Plastics Management : A New Approach

Cheap to produce and long to degrade, plastic was once a manufacturing miracle. Now, plastic is an environmental plague, clogging landfills and choking waterways.

Global plastic production has gone up from 300 million metric tonnes to 360 million metric tonnes in the last five years- claims a scientist from the Goa-based National Institute of Oceanography.

Each human being uses, on average, 30 kg of plastic per year.

Billions of plastic are discarded over landfills and much of it, due to mismanagement, end up getting piled in the ocean.

At least 8 million tons of plastic end up in our oceans every year.

You may have heard of an ancient process of pyrolysis, in which the plastic components are burnt in absence of air to turn it into oil and other chemicals and fuels.

Many companies like Adidas are attempting an effort to incorporate plastic into their products.

But all these existing processes still end up with some residue that needs to be stockpiled or buried, and thus those residues still contribute to filling up of the lands and causing environmental consequences.

Scientists are trying to solve this ever-growing problem with more sustainable and creative solutions.

Very recently two scientists Steve Techtmann and Ting Lu have, under a project funded by Defense Advanced Research Projects Agency (DARPA) claimed to improve a process for converting plastic trash into protein powder and lubricants using a combination of chemicals and high heat (pyrolysis). They call their project a food 'generator.'

The researchers predicted a system in which individuals may deposit plastic garbage or non-edible biomass into a slot. The waste goes into processing reactors where heat is used to break it down. The byproduct is then put into a tank with a bacterial population, which feasts on it. The cells are then dried down into a powder and stored for subsequent use.

Francesco Stellacci, head of the Supramolecular Nanomaterials and Interfaces Laboratory at EPFL’s School of Engineering, began thinking about whether there was a way to solve the problem of used plastics and recycle it more effectively. Stellacci established a collaboration with Prof. Sebastian J. Maerkl in the Bioengineering Institute at EPFL co-advising a Ph.D. student, Simone Giaveri, the team has published its conclusions, based on scientific research, in Advanced Materials.

Proteins as a pearl necklace.

The Amino acids are the monomers that form the basic component of a long chain protein polymer, which in turn makes up our entire world.

“A protein is like a string of pearls, where each pearl is an amino acid. Each pearl has a different color, and the color sequence determines the string structure and consequently its properties. In nature, protein chains break up into the constituents amino acids and cells put such amino acids back together to form new proteins, that is they create new strings of pearls with a different color sequence,” Giaveri says.

In the lab, Giaveri initially attempted to replicate this natural cycle, outside living organisms. “We selected proteins and divided them up into amino acids. We then put the amino acids into a cell-free biological system, that assembled the amino acids back into new proteins with entirely different structures and applications,” he explains. For instance, Giaveri and Stellacci successfully transformed silk into a protein used in biomedical technology. “Importantly, when you break down and assemble proteins in this way, the quality of the proteins produced is the same as that of a newly synthesized protein. Indeed, you are building something new,” Stellacci says.

What are plastics?

Plastics synthetic and semi-organic polymers are made from natural materials such as cellulose, coal, natural gas, salt, and crude oil through a polymerization or polycondensation process to induce molecular bonding.

Thus, the mechanisms naturally occurring in proteins could be applied to plastics as well. “It will require a radically different mindset. Polymers are strings of pearls, but synthetic polymers are made mostly of pearls all of the same color, and when the color is different the sequence of color rarely matters. Furthermore, we have no efficient way to assemble synthetic polymers from different color pearls in a way that controls their sequence.” He would also point out, however, that this new approach to plastic recycling appears to be the only one that truly adheres to the postulate of a circular economy. “In the future, sustainability will entail pushing upcycling to the extreme, throwing a lot of different objects together, and recycling the mixture to produce every day a different new material. Nature already does this,” he concludes.

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