Resource Recovery: Transforming Waste into Sustainable Bioplastics
Plastics have undeniably transformed modern society, providing convenience and versatility across individuals and industries. However, this convenience comes at a significant environmental cost. According to the World Population Review, Malaysia generates 41.3 kg of plastic waste per capita annually, with approximately one million tonnes of mismanaged plastic waste. This places the country among the highest in the global mismanaged waste index. A major contributor to this issue is the widespread use of single-use plastics, which account for nearly half of all plastic production.
Recognising the severity of plastic pollution and the lack of affordable eco-friendly alternatives, the Malaysian government has outlined a roadmap towards zero single-use plastics by 2030. A key strategy in this transition must be the shift from conventional petroleum-based plastics to biodegradable alternatives such as bioplastics. Among various bioplastics, polyhydroxyalkanoates (PHA) are an attractive option due to their mechanical properties, which resemble widely used plastics like polypropylene and polyethylene. The properties of PHA depend on the monomer types and the chain length. For instance, a copolymer, poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHB-co-HV), exhibits enhanced toughness and flexibility compared to homopolymer poly-3-hydroxybutyrate (PHB), making it more suitable for commercial applications.
Despite its potential, large-scale PHA production through biological processes is deemed challenging. High production costs arise from complex bioprocessing steps, including sterilisation, the use of pure carbon substrates, and reliance on pure microbial cultures, contributing to nearly 50% of total production costs. Researchers are exploring cost-effective alternatives such as waste-derived substrates and mixed microbial cultures. Studies have shown that these approaches can achieve a PHA content of over 70%, but issues such as low volumetric productivity and inconsistent quality in mixed-culture systems remain significant hurdles.
Scaling up PHA production to pilot and industrial levels presents additional difficulties, with only a few successful case studies reported when mixed cultures are used. Instead of using mixed cultures, an approach involving extremophilic microorganisms that can thrive in non-sterile conditions while producing high-quality PHA is another promising option. Additionally, downstream processing methods used for extraction significantly impact PHA quality. Therefore, an efficient, environmentally friendly, and cost-effective PHA extraction technique is required to produce consistent, high-quality PHA.
To enhance the economic viability of PHA production, its applications must extend beyond biodegradability. PHA-based materials can be blended with other compounds to enhance mechanical strength, flexibility, and durability. Different monomer compositions allow for the customisation of PHA properties, making them suitable for a wide range of industrial applications. Moreover, PHA-based materials can be engineered to exhibit improved elastic behaviour and adaptable mechanical properties, broadening their usability. Additionally, PHA is a strong candidate for replacing conventional single-use plastics, with food packaging being one of the primary target markets.
In the Malaysian context, organic waste from dominant agricultural industries presents a potential feedstock for PHA production. Research has shown that palm oil mill effluent and crude glycerol, the by-products of the palm oil and biodiesel industries, serve as viable carbon sources for PHA synthesis. Successful implementation of these strategies could strengthen circular economy initiatives, particularly in the palm oil sector. While upstream processing in this industry has seen advancements in waste-to-energy conversion, wastewater treatment, and carbon emissions reduction, incorporating waste valorisation in both upstream and downstream processes can further enhance the circularity of the industry. This approach could serve as a scalable framework for promoting a circular economy across other industries.
Single-use plastics have an average lifespan of just 12 to 15 minutes, yet they can persist in the environment for up to 500 years. The urgent need for economic and environmentally friendly alternatives cannot be overstated. By integrating innovative bioplastic solutions, embracing circular economy principles, and harnessing Malaysia’s abundant waste resources, the country must accelerate its transition towards a more sustainable, plastic-free future.
Dr Yoon Li Wan
School of Engineering and Technology
Email: @email