As I’ve been living in Dublin, Ireland this summer and ignoring my duties to blog, I’d like to still report how many Sigg (aluminum) bottles I’ve spotted across Europe. Downtown Dublin’s hip scene rocks the bottles, the tourists rock the bottles. I see a trend of universal environmentalism and health consciousness here; or of just saving money.
The process of biodegradation
However. I’ve been working at University College Dublin, where Dr. Kevin O’Connor is leading a microbiology group’s study about bugs that can actually change toxic materials into biodegradable waste. The article, posted on the UCD website and lined with pictures of plastic water bottles, was too good for me to pass up. Here are some bits from the article:(http://www.ucd.ie/expertiseatucd/researchshowcase/2009/05MAY/plastic/index.html)
His current research in the field of biocatalysis has received a lot of attention recently but he’s been working on it since 2000. Making biodegradable plastic using different organisms was already a well-known procedure, one that the microbiologist and his team planned to expand on.
“What we were trying to do was come up with a different approach. We were asking if pollutants could be converted into valuable products like biodegradable plastic?”
Imagine if biodegradation caught on with water beverage companies. Imagine if all plastics could be biodegradable, clearing us of our landfill issues in the United States.
The original compound that Dr O’Connor used in the process was styrene, the main ingredient of polystyrene. But the team realised that the conversion of polystyrene itself to biodegradable plastics would be of greater value.
However, their particular bacterium didn’t grow on polystyrene. So he contacted Professor Walter Kaminsky in the University of Hamburg, an expert in pyrolysis – a special technique that uses temperatures of up to 520 degrees to heat the plastic in a vacuum, producing a liquid form of the styrene.
This process, I’m sure, cannot be cheap.
Dr O’Connor had a fair idea that their bug would grow when fed this styrene oil, and indeed it did, producing the biodegradable plastic PHA (polyhydroxalkanoate).
Extracting this plastic from the bacteria is a very simple procedure that involves soaking the bugs in a mild detergent. “Basically the detergent rips the bugs open in order to extract the small granules of plastic from each cell,” explains Dr O’Connor. The plastic is cleaned and it is then ready to be used.
This extraction process might be simple to carry out, but imagine the cost of the equipment needed to soak grand colonies of these bugs in detergent. I’m skeptical about whether a large-scale version of this process would be financially, or even technologically, feasible.
At the industrial level, the two-step process is carried out on a large scale, producing up to 1,000 litres of plastic – that’s a lot of bugs. Dr O’Connor is now working on improving the efficiency of the technique, using a combination of feeding and molecular strategies. At present some 30-35% of each bacterium is plastic; his team are looking to increase this yield to as much as 80%.
One one hand, this 80% may seem incredible, but the ranges of goods that could be made from this form of plastic may not span everything we imagine. Polystyrene water bottles and tupperware might be feasible for the largest companies to make, but probably not for all other products. Maybe we shouldn’t suddenly get excited that we could recycle anything plastic.
Keep in mind, we haven't really been recycling:
On the other hand, remember that the Sierra Club has reported that Americans discard over 30 million plastic bottles every day. Over 40% of the beverages purchased each day are plastic water bottles. Switching these plastics over to be more recyclable materials would significantly decrease our waste that won’t be broken down efficiently.
And think: no, people are not recycling enough at all, and materials aren’t really recyclable. In 2005 the EPA reported that only 5.8% of the then-26 million tons of plastics manufactured in the U.S. are recycled. We need biodegradable plastics if we will continue to use plastic products.
“Polystyrene is a very recyclable plastic,” stresses Dr O’Connor. The problem is, once it’s recycled, people aren’t quite sure what to do with it. Recycled polystyrene produces a plastic of a lower grade and so it cannot be used in the food industry. It can be made into ‘timber look’ plastic for making picnic tables and chairs, for example, but O’Connor says the market for this is limited.
Create a market through rattling the media. Imagine that by creating a greater hype in the public about the multiple environmental and health dangers of plastic material use, there will be a company incentive in the market to please customers and create polystyrene products. Call your local newspapers. Write a blog post. Po-ly-sty-rene.
Currently, polystyrene for recycling is exported to China. But Dr O’Connor believes this is an inefficient practice, and proposes instead a municipal recycling scheme, where people deposit their waste plastic.
I think I’ll be emailing Dr. O’Connor about the United States’ Bottle Bills, being passed and amended rapidly throughout the United States. Under these state systems, you pay an extra couple cents when you purchase a plastic product. You get the return when you collect your bottles and deposit them. Get your money back. To reciprocate, the U.S. can take Ireland’s example of its grocery stores charging customers for plastic bags. I’ve been stuffing loaves of bread and hummus in my purse after my evening EuroSpar trips.
And this revolutionary method of recycling is not limited to polystyrene, or Dr O’Connor’s particular bug, for that matter. “We have used our technology for polystyrene but you can apply the same strategy to recycling any plastic. Also there are hundreds of different bacteria that will make different types of plastic so opportunities are huge,” he says.
Market for competition and innovation! Bank on this, struggling scientists of America and Ireland! Grab a science lab and go.
But what does it really mean to be a biodegradable plastic?
This means the plastic can break down chemically without any catalyst or outside chemical. A biodegradable plastic bag would decompose on the side of the road instead of tangling up small birds and crowding our landscapes (this was the case in Ireland before the switch to no-bag stores). Biodegragation uses microorganisms, or “bugs,” to break down these films on the plastics. The materials are enlarged in structure and “metabolized until remaining materials” are no longer harmful to the environment. Easy.
Yet a downside to this process is that the carbon inside biodegradable plastics will be released upon this metabolism process, producing carbon dioxide, a greenhouse gas, into the air, potentially in high amounts. If made from other materials, like animal products, methane could be released instead. Methane is, of course, another great greenhouse gas. (http://www.astm.org/Standards/D6400.htm).
Yet we could still weigh this: would we rather have greater greenhouse gas emissions or greater landfill buildup? Unfortunately, plastics producers are making this critical choice. We as consumers need to instead decide upon this and be lobbying for legislation or pressuring companies. Write to Glad. Write to Aquafina.
What is recyclable for now? Not everything:
I’ve gotten many inquiries about which plastic materials are actually recyclable, so I’ll post a convenient guide I found online about what those little numbers on your plastic bottles mean. (http://www.ehow.com/how_2282329_determine-what-plastics-recyclable.html).
