Meena Miriam Yust and Arshad M. Khan
The practice of recycling has everything to commend it: On a finite planet, it conserves resources; it is meretricious allowing us, as it does, to pin a mental merit badge on our chests as we ready the assigned recycling bin once a week; and it is an activity that is all good. We are saving the planet, albeit in a small way, from some of the excesses of the developed world. And when everyone does their share, the impact has to be unavoidably significant. Right. Or, does it?
If we examine what we recycle, that is paper, glass, metal cans and plastic, the junk mail and other paper discarded is the most copious but plastic is close. Almost all of it used to go to the developed world's great recycling bin in the east ... China. It absorbed some 95 percent of EU recyclable waste and 70 percent from the US. But China began to grow its own domestic garbage with the growth of its economy. The consequences have not been unexpected. China announced a new policy in 2018, named inexplicably National Sword, banning the import of most recyclables, particularly plastics and contaminated materials.
Since then China's import of such recyclables has fallen 99 percent. Needless to say, metals and glass are not as seriously affected. For the American recycling industry, it has been a major earthquake. First, about 25 percent of recyclables are contaminated and not recyclable. Then there are plastic bags. Not only are these, too, not recyclable but they tend to jam up sorting machinery.
The sorting of waste sent to China had been taken over by families in port side communities. It became their livelihood, retrieving whatever fetched a price and dumping the rest. Piling up in ad hoc landfills, it washed down waterways into the ocean. They were not the only culprits. Thus we have had the phenomenon of whales being washed up dead, starved because stomachs were full of plastic -- 88 pounds densely packed in the stomach of one found in the Philippines and 50 pounds inside another in Sardinia. China's ban on waste imports has been followed by Malaysia and Vietnam. In March of this year, India joined them.
As the outlets for their waste disappear and as most of the plastics are not recycled, self-reliance has been forced upon developed countries. All to the good for the environment, because it will also curtail the use of plastics out of necessity. The truth is only a fraction of plastic waste is recyclable, generally the white transparent bottles of which some are preferred. Most ends up in landfills. A 2017 study in Science Advances determined that 90% of plastics ever produced are still in the environment. Yet in the past six decades an estimated 8 billion tons have been produced. Moreover, the usage trend is upwards and in 2014 some 311 million tons were produced worldwide.
There is though a small movement to restore reusable bottles, and a company called Loop Industries may be on the right track. Their founders announced at the World Economic Forum in 2019 that they aim to return to the milkman model, reusing bottles for everything from edibles to shampoo and detergent. Loop has partnered with Nestle, Proctor & Gamble, PepsiCo, and other large companies. Perhaps, if we all return to the milk bottle model of the 1950s -- refilling containers to be used again -- there may be greater hope for the planet. The good news is, some towns and states have already banned single-use plastic bottles.
Another intriguing possibility is to use the millions of tons of crustacean shells discarded. Scientists are now able to extract chitin and chitosan from shrimp and lobster shells. Still in the research stage, the process has to be made industrially feasible, and there are also problems with hazardous waste as it uses potent chemicals like sodium hydroxide. Biodegradable chitin and chitosan can be used as plastic substitutes to make surfboards and anti-microbial food packaging. Scotland-based CuanTec has developed a bacterial method that has eliminated 95 percent of the sodium hydroxide and also cut energy use by a third as the bacteria do all the work. They use shells from the langoustines common in northern Europe, and have already signed a contract with the large UK supermarket chain Waitrose to supply flexible film for packaging fish. The film's antibacterial properties extend fish shelf life by three days.
An unexpected and more insidious source of plastic pollution is synthetic clothing. Researchers have determined that acrylic clothing may release more than 700,000 plastic fibers in a single wash. Polyester releases about 500,000 fibers, and a poly-cotton blend releases about 137,000. These fibers end up in the water we drink and the fish we eat. Making matters worse is the presence of microplastic at depths up to the 1000 meters , investigated by Choy et al in the deep waters of Monterey Bay using a remotely operated vehicle (ROV). The ROV collected the samples at ten different depths. Maximum pollution was found, surprisingly, not at the surface but from 200 to 600 meters below. They also collected red crabs and found plastics in the gastrointestinal tract. Giant "sinkers," the particle filtering mucous houses used for feeding by larvaceans and discarded after use, were collected at depths ranging from 251 to 2967 meters to overlap and extend the range of the research. All contained microplastics. Clearly, ridding the oceans of plastic pollution is an almost unsurmountable problem.
Japanese manufacturers have come up with a washing machine filter to catch microfibers, which may provide some aid if more widely distributed. Yet we still do not know the efficacy of such devices. Curbing the problem at the source is still the most sensible if we wish to sustain the planet. It is up to us.
Returning to the cheap, convenient and therefore ubiquitous plastic bags, there is hope for now there are several different types : the most common are conventional plastic bags, then there are compostable bags designed to be recycled in industrial composters, biodegradable bags, and two types of oxo-biodegradable bags. The latter degrade in open landscapes or on water surfaces like oceans. None degrade too well in landfills. There is, however, another problem with compostable biodegradales: to repel water and oil these have in them perfluoroalkyl and polyfluoroalkyl substances in which an hydrogen atom has been replaced by fluorine. Known as PFAS, these persistent chemicals leach out of the plastic and remain in the compost to be absorbed by plants and later by humans to accumulate in their bodies.
However, it's back to landfills for the non-recyclables. In 2015, the US alone produced 34.5 million tons (or 13 percent of total municipal solid waste) of plastic waste from which a small fraction (9 percent or 3.1 million tons) was recycled, 5.4 million tons was incinerated with energy recovery and about 26 million tons ended up in landfills. Burning reduces volume by 87 percent. However, open burning produces pollutants including dangerous dioxins, so safe combustion requires a contained environment.
Unless there is a change, the plastic problem appears likely to keep growing. In 1950, the world produced only about 2 million tons compared to over 300 million tons in present times. The UN has taken a first step by adding plastic waste to the Basel agreement on hazardous waste -- 187 countries have signed up , the US under the Trump administration remains an exception.
Engineering institutions have become aware of the problem and are educating their young members. As reported in their July 2019 issue of IET Member News, the British electrical engineering professional body has two competitions sponsored by Greenpeace and Greenseas. For the Greenpeace prize, teams have to come up with methods, technologies and alternative delivery systems to reduce plastic packaging in supermarkets. And the Greenseas challenge requires competitors to develop a robotic machine to clear beaches of plastic cigarette stubs. The machine has to be large enough to collect a reasonable amount and painted brightly to attract attention and inform the public of the problem. Then there is OceanX Group, headed by a young engineer, that is developing automated monitoring and cleanup technology to remove plastic from waterways and better to detect sources. It employs artificial intelligence including drones.
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