Tuesday, June 12, 2018

Wastewater Treatment Plants are Key Route into UK Rivers for Microplastics

Date: June 11, 2018
Source: University of Leeds
Summary: Water samples from UK rivers contained significantly higher concentrations of microplastics downstream from wastewater treatment plants, according to one of the first studies to determine potential sources of microplastics pollution.


Water samples from UK rivers contained significantly higher concentrations of microplastics downstream from wastewater treatment plants, according to one of the first studies to determine potential sources of microplastics pollution.

Scientists from the University of Leeds measured microplastics concentrations up and downstream of six wastewater treatment plants and found that all of the plants were linked to an increase in microplastics in the rivers -- on average up to three times higher but in one instance by a factor of 69.

Lead author Dr Paul Kay, from the School of Geography at Leeds, said: "Microplastics are one of the least studied groups of contaminants in river systems. These tiny plastic fragments and flakes may prove to be one of the biggest challenges in repairing the widespread environmental harm plastics have caused. Finding key entry points of microplastics, such as wastewater treatment plants, can provide focus points to combating their distribution.

"However, pervasive microplastics were also found in our upstream water samples. So while strengthening environmental procedures at treatment plants could be a big step in halting their spread, we cannot ignore the other ways microplastics are getting into our rivers."

Microplastics are pieces of plastic with a diameter less than five millimetres. They come from a wide range of materials including tiny plastic beads found in health and beauty products, plastic fibres from clothing and plastic flakes that break down from packaging.

In addition to exposing river ecosystems to the pollutants found in microplastics, a huge quantity continues to flow downstream and is then flushed into the ocean, posing a further threat to marine environments. Recent research has also found microplastics in fish stocks eaten by humans.

The researchers examined 28 river samples from six different field sites across Northern England. The treatment plants included in the study varied in the size of the population they served, the treatment technologies used and the river's characteristics. These variations allowed for a broader understanding of how different factors could affect how much wastewater treatment plants contribute to microplastic pollution.

In addition to treatment plants providing an entry point for microplastics found in both commercial and domestic wastewater, such as clothing and textile microfibers that shed into washing machines, wastewater treatment plants may also contribute secondary microplastics as a result of plastics caught in the treatment process breaking down further.

The study categorised the types of microplastics found, into pellets/beads, fibres and fragments/flakes. Fragment and fibres made up nearly 90% of the microplastics found in the river samples.

"By categorising the types of microplastics we can identify what aspects of our lifestyle are contributing to river pollution," said Dr Kay.

"Not that long ago microbeads in toiletries and cosmetics were the microplastics getting all the public attention. Seeing the amount of plastic microfibres from clothing and textiles polluting our rivers, we need to think seriously about the role of our synthetic fabrics in long-term environmental harm."

Story Source: University of Leeds. "Wastewater treatment plants are key route into UK rivers for microplastics." ScienceDaily. ScienceDaily, 11 June 2018. https://www.sciencedaily.com/releases/2018/06/180611133455.htm

Tuesday, June 5, 2018

Groundwater Pumping Can Increase Arsenic Levels in Irrigation and Drinking Water

Date: June 5, 2018
Source: Stanford University
Summary: Pumping an aquifer to the last drop squeezes out more than water. A new study finds it can also unlock dangerous arsenic from buried clays -- and reveals how sinking land can provide an early warning and measure of contamination.

For decades, intensive groundwater pumping has caused ground beneath California's San Joaquin Valley to sink, damaging infrastructure. Now research published in the journal Nature Communications suggests that as pumping makes the ground sink, it also unleashes an invisible threat to human health and food production: It allows arsenic to move into groundwater aquifers that supply drinking water for 1 million people and irrigation for crops in some of the nation's richest farmland.

The group found that satellite-derived measurements of ground sinking could predict arsenic concentrations in groundwater. This technique could be an early warning system to prevent dangerous levels of arsenic contamination in aquifers with certain characteristics worldwide.

"Arsenic in groundwater has been a problem for a really long time," said lead author Ryan Smith, a doctoral candidate in geophysics at the School of Earth, Energy & Environmental Sciences (Stanford Earth). It's naturally present in Earth's crust and a frequent concern in groundwater management because of its ubiquity and links to heart disease, diabetes, cancer and other illnesses. "But the idea that overpumping for irrigation could increase arsenic concentrations is new," Smith said.

Importantly, the group found signs that aquifers contaminated as a result of overpumping can recover if withdrawals stop. Areas that showed slower sinking compared to 15 years earlier also had lower arsenic levels. "Groundwater must have been largely turned over," said study co-author Scott Fendorf, a professor of Earth system science and a senior fellow at the Stanford Woods Institute for the Environment.

Releasing Arsenic from Clay

The research team analyzed arsenic data for hundreds of wells in two different drought periods alongside centimeter-level estimates of land subsidence, or sinking, captured by satellites. They found that when land in the San Joaquin Valley's Tulare basin sinks faster than 3 inches per year, the risk of finding hazardous arsenic levels in groundwater as much as triples.

Aquifers in the Tulare basin are made up of sand and gravel zones separated by thin layers of clay. The clay acts like a sponge, holding tight to water as well as arsenic soaked up from ancient river sediments. Unlike the sand and gravel layers, these clays contain relatively little oxygen, which creates conditions for arsenic to be in a form that dissolves easily in water.

When pumping draws too much water from the sand and gravel areas, the aquifer compresses and land sinks. "Sands and gravels that were being propped apart by water pressure are now starting to squeeze down on that sponge," Fendorf explained. Arsenic-rich water then starts to seep out and mix with water in the main aquifer.

When water pumping slows enough to put the brakes on subsidence -- and relieve the squeeze on trapped arsenic -- clean water soaking in from streams, rain and natural runoff at the surface can gradually flush the system clean.

However, study co-author Rosemary Knight, a professor of geophysics and affiliated faculty at the Woods Institute, warns against banking too much on a predictable recovery from overpumping. "How long it takes to recover is going to be highly variable and dependent upon so many factors," she said.

The researchers said overpumping in other aquifers could produce the same contamination issues seen in the San Joaquin Valley if they have three attributes: alternating layers of clay and sand; a source of arsenic; and relatively low oxygen content, which is common in aquifers located beneath thick clays.

The threat may be more widespread than once thought. Only in the last few years have scientists discovered that otherwise well-aerated aquifers considered largely immune to arsenic problems can in fact be laced with clays that have the low oxygen levels necessary for arsenic to move into most groundwater. "We're just starting to recognize that this is a danger," said Fendorf.

Satellite Insights

The revelation that remote sensing can raise an alarm before contamination threatens human health offers hope for better water monitoring. "Instead of having to drill wells and take water samples back to the lab, we have a satellite getting the data we need," said Knight.

While well data is important to validate and calibrate satellite data, she explained, on-the-ground monitoring can never match the breadth and speed of remote sensing. "You're never sampling a well frequently enough to catch that arsenic the moment it's in the well," said Knight. "So how fantastic to have this remote sensing early warning system to let people realize that they're approaching a critical point in terms of water quality."

The study builds on research led in 2013 by Laura Erban, then a doctoral student working in Vietnam's Mekong Delta. "That's where we started saying, 'Oh no,'" said Fendorf, who co-authored that paper.

As in the San Joaquin Valley, areas of the Mekong Delta where land was sinking more showed higher arsenic concentrations. "Now we have two sites in totally different geographic regions where the same mechanisms appear to be operating," said Fendorf. "That sends a trigger that we need to be thinking about managing groundwater and making sure that we're not overdrafting the aquifers."

Story Source:
Stanford University. "Groundwater pumping can increase arsenic levels in irrigation and drinking water." ScienceDaily. ScienceDaily, 5 June 2018.

Friday, February 16, 2018

Tiny Membrane Key to Safe Drinking Water

Date: February 14, 2018
Source: CSIRO Australia
Summary: Using their own specially designed form of graphene, 'Graphair' scientists have supercharged water purification, making it simpler, more effective and quicker.

Sydney's iconic harbour has played a starring role in the development of new CSIRO technology that could save lives around the world.

Using their own specially designed form of graphene, 'Graphair', CSIRO scientists have supercharged water purification, making it simpler, more effective and quicker.

The new filtering technique is so effective, water samples from Sydney Harbour were safe to drink after passing through the filter.

The breakthrough research was published today in Nature Communications.

"Almost a third of the world's population, some 2.1 billion people, don't have clean and safe drinking water," the paper's lead author, CSIRO scientist Dr Dong Han Seo said.

"As a result, millions -- mostly children -- die from diseases associated with inadequate water supply, sanitation and hygiene every year.

"In Graphair we've found a perfect filter for water purification. It can replace the complex, time consuming and multi-stage processes currently needed with a single step."

While graphene is the world's strongest material and can be just a single carbon atom thin, it is usually water repellent.

Using their Graphair process, CSIRO researchers were able to create a film with microscopic nano-channels that let water pass through, but stop pollutants.

As an added advantage Graphair is simpler, cheaper, faster and more environmentally friendly than graphene to make.

It consists of renewable soybean oil, more commonly found in vegetable oil.

Looking for a challenge, Dr Seo and his colleagues took water samples from Sydney Harbour and ran it through a commercially available water filter, coated with Graphair.

Researchers from QUT, the University of Sydney, UTS, and Victoria University then tested and analysed its water purification qualities.

The breakthrough potentially solves one of the great problems with current water filtering methods: fouling.

Over time chemical and oil based pollutants coat and impede water filters, meaning contaminants have to be removed before filtering can begin. Tests showed Graphair continued to work even when coated with pollutants.

Without Graphair, the membrane's filtration rate halved in 72 hours.

When the Graphair was added, the membrane filtered even more contaminants (99 per cent removal) faster.

"This technology can create clean drinking water, regardless of how dirty it is, in a single step," Dr Seo said.

"All that's needed is heat, our graphene, a membrane filter and a small water pump. We're hoping to commence field trials in a developing world community next year."

CSIRO is looking for industry partners to scale up the technology so it can be used to filter a home or even town's water supply.

It's also investigating other applications such as the treatment of seawater and industrial effluents.

Story Source:
CSIRO Australia. "Tiny membrane key to safe drinking water." ScienceDaily. ScienceDaily, 14 February 2018. https://www.sciencedaily.com/releases/2018/02/180214181846.htm.

Wednesday, February 14, 2018

Pride Tops Guilt as a Motivator for Environmental Decisions

Date: February 13, 2018
Source: Princeton University, Woodrow Wilson School of Public and International Affairs
Summary: A lot of pro-environmental messages suggest that people will feel guilty if they don't make an effort to live more sustainably or takes steps to ameliorate climate change. But a recent study finds that highlighting the pride people will feel if they take such actions may be a better way to change environmental behaviors.

A lot of pro-environmental messages suggest that people will feel guilty if they don't make an effort to live more sustainably or takes steps to ameliorate climate change. But a recent study from Princeton University finds that highlighting the pride people will feel if they take such actions may be a better way to change environmental behaviors.

Elke U. Weber, a professor of psychology and public affairs at Princeton's Woodrow Wilson School of Public and International Affairs, conducted the study -- which appears in the academic journal PLOS ONE -- along with Ph.D. candidate Claudia R. Schneider (who is visiting Princeton's Department of Psychology through the Ivy League Exchange Scholar Program) and colleagues at Columbia University and the University of Massachusetts Amherst.

Past research has shown that anticipating how one will feel afterward plays a big role in decision-making -- particularly when making decisions that affect others. "In simple terms, people tend to avoid taking actions that could result in negative emotions, such as guilt and sadness, and to pursue those that will result in positive states, such as pride and joy," said Weber, who also is the Gerhard R. Andlinger Professor in Energy and the Environment.

Pro-environmental messaging sometimes emphasizes pride to spur people into action, Weber said, but it more often focuses on guilt. She and her colleagues wondered which is the better motivator in this area. To find out, they asked people from a sample of 987 diverse participants recruited through Amazon's Mechanical Turk platform to think about either the pride they would feel after taking pro-environmental actions or the guilt they would feel for not doing so, just before making a series of decisions related to the environment.

The participants were prompted to think about future pride or guilt by one of three methods. Some were given a one-sentence reminder -- which remained at the top of their computer screens as they completed a survey -- that their environmental choices might make them either proud or guilty. Others were given five environmentally friendly or unfriendly choice scenarios and asked to consider how making each choice might make them feel pride or guilt. Still others were asked to write a brief essay reflecting on their future feelings of pride or guilt over a real upcoming environmental decision. In the end, there were six groups: one for each of the three reflection methods and within each one section that considered future pride and another that reflected on future guilt.

Next, the participants were asked to make five sets of choices, each with "green" (environmentally friendly) or "brown" (environmentally unfriendly) options. In one scenario, for example, they could choose a sofa made from environmentally friendly fabric but available only in outdated styles, or they could pick a more modern style of sofa made from fabric produced with harsh chemicals. In another scenario, they could pick any or all of 14 green amenities for an apartment (such as an Energy Star-rated refrigerator), with the caveat that each one added $3 per month to the rent. A control group made the same decisions without being prompted to think about future pride or guilt.

The results revealed a clear pattern across all of the groups. "Overall," Weber said, "participants who were exposed to anticipation of pride consistently reported higher pro-environmental intentions than those exposed to anticipated guilt."

A likely explanation, she said -- one that's backed up by a great deal of past research -- is that some people react badly and get defensive when they're told they should feel guilty about something, making them less likely to follow a desired course of action. Thus, guilt-based environmental appeals run the risk of backfiring.

"Because most appeals for pro-environmental action rely on guilt to motivate their target audience, our findings suggest a rethinking of environmental and climate change messaging" to harness the power of positive emotions like pride, Weber said.

Story Source:
Princeton University, Woodrow Wilson School of Public and International Affairs. "Pride tops guilt as a motivator for environmental decisions." ScienceDaily. ScienceDaily, 13 February 2018. https://www.sciencedaily.com/releases/2018/02/180213120429.htm

Tuesday, January 16, 2018

A Biological Solution to Carbon Capture and Recycling?

E. coli bacteria shown to be excellent at CO2 conversion


Date: January 8, 2018
Source: University of Dundee
Summary: Scientists have discovered that E. coli bacteria could hold the key to an efficient method of capturing and storing or recycling carbon dioxide. They have developed a process that enables the E. coli bacterium to act as a very efficient carbon capture device.


Rendering of bacteria.
Credit: © 7activestudio / Fotolia

Scientists at the University of Dundee have discovered that E. coli bacteria could hold the key to an efficient method of capturing and storing or recycling carbon dioxide.

Cutting carbon dioxide (CO2) emissions to slow down and even reverse global warming has been posited as humankind's greatest challenge. It is a goal that is subject to considerable political and societal hurdles, but it also remains a technological challenge.

New ways of capturing and storing CO2 will be needed. Now, normally harmless gut bacteria have been shown to have the ability to play a crucial role.

Professor Frank Sargent and colleagues at the University of Dundee's School of Life Sciences, working with local industry partners Sasol UK and Ingenza Ltd, have developed a process that enables the E. coli bacterium to act as a very efficient carbon capture device.

Professor Sargent said, "Reducing carbon dioxide emissions will require a basket of different solutions and nature offers some exciting options. Microscopic, single-celled bacteria are used to living in extreme environments and often perform chemical reactions that plants and animals cannot do.

"For example, the E. coli bacterium can grow in the complete absence of oxygen. When it does this it makes a special metal-containing enzyme, called 'FHL', which can interconvert gaseous carbon dioxide with liquid formic acid. This could provide an opportunity to capture carbon dioxide into a manageable product that is easily stored, controlled or even used to make other things. The trouble is, the normal conversion process is slow and sometime unreliable.

"What we have done is develop a process that enables the E. coli bacterium to operate as a very efficient biological carbon capture device. When the bacteria containing the FHL enzyme are placed under pressurised carbon dioxide and hydrogen gas mixtures -- up to 10 atmospheres of pressure -- then 100 per cent conversion of the carbon dioxide to formic acid is observed. The reaction happens quickly, over a few hours, and at ambient temperatures.

"This could be an important breakthrough in biotechnology. It should be possible to optimize the system still further and finally develop a 'microbial cell factory' that could be used to mop up carbon dioxide from many different types of industry.

"Not all bacteria are bad. Some might even save the planet."

Not only capturing carbon dioxide but storing or recycling it is a major issue. There are millions of tonnes of CO2 being pumped into the atmosphere every year. For the UK alone, the net emission of CO2 in 2015 was 404 million tonnes. There is a significant question of where can we put it all even if we capture it, with current suggestions including pumping it underground in to empty oil and gas fields.

"The E. coli solution we have found isn't only attractive as a carbon capture technology, it converts it into a liquid that is stable and comparatively easily stored," said Professor Sargent.

"Formic acid also has industrial uses, from a preservative and antibacterial agent in livestock feed, a coagulant in the production of rubber, and, in salt form, a de-icer for airport runways. It could also be potentially recycled into biological processes that produce CO2, forming a virtuous loop."

Story Source:
University of Dundee. "A biological solution to carbon capture and recycling? E. coli bacteria shown to be excellent at CO2 conversion." ScienceDaily. ScienceDaily, 8 January 2018. https://www.sciencedaily.com/releases/2018/01/180108101359.htm

Friday, January 5, 2018

One-Step Catalyst Turns Nitrates into Water and Air

Date: January 4, 2018
Source: Rice University
Summary: Engineers have found a catalyst the cleans toxic nitrates from drinking water by converting them into air and water.


Rice University's indium-palladium nanoparticle catalysts clean nitrates from drinking water by converting the toxic molecules into air and water.
Credit: Jeff Fitlow/Rice University

The research is available online in the American Chemical Society journal ACS Catalysis.

"Nitrates come mainly from agricultural runoff, which affects farming communities all over the world," said Rice chemical engineer Michael Wong, the lead scientist on the study. "Nitrates are both an environmental problem and health problem because they're toxic. There are ion-exchange filters that can remove them from water, but these need to be flushed every few months to reuse them, and when that happens, the flushed water just returns a concentrated dose of nitrates right back into the water supply."

Wong's lab specializes in developing nanoparticle-based catalysts, submicroscopic bits of metal that speed up chemical reactions. In 2013, his group showed that tiny gold spheres dotted with specks of palladium could break apart nitrites, the more toxic chemical cousins of nitrates.

"Nitrates are molecules that have one nitrogen atom and three oxygen atoms," Wong explained. "Nitrates turn into nitrites if they lose an oxygen, but nitrites are even more toxic than nitrates, so you don't want to stop with nitrites. Moreover, nitrates are the more prevalent problem.

"Ultimately, the best way to remove nitrates is a catalytic process that breaks them completely apart into nitrogen and oxygen, or in our case, nitrogen and water because we add a little hydrogen," he said. "More than 75 percent of Earth's atmosphere is gaseous nitrogen, so we're really turning nitrates into air and water."

Nitrates are toxic to infants and pregnant women and may also be carcinogenic. Nitrate pollution is common in agricultural communities, especially in the U.S. Corn Belt and California's Central Valley, where fertilizers are heavily used, and some studies have shown that nitrate pollution is on the rise due to changing land-use patterns.

Both nitrates and nitrites are regulated by the Environmental Protection Agency, which sets allowable limits for safe drinking water. In communities with polluted wells and lakes, that typically means pretreating drinking water with ion-exchange resins that trap and remove nitrates and nitrites without destroying them.

From their previous work, Wong's team knew that gold-palladium nanoparticles were not good catalysts for breaking apart nitrates. Co-author Kim Heck, a research scientist in Wong's lab, said a search of published scientific literature turned up another possibility: indium and palladium.

"We were able to optimize that, and we found that covering about 40 percent of a palladium sphere's surface with indium gave us our most active catalyst," Heck said. "It was about 50 percent more efficient than anything else we found in previously published studies. We could have stopped there, but we were really interested in understanding why it was better, and for that we had to explore the chemistry behind this reaction."

In collaboration with chemical engineering colleagues Jeffrey Miller of Purdue University and Lars Grabow of the University of Houston, the Rice team found that the indium speeds up the breakdown of nitrates while the palladium apparently keeps the indium from being permanently oxidized.

"Indium likes to be oxidized," Heck said. "From our in situ studies, we found that exposing the catalysts to solutions containing nitrate caused the indium to become oxidized. But when we added hydrogen-saturated water, the palladium prompted some of that oxygen to bond with the hydrogen and form water, and that resulted in the indium remaining in a reduced state where it's free to break apart more nitrates."

Wong said his team will work with industrial partners and other researchers to turn the process into a commercially viable water-treatment system.

"That's where NEWT comes in," he said. "NEWT is all about taking basic science discoveries and getting them deployed in real-world conditions. This is going to be an example within NEWT where we have the chemistry figured out, and the next step is to create a flow system to show proof of concept that the technology can be used in the field."

NEWT is a multi-institutional engineering research center based at Rice that was established by the National Science Foundation in 2015 to develop compact, mobile, off-grid water-treatment systems that can provide clean water to millions of people and make U.S. energy production more sustainable and cost-effective. NEWT is expected to leverage more than $40 million in federal and industrial support by 2025 and is focused on applications for humanitarian emergency response, rural water systems and wastewater treatment and reuse at remote sites, including both onshore and offshore drilling platforms for oil and gas exploration.

Additional study co-authors include Sujin Guo, Huifeng Qian and Zhun Zhao, all of Rice, and Sashank Kasiraju of the University of Houston. The research was funded by the National Science Foundation, the Department of Energy and the China Scholarship Council.

Source: Rice University. "One-step catalyst turns nitrates into water and air." ScienceDaily. ScienceDaily, 4 January 2018. www.sciencedaily.com/releases/2018/01/180104160819.htm