Dealing with plastic waste

Materials World magazine
,
1 Jul 2018

The amount of single-use plastic littering the countryside, rivers, and oceans has stirred plenty of emotion in recent months. But, what can be done to change this? Stuart Patrick* investigates.

Currently, most plastic materials are derived from fossil feedstock, such as natural gas, oil, and coal. In fact, around 4–6% of all the oil and gas used in Europe goes towards the production of plastic. The positive aspect of plastics – durability, versatility, and recyclability – have come back to haunt the sector, particularly in Asia, where it has not been easy to set up proper waste handling of end-of-life materials, mainly because of financial considerations.

But does this issue really justify the current anti-plastics agenda sweeping the UK and elsewhere? Plastic-free aisles in supermarkets may be one thing, but how might people react to being treated in a plastic-free hospital ward, where single-use plastics are vital for healthcare. The point here, of course, is that the waste articles are collected on site and incinerated in facilities designed for the purpose. 

Non-plastic alternatives will break down quicker when discarded, but is this not just encouraging more littering? The human behavioural mindset of ‘out of sight, out of mind’ that results in littering is a significant contributor to the problem.

Last October, scientists at the Helmholtz Centre for Environmental Research, Germany, found that 10 rivers – two in Africa and the rest in Asia – discharge 90% of all plastic marine debris. The Yangtze, China, alone carries 1.5m tonnes a year. A total of 2% of global ocean litter comes from Europe and North America, with the USA ranking 20th on the worst offenders list and European coastal countries a combined rank 18th.

However, it is therefore important to take a global view of the situation as a whole.

Follow the waste

Let’s look at Europe first. UNESCO’s website, states, ‘Land-based sources, such as agricultural run-off, discharge of nutrients, and pesticides and untreated sewage, including plastics, account for approximately 80% of marine pollution, globally. 

‘Seven of the EU member states plus Norway and Switzerland recover more than 80% of their used plastics. These countries adopt an integrated waste and resource management strategy to address each waste stream with the best options. 

According to the Plastics Europe 2017 annual report, 10 European countries run at 90% and higher for recycling and energy recovery, with the latter being a significant contributor. The UK figure for 2016 on the same basis is around 70%. On the positive side, the UK recycling rate was on a par, running at 35%, with the highest being over 40% in Norway and Sweden.However, waste and disposal remain an issue in most of the world.’ Note that recovery includes energy recovery from incineration.

Burn baby, burn

So, is energy from waste (EFW) the best option? Keith Freegard, Director and founder of Axion Recycling Ltd, and Vice Chair of the British Plastics Federation’s Recycling Group, argues that low-grade plastic materials are better left in the ground for mining, rather than burned for energy. Writing on the British Plastics website in February 2018, he explained that, in addition to producing more CO2, ‘creating energy from waste also produces between 25–30% residual incinerator bottom ash’.

Although generating heat and power from waste sounds appealing, it is inefficient when compared to burning gas in a modern generator system. Burning natural gas also produces fewer emissions and there is zero solid ash waste generated. 

Freegard added, ‘Increasing incineration capacity stifles innovation in alternative resource recovery technologies. Investment is diverted from developing new processes towards building plants for burning materials to inefficiently create power.’

Another viewpoint is that EFW operators do not want to burn lots of plastic due to the impact on plant throughput, operating costs, and potential emissions. If not EFW, then what else?

For starters, Recycling Technologies, UK, has built a machine that converts all flexible plastics into crude oil by a process known as thermal cracking. 

They intend to sell the machines across the world. Meanwhile, another British company, MacRebur, is pioneering the use of plastic waste as a part bitumen replacement in asphalt roads to give a stronger and longer lasting road surface.    

Europe’s first waste-to-methanol plant is being planned in Rotterdam, Netherlands, in which Enerkem, a Canadian company, is working with AkzoNobel and Air Liquide to develop a plant that will convert 350,000 tonnes of waste, including plastics, into 270 million litres of methanol, annually. The methanol will be used as a biofuel and chemical intermediate. The plant will be double the size of Enerkem’s first facility in Alberta, Canada.

Simpler methods of increasing sustainability can also be implemented in regards to single use plastics, and the variety of future schemes associated with them.

Ambitious goals

Another idea that has found favour for recovering plastic is a deposit return scheme (DRS), as witnessed by the UK government’s announcement that it intends to introduce a DRS following consultation. One key thing will be with how the economics of increased recycling capacity and corresponding high-quality recycled material availability can be made to work without adversely affecting kerbside collection. The cost differential between good recyclate and fresh virgin polymer is also a key issue.

The UK government is also aiming, as part of its 25-year environment plan, to eliminate avoidable plastic waste by 2042. This will focus on extending the 5p carrier bag charge to all retailers in England, investigate how taxes or charges could reduce waste, and inject £20m into plastic innovation. 

In terms of Europe, the European Commission has stated that by 2030, all plastic packaging will be recyclable or reusable. It is envisaged that there will be a decrease in the production of single-use plastics, with an aim that by 2030, more than 50% of plastic waste generated on the continent will be recycled. 

This will require a four-fold increase in sorting and recycling capacity and similar growth in demand for recycled plastics. Plastics Europe’s new voluntary commitment aims for a 60% level by 2030 for recycling or reuse, with a 100%-target by 2040.

In addition, the EU has also just published its Single Use Plastics Proposal banning some plastic products and putting the burden of cleaning up waste on manufacturers. There should also be raised awareness of reuse and waste management options and the impact of litter / inappropriate waste disposal for items. The main thrusts of the proposal cover: 

  • Reduce consumption of food containers and cup, plastic straws, stirrers, cutlery, plates, cotton buds and sticks for balloons should be prohibited if suitable and more sustainable alternatives exist, bottles and their caps / lids should only be sold if the caps and lids remain attached to the container, wet wipes, sanitary towels and balloons should be clearly labelled with appropriate waste disposal and the negative environmental impact of littering or the presence of plastic 
  • Food containers, packets or wrappers, beverage containers, cups, tobacco products, wet wipes, balloons and lightweight plastic carrier bags shall have an extended producer responsibility (EPR) scheme. The producers of these products shall cover the cost of collection of waste and transport and treatment. They should also cover the cost of cleaning up litter and awareness raising measures.  
  • Necessary measures should be taken to collect separately, by 2025, 90% of bottles. This is through a DRS or establishing separate collection targets for relevant EPR schemes. A possible legal challenge could be raised at a European level on this proposal as this could appear to be discriminatory and disproportionate with the consumer and user of plastic absolved of responsibility with regards to responsible disposal of items used.

The great garbage patch

As mentioned, these initiatives share a common desire to cut the amount of plastic in the oceans. Research into the constituents of marine debris has been carried out by scientists of the Ocean Cleanup Foundation, looking at the Great Pacific Garbage Patch, which is the largest accumulation of ocean plastic in the world, covering 1.6km2, located between Hawaii and California, USA.

The patch is the target of a US$32m clean-up campaign launched by a Dutch teenager, Boyan Slat, now 23, and head of Ocean Cleanup, the organisation he founded to do the job. The clean-up system is made of durable plastic and consists of floating screens that are 3m deep, suspended from strong U-shaped tubes, 1km long. All is held in place by a sea anchor. Plastic waste is collected as the ocean currents flow past the screens. If successful, more systems could be rolled out.

A study, Evidence that the Great Pacific Garbage Patch is rapidly accumulating plastic published in Scientific Reports, in October 2017, found that the patch included microplastics, which made up 94% of an estimated 1.8 trillion pieces of plastic. However, that only amounts to 8% of the total tonnage. The 79,000 metric tonnes of plastic are mostly abandoned fishing gear – not plastic bottles or packaging. Scientists also estimated that 20% is from the 2011 Japanese tsunami. 

In the UK, the British Plastics Federation has convened an initiative for leading brands, retailers, government departments, and representatives of the plastics industry to consider how the amount of discarded plastic entering rivers and seas can be reduced.

Education, education, education

Meanwhile, the Marine Litter Action Network, brings together more than 60 organisations, including retailers, plastics manufacturers, scuba divers, and marine conservationist to raise awareness, share best practices, and use and expand existing marine conversation campaigns. 

The difficultly can arise with microplastics, however. There is some contention over their size, although the US National Oceanic & Atmospheric Administration classifies microplastics as less than 5mm in diameter, with variance from 0.05µm to 5mm.  

Much has also been said about using biodegradable plastics, made from renewable resources. However, the European Bioplastics Organisation says that the process of biodegradation is dependent on certain environmental conditions. Products suitable for industrial composting (defined bythe EN 13432 standard) are fit for the conditions in a composting plant, but not for those outside in nature. 

No international standard describes the biodegradation of plastics in the marine environment. The International Organisation for Standardisation and American Society for Testing Materials are woriking to address this. But, the only true way to solve the problem is to ensure it does not find its way into the oceans.

*Stuart Patrick FIMMM MRSC is Interim Chair of the IOM3 Polymer Society Board and a member of the Institute’s Sustainable Development Group.