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A recent plastic container you have picked up from the shelves of the supermarket might seem very invaluable: the material is durable, costs less and it will also protect your product from external conditions. But what after it has served its purpose and instead of being re-used it ends up in bins?
We know plastic products are non-biodegradable and hence our plastic dump ends up making their forever home in landfills or maybe water bodies. And if pertained to stay for longer, they will become microplastics, eventually disrupting the entire ecosystem.
Look out for the best possible ways to re-use your plastic products. And the products, you have dumped will go to the recycling plant- few will be sorted out for ‘mechanical recycling’ and rest will find up a place in nature to stay for many decades (obviously we don’t aim for this). Mechanical recycling does not alter the properties of the material; rather it simply changes its physical form from one to another. This technology has failed to target all the synthetic plastics available and works out well with HDPE, PET, and PP.
And next on the list is chemical recycling, which ensures to target all of the plastic available and convert them into useful energy resources. Here, the polymer is broken down into its monomer which is further used as a feedstock for various energy production processes. Chemical recycling is a broad term, which comprises of many technologies based upon the required end product.
Chemical recycling or advanced recycling was introduced as a technique that could effectively curb the increasing plastic pollution but several studies counter the same. It’s important to evaluate this recycling technique from various aspects before seeking it as an ultimate solution to our waste.
To begin with chemical recycling, several big infrastructures are required to act as collection centers and efficient sorting facilities. Also, each plant needs to target maximum waste so that the entire process can be economically feasible. It is estimated that if we aim to increase the recycling rate by 50% as of 2030, $15 billion investment per year will be required. But around $2 billion investment into this technology has been made by 2017, which has yielded only failed products.
Not only the pre-planning phase but after the thermal degradation process, highly contaminated products are produced that need to be purified to be converted into polymer. But this purification alone is a high-cost consumption factor.
Chemical recycling aims to target all types of plastic including mixed plastic waste but that’s not enough to proceed with the recycling process. When the hydrocarbon bonds of the polymer compounds are broken, the resultant monomer differs from the original monomer. To state with an example, Polypropylene, polyethylene, and PVCs are highly susceptible to thermal degradation which results in extensive property loss of the material.
Also, the outputs (oils or gas) extracted from chemical recycling are rich in impurities which compels manufacturers to burn it as a fuel, rather than investing further in purification to convert it into a polymer.
Each phase in chemical recycling is a highly energy-consuming process. Starting from collection-sorting, then de-contamination and thermal breakdown to re-polymerization, all stages require high energy and pressure. Study shows that to process a ton of waste into fuel, the same amount of fossil fuel will be required as an energy source.
As of now the data available for chemical recycling is from the lab-based experiments conducted, which only shows the viability of the process. No real-time proofs for successful outputs are available yet. This also fails to mention the impact of the process on the environment. Lab-scale data available for solvent-based processes (that aim to remove additives) have failed to deliver the same output when the process was scaled up.
A recent report released by GAIA, claims that chemical recycling is polluting and bad for the environment. Each step in chemical recycling is contributing to greenhouse gases. From processing of waste to chemical processes and also the end product usage, leaves an impact on the environment. With high energy requirements at each stage, a high amount of carbon dioxide is released into the atmosphere.
The synthetic crude oil obtained from pyrolysis when compared to diesel has solid residues and PAHs which in turn will produce soot, nitrogen oxides, carbon monoxide. To avoid these emissions, pyrolysis oil needs to be cleaned which is an expensive and difficult process but purification of this oil releases toxic waste streams that make diesel better alternative.
Where plastic itself has toxic substances, during pyrolysis or gasification, high-heat interaction releases hydrogen cyanide, high-temperature tars, benzene, and many others.
All the factors to consider the viability of chemical recycling have put its use into question. If plastic is converted to oil or back into plastic, it will not benefit the environment. Converting plastic into oil will neither contribute to the term ‘recycling’ nor will it stop from further production of virgin plastic. Whereas, plastics converted back into plastic leave a harmful impact and are an expensive process that will require scaling up of plants to make it economically feasible. As of 2000, out of 37 facilities for chemical recycling, only 3 are still working and none has been successful.
Where we are far away from dealing with plastic and its problems, a more secured future can be expected from controlling the production and usage of plastic and shifting to reliable environment-friendly alternatives. But what will be the scenario of Bioplastic in the future?
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