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With disposable carrier bags at supermarkets slated to cost at least 5 cents per piece starting Jul. 3, 2023, discussions about possible alternatives to replace conventional plastic bags have taken place.

As Parliament debated the Resource Sustainability (Amendment) Bill on Mar. 24, 2023, two Members of Parliament (MP) --- Ang Mo Kio MP Gan Thiam Poh and Tanjong Pagar MP Joan Pereira --- rose to weigh in on the debate.

During their speeches, the MPs asked about encouraging supermarkets to switch to biodegradable plastic bags and if the Ministry of Sustainability and the Environment will support such an initiative.

Prior to the Mar. 24 debate, questions about the use of biodegradable plastics had been raised at least several times in Parliament: once in 2020, twice in 2021, and most recently in Feb. 2023.

Each time, the answer was the same: no, there are no plans to encourage their use over that of conventional plastics because they are not helpful in the Singaporean context.

Here is why.

All trash is incinerated

Most of the trash in Singapore ends up in Pulau Semakau Landfill, Singapore's one and only landfill.

However, instead of simply burying the trash you so nicely bagged, trash collected from all over Singapore are processed before they get to Semakau.

First, they are sent to one of four incineration (or waste-to-energy) plants around Singapore.

The resulting ashes and debris, or incinerated bottom ash, as well non-incinerable waste like sludge, are transported to Tuas Marine Transfer Station (TMFS).

There, the treated waste are then loaded onto barges before being ferried to Semakau for landfilling.

Every non-recyclable item that ends up in a bin will be incinerated and turned into ash.

According to NEA, incineration reduces the volume of waste by 90 per cent.

So, biodegradable plastic bags are of no help in Singapore since they end up with the same fate as all other types of disposable carrier bags.

When mixed with conventional plastics, biodegradable plastic bags could also interfere with the recycling process, NEA noted in 2019 study on the life-cycle impact of carrier bags and food packaging.

Biodegradable plastics are made like conventional plastics, but contain additives to help hasten its degradation.

These additives are not recyclable.

When mixed with regular plastic recyclables, they reduce the quality of the new materials that can be produced.

Even so, do biodegradables actually work?

Doubts have also been cast on the efficacy of biodegradables.

According to World Wildlife Fund (WWF), biodegradables may not work as well out in nature.

Writing on its blog, WWF noted that biodegradable plastics are "tested under controlled conditions in a lab", including factors such as oxygen levels, UV exposure, temperatures and other variables.

"But nature does not have controlled conditions, so it can never be certain that biodegradable plastic will actually biodegrade in the natural world if it is littered," WWF explained.

So, even if Singapore landfills solid waste instead of incinerating them before landfilling, biodegradables may actually linger in the environment just as conventional plastics do.

Top image via Zhangxin Zheng, Fiona Tan