September 2009, Vol. 21, No.9

Research Notes

Making Biodegradable Plastic From Wastewater

A team of students from University of California (UC)–Davis has developed a novel and possibly lucrative byproduct from the wastewater treatment process — biodegradable plastic.

The plastic, polyhydroxylalkanoate (PHA), is produced from carbon in influent. Microbes synthesize PHA as a means to store energy. PHA then can be harvested for a variety of commercial applications. Depending on different subunits, PHA can be designed with a range of different physical properties.

Led by Frank Loge, professor of civil and environmental engineering at UC–Davis, the team of six students submitted their research to the U.S. Environmental Protection Agency’s P3 (People, Prosperity, and the Planet) competition in 2008. The team won the Sustainable Design Award and garnered funding for further research, which is still ongoing at UC–Davis.

According to Loge, “There is really no cost in producing the plastic, because the plastic is made concurrent with wastewater treatment, and it is made in such a way that it doesn’t really require any additional equipment than what already exists at a wastewater facility.”

PHA is materially similar to polypropylene and can be used almost anywhere polypropylene is currently used. John Bissell, a member of the P3 student team, expects immediate demand for PHA in the disposable plastic market but also points out the unique qualities of PHA. “We expect that material properties and biodegradability of PHA will not only complement existing plastics but enable new applications and devices, such as tissue scaffolds, disposable construction materials, and single-season irrigation piping,” he said

In the team’s final report to the P3 competition, they noted that the Whittier Narrows Water Reclamation Plant (El Monte, Calif.), where they planned a pilot test of PHA production, could make $12 million per year selling raw PHA at a market price of $15/kg ($7/lb).

This led Bissell, along with several other P3 team members, to form Micromidas Inc. (Sacramento, Calif.) as an avenue to commercialize their research. The company’s technology is still in the development stage, but Bissell hopes to demonstrate the technology on an intermediate scale in about 2 years.