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A pilot-scale project in Olgergen, Holland, is investigating the use of algae cultivation as a method to remove nutrients from wastewater. The project, under development by Ingrepro Renewables, is housed at Waterstromen bv, a water treatment facility that treats municipal wastewater and wastewater sourced from a nearby potato processing plant.

The water treatment facility produces a variety of energy products and coproducts from the wastewater it takes in. Along with the pilot-scale algae project, Waterstromen spokesman Richard Haarhuis noted that the facility also houses an anaerobic digestion system and produces fertilizer for local potato crops. A portion of the methane produced through anaerobic digestion is fed into a combined heat and power plant that provides process heat to the facility. Excess power is fed to the grid while the remaining methane is shipped back to the potato processing facility, where it provides power for the plant.

Ingrepro’s pilot-scale algae facility at the water treatment plant consists of three 300-square-meter open ponds. According to the company’s managing director of renewable, Marcel Oogink, the three ponds allow his team to evaluate the impact of production variables, such as pH and nutrient levels in order to determine the impact of these factors on yields.

“The algae is a development project, and we are testing several effluents from [the water treatment process]…we can also mix the several streams with each other and then send it to the ponds,” Oogink said. The plant produces 5 to 10 tons of algae per year, he continued. In addition to the pilot facility at Waterstromen, Oogink also noted his company operates a 3,000-square-meter facility in northern Holland.

Although many algae companies are targeting oil production, Ingrepro Renewables is targeting protein production at the water treatment facility. The goal is to use algae produced in the plant in pet food or fertilizer applications. Oogink said that while the algae grown in the pilot plant does produce some oil, the strain of algae the facility is growing is hard to “crack,” meaning it is difficult to extract the oil.

To harvest the algae, Ingrepro Renewables uses a system that has traditionally been used in other wastewater treatment applications. A company employee explained that the system creates tiny air bubbles in the algae solution that rise to the surface, carrying the algae cells with them. The algae is then skimmed off the surface.

According to Oogink, Ingrepro Renewables is also working to develop an algae encapsulation technology. Information supplied by the company states that wastewater flows around encapsulated algae beads, which would efficiently absorb nutrients. Because the algae are encapsulated in beads, the company said water separation could be simplified.