Technology could make treatment and reuse of oil and gas wastewater simpler, cheaper – University of Colorado + MIT + Rice Universities (NEWT)

Oil and gas operations in the United States produce about 21 billion barrels of wastewater per year. The saltiness of the water and the organic contaminants it contains have traditionally made treatment difficult and expensive.

Engineers at the University of Colorado Boulder have invented a simpler process that can simultaneously remove both salts and organic contaminants from the wastewater, all while producing additional energy. The new technique, which relies on a microbe-powered battery, was recently published in the journal Environmental Science Water Research & Technology as the cover story.

“The beauty of the technology is that it tackles two different problems in one single system,” said Zhiyong Jason Ren, a CU-Boulder associate professor of environmental and sustainability engineering and senior author of the paper. “The problems become mutually beneficial in our system—they complement each other—and the process produces energy rather than just consumes it.”

The new treatment technology, called microbial capacitive desalination, is like a battery in its basic form, said Casey Forrestal, a CU-Boulder postdoctoral researcher who is the lead author of the paper and working to commercialize the technology. “Instead of the traditional battery, which uses chemicals to generate the electrical current, we use microbes to generate an electrical current that can then be used for desalination.” 

This microbial electro-chemical approach takes advantage of the fact that the contaminants found in the wastewater contain energy-rich hydrocarbons, the same compounds that make up oil and natural gas. The microbes used in the treatment process eat the hydrocarbons and release their embedded energy. The energy is then used to create a positively charged electrode on one side of the cell and a negatively charged electrode on the other, essentially setting up a battery.

Because salt dissolves into positively and negatively charged ions in water, the cell is then able to remove the salt in the wastewater by attracting the charged ions onto the high-surface-area electrodes, where they adhere.

Not only does the system allow the salt to be removed from the wastewater, but it also creates additional energy that could be used on site to run equipment, the researchers said.

“Right now oil and gas companies have to spend energy to treat the wastewater,” Ren said. “We are able to treat it without energy consumption; rather we extract energy out of it.”

Some oil and gas wastewater is currently being treated and reused in the field, but that treatment process typically requires multiple steps—sometimes up to a dozen—and an input of energy that may come from diesel generators.

Because of the difficulty and expense, wastewater is often disposed of by injecting it deep underground. The need to dispose of wastewater has increased in recent years as the practice of hydraulic fracturing, or “fracking,” has boomed. Fracking refers to the process of injecting a slurry of water, sand and chemicals into wells to increase the amount of oil and natural gas produced by the well.

Injection wells that handle wastewater from fracking operations can cause earthquakes in the region, according to past research by CU-Boulder scientists and others.

The demand for water for fracking operations also has caused concern among people worried about scarce water resources, especially in arid regions of the country. Finding water to buy for fracking operations in the West, for example, has become increasingly challenging and expensive for oil and gas companies.

Ren and Forrestal’s microbial capacitive desalination cell offers the possibility that water could be more economically treated on site and reused for fracking.

To try to turn the technology into a commercial reality, Ren and Forrestal have co-founded a startup company called BioElectric Inc. In order to determine if the technology offers a viable solution for oil and gas companies, the pair first has to show they can scale up the work they’ve been doing in the lab to a size that would be useful in the field.

The cost to scale up the technology also needs to be competitive with what oil and gas companies are paying now to buy water to use for fracking, Forrestal said. There also is some movement in state legislatures to require oil and gas companies to reuse wastewater, which could make BioElectric’s product more appealing even at a higher price, the researchers said.

MIT – Toward Cheaper Water Treatment for Oil & Gas Operations

MIT spinout makes treating, recycling highly contaminated oilfield water more economical

Also Read: Nanotechnology Enabled Water Treatment or NEWT: Transforming the Economics of Water Treatment: Rice, ASU, Yale, UTEP win $18.5 Million NSF Engineering Research Center

 

 

 

Explore further: New contaminants found in oil and gas wastewater

More information: “Microbial capacitive desalination for integrated organic matter and salt removal and energy production from unconventional natural gas produced water.” Environ. Sci.: Water Res. Technol., 2015,1, 47-55 DOI: 10.1039/C4EW00050A

Provided by: University of Colorado at Boulder

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Yale Study Confirms: Fracking Does Not Contaminate Drinking Water

Yale researchers have confirmed that hydraulic fracturing – also known as “fracking” – does not contaminate drinking water. (Photo : Flickr: Konstantin Stepanov)

Yale researchers have confirmed that hydraulic fracturing – also known as “fracking” – does not contaminate drinking water. The process of extracting natural gas from deep underground wells using water has been given a bad reputation when it comes to the impact it has on water resources but Yale researchers recently disproved this myth in a new study that confirms a previous report by the Environmental Protection Agency (EPA) conducted earlier this year.

After analyzing 64 samples of groundwater collected from private residences in northeastern Pennsylvania, researchers determined that groundwater contamination was more closely related to surface toxins seeping down into the water than from fracking operations seeping upwards. Their findings were recently published in the journal Proceedings of the National Academy of Science.

 

“We’re not trying to say whether it’s a bad or good thing,” Desiree Plata, an assistant professor of chemical and environmental engineering at Yale University, told News Three in a Skype interview. “We saw there was a correlation between the concentration and the nearest gas well that has had an environmental health and safety violation in the past.”

Researchers also noted that shale underlying the Pennsylvania surface did not cause any organic chemicals to seep into groundwater aquifers. However, these findings may not be applicable to all locations worldwide.

“Geology across the country is very different. So if you’re living over in the New Albany-area shale of Illinois, that might be distinct from living in the Marcellus shale in Pennsylvania,” Plata explained.

Researchers from Duke University also recently gave people a reason to trust fracking companies. In a study published in Environmental Science & Technology Letters, scientists explained that hydraulic fracturing accounts for less than one percent of water used nationwide for industrial purposes. This suggested that the natural gas extraction processes are far less water-intensive than we previously thought.

It’s hoped that these studies will help people better understand the safety of fracking.

GSA and DOE: Gaps in Knowledge About ‘Best Practices’ for Fracking and a Sustainable Energy Future: The Water Impact

Though applied since the 1940s, hydraulic fracturing boomed in the 1990s, according to The Geological Society of America. New technology allowed the practice to be applied to horizontal wells for extracting shale gas. Unprecedented growth followed. According to a 2014 report by FracTracker Alliance, over 1.1 million active oil and gas wells exist in the U.S.

“The rapid pace of shale gas development in the U.S. has naturally led to several gaps in knowledge about environmental impacts,” said Douglas Arent, executive director of the Joint Institute for Strategic Energy Analysis at the U.S. Dept. of Energy’s National Renewable Energy Laboratory.

Arent and colleagues recently published a paper in MRS Energy & Sustainability overviewing the developments of unconventional gas in the U.S., particularly focusing on trends in water and greenhouse gas emissions.

“If unconventional natural gas is produced and distributed responsibly, and incorporated into resilient energy systems with increasing levels of renewables, then gas can likely play a significant role in realizing a more sustainable energy future,” said Arent.

Image: EPA

Water

With many U.S. states experiencing droughts—the west coast especially—water resources are stressed. Fresh water is a valuable resource. Even if one removes hydraulic fracturing from the equation, other domestic, agricultural and industrial water needs abound.

A recent Stanford Univ. study found that regardless how deep a well was, amounts of water used to frack were indistinguishable. The average volume used to frack, according to the study, was 2.4 million gallons.

“Groundwater depletion—a situation in which water is withdrawn from aquifers faster than it can be replenished—is occurring in many areas where there are shale plays,” Arent et al. write. “Depletion not only reduces the quantity of available water, it can also result in an overall deterioration of water quality.”

Water quality degradation can occur in a myriad of ways, from leaking wells and poor wastewater treatment practices, to spills and toxic element accumulation in soil. Clarity regarding the sources and mechanisms of contamination are needed, followed by an examination of effective practices to eliminate risks, according to the researchers.

“Currently, best management practices to mitigate (water) quantity and quality related risks have not been established by industry and stakeholder groups,” the researchers write. Further, no uniformity exists across the country. Individual states are responsible for regulations regarding well construction, and mitigating potential risks to water quality. Often separate state regulations don’t mesh due to each state’s geological makeup.

An “analysis will be critical to establishing those (best management practices) and government regulations, where needed, which will ensure that shale gas can be responsibly and sustainably produced,” write the researchers.

Greenhouse gas emissions
Natural gas production, compared to coal production, results in half the carbon emissions per unit of energy. The researchers contend natural gas can offer greenhouse gas mitigation benefits relative to coal, if methane emissions are small.

In 2014, the Environmental Protection Agency reported methane gas emissions from fractured natural gas wells decreased by 73% since 2011.

“Significant work is needed to measure and verify methane emissions across the full production, transportation and distribution value chain,” the researchers write. “If natural gas is to help mitigate climate change, it will do so primarily by displacing coal. However, in the long term, natural gas itself…will not significantly alter long-range climate projections.”

While natural gas, according to the researchers, will play an important role in the U.S.’s energy future, renewable energies or carbon capture and storage will be needed to meet carbon mitigation goals.

“More transparent and accessible data related to water use and emissions from shale gas development and use…are essential to providing a more complete understanding of all the pathways to a decarbonized energy future,” said Arent.

 

Buckyballs offer environmental benefits: Removing Toxic Metal Particles from Water – Selectively

Treated buckyballs not only remove valuable but potentially toxic metal particles from water and other liquids, but also reserve them for future use, according to scientists at Rice University.

The Rice lab of chemist Andrew Barron has discovered that carbon-60 fullerenes (aka buckyballs) that have gone through the chemical process known as hydroxylation can aggregate into pearl-like strings as they bind to and separate metals – some better than others – from solutions. Potential uses of the process include the environmentally friendly removal of metals from acid mining drainage fluids, a waste product of the coal industry, as well as from fluids used for hydraulic fracturing in oil and gas production.

Barron said the treated buckyballs handled metals with different charges in unexpected ways, which may make it possible to pull specific metals from complex fluids while ignoring others.

The study led by Rice undergraduate Jessica Heimann appeared in the Royal Society of Chemistry journal Dalton Transactions.

Previous research in Barron’s lab had shown that hydroxylated fullerenes (known as fullerenols) combined with iron ions to form an insoluble polymer. Heimann and colleagues conducted a series of experiments to explore the relative binding ability of fullerenols to a range of metals.

“It’s all very well to say I can take metals out of water, but for more complex fluids, the problem is to take out the ones you actually want,” Barron said. “Acid mining waste, for example, has large amounts of iron and aluminum and small amounts of nickel and zinc and copper, the ones you want. To be frank, iron and aluminum are not the worst metals to have in your water, because they’re in natural water, anyway.

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A transmission electron microscope image shows the aggregated “strings of pearls” that form when hydroxylated carbon-60 molecules crosslink with metals – in this case, iron and nickel – in a solution. The research at Rice University suggests …more

“So our goal was to see if there is a preference between different types of metal, and we found one. Then the question was: Why?”

The answer was in the ions. An atom or molecule with more or fewer electrons than protons is an ion, with a positive or negative charge. All the metals the Rice lab tested were positive, with either 2-plus or 3-plus charges.

“Normally, the bigger the metal, the better it separates,” Barron said, but experiments proved otherwise. Two-plus metals with a smaller ionic radius bound better than larger ones. (Of those, zinc bound most tightly.) But for 3-plus ions, large worked be

“That’s really weird,” Barron said. “The fact that there are diametrically opposite trends for metals with a 2-plus charge and metals with a 3-plus charge makes this interesting. The result is we should be able to preferentially separate out the metals we want.”

The experiments found that fullerenols combined with a dozen metals, turning them into solid cross-linked polymers. In order of effectiveness and starting with the best, the metals were zinc, cobalt, manganese, nickel, lanthanum, neodymium, cadmium, copper, silver, calcium, iron and aluminum.

The “pearl” reference isn’t far from literal, as one inspiration for the paper was the fact that metal ions are cross-linking agents for proteins that give certain marine mussels an amazing ability to adhere to wet rocks.

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Treated carbon-60 molecules have the ability to recover valuable metals from liquids, including water and potential pollutants. In testing various metals, Rice University researchers found that charge and ionic radius influence how the metals …more

Heimann, a senior, started on the project before spending a semester at Rice’s sister institution in Germany, Jacobs University. “I initially worked with carbon nanotubes, oxidizing them to see how they would bind metals, and then I went abroad,” she said. By the time she came back, Barron was ready to try C-60. “Coming from Rice and its history with buckyballs, I thought that would be really cool,” Heimann said.

“I liked being able to see the end goal of making a filter that could be used to address contaminated water,” she said.

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Rice University undergraduate student Jessica Heimann, left, and chemist Andrew Barron led a project in which carbon-60 molecules, aka buckyballs, were treated to allow them to remove valuable but potentially toxic metals from water and other …more

Barron said fullerenols act as chelate agents, which determine how ions and molecules bind with metal ions. Experiments with various metals showed the fullerenols bound with them in less than a minute, after which the combined solids could be filtered out.

Barron said the choices of aluminum, zinc and nickel for testing were due to their co-presence with iron in acid mining drainage water. Similarly, cadmium was tested for its association with fertilizer and sewage sludge and copper with mining discharge. Nickel, lanthanum and neodymium are used in batteries and drive motors in hybrid vehicles.

Barron said the research shows the versatility of the buckyball, discovered at Rice in 1985 by Nobel Prize winners Rick Smalley, Robert Curl and Harold Kroto. It also points the way forward. “The understanding we now have is allowing us to find alternatives to C-60s to design ways in which we can separate out metals more efficiently,” he said.

Explore further: Buckyballs enhance carbon capture: Environmentally friendly material targets flue gases, wells