To Deal with Plastic Trash, All You Need is Bugs

Outlawed now in some places, or only available to tote your purchases at a ridiculous premium, the billions of “T-shirt” bags used every year present a serious waste management problem. Whether blowing across the landscape like synthetic tumbleweeds, floating in the ocean as ersatz jellyfish, or clogging up municipal waste streams, finding a way to deal with them could really make a difference. And finding a bug that eats polyethylene and poops antifreeze might be a great first step in bioremediating the mess.

As with many scientific discoveries, learning about the useful and unexpected eating habits of the larval stage of the Greater Wax Moth Galleria mellonella can be chalked up to serendipity. It began when biochemist [Federica Bertocchini] cleaned a wax moth infestation from her beehive. She put the beeswax-loving pests in a plastic bag, later finding they had chewed their way out. Intrigued, she and [Paolo Bombelli] ran some experiments using the bugs. They showed the mechanism wasn’t just mechanical and that the worms were digesting the polyethylene, to the tune of 92 mg consumed for 100 worms in 12 hours. That’s about 1,000 times faster than bioremediation with bacteria.

Furthermore, the bugs excrete ethylene glycol, a useful industrial chemical, in the process. Finally, to see if the process can scale, the researchers showed that a homogenate of wax moth larvae could digest PE sheets. This could lead to an industrial process if the enzymes involved can be isolated and engineered. The letter describing the process is a fascinating read.

While this one may not a classically hackish way to deal with plastic recycling, the potential for this method is huge. We look forward to seeing where this goes.

[Images: César Hernández/CSIC]

Soda Bottles Used as Heat-Shrink for Wood Joinery

Nobody is likely to confuse it with the beautiful joinery that makes fine furniture so desirable. But as a practical technique, using plastic bottles as heat-shrink tubing for composite joints is pretty nifty, and the pieces produced are not without their charm.

Undertaken as an art project to show people what can be done with recycled materials, [Micaella Pedros]’ project isn’t a hack per se. She started with bottles collected around London and experimented with ways to use them in furniture. The plastic used in soda and water bottles, polyethylene terephthalate (PET), turns out to shrink quite a bit when heated. Rings cut from bottles act much like large pieces of heat-shrink tubing, but with more longitudinal shrinkage and much more rigidity. That makes for a great structural component, and [Micaella] explored several ways to leverage the material to join wood. Notches and ridges help the plastic grip smoother pieces of wood, and of course the correct size bottle needs to be used. But the joints are remarkably strong – witness the classic leaning-back-in-a-chair test in the video below.

Its aesthetic value aside, this is a good technique to file away for more practical applications. Of course, there are plenty of ways to recycle soda bottles, including turning them into cordage or even using them as light-pipes to brighten a dark room.

Continue reading “Soda Bottles Used as Heat-Shrink for Wood Joinery”