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 boast 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 in the neighborhood where I lived. I started collecting my recyclables and taking them to the university recycling center. I was shocked to see how much material I accumulated. I always thought of myself as a conscious consumer, but it was A LOT. Every week 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. It kind of defeats the purpose, doesn’t it?
The act of recycling is useful because it helps develop a more conscious attitude toward consumption and instill behaviors that will hopefully help us break away from 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. They simply put out their garbage for valet pickup, whereas I sort my trash and take the largest portion 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 lies 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 just 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, some recycling trucks 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 process of recycling 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 the plastic bottles for them to be acceptable recycling material. And no, neither the alternative milk cartons nor the Paleo frozen dinner packages can be recycled, as those are made of composite materials (layers of paper, plastic and metal) that are impossible to separate effectively.
Despite its noble intentions and virtue signaling potential, our current approach to recycling does not 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. Recycling plastic is extremely difficult because the chemical process of making a new product requires exceptional purity of incoming materials. 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 approaching this problem? Yes! A number of companies are implementing a new process called chemical recycling. Instead of mechanically processing plastic materials, chemical recycling uses enzymes and solvents to break them down into small starting molecules, which facilitates 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.
On the quest for a greener alternative, researchers have turned to plastic degrading microorganisms. The recently discovered bugs have evolved over decades coinciding with accumulation of plastic in the environment and have 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 oceans and landfills. There is also a possibility of using these organisms in industrial settings, similar to current recycling plants, to degrade waste materials and convert them into new valuable products. Unlike recycling, biological processing does not require pure starting materials; in fact, microbes thrive in the presence of food particles. Additionally, there is a way to turn it into upcycling by converting waste into biofuels and added-value products.
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 food-contaminated 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 bioprocesses that put out value-added products, the operation of such biorefineries can be made economically profitable.
The biggest challenge in executing this ambitious plan is that it is hard to find an organism that is simultaneously good at 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 shown to degrade plastic do so at a very slow rate and do not produce anything besides CO2 and normal (read: useless) products of bacterial growth. 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: like asking your pet to catch mice, give milk and clean your house all at the same time.
With the grand goal 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 to the task – we are actively working on developing molecular tools, discovering new organisms, and engineering them to have the desirable characteristics of industrially useful strains. But don’t expect us to come up with a solution tomorrow. In the meantime, please do your part to reduce consumption of unnecessary products and use your consumer influence to convince companies to minimize 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 efforts 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