Energy Management and Sustainability

Energy Management and Sustainability
Online total solids measurement enhances gravity belt thickener operation

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Plant uses microturbines to generate heat and power

Problem: When energy bills at the York (Pennsylvania) Wastewater Treatment Plant topped $63,000 per month and service of the plant’s four internal combustion engines required 110 gallons of oil every 700 hours, city officials knew it was time to update the plant’s 23-year-old cogeneration system.

Solution: The York City Sewer Authority selected a CR600 Power Package from Capstone Turbine Corporation for the 600 kW combined heat and power system. Separately, they purchased a C1000 Power Package for 1 MW of additional capacity based on the facility’s fluctuating demand. The CR600 operates on digester methane; C1000 is a low-pressure dual-mode unit fueled by utility-supplied natural gas.

Result: York officials estimate the cogeneration system generates more than 2.5 million kWh annually, reduces energy costs by $278,000 per year, and lowers carbon dioxide emissions by more than 1.5 million pounds annually. “We were looking for an opportunity to invest in future infrastructure development, not look to the past,” says J.T. Hand, sewer authority chairman. 818/734-5300; www.capstoneturbine.com.


Generator sets use biogas to power treatment plant

Problem: The Encina Wastewater Authority (EWA) in Carlsbad, California, serves 350,000 customers in north San Diego County. Faced with the challenge to operate economically and maintain high quality, EWA decided it needed to be more energy efficient.

Solution: Biogas fuels four G3516 engine-generator sets from Caterpillar, supplied by local dealer, Hawthorne Power Systems, which also provided application engineering and documentation, engine monitoring and control systems, and electric power distribution and monitoring.

Result: On a typical day, the generator sets run on biofuel; one unit runs on natural gas alone for four to eight hours during peak rate times. Producing about 12 million kWh per year, the units meet about 71 percent of the authority’s energy needs. 309/675-1000; www.catelectricpowerinfo.com.


Solids handling pump rectifies clogs caused by flushable wipes

Problem: The Town of Salem, Wisconsin, manages 25 lift stations that serve its population of 12,000. Lift station 18, a triplex station, was clogging weekly due to flushable wipes. Brad Zautcke, utility district manager, says his team had to unclog the pump by pulling out the rags with needle-nose pliers; this meant confined-space entry with a three-man crew. Each service call cost at least $300.

Solution: Crane Pumps & Systems provided a Barnes 4SHVA 30 hp solids handling pump as a demonstration replacement for the station in September 2013. The pump was installed a month later. The next time the pump was pulled was October 2014 for its annual maintenance. The pump has a non-recessed vortex impeller.

Result: The pump paid for itself in the first six months and continues to operate clog-free. 937/778-8947; www.cranepumps.com.


Renewable fuel and cogeneration combined at Georgia plant

Problem: Columbus (Georgia) Water Works (CWW) supplies drinking water and wastewater treatment for 230,000 residents. The utility was exploring biogas-fueled cogeneration.  

Solution: Cummins Energy Systems Business North America provided generator sets, switchgear and waste heat recovery systems along with supporting equipment. The company also helped design the generator set room and provided engineering for heat recovery and utility mains switching. The company installed two 1.75 MW C1750 N6C lean-burn gas generator sets, managed by a DMC300 digital control system, along with remote monitoring and switchgear. The generator sets can run on digester or natural gas.

Result: Since the utility has gas storage, it operates the system at the baseload rating for about 12 hours per day; the system operates for 4,000 hours a year. 800/888-6626; www.cumminspower.com.


Water authority prevents VFD-induced bearing damage with shaft grounding rings

Problem: The City of Hutchinson, Kansas, had just completed a 10 mgd reverse osmosis water treatment plant. Within two months, one of the 250 hp vertical hollow-shaft motors that pump to the water towers was making the telltale whine of fluted bearings. After that pump’s bearings were replaced, the rest of the plant’s motors began making the same noise.

Solution: Plant personnel concluded that VFD-induced shaft voltage was the cause of the problem and began shipping motors to Independent Electric Machinery (IEMCO), a repair shop with a process to prevent electrical bearing damage in vertical hollow-shaft motors. After replacing damaged bearings, IEMCO installed an AEGIS Shaft Grounding Ring from Electro Static Technology next to the motor’s guide (lower) bearing and applied ceramic insulation to the carrier that holds the thrust (upper) bearing in place at the motor’s drive end.

Result: Before long all 17 pump motors had been protected. All are still running without any problems. 866/738-1857; www.est-aegis.com.


Filter manufacturer improved metering pump accuracy

Problem: New Logic Research in Emeryville, California, provides high-performance membrane filtration systems. Series i VSEP systems, used in applications from brine minimization and landfill leachate treatment to chemical process clarifications, have a clean-in-place cycle that requires leak-free, accurate dosing of chemical cleaners.

Solution: The manufacturer selected Bran+Luebbe ProCam double diaphragm metering pumps from SPX for use on chemical totes. The pumps have variable stroke length and are available in five models with flow rates up to 158.5 gph and operating pressures up to 150 psig. They use mechanically actuated dual PTFE diaphragms to ensure safe, reliable, corrosion-resistant operation.

Result: The pumps deliver consistent dosing rates during the cleaning cycle, minimizing chemical usage and ensuring thorough membrane cleaning. They have operated reliably and reduced the risk of emissions. 800/252-5200; www.spx.com.


City replaces piston pumps with new efficient model

Problem: The Stockton (California) wastewater treatment facility operations/maintenance staff had to keep aging equipment functional. The two 20-
year-old KSP 25 piston pumps supplied by Schwing Bioset in the biosolids dewatering building moved dewatered cake to the truck-loading building several hundred feet away.  

Solution: The city replaced the old pumps with Schwing Bioset’s KSP 25 high-efficiency piston pumps. The new pump systems have hydraulic power packs, twin screw feeders and control systems. The pumps were replaced in a series to phase out the old system while the plant continued to operate.

Result: A brand-new turnkey cake pumping system was turned over to the city during 2015. 715/247-3433; www.schwingbioset.com.


United Water solves data problem with magnetic flowmeter

Problem: United Water operates regulated water systems in eight states and provides contract services to over 5 million people. The company needed to pinpoint and stem water loss quickly and easily, even in no-power situations, to save water and energy and improve its bottom line.

Solution: The SITRANS FM Mag 8000 flowmeter from Siemens Industry provides accurate water balance data, pinpointing line breaks and saving water. The 10-year battery life provides consistent monitoring, and the remote mounting enables freedom for installation, making maintenance easier and safer.

Result: With the data from the flowmeters, United Water operators can see water used, consumed or lost in the EOps system, helping to pinpoint leaks. A spike in usage indicates a leak, and the flow data is fed back to the model to triangulate where the leak is. Operators saw a water savings of 1 mgd and detection times shortened to less than 24 hours. 800/365-8766; www.usa.siemens.com.


Brewery uses produced thermal energy for factory boiler

Problem: The Birra Peroni Group brewery in Bari, Italy, was expanding production, and its wastewater treatment plant from 1995 was inadequate and outdated. The challenge was to revamp, install and start up a new plant without interfering with normal production operations.

Solution: RWL Water inserted an Expanded Granular Sludge Bed anaerobic reactor, which, with two existing anaerobic digesters, produces biogas for the factory boiler. The plant also provides aerobic treatment and final clarification.

Result: RWL Water provided a cost-effective design and installed it without disrupting production. The system capacity is 580,800 gpd. 800/
879-3677; www.rwlwater.com.


Online total solids measurement enhances gravity belt thickener operation

Problem: The City of Lethbridge (Alberta) Wastewater Treatment Plant processes waste activated sludge from its secondary clarifiers through a gravity belt thickener before anaerobic digestion. Controls including timed pumping of the sludge and polymer dosing required constant operator input and maintenance.

Solution: Tecumseth, a Valmet Automation distributor, recommended adding online measurement of the waste activated sludge solids using the ValmetTS Total Solids Analyzer. It was installed on the common header from the secondary clarifiers feeding the thickener. The device provides a constant measurement of the total solids, used to automatically dose polymer.

Result: Plant operators optimized mixing and dosing, reducing polymer usage by at least 25 percent. Operator attention, manual sampling and unplanned maintenance were greatly reduced. Enhanced thickening has improved digesting operations. 360/608-1585; www.valmet.com/automation.



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