Biodegradable vs Compostable plastic: how different are they?

As the issue of plastic waste mounts, we look to biodegradable and compostable materials as our beacon of hope. But how are they different and what does that mean for sustainability? 

Plastics have been plaguing us and the environment for a really long time since its creation in the 19th century. It is only going to continue as conventional plastics can last in the oceans for hundreds of years without breaking down. It is estimated that by 2050, there will be more plastic than fish by weight in the ocean, according to the Ellen McArthur Foundation. So, people have been looking for ways to overcome this issue by increasing the uptake of biodegradable and compostable plastics. Catering company Grain or hotel chain Shangri-La have already started adopting them to reduce plastic waste. Let’s take a closer look at the differences between biodegradable and compostable plastics, and see which one is better? 

Before delving deeper, let’s take a look at the official definitions under the European Regulations: 

Biodegradable means that something breaks down naturally because of weather conditions and bacteria or fungi. However, this process can be very long, sometimes taking decades. For example, an OXO-bio bag is “biodegradable”. Meaning it is composed of 90-95% of plastic, and can be reduced into small pieces relatively easily but will never fully decompose and may stay on the planet in some form forever.  

Compostable is a subset of biodegradable which means it can break down naturally in less than 12 months. This makes it suitable for commercial composting together with food waste. It creates a great balance of microbes, moisture, and warmth. In turn, the waste gets transformed into nutrient-rich compost that will in turn help plants thrive. 

Under this, we can further split them into ‘industrial-compostable’ and ‘home-compostable’ plastics. Industrial-compostable plastics require specific conditions in a commercial setting to break down. 

In Singapore, home-compostable materials are generally better than industrial-compostable or biodegradable ones. They do not contain toxic chemicals unlike biodegradable plastics and they can be composted in the comfort of your home, unlike industrial-compostable materials. 

 

Reasons why home-compostable plastics are better 

  • Home-compostable plastics can be broken down domestically or commercially. As long as they are mixed with food waste and put into compost bins, they can become nutrient-rich fertilisers. However, biodegradable and industrial-compostable plastics can only be processed commercially as they require specific processes, moisture and temperature (between 50 and 60 degrees celsius).  
  • Compostable plastics yield nutrient-rich compost that can be useful for community gardening, local agriculture or just growing plants at home. It is not possible to do this with biodegradable plastics. 

  • Also, compostable plastics do not leave toxic material or release many harmful gases, but biodegradable plastics can do. They tend to contain trace heavy metals due to the production process which then pollutes the soil and waterways. 

  • Countries and regions like Singapore don’t have the ability to manage biodegradable or industrial-compostable plastics. Hence, they will eventually be incinerated. So, if domestic composting is available, home-compostable plastics are better. 

Some compostable plastic alternatives come from Vegware in Hong Kong or bagasse fibre containers carried by Bizsu. Admittedly, the uptake of such compostable plastics is still slower in Singapore. However, the entire biodegradable plastics market (for both biodegradable and compostable materials) is projected to double from US$3.02bn in 2018 to US$6.12bn by 2023. Hence, there is hope for choosing better plastics and materials in the future. 

 

Our Final Verdict?

Home-compostable materials are a great alternative to regular plastics. In the context of Singapore, they are better than biodegradable or industrial-compostable plastics. The caveat is that we have to be able to compost these plastics ourselves otherwise they still get incinerated. Home composting systems like the Urban Composter sold by The Green Collective is a simple way to kickstart our composting journey. Alternatively, some places take in home-compostable plastics along with food waste to compost. For example, some of the 1500 community gardens in Singapore do so because of the Community in Bloom initiative by NParks.  

At the same time, it is important to remember that home-compostable plastics still create waste. If they end up in water bodies, it will be too cold for microbes to effectively break down these plastics. Hence, the priority lies in reducing waste at its maximum and reusing what we have to overcome the plastic issue.  

 

Authors

Keith Wo is a locally-based environmentalist, currently studying in Yale-NUS and is the Chief Sustainability and Design Officer of MBF. He is passionate about sustainability issues and, as the content creator of Bizsu, he educates the public about them.  

Brice Degeyter is a French entrepreneur and helps companies develop business opportunities while protecting the environment. He is the founder of Bizsu, a company supplying sustainable, innovative and cost-saving products and services to corporations.  

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