Prickly Plastics

Stormwater Editor Blog Generic

Part of stormwater management is trash capture, and so much of our trash these days is plastic. We’ve all seen plastic bottles, disposable cutlery, and plastic bags in the streets of our cities, in the forests and rivers near our homes. We know that because traditional plastic is so durable, single-use plastics that find their way to the ocean break down into microplastics, which then threaten marine life and can even end up in the human food chain. While cutting down on our personal use of plastics is certainly admirable, wouldn’t it be nice if there were alternatives for those days you forget your reusable bags? 

There are already some plant-based plastic replacements currently on the market—you might even have seen some as utensils your local café. Often, these so-called compostable plastics are made of polylactic acid (PLA), a fermented plant starch, usually corn. According to an article published in Scientific American, PLA is only compostable at industrial composting sites, of which there are only 133 in the US. In a landfill, it’s estimated it could take from 100 to 1,000 years for one PLA bottle to decompose. In terms of preventing microplastics from harming aquatic life entering the food chain, PLA isn’t much of a step up.  

Sandra Pascoe Ortiz, a chemical engineering professor at the University of the Valley of Atemajac near Guadalajara, Mexico, is leading research into a different plant-based alternative to single-use plastics. Fronteras Desk reports that Ortiz’s lab has made a biodegradable plastic alternative by processing cactus juice with glycerin, animal fat, and wax. They use prickly pear cactus, which grow locally. “The cactus of this species contains a large amount of sugars and gums that favor the formation of the biopolymer,” Ortiz told Fast Company. The plastic can be poured into molds to make solid, plastic shapes (for, say, cutlery or even toys) or made into thin sheets strong enough to be used as bags.  

The cacti-based plastic isn't as durable as traditional, fossil fuel-based plastics or PLA alternatives, but that’s perfect for single-use, disposable plastics. Products made from the cactus plastic will break down within a few months in a backyard composter and will dissolve in only three weeks if left in water. Additionally, the plastic is nontoxic if eaten, which is particularly important since we know ingesting microplastics is incredibly detrimental to marine life.  

Much has been made of cutting back on our individual use of single-use plastics. Ultimately, however, we’re now a society of convenience, and it’s hard to put the genie back in the bottle. Truly biodegradable, carbon-neutral alternatives to single-use plastics won’t solve the plastics problem alone, but they could be a part of the solution. 

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