The struvite reactor is used for the recovery of phosphate from concentrated wastewater streams as struvite. Phosphate is becoming scarce which makes recovery increasingly interesting. Struvite precipitation is a cost-effective technology compared to, for example, the addition of iron salts, mainly due to significantly cheaper chemicals consumed and because the residual product has a positive value rather than being a major cost item.
The struvite produced is an excellent slow-acting fertilizer for N, P and Mg. In the struvite reactor magnesium (Mg2+), phosphate (PO43-) and ammonium (NH4+) or potassium (K+) are converted into struvite. By adding magnesium oxide (MgCl), phosphate and ammonium precipitate as struvite (MgNH4PO4.6H20 or MAP).
DeSaH uses an upflow reactor for struvite precipitation and has adapted the reactor design to make it suitable for small quantities of waste water. The smallest reactor is suitable for processing 200 L/d, but of course (much) larger reactors can also be built. Struvite precipitation is applied for the treatment of various phosphate-rich (50 mg/l PO4-P) wastewater streams.
Advantages of the struvite reactor:
- good quality struvite
- struvite of the same shape as fertiliser granules
- already usable for small quantities of waste water
- easy process control