Human Practices
At the root, plastic pollution is a societal issue. Our team determined early on that if we are to tackle plastic pollution, it is crucial to develop a project that not only permits bioremediation of our environment but that can be successfully integrated into our local community while considering the economic and social barriers already in place that have prevented progress towards the elimination of plastic waste within our province. A sustainable solution in Manitoba to achieve this goal required community involvement at all stages of our project development.
The Rise of Bio-Plastics
In the initial design phase, we focused our efforts on mixed-plastic waste. In Canada, all of our recyclable materials are thrown into one bin. There is no sorting of glass, cardboard, or different types of plastics, and we are reliant on both manual and high-tech sorting initiatives once the waste arrives at recycling facilities. However, we were aware that only 9% of plastic waste produced in Canada actually ends up in these recycling facilities, suggesting pitfalls in our approach to waste management (Government of Canada, 2023). Our plan was therefore to design a biological organism that was capable of breaking down multiple types of plastic to remove the need for physical sorting within our communities. At the same time, we worked to recruit advisors who would be able to guide our efforts in addressing plastic pollution on both biological and social levels. We recruited Dr. David Levin, an expert in the field when it comes to plastic degradation who has experience in the use of microbes to degrade various types of plastics, and Dr. Lori Wilkinson, an expert in survey creation who offered to guide us in our social science initiatives to address the social barriers in waste management practices.
As we continued on in our design phase, we were introduced to the growing influence of PLA plastic not only globally, but locally within Manitoba – and that although it is being advertised as a compostable plastic, it is still a major contributor to plastic pollution in landfills. We were introduced to Dr. Joe Ackerman, a bio-systems engineering professor at the University of Manitoba who has been working on PLA plastic breakdown in compost. He recently acquired a BioVator system, a stainless steel in-vessel composter, and informed us of the issues with PLA breakdown compared to the degradation of traditional food compost. PLA requires much higher temperatures compared to the ambient temperatures of food compost. The cold temperatures in Winnipeg, Manitoba (our hometown) only exacerbate the issue of slow PLA breakdown.
At the same time, we wanted to learn more about the current state of recycling programs in Manitoba and the issues associated with mixed-plastic waste. We met with the Multi-Material Stewardship of Manitoba (MMSM), a not-for-profit, industry-funded organization that focused on blue-bin recycling programs. They informed us that contrary to our beliefs, Manitoba’s recycling programs are actually quite strong, with a 94% participation rate across Manitoban communities, and a 72% recovery rate of recyclables from industry output (MMSM, 2022). Their experts informed us that Manitobans used to pre-sort their waste back when there was a high value for the individual commodities, but now these markets have crashed, making the blue-bin program the most economically feasible option. They also emphasized that this simple system and city-wide pick-up programs ensures the continued participation of Manitobans and are the best option to prevent plastic waste from ending up in landfills. Interestingly, they also informed our team that PLA is not accepted in the blue bin and is considered a contaminant when it ends up in recycling facilities.
Taking the feedback from Dr. Ackerman and the MMSM, we decided to pivot our project to focus on the issues associated with PLA breakdown, rather than mixed-plastic waste. It is clear that the blue-bin program is the most cost-effective initiative for our province as it ensures the highest amount of recycling participation. However, the lack of knowledge regarding recycling vs. composting streams, the clear struggles in PLA breakdown, and PLA’s current rise in the Canadian economy as a “green” plastic in the fight towards net-zero emissions by 2050 convinced our team to focus our efforts on PLA (Government of Canada, 2023). We therefore decided to engineer a biological organism that could be applied to compost and allow for the degradation of PLA plastic.
How to Make Compostable Plastic Actually Compostable?
At this point, we were left with two big questions when looking at our project development:
- What is the best way to improve PLA breakdown in composting?
- Is a bio-based solution a feasible option to solve this PLA problem? How would we deal with potential environmental release?
We met with Stephanie Chow, the sustainability coordinator at the Forks Market in Winnipeg who is a trailblazer in PLA composting initiatives. As part of the food vendor’s new lease agreements, businesses must swap their standard petroleum-based plastic containers and cutlery for PLA products, which are then composted on-site using a BioVator system. Stephanie informed us that the main challenges she has encountered with this process is the difficulty in maintaining high composting temperatures and the overall rate of PLA breakdown. She informed us that the BioVator does reach the high temperatures required for PLA degradation but these temperatures are difficult to sustain. She highlighted that the slow rate of degradation is a key factor in these plastics having to be run through the system multiple times.
Stephanie also introduced us to the Canadian composting standards that require sterilization prior to the use of the compost (55°C for at least three consecutive days for in-vessel composters) (CCME, 2005). This sterilization process is used in commercial and industrial settings per governmental agency requirements to kill any potential pathogens that may be present, to prevent release into the environment when the soil is re-used for landscaping or agricultural purposes.
It was clear that in contrast to Manitoba’s mixed plastic waste, a bio-based solution to address PLA plastic breakdown doesn’t require the re-invention of a completely new waste management system within our community. Targeting the slow rate of PLA breakdown through enzymatic catalysis and implementing the existing containment strategy through compost sterilization, it was clear that this was a realistic and responsible implementation of our prototype. To ensure our prototype can be readily integrated across existing composting programs in Winnipeg, we focused our efforts on developing a device for implementation in commercial and industrial settings. Our team previously brainstormed the potential use of our organism in compost accelerators, which are products that contain a mix of microorganisms to increase the rate of decomposition in compost. However, since most PLA plastic use tends to be in commercial settings and since this implementation does not allow for sterilization, we decided to focus on contained commercial composting systems that must adhere to compost quality regulations. Further, to eliminate the cost barrier associated with enzyme purification, we decided on the use of a surface-display mechanism to expose the PLA-degrading enzymes.
PLAnet Zero: A Project By the People, for the People
As our work continued in the development of our prototype, we wanted to continue our conversations with members of the waste management community. Our team members arranged a ride-along with Compost Winnipeg, a private compost pick-up service that acts as the link between businesses and industrial composting facilities. Although many residential areas and businesses use their services, the cost is still a major barrier preventing wide-spread use of their program. However, our city is working to deal with these barriers and has completed a pilot project for city-wide composting, showing that initiatives to improve the state of compost management in Winnipeg are being prioritized in our community.
To further our understanding regarding the current state of composting in Winnipeg, we then met with Kelly Kuryk from the Canadian Council of Ministers of the Environment (CCME). Kelly informed us that Winnipeg is still fairly under-developed for composting. Unless businesses have a contract with Compost Winnipeg or a facility like the Forks Market which offers composting on-site, most compost waste ends up in landfill. She emphasized that the rate of PLA breakdown seen with the BioVator system also applies to windrow facilities. Windrow composting is the process of putting organic waste in long piles, and periodically mechanically turning the piles to allow for aerobic breakdown of the waste. We learned through our meeting with Compost Winnipeg that all of the compost is collected in PLA bags and taken to a windrow facility for breakdown. Due to the slow rate of PLA breakdown, the bags do not break down enough, and end up wrapping around the blades of the windrow, causing wear and tear to the system, further emphasizing the burden of PLA plastic in composting facilities. We were also interested in learning about the governmental regulations surrounding the end-use of our produced compost. There are two compost quality standards outlined by CCME that determine compost end-use, that are determined based on four criteria: foreign matter, maturity, pathogens, and trace elements. Based on this criteria, compost is either divided into category A (unrestricted) or category B (restricted-use) (CCME, 2005). All composting facilities in Manitoba follow these CCME guidelines, as it is required to receive funding. Kelly informed us that our facilities take it one step further via the Compost Quality Alliance (CQA) testing established by the Compost Council of Canada that determines whether the finished compost can be used for planting in the home and garden industry or for agricultural and land reclamation uses (A&L Canada Laboratories, 2018). In the future, it is therefore of interest for our team to test the quality of our compost following field testing, to determine the best end-use of our compost.
It was clear that PLA breakdown was a challenge to different types of composting systems, including the BioVator and in windrow composting facilities. To further understand the scope of composting facilities in Manitoba, we met with Mark Milne, the Vice-President and General Manager of Enviroclean Landfill Solutions (ELS) in Morden, Manitoba. Windrow composting requires all open-air outdoor facilities, which when you’re living in one of the coldest cities in the world, does not allow for all-season composting. ELS developed unique Aerobic Rapid Bio-Digestion Machines that allow for indoor, in-vessel composting. These devices allow for very controlled conditions and allow ELS to process their compost in just 24 hours.
Mark was very interested in our use of an engineered biological organism to aid in the breakdown of PLA and even discussed the potential of field-testing our prototype using his systems in the future. This meeting with ELS establishes that there is room and support for a bio-based solution to PLA plastic in the composting community.
Following our numerous discussions with the waste management professionals, the end-users of PLAnet zero, we knew that we had to address the general public to not only fill the gaps regarding composting knowledge in Manitoba, but to get further feedback on our proposed project implementation. Over the course of our project development, we were working in parallel with our advisor Dr. Lori Wilkinson to develop a public survey outlining the recycling and composting practices of Manitobans. The goal of this survey is to determine the current state of knowledge regarding these waste management practices, and to gauge public opinion on the use of an engineered biological organism being implemented in composting facilities. As of October 12th, 2023, our survey has passed through our institutional ethics approval board, and we are in the process of collecting and analyzing the data.
When our UManitoba team members decided to take on plastic pollution, we knew that it would be a major feat. However, Canadians are clear in their goals to achieve net-zero plastic waste by 2030 as seen by the phasing out of petroleum-based plastics for PLA across the country. Our community is willing to change to ensure a better tomorrow. Through discussions with waste management experts across Manitoba, it was clear that this rise in bio-plastics required a novel bio-based solution to ensure that PLA was ending up where it belongs, in the compost bin, ensuring a circular economy where our products and materials are retained, recycled and reused to reduce and conserve our natural resources. PLAnet Zero offers a responsible and realistic solution to PLA plastic waste.
References
A&L Laboratories Canada. (2018). Compost Analysis. https://www.alcanada.com/content/solutions/compost-analysis
Canadian Council of Ministers of the Environment. (2005). Guidelines for Compost Quality. https://ccme.ca/en/res/compostgdlns_1340_e.pdf
Government of Canada. (2023). Plastic Waste and Pollution Reduction. https://www.canada.ca/en/environment-climate-change/services/managing-reducing-waste/reduce-plastic-waste.html
Government of Canada. (2023). Net-Zero Emissions by 2050. https://www.canada.ca/en/services/environment/weather/climatechange/climate-plan/net-zero-emissions-2050.html
Multi-Material Stewardship Manitoba. (2022). MMSM for a Greener Tomorrow: 2022 Annual Report. https://stewardshipmanitoba.org/mmsm/reports/