Team:Hong Kong HKU/Implementation


Implementation: Introduction has been designed with a vision to end the plastic pollution problem. Therefore, in tandem with the in-lab development of our bioreactor, we engaged with various start-ups and organisations and gained insights from them, and made concerted efforts to stay grounded in real-world practicality. Our main outcomes have always been to:
  • Rethinking food packaging and fast fashion through monomer recycling
  • Stopping PET plastic waste (and microplastics) from entering the environment

Our Design

Our system uses E. coli and S. elongatus to degrade PET into TPA and EG monomers with higher energy-efficiency and less waste in comparison to recycling plants. We plan to implement our project by following the prototype design as seen below, which would be able to accommodate all the system components as well as allow the addition or removal of reagents and organisms (see hardware for more details).

Figure 1: Bioreactor prototype design

Why Focus on PET Plastics?

PET plastics are commonly found in everyday objects - from clothes made of synthetic polyester fabric to foodwares such as bottles, table mats, etc. Despite the fact, PET is fully recyclable with established mechanisms to process the PET constituent monomers into recycled PET, the recycling rate today still remains far below what is potentially possible to be recycled.

Plastic waste is a global and local problem. Plastic waste around the world is typically disposed of without recycling, and every ocean in the planet has been found to contain plastic– it makes up 80% of all marine debris [1].

As a coastal city, Hong Kong needs to pay extra attention to the plastic waste problem and its impacts on the environment. Hong Kong already has a very high per-capita plastic waste disposal, with a minute amount of the plastic waste being recycled. To illustrate, it was found that 21% of its municipal solid waste is plastic waste, from which only about 14% is recycled [2]. PET bottles on the other hand, accounted for 8.3 million dumped every day [2].

Since then, the situation has continued to worsen. Under the COVID-19 pandemic, and the follow-up dine-in restrictions, Hong Kong people have switched to ordering take-away meals, which often come parcelled in disposable plasticware, contributing to record numbers of plastic waste disposed across the city.

Targeting PET for recycling would be of great use, given the surging abundance of disposed PET waste (in Hong Kong and around the world) and the established PET recycling mechanisms in place. As such, HKU iGEM decided to confront and attempt to solve the plastic waste problem using

How will we use it?

Keeping’s implementation in mind, we paid particular attention towards the collection of plastics and the production of recycled products using the degraded end-products of (namely TPA & EG monomers).

In terms of plastics collection, we have a potential collaboration with Clearbot, who manufactures AI-driven waste-collection robots (“clearbots”) in water bodies. Partnering together, we aim to create a new generation of “clearbots” with an built-in bioreactor to process marine plastics. Additionally, we also formulated a two-step solution for current generation “clearbots”, where collected plastic waste can be transferred to bioreactors on land for plastic sorting, processing and PET degradation.

On the production side, we can partner with local recycling plants, such as the New Life Plastics Ltd. at the EcoPark in Hong Kong, and plastic manufacturers who collaborate with individual external enterprises, to further process the PET monomers and produce new sustainable products from them. The recycling cycle has a decreased number of steps due to the provision of monomers, through which a circular economy is generated.

What can others do?

The drive to decrease plastic waste has also given rise to the plastic offset economy, where companies offer to intercept an amount of plastic before it reaches landfills or oceans for every dollar paid by another company or individuals. Combined with the global rise in environmental awareness amongst consumers and the potential material costs saved with, we expect to be well-received by investors and enterprises in an effort to have a greener supply chain. In the investors and enterprises doing so, they can also improve their company image through corporate social responsibility.

Future Opportunities

In the future, there is an alternative to using TPA and EG to recreate just plain plastic. To recycle the monomers, i.e. TPA and EG from PETase and MHETase digestion, we can utilise Pseudomonas sp. and their ability to manufacture bio-plastics. Pseudomonas strains produce poly-hydroxyalkanoates (PHA) as their source of energy [3], which can be used in lieu of traditional commercially produced plastic as an environmentally friendly alternative.

Other than advancements in project design, we may collaborate with BREED HKU, which is a student team from The University of Hong Kong that strives to breed “the next generation of bio-robots’. They hold a Guinness World Record for the fastest 50m swim by a robotic fish. Comparable to Clearbot, we hope that their technology could be used to help us collect plastic waste, but those that are underwater. A recent study found that the ocean floor contained up to 1.9 million plastic pieces per square metre [4]. Since microplastics are small and cannot be sieved out on a large scale without taking out marine life at the same time, we expect BREED HKU’s robotic fish to get up close and personal to these tiny plastic pieces and remove them from the surrounding water to reduce water pollution.

To read further about our project implementation, check out our entrepreneurship page where we break down the details about the above-mentioned aspects and more.


[1]IUCN (2018). IUCN Issues Brief, Marine plastics. [online] IUCN. Available at: [Accessed 20 Oct. 2021].

[2] ‌地球之友 Friends of the Earth. (2016). [online] Plastics. Available at: [Accessed 19 Oct. 2021].

[3] Mozejko-Ciesielska, J., Szacherska, K. and Marciniak, P. (2019). Pseudomonas Species as Producers of Eco-friendly Polyhydroxyalkanoates. Journal of Polymers and the Environment, [online] 27(6), pp.1151–1166. Available at: [Accessed 20 Oct. 2021].

[4] Amos, J. (2020). High microplastic concentration found on ocean floor. [online] BBC News. Available at: [Accessed 21 Oct. 2021].