It is estimated that between 4.8 and 12.7 million tonnes of plastic enters the ocean each year [1]. The middle amount of 8 million tonnes would be equivalent to the area of West Yorkshire (indicated in the map) covered ankle deep in plastics.
Plastics such as PS, PVC and PET were first commercially produced around the second world war and quickly became important materials due to their cheapness, ease of manufacturing and natural robustness and longevity. As of 2018, about 380 million tonnes of plastic is produced worldwide each year.
Microplastics have been used in toiletries like face-scrubs to exfoliate the skin. These plastics are washed away down the drain and are small enough (down to 1.6 μm) to bypass filtration systems. Eventually they make it to the sea and are eaten by small sea creatures.
The UK banned shops (with more than 250 employees) issuing free plastic carrier bags in 2015, then banned microbeads in toiletries in 2018, and looks set to ban plastic straws, drink stirrers and cotton buds in 2019. Meanwhile the EU proposes a more wide sweeping ban on single use plastics to commence in 2021 [2].
Once in the food chain, plastics are not digested and instead remain inside animals’ digestive systems indefinitely. As smaller organisms are preyed upon by larger ones, these plastics move up the food chain, and concentrate. This effect is called bio-accumulation and has already caused problems with other wastes as in the Minamata incident.
Since plastics do not degrade quickly it could be thought that consuming plastic would not cause significant harm. However, some plastics leach chlorine, PCBs or BPAs which can negatively affect the environment and even a human or animals hormonal system. Since an animal’s hormonal system has a huge impact on its behaviour, this effect multiplies and can have major effects on large populations. Additionally plastic buildup in animals digestive systems can affect eating habits, making them less able to survive.
Plastic can decompose by UV photodegradation, but this is a slow, inefficient process and is hampered in seawater.
Ocean currents have led to five plastic accumulation areas, the largest of which, “The Great Pacific Garbage Patch” is three times the area of France [3]. A Dutch-led initiative is currently underway to attempt to clean up this garbage patch by creating a barrier into which the plastics are moved naturally by the ocean currents [3]. However, others highlight that many tonnes of plastic have sunk to the seafloor and also the problem of microplastics, neither of which can be addressed by the Dutch system [4].
After decades of pressure from concerned citizens, the UK government has decided to act. They are seeking a technological solution over legislation, for speed and effectiveness.
The problem is plastics in the ocean, and the government has come to you, a small engineering firm, for an engineering solution. Which part of the problem you decide to tackle is up to you: reducing the proliferation of plastics, stopping plastics entering the water course or removing plastics from the oceans. However, your solution must be impressive as the recent publicity means the government seek visible action.
As you are a new engineering firm, you are eager to make a good name for yourself. You must consider materials, power supply, manufacture, reliability and produce a realistic timeline.
Since this is an environmental issue, Green campaigners will examine your solution and it must therefore be of net environmental benefit. For example, how much fuel would you consider acceptable to burn, to recover a certain amount of plastic?
The budget is large and the timeframe short, as the government wants to be seen to be acting on what is currently a hot topic. You have one week to present your solution to government, who are looking for out-of-the-box, flagship ideas.
[1] J. Jambeck, R. Geyer, C. Wilcox, T. Siegler, M. Perryman, A. Andrady, R. Narayan and K. Law, “Plastic waste inputs from land into the ocean”, Science, vol. 347, no. 6223, pp. 768-771, 2015.
[2] A. Neslen, “European parliament approves sweeping ban on single-use plastics”, The Guardian, 2018. [Online]. Available: https://www.theguardian.com/environment/2018/oct/24/european-parliament-approves-ban-on-single-use-plastics-uk-eu-brexit. [Accessed: 30- Oct- 2018].
[3] “The Ocean Cleanup Technology”, The Ocean Cleanup, 2018. [Online]. Available: https://www.theoceancleanup.com/technology/. [Accessed: 30- Oct- 2018].
[4] “Experts unsure if Ocean Cleanup is going to rid the seas of plastic”, ABC News, 2018. [Online]. Available: https://www.abc.net.au/news/2018-09-23/ocean-cleanup-great-pacific-garbage-patch-plastics/10285938. [Accessed: 30- Oct- 2018].