ViviMag, a vivianite recovery technology born out of the collaboration between Wetsus and TU Delft, has won the silver prize at the International Water Association's Project Innovation Award.
Urban mining wastewater
An innovative vivianite recovery technology born out of a collaboration between Wetsus and TU Delft has won the silver prize at the International Water Association's (IWA) Project Innovation Award.
Originating out of initial research by Wetsus and TU Delft, ViviMag is a technology for magnetically extracting the valuable element phosphorus from wastewater.
Vivianite is a pivotal mineral in sewage and can be salvaged using magnetic separation equipment used in the mining sector - a technique referred to as urban mining.
“ViviMag is a prime example of how basic scientific insights combined with a visionary collaboration with both private and public partners can lead to radical new solutions for our common future.”
Recently, engineering consultancy Royal Haskoning DHV joined the development team, with the pilot phase receiving financial funding from EIT Raw Materials, an EU innovation community.
Other partners involved in the collaboration include Kemira, STOWA, water authority Brabantse Delta, Vandcenter Syd, Aquaminerals, Aquacare and Waterschapsbedrijf Limburg.
"ViviMag is a prime example of how basic scientific insights combined with a visionary collaboration with both private and public partners can lead to radical new solutions for our common future,” said Leon Korving, project lead, Wetsus.
Retrofitting to existing processes
Most sewage treatment plants in Europe operate chemical phosphorus removal (CPR) by dosing iron salts.
With CPR, phosphorus precipitates as iron phosphate and is immobilised in the produced sludge. This sludge is often anaerobically digested for hygienisation and energy recovery by methane production.
Iron can also be added to the treatment process as a coagulant to enhance primary sedimentation and thus biogas production, or to prevent hydrogen sulfide emissions.
Research from Wetsus has suggested that vivianite is the main iron phosphate mineral that forms during the digestion of sewage sludge, provided that enough iron is present. The ViviMag system can be retrofitted into existing treatment processes.
Circular phosphate
Phosphorus is a vital ingredient in fertilisers and an essential additive for livestock feed.
Its primary source is phosphate rock, a non-renewable resource that’s mainly mined outside of Europe.
Phosphorus is absorbed by humans through food consumption in the form of phosphates and released again, especially through urine, thus entering wastewater.
It is removed from wastewater in treatment plants and finally ends up in sewage sludge.
Phosphorus-rich waste streams such as sewage have a high potential for phosphorus recovery, but it has to be eliminated from these wastewaters to prevent environmental damage, including harmful algae blooms.
It’s estimated that annually, Europe’s Sewage Treatment Plants (STPs) remove approximately 370 kilotons by immobilization in the sewage sludge.
The Dutch organisation believes that phosphate recovery from sewage sludge can cover 20 per cent of the European phosphate demand, and its separation from sewage sludge will create a new phosphate resource.
Several companies in Germany recently united to promote phosphorus recovery technologies ahead of a 2029 deadline. These companies collaborated to create a paper entitled “Sauberer Phosphor 2029” which outlines seven agreed-upon qualities for clean phosphorus recovery.
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