Patent ID: 11919792
Assignee: OSTARA NUTRIENT RECOVERY TECHNOLOGIES INC.
Field: Environmental technology (Chemistry)
Classification: CPC C | IPC C

Claim 0:
1. A method for treating phosphate-containing wastewater comprising fluoride, phosphate and silica, the method comprising:
(a) adding a first cation to the wastewater to precipitate fluorosilicate from the wastewater;
(b) adding a second cation to the wastewater to precipitate fluoride from the wastewater;
(c) raising the pH of the wastewater with a calcium-free base to precipitate the second cation from the wastewater;
(d) removing silica from the wastewater;
(e) precipitating phosphate from the wastewater;
(f) polishing the wastewater, comprising subjecting the wastewater to nanofiltration and/or reverse osmosis to obtain a liquid retentate comprising sodium ions and a treated phosphate-containing wastewater permeate;
(g) recirculating the liquid retentate comprising sodium ions to step (a) to enhance precipitation of fluorosilicate from the wastewater,
wherein step (e) comprises controllably adding magnesium and/or ammonia to precipitate the phosphate as struvite or a struvite analog.