Wastewater Cultivation of Microalgae for Bio-based Nylon Precursor Production

Isaiah Colina, Emma Harris, Kate Lindsay, Matthew Mulia, Jessica Sun and Henry Ting

Community Partner: lululemon
Degree: Bachelor of Applied Science
Program:
- Environmental Engineering
Campus: Vancouver

Our project

As part of its effort to reduce its reliance on fossil fuels, lululemon has set the ambitious goals to use preferred materials and end-of-use solutions to support ad advance a circular economy. This journey will require shifting away from some of their existing materials or finding new ways to make other materials, including nylon, a synthetic polymer used in the company’s clothing and that is traditionally made by processing petroleum into building block polymers.

We collaborated with the innovation team at lululemon to develop a microalgae cultivation and harvesting process that produces hydrolysate, a feedstock that can be used to produce nylon via a biomanufacturing process.

In addition to supporting lululemon’s goals, our process makes use of wastewater from dairy processing plants, thus providing a value-added use for wastewater.

Our design solution and process

Our proposed facility, located near several dairy farms in the Lower Mainland, will take in and reuse 800,000 litres of dairy wastewater per day that would otherwise be diverted. This water has a very high nutrient content that is highly supportive for algae growth. The water is piped and trucked into storage tanks to control the flow and then treated to remove basic sediments and increase the pH. It then goes into six ponds that are 250 metres long by 16 metres wide where the algae is cultivated and grown.

We then harvest the algae from the outflow and separate it from the water. The algae is dried and ground into a powder in our indoor processing facility, where it is treated and undergoes hydrolysis to produce hydrolysate, which is then further processed in an off-site processing facility to make nylon.

Getting to this solution required considerable research. To start, we needed to assess different microalgae strains and select the strain that had the qualities we needed in terms of growth rate, adaptability and biochemical composition.

The strain we selected can be used as a feedstock to produce hydrolysate, a biopolymer precursor for nylon, using microbial pathways.

As environmental engineering students, we are always looking at the larger system and exploring ways to make a process more sustainable. This led us to the idea of using the wastewater associated with dairy processing (such as the water used to make cheese or filter milk) within our production process.

Another significant consideration was location. We originally developed plans to build the system in the Okanagan where there is more sunlight for growing the algae. However, this location had fewer registered dairy processing facilities than the Lower Mainland, which meant we would need to truck in additional dairy wastewater (and then have higher emissions associated with transportation).

We selected a location in Delta where our facility can access wastewater feedstock from multiple dairy operations. The negative impact of fewer days of sunlight and more precipitation is outweighed by increased production from abundant source of dairy wastewater and reduced emissions.

The challenges we faced

We needed to learn a lot to work on this project – from understanding how the biochemistry works to figuring out if it was technically feasible to produce large volumes of hydrolysate within our production facility.

This is an emerging area of research and comparable applications are being done at a very small scale. We had to do a lot of literature reviews and calculations to arrive at our solution.

This project was unlike anything we’ve worked on in our degree. Many projects we’ve worked on prior to this were relatively straightforward and required us to apply practices that had been successfully used in other applications. This was an open-ended project where it was up to us evaluate and assess potential ideas and solutions. We think we did a good job of narrowing the scope, understanding our client’s needs and coming up with a feasible and innovative solution.

What we’re most proud of

This project had a lot of highlights. Working with Lululemon was extremely rewarding. It was fascinating to get a peek into all of the research that goes into product development at the company. Before we started this project we were not aware, for example, that Lululemon has scientists on staff. It was also interesting to work for a private-sector client.

Many environmental engineering projects and co-op positions are directly or indirectly linked to a government organization or project, and it was interesting to be developing a solution for a for-profit company.

Before this capstone project, we had not worked on projects that required this level of technical research. While it took us some time to gain the needed familiarity and expertise with the different elements of this project, there was a moment when everything came together and we could see how it could all work. In addition to learning so much over the eight months, it was also very rewarding to be applying our existing knowledge and skills in new ways.

Finally, we really capitalized on the opportunity to use our different skills to work together on a project that we are proud of. It makes us excited to think about our future and capacity to do great work in our future careers!

Our project’s future

This project could serve as a foundation for further exploration into the scalability and adaptability of microalgae-based materials across different industries, including the textile industry.

We’re excited to see the continued adoption of processes utilizing waste streams to produce sustainable materials over the next few years, and we’re proud to think we may have contributed in some small way to advancing sustainability efforts across the industry.