by Jessica Forsyth
It is estimated that approximately five million tonnes of plastic are used in the UK each year. Unfortunately, this extraordinary reliance on plastic has resulted in it becoming a common contaminant of the soil, the ocean, and the atmosphere. There can be no doubt that plastic pollution is one of the world’s most pressing environmental issues, but the question remains of how best to resolve it.
It is important to remember that the presence of plastic in the environment is not an inevitable by-product of its use, but a direct result of our irresponsible and unsustainable disposal of it. As a matter of fact, plastic itself has several environmental benefits. These include the impact it has on reducing food wastage by extending the shelf-life of fresh produce, as well as reducing CO2 emissions from the transportation of goods as a result of its lightweight properties.
Scientist Mark Miodownik argues that plastic is too valuable a material to replace. Rather than swapping in other materials, that if improperly disposed of will also cause problems, ‘the more valuable thing to do is to focus efforts on how to make the process of using plastic more sustainable’.
So how can we achieve this? Well, if you were to ask the average person how they thought they could help in the plastic pollution crisis, their answer would likely include the idea of improving their recycling habits. But should this be the focus of our attention? Many of us will be familiar with the ‘Reduce, Reuse, Recycle’ slogan. It is referred to as the ‘waste hierarchy’ because it lists the solutions to waste management in order of their effectiveness.
Interestingly, you will notice that recycling comes last on the list. The UK is considered to be a successful recycling nation with 45.7% of household waste classed as recycled. However, the majority of this recycling does not take place in the UK and where exactly our waste ends up and whether it is ‘truly recycled’ is unclear. Shamefully, in 2017/18 a report found that Westminster Council sent 82% of all household waste, including that put into recycling bins, for incineration. So perhaps we should focus more on reducing our consumption and improving our reuse of plastic.
A strategy that the scientists at the University of Portsmouth are focussing on is finding ways to reduce the demand to manufacture new plastic. They have engineered a super enzyme capable of breaking down plastic into its chemical building blocks from which new plastic can be made. In 2018, they discovered that an engineered version of an enzyme known as PETase was capable of breaking down plastic in a matter of days.
Since then, the scientists have discovered a similar enzyme known as MHETase that, when combined, creates a super-enzyme capable of degrading plastic six times faster than PETase alone. Both enzymes were found in a soil bacterium known as Ideonella sakaiensis. Fascinatingly, with so much plastic polluting the environment, it seems that these microbes have evolved ways of turning plastic into a source of energy. By exploiting this ‘naturally occurring plastic-degrading system’ scientists have found a new way of improving our ‘Reuse’ of plastic.
Finally, it is important to remember that manufacturing new plastic from fossil fuels is a relatively cheap process and if any means of recycling or reusing plastic is to compete with this, it needs to rival it in cost. The discovery of this super enzyme is an important step towards this as the increased speed of plastic breakdown translates to a significant reduction in the cost of the process and thus a big step towards its consideration for commercial use.
With the Covid-19 pandemic leading to a rise in single use plastic, the plastic pollution crisis is more evident than ever before. With the discovery of new ways to reuse or recycle plastic comes hope that we can begin to move towards a more circular economy ‘where everything has value and nothing is wasted’. Only then can we hope that we can continue to benefit from the use of plastic as a valuable material without it posing a threat to all life on earth.