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New system developed to extract phosphorus from wastewater

German researchers have developed a system to extract fertiliser from wastewater without relying on chemicals or large amounts of energy.

The process extracts nitrogen and phosphorus using a magnesium electrode, resulting in either struvite (magnesium ammonium phosphate) or potassium struvite, which can be applied directly to food crops.

Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB Project manager Dr Iosif Mariakakis said the process was purely electrochemical.

“This is also good news for water treatment plant operators – the process is very straightforward and doesn’t require them to stock chemicals,” Mariakakis said.

Unlike traditional methods, struvite can be extracted without additional chemicals, such as magnesium chloride (MgCl2) or sodium hydroxide (NaOH).

The system, named ePhos for market, also claims to use less energy, at just 0.78 kWh/m³ wastewater.

Results from long-term trials at the first treatment plant to pilot the technology showed the process was able to recover about 85% of the phosphorous.

“Our method is also suitable for the food industry and for processing service water,” Mariakakis said.

The only condition is that the water to be processed must contain plenty of phosphate.

The institute stated the system was likely to quickly gain a foothold across Europe, where it will soon be mandatory to separate phosphorous from sewage sludge.

In the United States, a licensing agreement was recently signed with water treatment system provider Ovivo, which is marketing the technology in the USA, Canada and Mexico.

Meanwhile, the institute is working on developing its reactor concept further.

“We plan to expand ePhos by adding processing modules that allow water treatment plants to recover ammonium, too,” Mariakakis said.