A model for higher performance
In the business world, high value is placed on strategies that can streamline day-to-day tasks, saving time and labor, and making operations more cost-efficient. The same holds true for the way water and wastewater treatment professionals view instrumentation solutions. Enhanced process control can help utilities realize greater accuracy and higher operational efficiencies.
These potential benefits were the driving factors behind the approval of new modeling software that will be installed in the Westminster (Md.) Wastewater Treatment Plant (WWTP). The $48,000 upgrade is anticipated to be a valuable asset in the city’s efforts to meet the rigorous state-driven enhanced nutrient removal goals to limit the amount of nitrogen and phosphorus entering the Chesapeake Bay.
“The new software will bring a needed boost in process efficiency, helping the treatment system overcome the technical barrier of treating wastewater to nitrogen and phosphorus concentration limits of 3 mg/L and 0.3 mg/L, respectively,” said Jeff Glass, director of public works with the City of Westminster.
Utilizing an “integrated approach for increased program control, the software will effectively trim, streamline, and optimize every component of the system process, minimizing overdosing and ensuring that only chemicals that are needed are actually used,” Glass said. “Additionally, the software has the capability to predict the process adjustments necessary to react to high flows or any changed conditions so effluent quality is maintained.”
Specifically, the new program will help model precise chemical concentrations and feed rates required for maximum performance and efficiency in the facility’s denitrification process, said John Rawlings, superintendent of the Westminster WWTP. “Once the model is calibrated to the plant’s treatment process, it will have the ability to plot exactly what is necessary in order to produce a desired quality of effluent,” he said. “This takes into account every internal and external factor that could potentially affect the process — the system needs to be able to constantly adjust based on changing data.”
Rawlings expects that as the program evolves and is more completely integrated with the plant’s operation, it will be capable of providing full automation. “Operators will still be needed to oversee the operation, collect and review data, and make adjustments to the system based on results,” he said.
With anticipated savings in chemical and electrical costs of $17,000 to $20,000 per year, the city’s investment in the program has the potential to pay for itself in 2.5 years, Rawlings said.
An advanced approach to water quality monitoring
In Fort Collins, Colo., a proposed pilot project would establish a series of real-time, on-line water monitoring instruments in the Cache La Poudre River in order to provide utilities with a greater and more detailed picture of water quality conditions.
The pilot would present “a viable means to better understanding background nutrient levels in receiving waters and how concentrations may be affected depending on various factors and events, including wastewater treatment plant discharges, as well as other nonpoint discharge occurrences,” said Kevin Gertig, water resources and treatment operations manager at the City of Fort Collins. “In contrast to taking ‘grab samples,’ or composite sampling in the case of a larger utility, access to continuous, real-time water quality data is anticipated to be considerably more beneficial and useful,” Gertig said.
This information conceivably could help municipalities from a permitting standpoint, Gertig said. “Although different from state to state, most permits are based upon existing water quality conditions in a watershed. “Data sets depicting background information of a particular water source would enable an end user to demonstrate subtle or not so subtle changes in water quality, such as nocturnal deviations or the effects of a thunderstorm, for example,” he said.
According to Gertig, studies conducted by Colorado State University (CSU; Pueblo) demonstrate that it could be critical for WWTPs to monitor nutrient concentrations, given pending regulations that might require plant upgrades. “On-line monitoring would help both regulators and facilities understand the effects of nonpoint loading of nitrogen and phosphorus,” Gertig said. “Changes in nutrient concentrations could be due to variations based upon human and ecological issues, and not always directly related to wastewater treatment discharges.”
A public-–private–academic collaboration, the pilot project is being spearheaded by Mazdak Arabi, an associate professor in the CSU Department of Civil and Environmental Engineering. The City of Fort Collins Utilities, local monitoring equipment manufacturers, and the Colorado Water Innovation Cluster (Fort Collins) will participate.
“To our knowledge, this will be the first project of its kind to provide real-time, on-line monitoring of nitrogen and phosphorus levels with new lower detection methods,” Gertig said. “The hypothesis is that there will be a real need for this level of monitoring, especially if the U.S. Environmental Protection Agency (EPA) implements more stringent nutrient regulations.”
In order to be validated, the monitoring capabilities of the pilot project will need to meet the accuracy of EPA standard instruments, Gertig noted. “In this sense, the project is a field verification to demonstrate if this technology is feasible and can be applied on a watershed-level scale.”
In an effort to help reduce nutrient runoff into waterways, ScottsMiracle-Gro Co. (Maryville, Ohio) has promised to remove all phosphorus from some of its popular lines of products by 2012 and increase its effort to find more efficient ways to use nitrogen in its lawn fertilizer products.
“Healthy, sustainable lawns and landscaping are essential to protecting our rivers, estuaries, lakes, and streams,” said Chris Wible, director of Environmental Stewardship at Scotts in a July press release. “At ScottsMiracle-Gro, we are committed to doing our part to ensure our company and lawn care products advance water quality and conservation.”
In 2006, the company signed a memorandum of understanding with the Chesapeake Executive Council, whose current members include Lisa Jackson, administrator of the U.S. Environmental Protection Agency; Michael W. Brubaker, chair of the Chesapeake Bay Commission (Annapolis, Md.); and Vincent C. Gray, the mayor of the District of Columbia, as well as the governors of Maryland, Pennsylvania, and Virginia. The memorandum supported a stewardship program that would reduce nutrient runoff from residential lawns.
As part of that program, ScottsMiracle-Gro agreed to the goal of reducing phosphorus in its lawn maintenance fertilizers by 50% by the end of 2009, which it accomplished. The company plans to remove all phosphorus from many of its fertilizers by 2012, including its Turf Builder brand.
“Our ongoing research found that well-established lawns generally have enough phosphorus in the soil for grass to thrive, and that consumers will continue to see the results they expect,” said Rich Shank, the company’s chief environmental officer. “Phosphorus is needed in new lawns, or when soil tests determine that a lawn’s soil is phosphorus-deficient.”
Because phosphorus is essential to the initial root development of grass, according to a company press release, the nutrient will remain in the company’s starter fertilizers. It also will remain in its organic lawn food “as it naturally occurs in the organic materials contained in the product,” according to the press release.
The company also is looking into ways to optimize the nitrogen in lawn fertilizers.
“Unlike phosphorus, nitrogen doesn’t readily bind to the soil and is more water-soluble,” Shank said. “But if there is too much nitrogen, there is danger of having it running off into waterways. More important is how much nitrogen is applied. Scotts is researching various slow-release nitrogen technologies that still maintain high product quality and meet consumer expectations.”
In addition to changing how the company uses nutrients in its fertilizers, “we are also working to educate consumers that proper lawn care practices will help protect our precious water resources,” Wible said in the July press release.
The company has included water conservation messages in its advertising, website, and digital outreach tools.
From digesters to the fuel tank
Orange County, Calif., WWTP tests feasibility of converting methane into fuel for hydrogen-powered vehicles
Will the local wastewater treatment plant (WWTP) become the place to go to fill up your car’s tank? If one day the tank takes hydrogen instead of gasoline, the answer could be “yes.” With this possibility in mind, a pilot project at a Southern California WWTP is testing the feasibility of converting methane into fuel for hydrogen-powered vehicles.
In a first-of-its-kind application, the 772,000-m3/d (204-mgd) Reclamation Plant No. 1, which is owned by the Orange County Sanitation District (OCSD; Fountain Valley, Calif.), has been outfitted with fuel-cell technology capable of converting methane from the plant’s mesophilic anaerobic digesters into hydrogen. Although much of the hydrogen is consumed by the fuel cell as it produces electricity, the excess hydrogen that remains is collected, purified, and made available for use by vehicles powered by fuel cells. Funding for the $8 million pilot project came from public and private sources, including OCSD, the U.S. Department of Energy, the California Air Resources Board, the South Coast Air Quality Management District, and Air Products and Chemicals (Air Products; Allentown, Pa.). FuelCell Energy (Danbury, Conn.) supplied the fuel-cell technology.
The fuel cell installed at the OCSD plant is designed to generate nominally 300 kW of electricity and approximately 50 kg/d (110 lb/d) of hydrogen, said Ed Heydorn, business development manager for hydrogen energy systems at Air Products, a hydrogen provider and developer of hydrogen fueling stations. “That’s enough to support 100 to 150 vehicles,” he said. Automakers currently lease, rather than sell, hydrogen-fueled vehicles to the general public. However, automakers have indicated that they intend to launch commercial sales of such vehicles in 2015, Heydorn said.
In August, Air Products opened a fueling station at OCSD’s Reclamation Plant No. 1, the company’s 11th such installation in California. “The fueling station is located on our property just outside the front gate of our facility,” said Jeff Brown, senior engineer and project manager at OCSD.
Although OCSD is able to use the electricity generated by the fuel cell, the amount is relatively minor, Brown noted. Therefore, the “main benefit to OCSD is the opportunity to evaluate the real-world performance of an environmentally benign power-generating technology using our renewable biogas as its fuel source,” he said.
As a potential feedstock for renewable energy, biogas from wastewater has the benefit of being continuously available in large, concentrated volumes, Heydorn noted. Meanwhile, wastewater treatment facilities tend to be located near urban populations, the most likely candidates for hydrogen-fueled vehicles. Currently, the fuel cell at the OCSD facility is harnessing only about 5% of the methane generated by the treatment plant. However, Air Products is keen to test whether the technology can be operated on a grander scale. “You can see how this would move to large-scale fuel cells in the megawatt size and then large-scale hydrogen production,” Heydorn said. To this end, Air Products is planning to deploy a 1-MW fuel cell at a European WWTP in the future.
— Jay Landers,
©2011 Water Environment Federation. All rights reserved.