This machine draws fertilizer from sewage

The ePhos reactor harvests phosphorus from wastewater(Credit: Fraunhofer IGB)

Researchers at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart, Germany, have developed a new method to harvest phosphorus, a key component of agricultural fertilizers, from wastewater. It incorporates a reactor that is environmentally-friendly, doesn't rely on chemicals, and is ready to be marketed.

Called ePhos, the reactor can be installed at water treatment plants where the raw materials could be gleaned from sewage, adding an extra revenue stream for the plants. The reactor is powered with an electrolysis cell that enables the extraction of nitrogen and phosphorus with a magnesium electrode. The outcome of this process is either struvite (magnesium ammonium phosphate) or potassium struvite.

The main advantage of the process is that it is electrochemical, so it doesn't require the addition of salt or lye, the researchers say, and water plant operators don't need to stock chemicals.

Trials have produced encouraging results as the process succeeded in recovering, on average, 85 percent of phosphorous. The researchers are now working to improve the reactor by adding processing modules so plants can recover ammonium as well.

The method could meet growing demand for phosphorus as supply becomes more difficult and expensive. Europe, for example, is largely dependent on imports from other regions. "The only condition is that the water to be processed must contain plenty of phosphate," says project manager Dr. Iosif Mariakakis.

The researchers have signed a licensing agreement with water treatment system provider Ovivo in the US. The company is marketing the technology in that country as well as Canada and Mexico.

The technology was recently showcased at IFAT, the main trade fair for water, sewage, waste and raw materials management that took place in Munich, Germany, between May 30 and June 3.

Source: Fraunhofer

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