Dr. Gross and Dr. Wen developed the algae reactor at the BioCentury Research Farm.

Researchers at Iowa State University, in Ames, Iowa, are developing technology, using algae, that improves the efficiency of wastewater reclamation. 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.

“This reactor greatly improves the efficiency of carbon dioxide and sunlight absorption,” 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. “We found that the biomass productivity is about 10 times higher than a conventional system.”

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

Recognizing that the algae produced from this new process can be harvested, pelletized and used as a sustainable fertilizer, Dr. Wen and Dr. Gross started a company, Gross-Wen Technologies, which obtained a USDA Small Business Innovation Research grant to develop an algae-based fertilizer.

The two have also produced a mobile version of the system that can travel to communities and businesses around the state. The trailer was recently taken to Dallas Center for a project at its water treatment facility.

“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,” Dr. Wen said.

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

According to the two developers more restrictive regulations for the removal of nutrients, such as nitrogen and phosphorus from wastewater, are coming for communities in Iowa, 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. These communities are looking at upgrades to their existing treatment systems costing up to $5 million, the researchers say, 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,” says Dr. Wen.

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