5th ACE Call Awards

Engineering Solutions Inspired by Plastics-eating Worms to End Plastic Waste

PI: Cao Bin (CEE)
Co-PI: Liang Zhao Xun (SBS & SCELSE); Chen Ming-Hsu (SCBE); She Qianhong (CEE & NEWRI)

The large-scale production and use of plastics coupled to a low recycling and incineration rate (~20%) for plastic waste has resulted in severe plastic pollution to the environment. To address this global concern, it is imperative to develop efficient, cost-effective processes to convert plastic wastes to valuable commodities. The state-of-the-art plastic recycling involves mechanical and/or chemical methods, which often require extensive use of energy and toxic chemicals. Biotechnological processes employing depolymerizing enzymes are a promising, more sustainable alternative that can be operated under mild conditions. One challenge that limits the application of biotechnological processes is the highly heterogenous nature of plastic waste and the lack of highly active enzymes for depolymerization of mixed plastics. In particular, although PE and PS represent ~43% of total plastic production, there has been no PE/PS-depolymerizing enzymes or biochemical processes available for PE/PS bio-upcycling. Mealworms and wax moths have been observed to be capable of ingesting PS/PE plastics and reducing their weight. We aim to learn from these plastic-eating worms on how to deal with plastic waste. We will unravel biochemical mechanisms responsible for depolymerization in the gut metagenomes of the worms and then use them to develop microbial processes for depolymerization of plastic wastes in bioreactors.

This proposed project deviates from conventional mechanical/chemical methods for plastic recycling and explores the cutting-edge research domain of biotechnological upcycling of plastic waste. The idea of learning how to breakdown plastics from plastic-eating worms is audacious and the approaches we propose are unconventional. The completion of this project will lead to the development of disruptive methods to address the global challenge of plastic waste.

From Unsorted Plastic Waste to Value-Added Products

PI: Li Hong (MAE)
Co-PI: Zhou Yan (NEWRI); Yulan Wang (LKCM)
Collaborator: Ding Ovi Lian (ERIAN)

The overarching project goal is to develop a sustainable strategy to convert unsorted plastic waste mixture to value-added products (animal feed and green hydrogen) with zero net carbon emission to close the carbon cycle of plastic. An interdisciplinary approach leveraging the advances of mechanochemistry, electrochemistry, and microbial engineering will be employed through an integrated decentralized process at room temperature. Owing to the very different chemical properties of the plastics, pre-treatment of the waste mixture is composed of several processes. Briefly, the unsorted plastic waste will be cutting into micro-particles, and then hydrolysed in alkaline solution to remove hydrolysable plastic such as PET. The alkaline solution with hydrolysed plastic will be electrolyzed. The resulting solid product will go through a reactive microwave liquefaction process to be converted into liquid oxygenate. The remaining solid portion will be decomposed by a reactive mechanochemical process to obtain primarily oxidized oligomers dissolvable in alkaline electrolyte. As such, the plastic waste mixture will be dissolved in alkaline electrolyte that will be electrolyzed in a Hybrid Electrolyzer (patent No. 10201900445W) that can be driven by solar energy [paper Nature Communication (2021)]. The anodic product of electrolysis is dominated by organic acids, which will be converted to single-cell protein (SCP), an animal feed, in microbial reactions (patent No. 10202012724X). The cathodic product of electrolysis is green hydrogen fuel, which is essential for decarbonisation. Leveraging the energy storage strategy of solar-driven electrolysis, the net carbon emission can be decreased to zero.

The proposed multidisciplinary research involves four members from two colleges and two research centres to address the plastic waste challenge in an integrated interdisciplinary approach, which may offer a truly sustainable and viable solution to end the plastic waste. Thus, the proposed research is unsuitable for AcRF Tier-1 that seeds near-term external grant usually focusing on fundamental science.

Developing a Public-Private Partnership by Crowdfunding to Create Sustainable Plastics Upcycling Technologies

PI: Soo Han Sen (SPMS)
Co-PI: Chang Xin (NBS); Md Saidul Islam (SSS); Quah Teong Ewe, Euston (SSS)

Plastics recycling has historically been confined to mechanical processes that transform specific categories of plastics into equivalent or lower quality products, waste-to-energy schemes, or energy-intensive thermal processes that convert plastics into low-grade fuels. This project will build upon patented technology by the Principal Investigator that can potentially use renewable solar energy to upcycle non-biodegradable polyethylene, commonly found in packaging materials and single-use plastic bags, into formic acid, which is a chemical feedstock and fuel. A continuous flow reactor will be developed to demonstrate that the technology can be scaled up to handle post-consumer plastics. Nonetheless, such emerging deep tech innovations will need lengthy fundamental research before they can be turned into a start-up company to attract angel investors. To disrupt this traditional funding model, our team will conduct capital budgeting estimates and techno-economic analyses to guide the development of a crowdfunding scheme to create a public-private partnership to secure longer-term funding support. To aid this process, surveys will be conducted to gauge public awareness about the global plastics problem and their reservations or attitudes toward sustainable technologies. In addition, since the plastics upcycling technology relies on the availability of sorted plastics, we will also obtain insights about public support for more regulations on sorting recyclables. The insights we gain from the surveys will be employed to design the crowdfunding scheme. Furthermore, we can then create a communication plan and white paper to engage the government in introducing policies on sorting recyclables, especially plastics, which will be more conducive for the exploitation of the plastics upcycling technologies we will develop. This proposal is thus unique in synergising emerging scientific breakthroughs with new financing models and public outreach to potentially create a self-sustaining project that can bring plastics upcycling technology from the laboratory to the market.

Deep sea degradation of polymer-packaging litter – a new way to assess new materials

PI: Janelle Thompson (ASE)
Co-PI: Fei Xunchang (CEE)
Collaborator: Jamie Hinks (SCELSE)

By late 2019 marine plastics and microplastics were receiving a lot of media attention; pictures of animals ensnared in plastic litter emotively fuelled this public interest. As the world recovers from COVID-19, such images will likely resurface, but this time with masks and take-out dining containers littering the shoreline and endangering wildlife. The mundane reality, however, is that the majority of marine plastic litter quietly sinks to the seabed where it is conveniently forgotten about. Knowing the fate of this plastic litter is a global priority and it is essential that deep sea plastic biodegradation is understood under conditions that are actually relevant to the deep sea.

Unfortunately, the skills to assess deep sea plastic biodegradation are globally rare and insights into how plastic degradation may change at the high pressures characteristic of the seabed are lacking. The result is that to date, no such studies have been carried out. The combination of skills that exist between SCELSE, ASE, and CEE represent a complementary blend that uniquely positions NTU to carry out such trailblazing research.

The project on deep sea plastic biodegradation proposed herein will allow a natural collaborative team to form and develop a track record in deep sea plastics degradation, it will then be well positioned to leverage competitive research funding. Moreover, the opportunity to consider questions intersecting the field of social science is an advantage of the ACE fund and it will allow our team to evaluate the wider societal implications of our work and put the knowledge that we generate to use to stimulate new avenues in waste plastic mitigation.

Facing Plastic Waste Through Virtual Reality (VR): Using Narratives to Promote Plastic Recycling Behaviours among Youths

PI: Shirley S. Ho (WKWSCI)
Co-PI: Benjamin Li Junting (WKWSCI); Grzegroz Lisak (CEE & NEWRI); Shanti Divaharan (NIE)

This one-of-its-kind study draws on expertise from the fields of communication, education, and environmental engineering to develop an immersive virtual experience using Virtual Reality (VR) technologies to bring participants closer to the real-life consequences of plastic waste. The primary objective of this research is to gain an empirical understanding of how we can create awareness and encourage plastic waste recycling behaviour among secondary school students in Singapore by exploring the impact of different narratives using VR on plastic recycling behaviour.

We seek to leverage on VR technologies to bring the impact of plastic waste on the environment, closer to the general public. VR is a unique tool that facilitates multi-sensory immersion in a designed environment, allowing individuals to interact with the environment and realistically transport individuals to a different time or location. Through the demonstration of and interactions with the unseen effects of micro and macro plastic particles on the environment, wildlife, and human health, we aim to test the effectiveness of different narratives that incorporate emphasis on individual vs. collective responsibility, through a first- or third-person perspective, in encouraging plastic recycling behaviour.

The development of values and worldviews coincides with several aspects of emotional, cognitive and identity development during adolescence. Such values include social responsibility, which motivates behaviours that involve helping and contributing to society, where these values are stable and enduring till adulthood, making it worthwhile to examine youth behaviours.

We are confident that the proposed ideas reflect the merits of ACE and we expect that the outcome of this project can formulate recommendations to best address the first steps towards the eradication of plastic waste in the environment at the individual level. This will allow us to mobilise individuals in a coordinated effort to tackle global environmental challenges.