Poop Plastic Puts Waste to Work
It's ultimate dream: Take human waste and turn it into one of the most ubiquitous materials around, plastic. The Sacramento-based startup Micromidas has the technology to do it. And no, their polymer doesn't stink.
When Micromidas CEO John Bissell and his colleagues were undergrads at UC Davis, they recognized that plastic and sludge from wastewater treatment facilities were two very large problems. After graduating in 2008, they started their company to develop technology that could offer a solution.
Usually wastewater treatment facilities separate the liquids from the solids in a large settling tank, Bissell told me. He and his colleagues presented their innovation at the PopTech conference currently underway in Camden, Maine. The heaviest nastiness at the bottom is incinerated or sent to a landfill or used to grown non-edible crops that are tilled. Not great options. Micromidas can take that sludge and turn 50 to 70 percent of it into plastic by feeding it to their own special microbes.
"Traditionally in biotech you take a bug, play with its genetic code, and make a Michael Jordan bug for whatever you want to do," Bissell explained. "Instead, we form teams, like a pro sports teams." Their robust bugs eat the sludge, get really fat, and that fat turns into a form of polyester. Then, Bissell says, the bugs are killed and the polyester is extracted. This polyester is part of a family of plastics called polyhydroxyalkanoates or PHA.
Of the plastic, Bissell says that it will biodegrade nontoxically in the body. "Usually things are measured in terms of the lethal limit," he said. "There is no lethal limit to this. You'd have to choke on it for it to hurt you." Definitely wouldn't want to test that, but the properties of the plastic mean that it biodegrades in the environment within a year and a half, depending on the fill thickness. If the final plastic product doesn't have many additives, it could be composted in the yard, although Bissell points out that the requirements for industrial compostability are more stringent than backyard composting.
Micromidas's plastic is an analog to polyethylene, polystyrene, polypropylene, and PET, Bissell says. Between 20 to 60 percent of the applications that use those materials could probably use their polymer, or a blend with the polymer and other chemicals. In terms of cost, the company plans to either be on par with petroleum-based resin or actually beat it.
Currently the polymer is at the pilot stage, with the company operating a several-thousand-liter system that has a maximum capacity of a few kilos daily. They're starting to work with industrial partners on applications, but haven't publicly announced most of those companies yet. When I asked about the byproducts from this process, Bissell said that they actually have a negative water footprint because water is a residual. Sounds like a gold medal bug team to me.
Photo: Micromidas takes sludge from the bottom of wastewater treament facilities and turns it into plastic. Credit: Luke Jones.