Legend has it that King Midas turned everything he touched into gold. The engineers at West Sacramento, CA-based Micromidas www.micromidas.com use hungry bacteria to turn something no one wants to touch - solid human waste - into something many people treasure: biodegradable plastic.

The company’s process holds the promise of mitigating three environmental ills: the ever-increasing amount of solid waste our population generates; the use of potentially scarce, expensive petroleum to make plastic; and the fate of plastic packaging that doesn’t make its way into the recycling stream.

What began several years ago as an Environmental Protection Agency award-winning research project under Frank Lope at the University of California–Davis became an independent private enterprise in 2009, and it is already breaking even.

“Two years ago, we developed a bench-top-scale proof of concept. We received venture capital backing last spring, and now we’re at the 1,000-L pilot plant stage,” says Ryan Smith, Micromidas’ chief technical officer. “The next step will be to go on site to a municipal waste treatment plant and do a pre-commercial demonstration to show the economies of scale.”

Currently, Micromidas sends a truck to several wastewater treatment plants throughout Northern California to collect solid waste that municipalities would otherwise have to send to landfills. The company runs that solid waste through an anaerobic digestion process that breaks it down to the nutrient level. Smith said, “We then feed those nutrients to our ‘superbugs’ in a bioreactor; they eat massive quantities of the nutrients and, just as humans store fat, these microbes store polyesters in their bodies. At a certain point, we harvest the bacteria, run it through an extraction process to derive the polyhydroxyalkanoate (PHA) resin and sell it to plastics companies.”

Functionally similar to PP or PS

Smith noted that the resin is similar in function to polypropylene, adding, “At the processing level, it behaves much like polystyrene; it can be made into fibers and may be able to be foamed.”

It is beginning to be used in manufacturing, he said; one medical device company has licensed the bioplastic to make internal stents and sutures.

Although it is fundamentally a plastic, Smith said, the PHA resin has a three-carbon backbone and produces enzymes that are recognized in nature. A true bioplastic, Micromidas’ resin has been shown in tests to be marine-biodegradable in less than 12 months.

 “The term ‘bioplastic’ is overused in this industry,” Smith argued. “It does not have a science-based, commonly agreed-upon definition, and we have no problem poking the underbelly of that concept.”


-Heidi Parsons, Senior Editor, Packaging Strategies

Source: Packaging Strategies’ July 31 newsletter. For more information, visit www.packstrat.com