1 . The negative impacts of plastic have been well-documented. Half plastics produced annually worldwide end up in landfills or the environment. Now, French start-up Carbios wants to help relieve the world’s plastic pollution problem with a bacterial enzyme (细菌酶) that digests PET—the most plentiful plastic used to produce packaging, and plastic bottles—and turn it into its chemical building blocks. The resulting material can be used to create anything and, more importantly, can be continuously recycled.

“Mechanical recycling is limited,” explains Carbios CEO Martin Stephan. “To make a plastic bottle with that technology, you need a plastic bottle as an input material. After several cycles of recycling, the plastic is of lower quality and can only be used for something like the backing of a carpet before it is thrown away entirely. So it’s not a solution for plastics, whereas our solution is a limitless recycling solution.”

The company’s search for the ideal plastic-eating bacteria began about a decade ago, with 100000 promising candidates. The list was soon cut down to one, which was first discovered in 2012. Once the perfect competitor had been identified, Carbios scientists began to improve its plastic digesting power and keep its table at 65℃—the ideal temperature for fast degradation (降解). The improved enzyme was able to downgrade a ton of plastic in less than 10 hours.

To breakdown the plastic, the waste is placed in are actor with water and the enzyme and heated for 16 hours at 65℃. The resulting mix is then purified. This allows for the recovery of the building blocks that makeup PET plastics.

The recycling process, which is currently in its pilot stage, will be tested on a large range by 2021. Carbios hopes to launch the technology commercially in the near future. Though Carbios’ recycling technique will certainly help reduce plastic pollution, it is only part of the solution. Only if people do a better job of ensuring plastic waste ends up in a recycling can, can we win the battle.

3 . Turtles have an unfortunate habit of eating plastic objects floating in the sea. These then cannot be broken down and digested, and may ultimately kill them.

It is widely assumed that this special liking for plastics is a matter of mistaken identity. Floating plastic bags, for instance, look similar to jellyfish, which many types of turtles love to eat. Yet lota of plastic objects that end up inside turtles are not similar to jellyfish. Joseph Pfaller of the University of Florida therefore suspects that the smell of micro-organisms (微生物) which grow on floating plastic objects fools turtles to feed.

Researchers at the University of California noticed that certain chemicals, which are released into the air by micro-organism — colonised plastics, are those which many seabirds sniff to track down food. These chemicals mark good places to hunt because they indicate an abundance of the seaweed and bacteria. Since turtles are known to break the surface and sniff the air when swimming towards their feeding areas, Dr. Pfaller indicated that they are following these same chemicals, and are fooled into thinking that floating plastic objects are edible.

To test that idea, he and his colleagues set up an experiment. They arranged for 15 of the animals, each around five months old, to be exposed, in random order, to four smells delivered through a pipe to; the air above an experimental area. The smells were: the vapour from deionised (去离子) water; the smell of turtle-feeding meal; the smell of a clean plastic bottle; and the smell of a similarly plastic bottle that had been kept in the ocean for five weeks to allow seaweed and bacteria to grow on it. Two of the smells-the smell of meal and that of five-week-old bottles-proved far more attractive to the animals than the others.

On the face of it, then, the turtles were responding to the smell of old bottles as if it were the smell of food. In an unpolluted ocean, pretty well anything which had this smell would be edible-or, at least, harmless. Unfortunately, five-week-old plastic bottles and their like are not.