we have a recycling problem- can biotechnology fix it?
Recycling is great. I applaud municipalities, such as New York, San Francisco, Vancouver and Singapore, that have established wide-reaching programs and achieved substantial compliance and conversion. I am amazed and inspired by countries like Sweden that have achieved an almost entirely waste-free circular economy. I dream of a world where every newspaper is made from 100% post-consumer recycled paper, every kombucha bottle gets refilled at the facility again, where plastic containers are transformed into carpet fibers and no dolphin has to deal with plastic bottles unless it is for a cute Christmas-in-Hawaii Coca-Cola commercial. Unfortunately, this is not the case.
The US recycles only about 9% of all its plastic. When I moved to Florida from Colorado where people recycled in their sleep, I was appalled by the lack of recycling options my apartment complex. I started collecting my recyclables and taking them over to the university recycling center. I was shocked to see how much I was generating. I always thought of myself as a conscious consumer, but it was still a lot. Every two weeks I would fill up a couple of paper bags with empty blueberry containers, LaCroix cans, junk mail and an occasional wine bottle (or two). The worst was when I first moved in and was ordering things online. Not to name any names, but some of those “eco-friendly” subscription services use an exuberant amount of packaging. Kind of defeats the purpose, doesn’t it?
Recycling is good because it helps develop a more conscious attitude towards resources and instill the behaviors to change the current paradigm of wastefulness. It is good for the simple fact that it makes you realize how much unnecessary packaging most products come in, how much we consume and how much waste we generate. Also, it gives me a sense of moral superiority over my neighbors who seem to produce orders of magnitude more trash than I do. (How do I know? Because everyone puts out their garbage for valet pickup. It’s another strange Florida thing.) I, on the other hand, sort my trash and take the largest proportion of it out to my car when no one is watching. On the surface, I am the one generating the least trash, but in reality, the amount is probably the same: mine is just out of sight and out of mind.
Here is the hidden problem with recycling: it makes people feel better about the amount of waste they produce, because it does not look like trash. It is not smelly and gross, like the other stuff. It sits neatly in the plastic bin in your garage, next to some tools and bikes, making it look like something that can be used later. But like those tools and bikes, it rarely actually gets used. Unfortunately, with China no longer accepting our recycling, those items that you meticulously sort, end up joining their smelly garbage friends in the landfill. Running recycling plants in the US is economically unprofitable. With the few existing recycling facilities operating at capacity, the recycling trucks just get turned around and sent back to landfill sites.
At this point in time, the biggest benefit of recycling is making you feel good about yourself. You feel like a responsible citizen doing your part to save the planet. You put away your empty bottles into a blue bin and go to sleep peacefully, dreaming about how those bottles get reincarnated as shiny new products. Most people do not realize how difficult and inefficient the recycling process is. It uses a lot of energy, which comes from burning fossil fuels. Plastic can only be recycled a number of times before it loses its material properties and yes, you do have to actually wash clean and take the ring off the plastic bottles for them to be acceptable recycling material. And no, the Silk cartons cannot be recycled in most places, nor can your Blue Apron frozen dinner packaging, as those are made of composite materials (layers of paper, plastic and metal) that are impossible to separate effectively.
What recycling does not accomplish is actually make a dent in the amount of resources we use, as economic and environmental analyses of the impact of recycling have shown. Remember that there is Reduce and Reuse before Recycle? Those steps have a much greater effect on sustainability than recycling does. Recycling works well for glass and metals, which can be recycled almost indefinitely. But plastic can only be recycled 2-3 times before becoming unusable. Plastic recycling is extremely difficult due to the chemical processes involved in making the new product, which requires that the starting material be extremely pure. There are also strict regulations when it comes to the quality and material source if the reclaimed product is to be used for food packaging.
Are there alternatives to recycling the way it is done right now? Yes, there are. There are a number of companies that are implementing a new process called chemical recycling. Instead of mechanically processing plastic materials, it uses enzymes and solvents to break them down into small starting molecules, which allows recovery of pure material and extends the number of cycles plastic can be reused without losing quality. However, this process requires high temperatures and uses harsh chemicals, making it not the most environmentally friendly. Scientists are still on a quest for a truly “green” recycling alternative.
Recently there has been a lot of research into plastic degrading microorganisms. These newly discovered bugs evolved over the last few decades coinciding with the accumulation of plastic in the environment and developed ways to use it as a food source. Scientists have been looking into how to harness this unique ability for remediation of plastic pollution in the ocean and land environments. There is also a possibility of using these organisms in an industrial setting, similar to current recycling plants, to degrade the waste materials and biologically convert them to new valuable products. Unlike recycling, biological processing does not require pure starting materials; in fact, microbes benefit from the presence of food particles. Additionally, this process can turn plastic into biofuels or more expensive compounds, adding value to it.
The advantage of using microorganisms for dealing with plastic waste is that they do not require high temperatures or harsh reaction conditions. They can grow on mixed waste material, which simplifies the pre-treatment process. They also do not generate harmful byproducts. In fact, by using different types of organisms in the same reactor, it is possible to achieve a carbon neutral outcome where one type of organism consumes the CO2 produced by the respiration of the other microbes that degrade the plastic. Finally, by designing the bioprocess to make value-added products, the operation of such a biorefinery can be made economically profitable.
The big challenge is that it is difficult to engineer an organism that is simultaneously good as degrading plastic, efficient at making the valuable product and robust enough to survive in the not-so-ideal conditions of the processing facility. The microbes that have been found to degrade plastic do so at a very slow rate and do not produce much beyond CO2 and normal (read: useless) products of bacterial growth. Additionally, to break down the chemical links in the plastic, the organism needs to be able to attach tightly to its surface and get into the hard-to-reach microscopic corners, while still having access to oxygen to grow. It is kind of a lot to ask from one little guy: just like asking your pet to catch mice, give milk and clean your house at the same time.
With the grand idea of harnessing the power of biotechnology to solve the world’s most pressing problems comes the challenge of figuring out how to implement these ideas in practice. Scientists are up for the challenge – we are actively working on developing molecular tools, discovering new organisms and engineering them to have the desirable characteristics that we would like to see in an industrially robust strain. But don’t expect us to come up with a solution tomorrow. In the meantime, please do your part to reduce your consumption of unnecessary products and use your consumer influence to convince companies to reduce packaging and use more sustainable materials. You do not need to be a scientist to make a positive impact in the world. Everyone’s actions and everyone’s effort add up to much more than what any one of us scientists can achieve.
Geyer R, Jambeck JR, Law KL. Production, use, and fate of all plastics ever made. Sci Adv. 2017 Jul 19;3(7):e1700782: https://advances.sciencemag.org/content/3/7/e1700782
Yoshida, S., et al. "A bacterium that degrades and assimilates poly(ethylene terephthalate). " Science 351.6278 (2016): 1196-1199: https://www.ncbi.nlm.nih.gov/pubmed/26965627
Austin, Harry P., et al. "Characterization and engineering of a plastic-degrading aromatic polyesterase." Proceedings of the National Academy of Sciences 115.19 (2018): E4350-E4357: https://www.ncbi.nlm.nih.gov/pubmed/29666242