Blowers decrease energy consumption and reduce noise, heat and maintenance costs

Problem: King County, Wash., wanted more energy efficient blowers at the South Plant in Renton. With the support of Puget Sound Energy and the Washington State Public Works Board, the plant secured incentives and a low-interest loan toward the retrofit. The county also needed to improve working conditions, increase operational reliability and reduce scheduled maintenance expenses.

Solution: The county replaced its blowers with APG-Neuros turbo blowers. The retrofit aligned with ongoing strategic efforts to protect water quality and decrease energy consumption in all county facilities by 20 percent by 2020.

Result: The county estimates the two new blowers will save $55,000 a year and reduce energy consumption by 782,268 kWh per year. 866/592-9482;

Separation technology system recycles frac water

Problem: Industrial Systems Inc., a hydraulic fracturing operation on the western slope of Colorado, experienced up to 30 percent flowback rate from water pumped into the ground. In addition, eight barrels of high-saline produced water surfaced with every barrel of crude. Operators needed a cost-effective way to manage the water. Trucking and disposal cost $3 to $12 per barrel and posed environmental risks.

Solution: OriginOil’s Electro Water Separation technology offers a high-speed, chemical-free process that efficiently extracts oils, suspended solids, insoluble organics and bacteria from frac flowback and produced water for reuse. By circulating wastewater through reactor tubes, the system applies low-voltage electro-pulses that coagulate the oil and suspended solids. The oil and solids are then lifted to the surface by a cloud of micro-bubbles generated by a second surge of pulses in the flotation chamber. The process, integrated with a downstream polishing technology into a CLEAN-FRAC system, allows operators to clean and reuse water on site.

Result: OriginOil successfully demonstrated a 1,000-barrel-per-day commercial-capacity system with frac flowback and produced water for a disposal site in Delta, Colo. The technology, coupled with an infiltration membrane system from TriSep Corporation, removed 99.8 percent of turbidity, 100 percent of suspended solids and 99.2 percent of oil from the water. The results were verified by Lizard Analytical Laboratories, an independent lab in Grand Junction, Colo. 877/999-6645;

Gas cogeneration system uses digester gas to create power

Problem: The Downers Grove (Ill.) Sanitary District sought a solution for generating electricity from biogas from its 11 mgd treatment facility.

Solution: Tech 3 Solutions supplied a 280 kW cogeneration system that can burn up to 100,000 cubic feet per day of digester gas. The district also purchased a digester gas cleaning system from Unison Solutions.

Result: The district uses all the electric power from the unit and will use captured heat for two of its five anaerobic digesters. From startup in June to mid-August 2014, the plant had produced over 160,000 kWh. The district estimates the system will cut power costs by 25 to 40 percent annually. 305/666-1910;

Orthophosphate analyzer helps plant meet effluent limit

Problem: The Hartford (Wis.) Wastewater Treatment Plant faced a an effluent phosphorus limit of 0.075 mg/L. Chemical coagulant is added to the oxidation ditch to bind dissolved phosphorus (orthophosphate). Plant Superintendent Dave Piquett and his staff sought ways to add sufficient chemicals to meet treatment requirements without overdosing.

Solution: The P700 IQ orthophosphate analyzer from YSI, a Xylem brand, draws samples from the effluent channel, and the measurement is used in a feedback loop to control chemical feed upstream through analog outputs from a 2020XT controller included with the analyzer. The controller can manage and display up to 20 measurements, allowing staff to add measurements to optimize treatment.

Result: Besides controlling chemical addition, the unit has demonstrated low reagent consumption. Auto calibration ensures the accuracy of the online phosphate measurement. Measurements closely agree with results from numerous grab samples. Continuous monitoring provides the information needed to evaluate the effect of changes to treatment processes. 800/765-4974;

Piston pump used to convey biosolids in tight quarters

Problem: The 420 mgd (design) Village Creek Wastewater Treatment Plant in Birmingham, Ala., was challenged in transporting biosolids from dewatering to truck loading in a constrained space. While the transport distance was short, the layout precluded the use of screw or belt conveyors.

Solution: Operators installed a KSP50V(HD)L piston pump and piping system from Schwing Bioset to convey dewatered biosolids. The system includes a sliding-frame silo with 940 cubic feet of storage as buffering capacity. The pumps now transport the biosolids to a lime treatment process for land application.

Result: This solution enables the beneficial reuse of about 500,000 pounds of biosolids weekly for strip mine reclamation. 715/247-3433;

Village looks to wind to power wastewater plant

Problem: Faced with rising power costs and a volatile energy future, the Village of Cascade, Wis., wanted an alternative energy source.

Solution: Two community-friendly NPS 100-21 wind turbines from Northern Power Systems generate all the energy for the wastewater treatment facility’s aeration system, making it the first net-zero energy wastewater plant in Wisconsin.

Result: The village saves $30,000 a year, a significant amount for a community with an annual budget of $330,000. 800/906-6784;

Position transducers used to monitor drainage door position

Problem: The operator of the 676 mgd Stickney Water Reclamation Plant, in Cicero, Ill., needed accurate control of the position of valves that regulate drainage doors during treatment and integrate the information with the plant control system. The slidewires in use were unreliable and needed frequent replacement. Since each drainage door had different opening characteristics, the plant team had to be able to modify the analog output signal for the unit in the field. The unit had to be small enough to install in the valve actuator housing in a high-temperature, challenging environment.

Solution: Several field-programmable Camille-Bauer Kinax 2W2 position transducers from Absolute Process Instruments give an accurate and repeatable linear 4-20 mA signal for the valve position that can be interfaced with plant controls. At 1.95 inches in diameter and 1.10 inches deep, they fit in the actuator housing. They have temperature stability and cause no drag on the valve gearing. They are field-programmable and easily tailored to each door.

Result: The position transducers provided excellent accuracy and reliability to improve control of drainage door position. 800/942-0315;

Energy-efficient blower unit leads to big savings

Problem: The Victor Valley (Calif.) Wastewater Reclamation Authority’s 13 mgd treatment plant was being expanded to 18 mgd to account for growth, and the authority needed to upgrade its inefficient blower unit.

Solution: The authority received incentives through Southern California Edison’s Customized Solutions program for replacing its blower with a new unit from Piller TSC Blower Corporation. The company provides free pump testing to measure pumping plant efficiency and calculate the annual energy savings.

Result: The unit increased overall plant efficiency, lowered electricity costs and reduced the carbon footprint. It will save a projected 928,500 kWh annually, saving up to $98,000. 518/372-2496;

Recarbonation system reduces filter loading

Problem: A water treatment plant in Omaha, Neb., saw potential to minimize operation costs and reduce filter loadings with a different side stream recarbonation system. The existing system, installed in 2012, used over 2,000 gpm of finished water for its carrier stream and had no power turndown when operating at reduced rates.

Solution: The city tested and ultimately purchased a full-scale CDOX carbon dioxide injection system from BlueInGreen that delivered precise, automatic control of process pH using a 200 gpm carrier stream.

Result: The 1,800 gpm difference in carrier water significantly reduced pumping power usage and helped operators by directly reducing filter loading. The system also used significantly less carbon dioxide and 90 percent less power than the previous system. The plant team expects operation cost savings to pay for the system in just over 2 1/2 years. 479/527-6378;   


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