A new pilot project in Las Cruces uses algae from Yellowstone National Park’s Grand Prismatic hot spring to build an energy-positive wastewater treatment system. Photograph: Handout/Reuters

A new pilot project in Las Cruces uses algae from Yellowstone National Park’s Grand Prismatic hot spring to build an energy-positive wastewater treatment system. Photograph: Handout/Reuters

Mark Harris writes in the Guardian about a pilot project in Las Cruces, New Mexico, where Dr. Peter Lammers, a professor in algal bioenergy at Arizona State University, along with researchers at New Mexico State University, are diverting effluent from the city’s wastewater treatment plant into rows of long plastic bags primed with Galdieria sulphuraria algae.

This extremophile algae is sourced from the scalding, heavy metal laden, acidic, sulphurous springs of Yellowstone national park.

“Galdieria sulphuraria is one of the most interesting microorganisms on the planet,” says Dr. Lammers. “It grows in a witches brew, can degrade over 50 organic molecules and even photosynthesize like a plant.” That makes it ideal to use in…urban sewage farms.”

At the treatment plant, air enriched with carbon dioxide is pumped through the tubes, while plastic wing-like foils move slowly up and down to mix the concoction. Their aim: to build an energy-positive wastewater treatment that helps preserve rivers, lakes and estuaries, reclaims the chemical energy in sewage, utilizes sunlight to expand that energy footprint and ultimately pays for itself.

The algae use sunlight and carbon dioxide to grow, breaking down over 95% of the nitrogen and phosphates in a couple of days. Thanks to the algae’s photosynthetic growth, the system also creates around four times as much rich organic sludge as traditional sewage treatment. That sludge can then be turned into biofuel oil using hydrothermal liquefaction and catalytic hydrothermal gasification, both well established in the biofuels industry.

A pilot project in Las Cruces New Mexico, where scientists are experimenting with Galdieria sulphuraria algae to treat wastewater. Photograph: New Mexico State University

A pilot project in Las Cruces New Mexico, where scientists are experimenting with Galdieria sulphuraria algae to treat wastewater. Photograph: New Mexico State University

Dr. Lammers believes that algal systems could ultimately eliminate sewage farms’ electricity bills, which can account for anything up to 60% of operating costs today, or even generate a surplus.

A similar project in Phoenix, Arizona, is due to start within a month. “I’m hoping some enterprising company will see this as a package, almost a franchise opportunity, worldwide,” says Dr. Lammers. “In many parts of the world, they’re denuding forests because they need fuel for cooking. That’s stupid and self-defeating when you can produce cooking gas from wastewater. And if we can do this with primary sewage, let’s do it with waste from dairies, swine and poultry production, aquaculture, even food processing. Let’s capture it all and turn it into clean water and energy.”