o useful to man yet so problematic, plastic is the scourge of our modern age. While plastic has opened the way for a plethora of new inventions and devices, plastic pollution has become one of the most pressing environmental issues facing planet earth.
Mass production of plastics began just six decades ago and within that period, 8.3 billion tonnes of plastics have been produced, most of it as disposable products that end up as trash. It is estimated a mere 9 percent is recycled and another 12 percent incinerated. The bulk of it ends up in landfills or in the natural environment. As plastics takes years to degrade – as much as 450 years for the ubiquitous plastic PET bottle – the problem can only get worse with each passing day.
Recycling rate took a hit after China, the prime destination for recyclable waste, banned the import of waste on 1 January 2018, a significant percentage of which was plastic waste. Attempts by recyclers to re-route their waste elsewhere to Malaysia, Indonesia, the Philippines, Cambodia and Sri Lanka, countries where regulations are lax, have run into difficulties. Following public outcry, government regulations have been tightened up and hundreds of containers of untreated waste sent back to the countries of origin, including Australia, Canada, the UK and the US.
As Asia is home to all top five marine plastic trash offenders - China, Indonesia, the Philippines, Vietnam and Sri Lanka – the need for a solution has gained added urgency. Ocean Conservancy estimates the plastic litter problem is inflicting US$1.3 billion in damage annually to the region’s fishing, shipping and tourism industries.
Biodegradable plastic – weighing the pros and cons
The use of biodegradable plastic made from corn, coconut, potato or wood to replace single-use plastic does not always provide a solution. If buried in landfills, the biodegradable plastic bag degrades faster and has less adverse impact on the environment. But for Singapore where all waste ends up in the incinerator, it does not make any difference.
“Some biodegradable plastics may require more resources to produce and that would inevitably incur a higher carbon footprint,” Mr Liow Chean Siang, head of environmental certifications at the Singapore Environment Council, told Channel News Asia. “Consumers may have less guilt in using such bags but ultimately this could have little impact on reducing carbon footprint or greenhouse gas emissions.”
Biodegradable plastic may also interfere with the recycling process when mixed with conventional plastics.
Still, there are those who see the merits of switching to biodegradable alternatives, as it is well-nigh impossible to do away with single-use plastics for food packaging or for medical purposes.
More palatable option
Developing biodegradable plastic from food waste may be a more palatable option as it puts to good use a waste product and reduce disposal at landfills. A team led by Professor William Chen, director of the Food Science and Technology Programme at the Nanyang Technological University (NTU), has invented the biodegradable food wrap made of cellulose extracted from the mushy residue after soya beans are crushed to make soya bean curd and soya milk.
Though cellulose-based plastic wraps are not new, most are made from food crops like corn or potato. As the NTU wrap is made from a waste product, which does not compete with edible crops for land, it is a more sustainable option. Soya beans waste is freely available as soya beans are a staple in the Asian diet. In Singapore, 30 tonnes of soya bean residue are produced every day.
The team is conducting a feasibility study to assess the commercial viability of soya bean food wrap. Work is also underway to transform the cellulose-rich husks of durians into plastic wrap. With annual consumption of 12 million durians a year, Singapore has an ample supply of discarded husks which can be re-purposed.
Raising recycling rate
Greater effort is being made to improve recycling rates from the present dismal level. Unlike other materials like metal, paper or rubber, recycling plastic waste is proving to be trickier. As plastics collected from the community are a mixture of different polymers that are typically blended with additives such as pigments, stabilisers and sealants during the manufacturing process, recycling them is difficult and expensive. Until now, plastics which are contaminated with food waste are simply discarded.
In Singapore, only four percent of the 949,300 tonnes of plastic waste generated in 2018 was recycled, the lowest for any commodity. Only seven percent of the recycling was undertaken locally while the rest was shipped overseas.
This is about to change as the National Environment Agency (NEA) has plans to step up plastic recycling. As NEA’s chief executive Tan Meng Dui wrote in his op-ed column in The Straits Times on 3 December 2019, “The recycling of plastic waste is an area ripe for transformation. With increased demand for recycled plastics from fast-moving consumer goods, companies and impending European Union regulations requiring a minimum amount of recycled content in packaging, Singapore is working on plans to develop the mechanical recycling industry here.”
NEA is also exploring chemical recycling facilities, which can take in “dirtier” plastics of lower recycling value. Wrote Mr Tan, “These efforts will enhance our resilience in plastic waste management, increase our plastic recycling rate, and possibly spawn new economic value in green feedstock for the petrochemical industry