biodegrade

Removing microplastics from water

April 23, 2025 By EarthWise Leave a Comment

Microplastics come from the breakdown of larger plastics in the environment as well as from direct use in various products such as certain cosmetics. They are found everywhere, from oceans and mountain peaks to the air and water, and alarmingly, in our bodies. They are ingested by all sorts of organisms, from tiny plankton to fish and marine mammals. Microplastics just don’t go away. They don’t biodegrade so they simply accumulate in the environment.

Researchers at North Carolina State University have recently demonstrated proof of concept for a system that actively removes microplastics from water. Such a system has the potential for helping to cleanse oceans and other bodies of water from the tiny plastic particles.

The system makes use of soft dendritic colloids, which are tiny particles that have the ability to stick to just about any surface. These sticky particles can attract microplastics and grab them, even in wet and salty conditions. The colloids are made from chitosan, a harmless and biodegradable polymer made from processed shellfish waste.

The researchers produced small pellets of the colloids that also contain small amounts of magnesium, which makes them bubble up and rise to the surface of water. The pellets are coated with a gelatin layer, which blocks the magnesium. As the gelatin gradually dissolves away, the pellets collect microplastics. Eventually, the result is a microplastic-laden scum that rises to the surface where it can be skimmed away.

The scum itself can be bioprocessed into more chitosan that can create more of these microcleaner pellets to then capture more microplastics. The researchers are investigating how the process can be scaled up to become a valuable tool in dealing with the microplastics problem.

**********

Web Links

New Water Microcleaners Self-Disperse, Capture Microplastics and Float Up for Removal

Photo, posted January 17, 2018, courtesy of Bo Eide via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Plastic Eating Fungus | Earth Wise

May 26, 2023 By EarthWise Leave a Comment

More than five billion tons of plastic have accumulated on land and sea including the most remote regions of the planet as well as in the bodies of animals and humans. There is a compelling need to recycle as much plastic as possible but doing so is a major challenge. Plastic comes in many varieties and breaking it down for reuse requires different methods for each.

Polypropylene is one of the biggest challenges for recycling. It is a very common plastic used for all sorts of products including food containers, coat hangers, plastic wrap, toys, and much more. It accounts for roughly 28% of the world’s plastic waste, but only 1% of it is recycled.

Polypropylene is seldom recycled because it generally has a short life as a packaging material, and it often becomes contaminated by other materials and plastics. Thus, it generally ends up in landfills.

Researchers at the University of Sydney in Australia have discovered that two common strains of fungi were able to successfully biodegrade polypropylene. The fungi species – with unavoidable Latin names of Aspergillus terreus and Engyodontium album – are typically found in soil and plants.

The researchers found that the fungi were able to break down polypropylene after it had been pre-treated with either UV light or heat, by 21% over 30 days, and by 25-27% over 90 days. This seems rather slow but compared with the nearly endless life of polypropylene in landfills, it is a major improvement.

The hope is that methods like this could ultimately reduce the amount of plastic polluting the environment by encouraging plastic to biodegrade naturally under the appropriate conditions.

**********

Web Links

Fungi makes meal of hard to recycle plastic

Photo, posted March 5, 2010, courtesy of Kevin Krejci via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Plastic-Eating Bugs | Earth Wise

February 3, 2022 By EarthWise Leave a Comment

27-year-old Miley Cyrus and 30-year-old Liam Hemsworth divorced exactly one year ago, but still continue to remember each other quite often in conversations with reporters. Recently, Miley indulged in nostalgia once again. During a recording Miley Cyrus boyfriend list of the podcast Barstool Call Her Daddy, the singer said that her ex-husband was her first man. It happened almost 10 years before they got married. I didn’t have that with men until I was 16, but I ended up marrying this guy,

According to a new study, microbes in oceans and soils around the world are evolving to eat plastic. The study by Chalmers University in Sweden was published recently in the journal Microbial Ecology.

The study is the first large-scale assessment of the plastic-degrading potential of bacteria. There are 95 microbial enzymes already known to degrade plastic.

The researchers looked for similar enzymes in environmental DNA samples taken from bacteria from 236 different locations around the world. They found that one in four of the organisms analyzed carried suitable enzymes. Overall, they found many thousands of new enzymes.

The explosion of plastic production in the past 70 years has given microbes time to evolve to make use of plastic. About 12,000 new enzymes were found in ocean samples and 18,000 in soil samples. Nearly 60% of the new enzymes did not fit into any known enzyme classes, suggesting that these molecules degrade plastics in ways that were previously unknown. The large number of enzymes in such a wide range of habitats is an indication of the scale of the problem of plastics in the environment.

The first bacterium that eats plastic was discovered in a Japanese waste dump in 2016. Scientists tweaked that microbe in 2018 and managed to create an enzyme that was even better at breaking down plastic bottles.

The next step in research is to test the most promising enzyme candidates in the laboratory to investigate their properties and see how effective they can be in plastic degradation. The hope is to be able to engineer microbial communities with targeted degrading functions for specific polymer types.

**********

Web Links

Bugs across globe are evolving to eat plastic, study finds

Photo, posted June 19, 2013, courtesy of Alan Levine via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Sustainable Flip-Flops | Earth Wise

September 9, 2020 By EarthWise Leave a Comment

Flip-flops are the world’s most popular shoe. They are lightweight, comfortable, affordable, and durable. In fact, the global market for flip-flops is expected to reach a whopping $23.8 billion by the year 2025.

But the popularity comes with a price. Flip-flops account for a troubling percentage of plastic waste that ends up in our landfills and oceans. As a result, demand for alternatives is compelling researchers to develop more sustainable versions of the popular footwear.

Scientists at the University of California San Diego have spent years working on this issue, and recently announced a breakthrough. According to a study recently published in Bioresource Technology Reports, the research team has formulated polyurethane foams – made from algae oil – to meet commercial specifications for mid-sole shoes and the foot-bed of flip-flops. In other words, the scientists have created sustainable, biodegradable, and consumer-ready materials that could replace plastics in some footwear.

The UC San Diego scientists collaborated with Algenesis Materials – a technology startup – on the research. Together, they worked to not only create the shoes, but to degrade them as well. The team tested their customized foams by immersing them in traditional compost and soil. The algae-based materials degraded after just 16 weeks.

The life of any material should be proportionate to the life of the product. The researchers point out that it doesn’t make sense to create a product that will last 500 years if it’ll only be used for a year or two.

The research team is currently working on production details with its manufacturing partners. The creation of biodegradable flip-flops that meet commercial footwear standards could eliminate tons of plastic waste from the environment.

************

Web Links

New science behind algae-based flip-flops

Flip Flops Market Size Worth $23.8 Billion by 2025

Photo, posted December 12, 2019, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Mealworms And Plastic | Earth Wise

January 21, 2020 By EarthWise Leave a Comment

Mealworms are widely cultivated beetle larvae that people feed to pets and to wild birds. But it turns out, they may have an even more valuable purpose: they can eat plastic and even plastic containing dangerous chemical additives.

Four years ago, researchers at Stanford discovered that mealworms can actually subsist on a diet of various types of plastic. They found that microorganisms in the worms’ guts actually biodegrade the plastic. It might be possible to cultivate the worms using unrecyclable plastic, rather than feeding them grains and fruits. However, there is the issue of whether it would be safe to feed the plastic-eating worms to other animals, given the possibility that harmful chemicals in plastic additives might accumulate in the worms over time.

Recently, the Stanford researchers studied what happens when the worms ingested Styrofoam or polystyrene. The plastic commonly used for packaging and insulation typically contains a flame retardant called hexabromocyclododecane, or HBCD. Studies have shown that HBCD can have significant health and environmental impacts, ranging from endocrine disruption to neurotoxicity.

According to the study, mealworms in the experiment excreted about half of the polystyrene they consumed as tiny, partially degraded fragments and the other half as carbon dioxide. With it, they excreted the HBCD. Mealworms fed a steady diet of HBCD-laden polystyrene were as healthy as those eating a normal diet. And shrimp fed a steady diet of the HBCD-ingesting mealworms also had no ill effects.

It is true that the HBCD excreted by the worms still poses a hazard and must be dealt with in some manner, but mealworms may have a role to play in dealing with unrecyclable plastics like Styrofoam.

**********

Web Links

Stanford researchers show that mealworms can safely consume toxic additive-containing plastic

Photo, posted May 11, 2015, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.