Iowa State University Improves Algae Technology to Treat Wastewater for Communities and Businesses

Martin Gross, left, and Zhiyou Wen developed this algae reactor at the BioCentury Research Farm.

AMES, Iowa — Iowa State University technology that improves the efficiency of wastewater reclamation using algae has gotten the attention of small Iowa communities and the largest wastewater treatment system in the world.

“This reactor greatly improves the efficiency of carbon dioxide and sunlight absorption. We found that the biomass productivity is about 10 times higher than a conventional system,” said Zhiyou Wen, professor of food science and human nutrition, who developed the system with Martin Gross, a postdoctoral fellow in the Center for Crops Utilization Research.

The system uses vertical conveyor belts, about six feet tall and three feet wide, which revolve in a continual loop, cycling through the wastewater and air as multiple layers of algae grow on them.

The Metropolitan Water Reclamation District of Greater Chicago has tested the Revolving Algal Biofilm treatment system. It has finished a yearlong study treating waste streams from one of its water reclamation plants and extended the research project another year because of promising results.

Algae absorbs phosphorus and nitrogen from the wastewater along with carbon dioxide from the air. Wastewater is typically treated with a bacterial process, which produces sludge that creates odor and disposal issues.

The algae produced from this new process can be harvested, pelletized and used as a sustainable fertilizer. Wen and Gross have started a company, called Gross-Wen Technologies, which obtained a USDA Small Business Innovation Research grant to develop the algae-based fertilizer. Gross serves as CEO of the company.

Wen and Gross also produced a mobile version of the system that can travel to communities and businesses around the state.

“Instead of inviting a local community’s water treatment personnel to come to our ISU facility to perform water treatment tests, we built this trailer to take to the community to treat wastewater on site,” Wen said.

The trailer was recently taken to Dallas Center for a project at its water treatment facility.

Wen said more restrictive regulations for the removal of nutrients, such as nitrogen and phosphorus from wastewater, are coming for communities in the state, likely requiring costly treatment facility upgrades that could be avoided with implementation of the algae system. There are about 500 small communities in Iowa that could be impacted by the new regulations.

He said these communities are looking at upgrades to their existing treatment systems costing up to $5 million, which is a huge burden on these small towns.

“So that’s the niche for us. We have this algae cultivation system that can help these communities meet their new nutrient limits at a fraction of the cost of other systems,” Wen said.

The trailer also was recently used to test the system at CJ Bio America, a feed supplement company in Fort Dodge. It generated data to determine the cost of implementing the algae system at the plant.

Martin Gross, left, and Zhiyou Wen take a sample of algae in the portable algae water-treatment unit.