Cleaning up the Plastics Mess. What Role Do Engineers Play?
Tom Spendlove posted on October 15, 2019 |

The 2016 Project Mainstream report The New Plastics Economy makes our future look grim. One of the main goals of the report was to provide a “comprehensive global perspective of the broader plastic packaging economy” along with a discussion about how much plastic we create and where that plastic has been landing over time.

In 2025 oceans could contain one ton of plastic for every three tons of fish.
In 2025 oceans could contain one ton of plastic for every three tons of fish.

One particularly concerning part of the report is a section about ocean plastics—at least eight million tons of plastics leak into the ocean every year. The report uses the analogy of one garbage truck full of plastics emptying into the ocean each minute, with that number doubling by 2030 and quadrupling by 2050. In 2025 oceans could contain one ton of plastic for every three tons of fish, and by 2050 the plastic could outnumber the fish.

As the oceans build up with more and more plastic, the oceans’ inhabitants are also suffering. A June 2019 study published in the Royal Society B that focused on Astrangia poculata temperate coral in the Atlantic Ocean found more than 100 microplastic particles per polyp in coral colonies. A disappointing finding of the study was that these coral preferred microplastic beads over brine shrimp eggs of the same size when offered a choice of food. Another article in Environmental Pollution looked at the 11 billion plastic pieces estimated to be spread along the Asia-Pacific ocean region, focusing on nylon, polyester and polypropylene and the sea anemone species Aiptasia pallida. The study found that while anemone did not ingest any polyester or polypropylene microfibers when offered these materials alone, more than 80 percent of the animals ingested the microfibers when a shrimp homogenate was added. Matthew Savoca’s  study on anchovies in 2017 found that plastic debris odors could stimulate a foraging behavior in anchovy schools, but only in medium to high concentrations of plastic debris. This had the possible cause of leading anchovies to seek out large clumps of plastic debris as food, with the potential of pushing the plastic further up the food chain into seabirds, fish and sea turtles.

All of this plastic pollution creates challenges that we engineers can work to overcome, and several of us are already hard at work on finding solutions. Starting from the wide global view and production side, The New Plastics Economy is a movement to create a circular economy for plastic.

Unnecessary plastic packaging is eliminated with the Ellen MacArthur Foundation’s five-part Vision. (Image courtesy of the Ellen MacArthur Foundation.)
Unnecessary plastic packaging is eliminated with the Ellen MacArthur Foundation’s five-part Vision. (Image courtesy of the Ellen MacArthur Foundation.)

The Ellen MacArthur Foundation leads the initiative with an ambitious Vision proposal, where unnecessary plastic packaging is eliminated; all plastic packaging is completely reusable, recyclable or compostable; all plastic use does not consume finite resources; and plastic packaging is free from hazardous chemicals during production, use and reuse. The Vision’s circular economy focuses on five main ideas:

  1. The Dialogue Mechanism to collection companies and cities around the world to perform the projects
  2. The Global Plastics Protocol to develop targets for plastic use and production
  3. The Innovation required to globally change the way we use plastics
  4. The Evidence Base to show economic and scientific progress and challenges
  5. The Stakeholder Engagement to bring academics, governments, NGOs and industry members together to work on the projects.

The consumer side of the ocean plastic problem revolves around removing the plastic microbeads and microfibers currently in the oceans. On a smaller but still ambitious scale, several plastic cleaning projects are entered into the Google Science Fair each year. The Grand Prize winner of the 2018-2019 Science Fair was Fionn Ferreira from Ireland, who won with his project, An Investigation Into the Removal of Microplastics from Water Using Ferrofluids. Ferreira was concerned that very little microplastics filtering was occurring in European wastewater treatment centers and took inspiration from an article outlining iron oxide as a tool for cleaning oil spills. After building a visible light spectrometer to measure microplastic concentrations, Ferreira used a microscope and visual counting as a secondary testing method.

Testing was done by adding magnetite powder and oil to a water sample containing microplastics, then agitating the sample to allow the materials to mix, and finally using a neodymium magnet to remove the oil and magnetite from the samples. Ferreira’s testing found that the average quantity of microplastics removed from the samples was 87.6 percent. A nice addition to this project is that Ferreira used free spectrometry software called Spectragryph that we covered here onengineering.com back in 2016.

India, with plastic consumption that is one-tenth of the U.S., pays Kerala fishermen for the plastic trash their nets drag in. (Image courtesy of Economic Times.)
India, with plastic consumption that is one-tenth of the U.S., pays Kerala fishermen for the plastic trash their nets drag in. (Image courtesy of Economic Times.)

Progress isn’t just being made in big cities and by big industries. Indian fisherman in Kerala drag trawler nets that catch plastic refuse along with fish. Fisheries minister J. Mercykutty Amma devised the Suchitwa Sagaram (Clean Sea) campaign that pays the fisherman to remove the plastic from the ocean. As of 2018 the 28 members of the fishing villages had collected 25 tons of plastics bags, bottles, nets and ropes from rivers that feed the Indian Ocean.

The Ocean Cleanup was founded in 2013 by Boyan Slat and works on a moonshot level of operation to clean up the ocean’s biggest gyres. Its technology seeks to create artificial shorelines and use the ocean’s currents to wash the plastic waste up onto those shorelines. Floating masses sit atop a skirt deployed into the water to catch debris in a wide line, and then a parachute slows down the system to create different speeds between current and float. When we first wrote about this project in 2014 and following Slat’s TEDx Talk in Delft, he focused on the shape of the net inspired by a manta ray’s fins. Using the current, wind and waves will collect the plastic waste where it can be captured and removed from the ocean. The system uses algorithms to find the zones where these nets can catch the most plastic, and after being deployed, the systems can autonomously operate while being monitored from a home base.

After a huge array of scale model and prototype testing along with gyre mapping, System 001 was launched on September 8, 2018, and returned to shore in January 2019. System 001/B launched in June 2019 and as of October 2 was pulling in plastic pieces as small as 1 millimeter long. Team members working with partner institutions have built up an incredible body of scientific publications, and the project’s amazingly ambitious goal is to clean 50 percent of the Great Pacific Garbage Patch in the first five years after its deployment. The team is now working on System 002 using knowledge from its tests, and a major announcement is scheduled for October 26, 2019.

We’ve written about engineers and scientists who use bacteria to eat away at plastic waste, work together to hack away at pollution in the Great Lakes, create robots to clean up the Toronto shoreline, treat river cleanup like a game using crowd controls and an unmanned trash robot, and even eliminate plastics altogether and innovate to the next big material. With the threat of ocean plastics looming, it’s great to know that engineers are working on many solutions, and it’s exciting to see the next wave of projects that are meant to clean our planet’s waters.

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