Plastics waste comes from various industries including construction, agriculture, automotive and chemical. In Asia-Pacific, plastic pollution costs the economy US$1.3 billion annually. Most plastics in the market are primarily petroleum-based, with projected production of more than 12 million tonnes of plastics waste from 2020 to 2030 where 83% of the plastic waste comes from packaging.1

The existing widely used plastics are difficult to degrade. They contain additives and improvers and require a large amount of energy to recycle or upcycle them. Thus, many businesses today do not find it economically feasible to recycle plastics.

In Singapore, a total of 750-950 kilotonnes of plastic waste is generated annually but only 9% goes into recycling while 91% of plastic waste are incinerated and ended up in the landfill.2 In 2019, the government announced the Zero-Waste Master Plan as part of Singapore’s key strategies to build a sustainable, resource-efficient and climate-resilient nation. The plan includes promoting a circular economy with the aim of reducing waste sent to landfills by 30% by 20303.

Limitations of Current Recycling Solutions

Conventionally, the recycling that takes place today is termed mechanical recycling. The plastic is crushed and then remelted into granules to become new products. Not all plastics can be mechanically recycled, however, and each time the recycled plastic goes through another round of recycling, its strength deteriorates. Eventually, it will reach the end of its life where it can no longer be recycled.

There is thus a need to extend the life of recyclable plastics through innovative means in addition to mechanical recycling.

Catalytic Pyrolysis As a Promising Technology Solution

Catalytic pyrolysis is a sustainable technology where plastics wastes are converted to high quality liquid oil and other value-added products by splitting the polymer chains. These catalysts can be made less costly from sand and incinerator bottom ash that are available in abundance.

At A*STAR’s Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), plastics waste is viewed as a valuable resource. ISCE2 is focused on developing economically feasible and low carbon footprint technologies to turn plastic waste into:

• valuable chemicals or feedstocks: light olefin, syngas
• high-value materials: carbon nanotube, graphene, activated carbon, diamond
• sustainable fuels with more than 90% of the yield: hydrogen, methane, jet fuel.

New Technologies and Circular Plastic Materials

ISCE2 has created new energy efficient technologies which can depolymerise waste plastics into monomers and fine chemicals under mild conditions, such as at a low temperature of 40°C.

ISCE2 also aims to create new circular plastic materials for easy chemical recycling. This combines high materials performance with facile recycling over multiple cycles, either via mechanical recycling or chemical recycling, with minimal deterioration of materials properties in these circular plastics.

Applying The New Technologies For A Sustainable Circular Economy

A circular plastics economy built on infinitely-recyclable polymers is essential to recapture material values and minimise waste generation. This could potentially generate a viable post-use plastics economy that provides strong impetus to enhance waste plastic collection, sorting and recycling capabilities, positioning Singapore as an important global player in sustainable materials development and the future circular plastics economy.

Author: As Senior Director of NRF, Prof Yeoh is responsible for developing R&D strategy and managing Singapore’s national R&D programmes in urban systems to meet national needs in areas such as energy, water, and land & livability. As Chief Sustainability Officer at A*STAR, Prof Yeoh directs the R&D in energy and environmental sustainability focusing on decarbonisation and sustainable green materials and processes. Prof Yeoh is Immediate Past President of the Institution of Engineers(IES), Chairman of IES Awards Committee, President of IES from 2018 to 2020, President of the INCOSE Singapore Chapter from 2009 to 2011, Deputy President of IES from 2017 to 2018 and Vice President of IES from 2014 to 2017. He is a member of the PUB Water Technology Advisory Panel (WTAP), and Energy Studies Institute.

References: 1. UNEP Report Finds ASEAN in Need of Comprehensive Approach to Plastic Pollution

2. Waste Statistics and Overall Recycling

3. Singapore’s Zero Waste Masterplan