Method and assembly for recovering magnesium ammonium phosphate

A method for recovering magnesium ammonium phosphate (MAP) from a sludge, comprising:

• providing a first reaction tank containing the sludge;
• providing a second reaction tank connected to the first reaction tank via a supply line;
• creating an aerobic environment and an alkaline environment in the first reaction tank by CO2 stripping;
• circulating the sludge in the first reaction tank, which includes introducing air into the first reaction tank;
• adding cationic magnesium to the sludge in the first reaction tank to form MAP crystals in the sludge;
• transferring the sludge containing the MAP crystals from the first reaction tank to the second reaction tank via the supply line;
• setting an anaerobic environment in the second reaction tank to allow phosphorus release from the sludge and formation of additional MAP crystals in the second reaction tank;
• supplying MAP crystals from the second reaction tank to the first reaction tank;
• grading the MAP crystals in the first reaction tank by introducing air;
• collecting the MAP crystals in an extraction device from a lower conical- or funnel-shaped section of the first reaction tank;
• and
• recovering the MAP crystals from the extraction device.