Waste to Value Transformation

Ms Esther Marie Lin (left) and Dr Teng Choon Peng (right) from IMRE, A*STAR, holding a bottle of pre-processed fruit waste juices and a bottle of bacteria cellulose fibres respectively

Singapore generated over 817,000 tonnes of food waste in 2021, however only 19 per cent of it was successfully recycled¹ . Based on our current rate of waste generation, Semakau Landfill is expected to be fully filled by 2035.

To support Singapore’s Green Plan 2030, which aims to advance Singapore’s sustainable development, A*STAR’s Institute of Materials Research and Engineering (IMRE) has developed processes which can transform food waste into sustainable composite materials like bioplastics, wood and even leather that are environmentally-friendly and biodegradable.

Fruit waste collected is first processed via juice extraction. The fruit juices are then fermented to produce bacteria cellulose. In this process, bacteria cellulose is first processed from a solid mat into loosely dispersed fibres, which are then mixed with a special formulation and subjected to heat treatment at 70°C to form the final sustainable material.

Bacteria cellulose formed after the fermentation of waste fruit juices

By producing materials from food waste instead of using fossil fuels and natural resources, we can cut down on waste and harmful emissions in a move towards achieving a circular economy.

¹Source: Nea.gov.sg - Food waste Management

Waste durian husks (left) processed using IMRE’s technology to form eco-friendly plant pots (right)

To combat climate change by reducing waste generation and carbon footprint, and supporting Singapore’s Green Plan 2030¹ to reduce 30 per cent of waste sent to the landfill by 2030 , there is a pressing need to introduce more sustainable processes to reduce waste generation.

A*STAR’s Institute of Materials Research and Engineering (IMRE) has developed technology to upcycle organic, inedible fruit waste like durian husks into eco-friendly plant pots, turning conventional waste streams into new, sustainable resources.

The eco-friendly plant pots created from durian husks are fully compostable and degradable in soil, leaving no microplastic trace or toxic residues, offering a green alternative to the non-biodegradable plastic that are created using fossil fuels. Seedlings usually have to be removed from conventional plastic pots to be replanted into the soil, causing waste generation as the plastic pots are usually thrown away thereafter and incurring potential transplant shocks to the plants due to the replanting process. However, there is no need to remove or throw away the eco-friendly plant pots as they can be transferred together with the plants and fully biodegrade in the soil after 3-6 months. This makes agricultural processes less tedious with less waste generation, and also prevents transplant shock in plants by avoiding the need for replanting. Beyond benefiting agricultural businesses, the eco-friendly plant pots can also benefit individuals and communities involved in the urban farming movement, which is growing in popularity in Singapore, for a more food-resilient future.

¹Source: Greenplan.gov.sg - Key targets
²Source: Businesstoday.com.my - Durian projects now closer to Singapore, worlds third largest durian consumer

Dr Zhang Lili from ISCE², A*STAR holding batteries. Carbon nanotubes (CNTs) formed from the plastic waste upcyling process can form essential components in such batteries.

Plastics take up to 500 years to decompose. In Singapore, about one million tons of plastic waste are generated annually and more than 95 per cent are typically incinerated. Our current rate of dumping incinerated waste is unsustainable, as Semakau Landfill is expected to be fully filled by 2035¹.

A*STAR’s Institute of Sustainability for Chemicals, Energy and Environment (ISCE²) has developed technology that can upcycle different types of plastic waste, even those which are contaminated, into hydrogen (H₂) and carbon nanotubes (CNTs), reducing plastic waste by transforming them into useful materials.

The waste plastic (including any contaminated plastic waste mixture) is processed through the reactor with a specially developed catalyst at an elevated temperature (450°C to 650°C), forming H₂ and CNTs. The H₂ produced can be used as a clean energy source, while the CNTs produced can be used to form essential components found in batteries and lightweight materials for vehicle bodies.

¹ Source: Nea.gov.sg - Waste statistics and overall recycling

An example of a 3D printed logo made from recycled polymer blend

Singapore is adopting a circular economy approach and A*STAR is contributing to this effort by upcycling industrial plastic waste.

Polyethylene Terephthalate, or PET, is a type of plastic and such waste is usually incinerated or deposited in landfills. Increasing consumer awareness and legislation are driving the trend toward sustainable solutions with lower environmental footprint. Singapore also aims to send one-third less waste to the Semakau Landfill by 2030¹ .

A*STAR’s Singapore Institute of Manufacturing Technology (SIMTech) has created a method to convert PET industrial plastic waste into 3D printable filaments for additive manufacturing. By modifying the materials of the industrial waste, the resulting filament is formulated to be printable, with functional mechanical properties fit for prototype usage.

By using the recycled filaments, we can reduce the consumption of raw materials for 3D printing of prototypes or souvenirs. This method demonstrates a sustainable approach of using plastic waste in 3D printing.

¹ Source: Straitstimes.com - Singapore aims to send one third less waste to semakau landfill by 2030 - Amy Khor

Carbonated materials made from CO₂ and waste materials, which can be used to make alternative sand

What if we can reduce carbon emissions and waste, while creating valuable alternative sand for use in construction?

Singapore’s power sector accounts for more than 20 million tonnes of CO₂ emissions annually, while Semakau Landfill is expected to be filled by 2035 due to an increasing amount of waste being produced. Conventional solutions for CO₂ capture to reduce carbon emissions are challenging due to the low CO₂ concentration (around 3-5 per cent) in flue gases produced at power plants .

To combat these issues, A*STAR’s Institute of Sustainability for Chemicals, Energy and Environment (ISCE²), the National University of Singapore and the Nanyang Technological University, Singapore, have collaborated to develop innovative technology that can create alternative sand from CO₂ and waste materials such as recycled concrete aggregates and incineration ash. Easily-available CO₂ and waste materials, that would otherwise exist as pollutants, can be upcycled into useful construction sand substitutes. The project supports Singapore’s push for a more sustainable circular economy, while addressing the growing demand for raw construction materials like sand.

¹ Source: File.go.gov.sg - Carbon capture utilisation and storage decarbonisation pathway for Singapore energy and chemical sectors [PDF]

How does machine learning play an important role in decarbonising our future?

Catalysts are critical to processes in the chemical industry. More than 80 per cent of all manufactured products in the world use catalysts within the manufactured process¹.However, existing methods of developing effective catalysts are time-consuming and there is an urgent need to find new catalysts to meet the objectives of carbon capture, utilisation and storage (CCUS) to support Singapore’s decarbonisation efforts and the transition to a green economy.

Researchers from A*STAR’s Institute of Sustainability for Chemicals, Energy and Environment (ISCE²), Institute of Materials Research and Engineering (IMRE) and Institute of High Performance Computing (IHPC) have teamed up to use machine learning and speed up the development of new catalysts via the Accelerated Catalyst Development Platform (ACDP). Areas of research and development include characterisation, screening, and synthesis of catalysts. Using the ACDP, the A*STAR team partnered an industry collaborator to develop catalysts to convert CO₂ to useful chemicals and fuels.

The ACDP accelerates the development of improved catalytic processes by up to fivefold of today’s standards for the petrochemicals, specialty chemicals, and power industries. This is important as oil refineries and power generation plants contribute 80 per cent of Singapore's greenhouse gas emissions².

Chemical manufacturing using CO₂, electricity and water is an emerging field that offers an attractive route to close the carbon cycle.

Chemicals manufacturing consumes large amounts of energy and is responsible for a significant portion of global carbon emissions. CO_2. emissions from primary chemical production amounted to 925 Mt (metric tons per capita) in 2021, a five percent increase as compared to 2020¹.

A team of researchers from A*STAR’s Institute of Sustainability for Chemicals, Energy and Environment (ISCE²) has developed a electrochemical system that produces valuable chemicals such as ethylene oxide which is a versatile chemical building block; and formic acid, a valued chemical reagent widely used in the chemical industry from CO₂ water and electricity at ambient temperature and pressure. The copper-based catalysts enable reactions to occur at high current densities (>300 mA/cm2 or milliampere per square centimetre), which increases the production rate per square area of electrolyser and expands the repertoire of chemicals that can be obtained from CO_2.