Sewage sludge could be promising bioplastic feedstock


In Texas, researchers at A&M University have deployed the bacterium Zobellella denitrificans ZD1 to convert sewage sludge into the biodegradable plastic polyhydroxybutyrate. 

PHA is known to be produced by several bacterial species as a supplemental energy reserve in carbon-rich environments with limited nitrogen, phosphorous, or oxygen. Cost issues associated with bacterial production of bioplastics have limited further development, however. 

“The price of raw materials to cultivate biopolymer-producing bacteria accounts for 25-45% of the total production cost of manufacturing bioplastics. Certainly, this cost can be greatly reduced if we can tap into an alternate resource that is cheaper and readily obtainable,” said Kung-Hui (Bella) Chu, professor in the Zachry Department of Civil and Environmental Engineering. “We have demonstrated a potential way to use municipal wastewater-activated sludge and agri- and aqua-culture industrial wastewater to make biodegradable plastics. Furthermore, the bacterial strain does not require elaborate sterilization processes to prevent contamination from other microbes, further cutting down operating and production costs of bioplastics.”

The work was detailed in a recent issue of American Chemical Society Omega.