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More eco-friendly desalination

May 14, 2025 By EarthWise Leave a Comment

There are about 16,000 operational desalination plants, located across 177 countries, which generate an estimated 25 billion gallons of fresh water daily.

For every gallon of drinking water produced at a typical desalination plant, one and a half gallons of brine are produced. Much of it is stored in ponds until the water evaporates, leaving behind solid salt or concentrated brine for further treatment. There are various other techniques for concentrating brines, but they are energy-intensive and environmentally problematic. The process called electrodialysis uses electrified membranes to concentrate salts.

Water flows into many channels separated by membranes, each of which has the opposite electrical charge of its neighbors. Positive salt ions move towards negatively charged electrodes and negative ions move toward positive electrodes. Two streams result, one containing purified water and one containing concentrated brine.

This eliminates the need for evaporation ponds, but existing electrodialysis membranes either result in leakage of salts into the environment or are too slow, making the process impractical for large-scale use.

Researchers at the University of Michigan have developed a new kind of membrane for electrodialysis. The new membranes don’t leak and are ten times more conductive than those on the market today which means that they can move more salt using less power. The membranes can be customized to suit a broad range of water types, which may help make desalination a more sustainable solution to the world’s growing water crisis.

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Making desalination more eco-friendly: New membranes could help eliminate brine waste

Photo, posted February 4, 2012, courtesy of David Martinez Vicente via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A new way to help purify water

February 27, 2025 By EarthWise Leave a Comment

Engineers at the University of Michigan and Rice University have developed a new technology for removing boron from seawater, an important step in turning seawater into safe drinking water.

Boron is a natural component of seawater that remains a toxic contaminant in drinking water after conventional filters remove salts from seawater. The boron levels in seawater are about twice as high as the World Health Organization’s most lenient limits for safe drinking water and 5 to 12 times higher than what many agricultural plants can tolerate.

Boron passes through the reverse osmosis membranes used in desalination plants in the form of boric acid. To remove it, the desalination plants normally add a base to the treated water that causes the boric acid to become negatively charged. An additional membrane then removes the charged boron, and an acid is then added to neutralize the water. All of this is expensive and complicated.

The new technology uses electrodes that remove boron by trapping it inside pores studded with oxygen-containing structures that bind with boron but let other ions pass through. Capturing boron with electrodes enables treatment plants to avoid the need for a second stage of reverse osmosis.

Global desalination capacity reached 95 million cubic meters a day in 2019. The new membranes could save nearly $7 billion a year. Such savings could make seawater a more accessible source of drinking water for a thirsty world. Freshwater supplies are expected to meet only 40% of the world’s demand by 2030.

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New water purification technology helps turn seawater into drinking water without tons of chemicals

Photo, posted August 21, 2018, courtesy of Alachua County via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Marine carbon dioxide removal

May 23, 2024 By EarthWise Leave a Comment

About 30% of the carbon dioxide emitted by human activity is absorbed by the oceans. As a result, they are getting warmer and more acidic, and the currents that help shape global weather are shifting. To try to reduce global warming, people want to be able to store even more carbon dioxide in the oceans without the negative effects of doing so.

There are multiple efforts across the globe to achieve effective marine carbon dioxide removal. Some are based on sinking carbon-rich materials to the bottom of the sea. This is the marine equivalent of capturing CO2 from the air and storing it underground. Other efforts involve increasing the alkalinity of the ocean, which increases its ability to chemically react with carbon dioxide as well as lowers its acidity, which is desirable in many ways.

Running Tide, a U.S.-based company, has been dumping thousands of tons of wood-industry waste 190 miles off the coast of Iceland. The company has also been experimenting with dumping algae and kelp and sinking it deep below the ocean. Such materials on land either get burned or decay, in both cases releasing CO2 into the atmosphere. On the deep-sea bottom, the carbon is trapped.

Other efforts involve pumping seawater through electrodialysis filter systems to remove excess acidity or adding alkaline rocks to increase water alkalinity.

All of these efforts are a form of geoengineering, and like proposed ideas to cool the atmosphere, pose potential risks. There is no silver bullet to solve the climate crisis. It will take a combination of many solutions to address the issue of excess carbon dioxide in the atmosphere. Marine carbon dioxide removal is one of the solutions that may play a role.

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Scientists Are Trying to Coax the Ocean to Absorb More CO2

Photo, posted February 22, 2018, courtesy of Bobbie Halchishak/USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Glacier Loss Day | Earth Wise

October 9, 2023 By EarthWise Leave a Comment

Glaciers are sensitive indicators of climate change that respond to changes in both temperature and precipitation. But they are not only affected by climate change, they also affect climate change. As glaciers melt, they contribute to sea level rise, alter regional hydrology, and influence the global energy balance.

A group of glacier experts from the University of Innsbruck in Austria introduced a concept called “Glacier Loss Day” or GLD as a way to measure the annual mass balance of glaciers. Mass balance is the difference between the amount of snow and ice that accumulates on a glacier and the amount that melts or sublimates. If the mass balance is positive, the glacier is growing. If the mass balance is negative, the glacier is shrinking.

GLD is the day during the year when the glacier has lost all the mass it gained during previous winter. This is a similar concept to Earth Overshoot Day, which marks the date when humankind’s demand for ecological resources exceeds the amount the planet can regenerate during the year.

The Hintereisferner, a glacier in the Tyrolean Alps, has been monitored for more than 100 years and there are continuous records of its mass balance since 1952. In 2022, the GLD on the Hintereisferner was measured on the 23^rd of June. In the two previous years, it was reached in the middle of August. Even in years with large negative balances, such as 2003 and 2018, GLD did not occur until the end of July.

Every summer in the future may not be like 2022, but the trend is clear. Climate change is taking its toll on glaciers. Experts project that the Hintereisferner will lose half of its volume in the next 10 to 20 years.

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Glacier Loss Day indicates record breaking glacier melt

Photo, posted July 20, 2023, courtesy of Pedro Szekely via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Humanity Weighs On The World | Earth Wise

April 6, 2023 By EarthWise Leave a Comment

There are countless ways in which humankind has had disproportionate effects on our planet and most of those effects have been negative. A recent study led by the Weizmann Institute of Science in Israel looked at the total combined weight of various groups of mammals on Earth. The results are that human beings and our domesticated mammals are the overwhelming majority of the total mass of mammals.

We think of large land mammals – elephants, bears, bison, wildebeests, and so on – as adding up to a massive amount of animal matter. The study determined that all wild land mammals put together add up to about 22 million metric tons. Wild marine mammals – such as dolphins and whales – add up to about 40 million tons in total. These sound like pretty big numbers until we look at the human and human-created side of the equation.

The study found that humans weigh about 390 million metric tons, while domesticated mammals – like sheep, cows, and pigs as well as dogs and cats – weigh about 630 million metric tons combined.

All told, wild mammals account for only 6% of all mammals by weight. People and their domesticated animals make up the other 94%. This enormous imbalance is an indication of how profoundly humans have reshaped life on Earth. House cats total twice the weight of African elephants and pigs add up to twice the weight of all wild land animals combined.

The conclusion to draw from the big picture here is that wild animals on Earth are not doing very well. We already knew this from many other perspectives, but this census by weight presents a stark picture of the extent to which we have taken over the planet and its ecosystems.

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Total Weight of Wild Land Mammals Less Than One-Tenth Weight of All Humans

Photo, posted December 27, 2006, courtesy of Nigel Hoult via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Science And False Beliefs

January 21, 2019 By EarthWise Leave a Comment

There are sizeable numbers of people who hold to beliefs that run counter to overwhelming contrary evidence. Flat Earthers and Holocaust deniers are well-known examples and, more recently, people – some of them in high places – who reject the evidence for climate change.

New research published in the journal Open Mind by developmental psychologists at UC Berkeley suggest that feedback, rather than hard evidence, boosts people’s sense of certainty when learning new things or trying to tell right from wrong. People’s beliefs are more likely to be reinforced by the positive or negative reactions they are exposed to than by logic, reasoning, and scientific data.

People’s learning habits can limit one’s intellectual horizons. According to the study, if you think you know a lot about something, even though you don’t, you’re less likely to be curious enough to explore the topic further and will fail to learn how little you know.

This phenomenon plays out in social media and cable-news echo chambers and explains how some people are easily duped by charlatans. Receiving positive feedback for what they are saying can make people believe they know more than they actually do. This confidence makes them less likely to seek out and learn more information about the subject, as well as take into account contradicting opinions or facts.

Another factor is that what influences people’s certainty is that their confidence tends to depend on what they heard most recently rather than on long-term cumulative data. A few pieces of recent information tend to get much more attention than an extensive body of data. If a crazy theory is able to make a correct prediction a few times, people tend to get fixed in their belief in that theory and be less open to other information.

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Here’s Why People Advocate False Beliefs, Conspiracy Theories Despite Evidence

Photo, posted February 2, 2007, courtesy of Tim J. Keegan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Australian Plastic Bag Ban

December 31, 2018 By EarthWise Leave a Comment

Last summer, the two largest supermarket chains in Australia – Coles and Woolworth’s – decided to stop offering single-use disposable plastic bags to customers. The initial public reaction was decidedly negative. However, within just three months after the radical change, the country’s National Retail Association reported an 80% drop in the consumption of plastic bags nationwide.

In that three-month period, it is estimated that 1.5 billion bags have been prevented from use. Some retailers are reporting reduction rates as high as 90% in the use of the bags. The move by the big supermarkets has paved the way for smaller businesses to follow suit. The smaller businesses typically can’t afford to risk the wrath of their customers with a major change like this. Customers have to learn to bring their own bags or buy reusable bags at the store.

In much of Australia, the phase-out of plastic bags has been legislated, but the state of New South Wales, home to Sydney, the country’s largest city, has not enacted such legislation. So, supermarkets themselves are doing the work of getting rid of the bags.

The change has not been without hiccups. For the first couple of months after the plastic bag ban was put in place, Woolworth’s saw poor sales in its stores. However, customers eventually got used to the new way of doing things and sales levels returned.

Disposable plastic bags often find their way into the oceans where they break down into microparticles. Studies have shown that these plastic bits are ingested by a wide variety of marine life. For example, a UK study found that 100% of sea turtles in the Pacific and Atlantic oceans as well as the Mediterranean Sea had plastic in their digestive systems.

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Australia-wide ban leads to ’80 per cent drop’ in plastic bag consumption

Photo, posted September 18, 2018, courtesy of Matthew Paul Argall via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Measuring Earth’s Outgoing Energy

October 2, 2017 By EarthWise Leave a Comment

The earth’s energy imbalance is the difference between the amount of solar energy absorbed by the earth and the amount of energy the planet radiates back into space as heat. If the imbalance is positive, that is, if more energy is coming in than going out, then the earth will get warmer over time. If the imbalance is negative, then the planet will get cooler.