U.S. researchers say algae grown in wastewater could be a promising source of biofuel while cleaning up the wastewater at the same time.

Researchers at the Rochester Institute of Technology say their project to develop biodiesel from microalgae is doubly "green" because in addition to creating biofuel, the algae consume nitrates and phosphates and reduce bacteria and toxins in the water, an RIT release said Thursday.

Biodiesel from algae could reduce diesel fuel's telltale black puffs of exhaust with cleaner emissions low in the sulfur and particulates that come from fossil fuels, the researchers say.

"Algae -- as a renewable feedstock -- grow a lot quicker than crops of corn or soybeans," RIT researcher Eric Lannan says. "We can start a new batch of algae about every seven days. It's a more continuous source that could offset 50 percent of our total gas use for equipment that uses diesel."

Starting with algae production from 30 gallons of wastewater in a lab at RIT and moving to 100 gallons in a 4-foot-by-7-foot tank, the researchers say they plan to build a mobile greenhouse at a wastewater treatment plant in the spring and scale up production to as much as 1,000 gallons of wastewater.