Eco-effective phosphorous recycling of wastewater containing phosphorous for cost-effective use of the nutrients in agriculture

operational area | usage

  • Use in P-containing wastewater (PO4-P > 70 mg/l, PO4-P > 100 kg/d)
  • Very effective in combination with anaerobic pre-treatment
  • Optional batch or continuous flow operation
  • Depending on the MAP quality requirement, various options available for treatment of the separated MAP

Technology | Process

The formation of magnesium – ammonium phosphate crystals (“MAP”, struvite) is achieved by pH adjustment (pH > 8.1), Mg(OH)2 metering and by adjusting the NH4-N concentration (if necessary). The tank is circulated by means of medium-sized bubble aeration and causes intensive chemical mixing and extension of the MAP crystal contact time. To retain the MAP crystals, a parallel plate separator is used at the tank overflow in the continuous flow process. In the batch process the crystals are retained by gravity sedimentation. The demandorientated NH4-N metering is achieved by determining the NH4-N concentration by means of ion-selective measurement. The necessary Mg metering is determined by measuring the PO4-P concentration. Positivedisplacement pumps are used the cyclical MAP removal. The MAP dewatering using a screw extruder, optionally in combination with MAP scrubbing to improve the MAP quality (reduction of the volatile solids [VS]). Optimisation of the MAP crystallisation is achieved with the help of turbid water return. Use of the RBS-MAP control module ensures that optimum efficiency of the PO4-P elimination with the lowest possible operating costs.

Process Engineering Components

MAP set consisting of:

  • Process-relevant equipping of the reaction tank (aeration, inlet and discharge system, MAP removal, MAP dewatering)
  • RBS-MAP control module for process optimisation


  • Eco-effective phosphorous
  • More economical use of supplies through control module for process optimisation
  • Reduction in the surplus sludge produced in a downstream aerobic treatment stage (reduced precipitated sludge quantity)
  • Increase in the VS of a downstream aerobic treatment stage (clearly reduced precipitated sludge)
  • Increase in the operational reliability of a downstream aerobic treatment stage (increase in the sludge age)
  • Reduced energy costs of a downstream aerobic treatment stage (NH4-N is incorporated in struvite)
  • By stripping carbon dioxide, pH increase without adding chemicals
  • Marketing of the separated MAP

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