Aerosol Cans Classified as Universal Waste by the EPA

The EPA has finalized a streamlined system for managing hazardous waste aerosol cans that the Agency estimates this change will save at least $5.3 million annually in regulatory costs.

 

“Today’s rule will benefit approximately 25,000 facilities across numerous industries such as the retail, construction, and manufacturing sectors” said EPA Administrator Andrew Wheeler. “The simplified structure of the universal waste program will help improve regulatory compliance, make aerosol can collection more economical, and facilitate the environmentally sound recycling of this common waste stream.”

 

The EPA anticipates that this final rule will promote greater consistency for the regulated community as several states already include aerosol cans in their universal waste programs. The final rule offers a more uniform, nationwide handling system and furthers our effective partnerships with states and tribes by making it easier for states to add this waste stream to their universal waste programs.

 

With this rule, the EPA is adding hazardous waste aerosol cans to the list of materials that can be managed under the Resource Conservation and Recovery Act’s universal waste management system. This system was established to streamline hazardous waste management for certain categories of hazardous waste that are commonly generated by a wide variety of establishments. Hazardous waste batteries, certain hazardous waste pesticides, mercury-containing equipment, and hazardous waste mercury lamps are the other federal universal wastes.

 

This change is expected to benefit the wide variety of companies generating and managing hazardous waste aerosol cans, including the retail sector, by providing clear, practical standards for handling discarded aerosol cans and protecting human health and the environment. The rule is expected to:

 

 

Annual training is required by 40 CFR 262.17(a)(7).  Learn how to complete EPA’s new electronic hazardous waste manifest, and the more than 60 changes in EPA’s new Hazardous Waste Generator Improvements Rule.  Environmental Resource Center’s Hazardous Waste Training is available at nationwide locations, and via live webcasts.  If you plan to also attend DOT hazardous materials training, call 800-537-2372 to find out how can get your course materials on a new Amazon Fire HD 10 tablet at no extra charge.

 

The joint committee of experts that maintains an NSF International drinking water treatment standard has recently updated it to allow a more efficient method of treating microorganisms in drinking water. The revision to NSF/ANSI 55: Ultraviolet Microbiological Water Treatment Systems establishes new criteria for use of UV-LED technology for microbial reduction and provides a new test method to certify manufacturer claims.

 

Treatment systems covered by the standard use ultraviolet light to inactivate or kill bacteria, viruses and cysts in microbiologically unsafe water (Class A systems) or to reduce the amount of non-disease-causing bacteria in disinfected drinking water (Class B systems).

 

“This is a significant update to the drinking water treatment standard. While non-disinfecting LEDs are found in everyday applications such as lighting fixtures and consumer electronics, this use of ultraviolet LED technology is very different. Lab testing shows that ultraviolet LED technology is effective at reducing bacteria and other types of microorganisms in drinking water,” said Jessica Evans, Director of Standards Development at NSF International. NSF is accredited by the American National Standards Institute (ANSI) to develop standards using its consensus-based process with a balanced group of stakeholders.

 

Originally developed in 1991, NSF/ANSI 55’s scope was limited to low-pressure ultraviolet (UV) radiation systems using low-pressure mercury bulbs, which was the only technology available in the marketplace at the time.

 

In 2014, the Drinking Water Treatment Units Joint Committee responsible for the NSF/ANSI standard began developing a protocol to address newer alternate UV technologies.

 

After considering several options, a task group recommended the approach of running a direct log-reduction test with an organism that would represent an entire class of organisms.

 

The task group concluded that the virus Q-beta is an acceptable surrogate to Rotavirus and the test method performs appropriately. This holds true at both ends of the UV wavelength range examined (254 nm to 285 nm). Testing with Q-beta directly is also a simpler, more consistent and less expensive protocol than having to conduct the collimated beam study required in the original protocol.

 

The existing protocol for current systems will remain in NSF/ANSI 55 for at least five years. Manufacturers will have the option to evaluate their product to the new test method or the older test method defined within the standard. For devices with wavelengths other than 254 nm, the new method using Q-beta would be required and would have the following criteria:

 

NSF/ANSI 55 was developed following the American National Standards Institute (ANSI) process designed to ensure openness, balance, consensus and due process for all stakeholders. The Drinking Water Treatment Units Joint Committee is comprised of stakeholders representing consumers, the water industry, and state and federal health and environmental agencies in the U.S. and Canada. The joint committee is comprised of 108 people (including 28 voting members, plus observers who offer input and expertise during the standard development process) and is facilitated by NSF International’s standards development group.

 

As the final step in the standards development process, NSF/ANSI 55 was ratified by NSF’s Council of Public Health Consultants, which includes representatives from the U.S. EPA and the Centers for Disease Control and Prevention (CDC).

 

 

TScientists from Tokyo Metropolitan University have developed a low-temperature catalyst for removing NOx gas from industrial exhaust using ammonia. Composed of bulk "defective" vanadium oxide instead of vanadium oxides supported on titanium oxide like in commercial catalysts, the catalyst works at lower temperatures (< 150 degrees Celsius) with much higher efficiency. The team demonstrated a clear improvement in performance and identified the reaction mechanisms responsible for the difference.

 

Nitrogen monoxide (NO) and nitrogen dioxide (NO₂), or nitrogen oxides (NOx), are common atmospheric pollutants created by burning fossil fuels, coal and natural gas. They are a major cause of photochemical smog and acid rain, which makes their removal from vehicle and factory emissions extremely important. A key technology for removing nitrogen oxides is their reaction with ammonia via selective catalytic reduction (SCR), where NOx is rendered harmless via reduction to nitrogen and water. In particular, vanadium oxides supported on titania are known to have excellent selectivity for conversion to nitrogen and have been successfully applied to stationary boilers.

 

However, a significant bottleneck for supported catalysts is the high temperature required for catalytic activity, often 200 to 400 degrees Celsius. This often results in units being placed close to e.g. the boiler in power plants, where they can be easily damaged not only physically by ash but by the accumulation of ammonium sulfates. These deactivating factors can be avoided if the unit is placed downstream after an electrostatic precipitator for removing dust and a desulfation system to remove sulfate deposits. However, this approach requires high catalytic activity at lower temperatures, since the temperature of the exhaust gas has generally dropped to around 100 degrees Celsius by this point. A catalyst is needed that works at lower temperatures.

 

Now, a team led by Yusuke Inomata and Toru Murayama from Tokyo Metropolitan University have developed a catalyst based on bulk vanadium oxides. Vanadium (V) oxide (V₂O₅) is a common state of vanadium oxide; the team however successfully synthesized a mixture of vanadium (V) and vanadium (IV) oxides, or "defective" vanadium oxide, by heating a precursor to 270 degrees Celsius. They found that this "defective" catalyst had excellent catalytic activity at temperatures down to 100 degrees Celsius; at this temperature, the speed at which NOx is converted to harmless nitrogen was 10 times faster than conventional titania supported vanadium oxide catalysts, showing exceptional performance where convertional catalysts fall short. The improvement was attributed to the presence of V(IV) which creates "Lewis acid" (electron-accepting) sites, promoting the reaction of nitrogen oxide with ammonia to become nitrogen.

 

Beyond practical application to industrial catalysis, the team hope that the mechanisms they have uncovered serve as a model system for further scientific studies.

 

 

“We know that 60 to 70% of the world’s population will be living in urban areas by midcentury,” said Kangning Huang, a Ph.D candidate at F&ES and lead author of the paper published in Environmental Research Letters. “So if you don’t know the change in urban heat island and you only focus on climate change from greenhouse gas-emissions, then you are underestimating the level of warming and heat that two-thirds of the global population will be exposed to.”

 

The paper was co-authored by Karen Seto, the Frederick C. Hixon Professor of Geography and Urbanization Science at F&ES, as well as Xia Li from East China Normal University in Shanghai and Xiaoping Liu from Sun Yat-Sen University in Guangzhou, China.
 
According to the authors, this research represents an important step toward understanding the future of urbanization. Although the UN’s World Urbanization Prospects has offered a trove of data on future urban population growth, it lacks specific information on how that growth will be distributed within countries and the changes in land uses.

 

Moreover, although the UN Intergovernmental Panel on Climate Change reports incorporate modeling studies on future warming due to greenhouse gas emissions, they do not provide global-scale projections of warming as a consequence of increasing UHIs.

 

The urban heat island effect is a phenomenon in which urban areas are significantly warmer than the surrounding countryside, inducing local climate effects that compound the global effects of greenhouse gas emissions.

 

In the new study, the authors predict the likely distribution of urban population growth based on range of factors including economic growth, topography, and transportation networks assuming a continuation of historical trends in urban expansion. Then, using mathematical models, they forecast the intensification of the urban heat island effect down to local and regional scales. The model produces spatial results at a resolution of five square kilometers.

 

“If you want to do a comprehensive assessment of the risk of warming, you need to have this information,” Huang said. “Climate impacts depend on location; it will be different, for instance, from Florida to California. So, it’s important to know where people are living and the resulting size of the urban areas.”

 

Likewise, any future policy decisions will be dependent on local and regional conditions, he said. Although the paper doesn’t make policy recommendations, it offers policymakers and scientists across the world a glimpse into what the future might look like in their regions, and an opportunity to craft policies that respond to those projections.

 

 

Thermoelectric materials can convert heat into electrical energy. This is due to the so-called Seebeck effect: If there is a temperature difference between the two ends of such a material, electrical voltage can be generated and current can start to flow. The amount of electrical energy that can be generated at a given temperature difference is measured by the so-called ZT value: The higher the ZT value of a material, the better its thermoelectric properties.

 

The best thermoelectrics to date were measured at ZT values of around 2.5 to 2.8. Scientists at TU Wien (Vienna) have now succeeded in developing a completely new material with a ZT value of 5 to 6. It is a thin layer of iron, vanadium, tungsten and aluminium applied to a silicon crystal.

 

The new material is so effective that it could be used to provide energy for sensors or even small computer processors. Instead of connecting small electrical devices to cables, they could generate their own electricity from temperature differences. The new material has now been presented in the journal "Nature".

"A good thermoelectric material must show a strong Seebeck effect, and it has to meet two important requirements that are difficult to reconcile," says Prof. Ernst Bauer from the Institute of Solid State Physics at TU Wien. "On the one hand, it should conduct electricity as well as possible; on the other hand, it should transport heat as poorly as possible. This is a challenge because electrical conductivity and thermal conductivity are usually closely related."

 

At the Christian Doppler Laboratory for Thermoelectricity, which Ernst Bauer established at TU Wien in 2013, different thermoelectric materials for different applications have been studied over the last few years. This research has now led to the discovery of a particularly remarkable material – a combination of iron, vanadium, tungsten and aluminum.

 

"The atoms in this material are usually arranged in a strictly regular pattern in a so-called face-centered cubic lattice," says Ernst Bauer. "The distance between two iron atoms is always the same, and the same is true for the other types of atoms. The whole crystal is therefore completely regular.”

 

However, when a thin layer of the material is applied to silicon, something amazing happens: the structure changes radically. Although the atoms still form a cubic pattern, they are now arranged in a space-centered structure, and the distribution of the different types of atoms becomes completely random. "Two iron atoms may sit next to each other, the places next to them may be occupied by vanadium or aluminum, and there is no longer any rule that dictates where the next iron atom is to be found in the crystal," explains Bauer.

 

This mixture of regularity and irregularity of the atomic arrangement also changes the electronic structure, which determines how electrons move in the solid. "The electrical charge moves through the material in a special way, so that it is protected from scattering processes. The portions of charge travelling through the material are referred to as Weyl Fermions," says Ernst Bauer. In this way, a very low electrical resistance is achieved.

 

Lattice vibrations, on the other hand, which transport heat from places of high temperature to places of low temperature, are inhibited by the irregularities in the crystal structure. Therefore, thermal conductivity decreases. This is important if electrical energy is to be generated permanently from a temperature difference – because if temperature differences could equilibrate very quickly and the entire material would soon have the same temperature everywhere, the thermoelectric effect would come to a standstill.

"Of course, such a thin layer cannot generate a particularly large amount of energy, but it has the advantage of being extremely compact and adaptable," says Ernst Bauer. "We want to use it to provide energy for sensors and small electronic applications." The demand for such small-scale generators is growing quickly: In the "Internet of Things", more and more devices are linked together online so that they automatically coordinate their behavior with each other. This is particularly promising for future production plants, where one machine has to react dynamically to another.

 

"If you need a large number of sensors in a factory, you can't wire all of them together. It's much smarter for the sensors to be able to generate their own power using a small thermoelectric device," says Bauer.

 

 

NY Attorney General James joined a multistate coalition in filing comments on the Environmental Protection Agency’s (EPA) Draft Policy Assessment regarding National Ambient Air Quality Standards (NAAQS) for Particulate Matter. Particulate Matter is a deadly pollutant emitted from a variety of sources including vehicles, factories, and power plants. Particulates are linked to many serious public health problems including premature mortality, cardiovascular disease, respiratory impacts, and cancer. In the comment letter, the attorneys general urge the EPA to consider and thoroughly evaluate the best available science on Particulate Matter emissions, exposure, and health effects and engage in a transparent, health-based assessment of the protectiveness of the current NAAQS.

 

“Particulate Matter is a deadly, substantial, and continuing threat to public health,” said Attorney General James. “It is imperative that NAAQS is based on a transparent, health-based assessment of the best available science to ensure they are adequately protective of public health and welfare. My office will continue to use every tool in our legal arsenal to fight for New Yorker’s right to breathe clean air and to keep them safe.”

 

In the comment letter, the attorneys general fault EPA for attempting to rush through the scientific process of reviewing the dangers from Particulate Matter exposure without essential input from the scientific community. Instead, the state coalition reminds EPA that the decision to revise current air quality standards should be transparent, based on current science, and in service of the public health. The attorneys general note EPA’s long-standing conclusion that exposure to fine Particulate Matter, known as PM2.5, is linked to serious harms to public health. The application of the current PM2.5 standards has led to reductions in ambient concentrations of Particulate Matter of 34 to 40 percent between 2000 and 2018. However, Particulate Matter at the level of current NAAQS continues to present significant health and welfare risks. Therefore, the coalition argues that EPA must remedy errors that are undermining the scientific integrity and transparency of the review process. The stakes are high: For example, current PM2.5 pollution levels in New York City are estimated to contribute to 2,300 deaths and 6,300 emergency department visits and hospitalizations for respiratory and cardiovascular disease each year.

 

Attorney General James joined the attorneys general of California, Minnesota, New Jersey, Oregon, and Rhode Island in filing the comments.

 

The Washington Department of Ecology has fined a boatyard on the Anacortes waterfront $30,000 for allowing polluted stormwater to flow into Fidalgo Bay, an important habitat for endangered Chinook salmon and other marine life.

 

Stormwater that flows off the facility at 2417 T Avenue contains high levels of copper and zinc, which are toxic to fish. Copper makes young salmon unable to avoid predators and adults unable to find their home rivers for spawning. Zinc can kill young salmon.

 

“Marine life is very vulnerable to these pollutants,” said Heather Bartlett, manager of Ecology’s Water Quality Program. “Other boatyards successfully prevent this sort of pollution with stormwater treatment and we expect no less of this facility.”

 

Paints that protect boat hulls from barnacles, algae and other marine growth contain copper and zinc. Maintenance of boat hulls can result in these metals entering stormwater, and treatment is needed at many boatyards.

 

Ecology also has ordered Marine Servicecenter to install a stormwater treatment system within 90 days. The order also gives the facility six months to put in place measures that prevent the metals from getting into stormwater.

 

Chairman of the House Committee on Transportation and Infrastructure Peter DeFazio (D-OR), and Chairman of the House Committee on Energy and Commerce Frank Pallone Jr. (D-NJ) introduced the “Safe, Accountable, Fair, and Environmentally Responsible (SAFER) Pipelines Act of 2019.” This comprehensive pipeline safety legislation takes numerous steps to improve pipeline safety and address climate change by reducing emissions, preventing pipeline leaks, and holding pipeline operators accountable for reckless actions. The DeFazio-Pallone bill also reinstates a 2016 EPA final rule that set limitations on methane emissions across the natural gas and hazardous liquid pipeline sector.

 

The SAFER Pipelines act of 2019 would make significant improvements to current law, including:

 

“There are nearly 3 million miles of pipelines transporting hazardous liquid and natural gas just feet below countless communities across the U.S., yet federal efforts to ensure these pipelines are safe, reliable and environmentally-sound are woefully outdated,” Chair DeFazio said. “And we have the numbers to back that up. Last year alone, there were 636 pipeline incidents that left eight people dead and injured another 90, including the horrific incident that killed one person, sent 21 others to the hospital, and damaged 131 structures in Merrimack Valley, Massachusetts. Moreover, it’s estimated that this industry is responsible for one-third of our country’s emissions of methane, a greenhouse gas that is 84 times more potent than carbon dioxide in the first few decades of its release and a major contributor to climate change. The legislation we are introducing today presents a significant opportunity to do better. We need pipeline operators to do their part to reduce methane emissions and prevent catastrophic leaks, and if they don’t, we can make sure they will be held accountable for putting our communities at risk and contributing to climate change.”

 

“This comprehensive legislation will help protect people, the environment and our climate from unsafe pipelines,” Chair Pallone said. “Pipelines should be the safest way to transport natural gas and oil, but they are not nearly as safe as they should be.  Despite the progress we’ve made on pipeline safety over the last 20 years, too much oil continues to spill into our environment, too many greenhouse gasses leak into our atmosphere and far too many people continue to die due to pipeline failures. Last month, the Keystone pipeline leaked nearly 400,000 gallons of oil onto farmland and wetlands.  This legislation rebalances the law in favor of people and the environment instead of corporations and profits. It also helps protect our climate by reversing the Trump rollback of President Obama’s methane rules.  This is a bold bill that is necessary to make our pipelines safe and secure.” 

 

EPA announced a settlement with Thatcher Group, Inc. (Thatcher) of Salt Lake City, Utah, resolving alleged violations of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) in Nevada, New York and Utah. Under the terms of a Consent Agreement and Final Order filed on November 14, Thatcher will pay a civil penalty of $300,415 to resolve the alleged violations.

 

“EPA’s pesticide laws ensure that consumers have clear and current information about products and how to use them safely,” said Suzanne Bohan, director of EPA’s regional enforcement program. “We will continue to work with our state partners to secure compliance with registration and labeling requirements that protect people from exposure to potentially harmful chemicals.”

 

This settlement resulted from an EPA-led investigation across several states and EPA regions.  Between 2014 and 2018, inspections of Thatcher’s production and distribution facilities in Nevada and Utah conducted by EPA, the Nevada Department of Agriculture (NDA), and the Utah Department of Agriculture and Food (UDAF) found Thatcher did not properly register pesticide products sold by its distributors and did not ensure its distributors used current labeling. Initial inspections conducted by EPA between 2014 and 2017 were followed up by state investigations, including a January 2018 UDAF inspection that found Thatcher was producing and distributing an unregistered disinfectant. NDA inspections completed in March 2018 also found the company’s Nevada facility was distributing disinfectants with outdated labeling.

 

Additionally, an EPA investigation found that Thatcher failed to register its pesticide facility in Williamson, New York, prior to producing pesticides in 2014 and did not report annual pesticide production data for 2015 and 2016 by the required due dates. An inspection conducted in October 2018 found the New York facility was distributing an unregistered sanitizer and an unregistered disinfectant.

 

FIFRA registration and labeling requirements protect human health and the environment by ensuring pesticides in the marketplace are tested and safe to use. The process of registering a pesticide is a scientific, legal, and administrative procedure through which EPA examines the ingredients of the pesticide; the specific site or crop where it is to be used; the amount, frequency, and timing of its use; and storage and disposal practices. The agency evaluates registration applications to assess a wide variety of potential health and environmental effects associated with use of the product. FIFRA’s labeling requirements provide the public with important, current information on how to safely use, store, and dispose of pesticide products.

 

 

The Minnesota Pollution Control Agency (MPCA) added 581 new water bodies with 728 new impairments to the state’s impaired waters list, bodies of water that do not meet water quality standards. More than a dozen watersheds were assessed in this report, including the Kettle, Otter Tail and Cottonwood Rivers. The list totals 5,774 impairments in 3,416 different bodies of water.

 

State and federal water quality standards are designed to protect lakes and streams for recreation, to support healthy fish and other aquatic life, and for other beneficial uses.

The 2020 impaired waters list includes water bodies in 14 watersheds:

 

Eighty-five percent of Minnesota’s impairments are due to non-point pollution, including nitrogen, bacteria, chloride and phosphorus. The 2020 impaired water list is the first to reflect the MPCA’s assessment of all 80 of the state’s major watersheds. The agency has completed its first cycle of statewide monitoring that began in 2008, as a result of funds from the Clean Water, Land and Legacy Amendment.

 

The 2020 impaired water list reflects the success of these efforts. The MPCA is proposing to remove four bodies of water from the list where restoration work has improved water quality. Sleepy Eye Lake (Brown County), Faille Lake (Todd County), and Waverly Lake (Wright County) now have nutrient levels low enough to meet recreational standards. Bacteria levels in a segment of Plum Creek (Stearns County) are now low enough to meet recreational goals.

 

Each of Minnesota's 80 watersheds must have a Watershed Restoration and Protection Strategy developed by 2023. The WRAPS sums up years of research on water impairments, their causes, and proposed solutions to meet water quality goals, as well as set protection strategies for waters that are in good condition. Watershed districts then develop comprehensive watershed management plans focused on priority issues like flooding, habitat, water quality, and recreation. Those plans must be completed by 2025. Soil and Water Conservation Districts, watershed districts, water management organizations, cities, counties, and townships play significant roles in implementing each plan.

 

The agency comprehensively evaluated water quality in eight watersheds each year for 10 years. As it begins the next 10-year cycle of watershed monitoring, the MPCA will use the baseline data from the first cycle to begin tracking water-quality trends.

 

Interested parties are invited to comment on Minnesota’s draft 2020 impaired waters list by January 14, 2020. The MPCA will respond to all comments it receives during the public notice period. The proposed list, accompanying documentation, and all comments and MPCA responses will be submitted to the U.S. Environmental Protection Agency for its review and approval.

 

The MPCA will hold a series of public meetings in December to answer questions on the draft 2020 impaired waters list. Meeting details are posted on the Impaired waters list webpage.

 

 

The Minnesota Pollution Control Agency (MPCA) has proposed new permit modifications for the 249 Minnesota municipalities covered under its municipal stormwater general permit. One new modification would require municipalities to address chloride pollution from de-icing salt. Some municipalities would be required to do outreach to educate businesses and institutions in their municipalities on appropriate salt use. Salt applied to roads, parking lots, and sidewalks to melt ice runs off into storm drains and is contributing to increased chloride in bodies of water around the state, which, at sufficient levels, is toxic to fish and other aquatic life.

 

Another proposed permit modification tightens up standards on properties being redeveloped. For instance, project proposers may be required to install stormwater treatment systems on sites where an acre or more of pavement is being replaced.  

 

“Managing stormwater runoff from municipal pavements is a critical part of improving and protecting water quality in Minnesota,” says Katrina Kessler, the MPCA’s Assistant Commissioner for Water. “The MPCA’s goal is to protect Minnesota’s waters while ensuring our permitting process is effective and efficient.”

 

The municipal stormwater general permit requires cities, townships, counties, hospitals, and other public entities that own or operate stormwater systems to develop stormwater pollution prevention programs and adopt practices that keep pollutants out of their storm sewer systems. Urban stormwater runoff can carry pollutants such as litter, oil, chemicals, metals, bacteria, sediment, and more into nearby lakes, rivers, streams, and wetlands.

 

The general municipal stormwater permit covers multiple entities with similar operations and types of water-quality protection concerns. It is issued for five years, after which it must be reissued. A final permit is expected to be completed by late spring 2020.

 

The MPCA is seeking input on the proposed permit, which is open for public comment until 4:30 p.m. on Friday, Jan. 10, 2020. You can read the proposed permit on the MPCA website. Submit comments via the survey form, or mail or email comments to Cole Landgraf, MPCA, 520 Lafayette Road N, St. Paul, MN 55155.

 

The MPCA will hold an interactive webinar via Webex on Wednesday, Dec. 11, from 9:00 a.m. to 12:00 p.m. to share information about the proposed permit. The agency will provide a brief presentation starting at 9:00 a.m., but the rest of the webinar will be devoted to answering questions. Find information on how to log on to the webinar on the Municipal stormwater webpage.

 

 

Synthetic compounds increasingly used in everyday products like shampoo and motor oil are finding their way into landfills and supercharging the biogas those landfills produce, researchers at the University of Michigan have found.

 

While it’s a problem today, the researchers say it could be an opportunity to get more energy out of landfill gas.

 

The compounds, called “siloxanes,” are efficient at conducting heat and interacting with water, and as such their popularity has increased in a variety of consumer products. That means more and more siloxanes are headed to your local landfill.

 

Biogas refers to fuel gases that are synthesized from different biological or organic feedstocks like landfill gas and wastewater treatment plants. In recent years, it has become clear that siloxanes have been damaging the power-generating equipment that’s fueled with landfill gas. But the researchers say the siloxanes could actually be harnessed to produce more energy.

 

The U-M team conducted the first chemical analysis of how siloxanes affect biogas. The researchers found that siloxanes increase the reactivity of biogas, leading to faster ignition in engines and the release of more energy. But those engines—typically power-generating gas turbines and reciprocating piston engines—can be damaged by the siloxanes in the biogas.

 

“Siloxanes are highly ignitable,” said Margaret Wooldridge, the Arthur F. Thurnau Professor of Mechanical Engineering and director of the Dow Sustainability Fellows Program at U-M. “They change the chemistry of biogas like crazy. The stuff is like rocket fuel, literally—crazy-reactive.” The siloxanes essentially change the biogas’s “flame speed,” which is a measure of how quickly a fuel combusts and drives a turbine or piston.

 

Biogas is composed mainly of methane. Methane gas is found in nature but it is also produced when organic material decomposes in landfills, along with hydrogen, carbon monoxide, and other hydrocarbons. Methane is the main component of natural gas and biogas, making both valuable sources of fuel and energy that are cleaner than coal.

 

In the atmosphere, however, methane is particularly good at trapping heat, adding to our global warming problem. In particular, methane is 30 times more effective a greenhouse gas than CO2. And according to the EPA, municipal solid waste landfills account for 14% of all human-related methane emissions in the U.S. each year—the third-largest source behind the gas and petroleum industry and agriculture.

 

That property has spurred efforts to capture methane from landfills and use it as a fuel, instead of allowing it to escape unchecked. In this study, U-M researchers separately tested hydrogen and carbon monoxide mixtures containing two siloxanes—trimethylsilanol (TMSO) and hexamethyldisiloxane (HMDSO)—against hydrogen and carbon monoxide mixtures with no siloxanes.

 

Specifically, the researchers clocked how long it took for each mixture to ignite. Fuels that have a shorter ignition delay are considered more ignitable or reactive—and hydrogen is one of the most reactive fuels we use. Hydrogen and carbon monoxide with TMSO produced ignition delay times that were 37% faster than the reference case. And HMDSO-infused methane produced delay times 50% faster.

 

The results of U-M’s research are published in the latest edition of Combustion and Flame. Researchers hope their work sheds light on how siloxanes alter engine performance when used as a fuel. “Trace concentrations of siloxanes have been a known problem in biogas applications—leading to the formation of abrasive silica deposits on engine components,” said Rachel Schwind, a doctoral student and study co-author. “For this reason, most prior research in this area has focused on how to remove them from the captured gas.”

 

Along with the problem siloxanes pose, there is also potential. Wooldridge said siloxanes could be key to deriving bolstered energy production from biogas. “We would love to be able to harness them as an energy source,” she said. “That would potentially negate the need for scrubbing or removal during biogas processing and reduce costs,” Schwind said. “If we can reduce those costs, it moves biogas closer to being a truly carbon neutral fuel. And if we can make landfill gas a more economically attractive option, landfill operators will have more incentive to capture and utilize this harmful greenhouse gas.”