Abstract: A method for treating phosphate-containing wastewater, such as phosphogypsum pond water. The method includes the steps of: (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 to precipitate the second cation from the wastewater; (d) removing residual silica from the wastewater; and (e) precipitating phosphate from the wastewater. The precipitated fluorosilicate may be sodium fluorosilicate. The precipitated phosphate may be struvite.

Abstract: Methods and systems for removal and recovery of phosphorus from wastewater and producing inorganic phosphorus complexes including digestate recycle.

Abstract: Methods and apparatus for precipitating dissolved materials from an aqueous solution are provided. In an embodiment, the method comprises: introducing the aqueous solution into a reactor and introducing a source of magnesium (Mg) into the reactor in a quantity sufficient to cause the dissolved materials to precipitate into crystals. The source of Mg is introduced into the reactor in the form of particles of a Mg-containing material. The source of Mg has a solubility in the aqueous solution of less than about 1 g/L. Alternatively, the concentration of Mg in the reactor is less than about 0.03 mol/L. In an embodiment, the apparatus comprises a reaction tank having an inlet and an outlet and a hydration tank associated with the reaction tank and configured for hydrating a source of Mg in an aqueous solvent and introducing the source of Mg as a hydrated slurry into the reaction tank.

Abstract: A homogeneous fertilizer granule comprises slow-release (e.g. struvite) and fast release sources of phosphorus (P). The homogeneous fertilizer granule may further contain other essential nutrients and micronutrients required by plants. A number of methods may be used to make such granules. One method includes introducing a struvite slurry or fines and a liquid supply of water soluble P into a granulator. Alternatively, dry raw materials can be mixed with water/steam and/or another binder prior to being fed into a granulator. In another embodiment, pre-mixed dry raw materials are mechanically compacted and crushed to yield homogeneous fertilizer particles.

Abstract: A method for treating, and recovering phosphate compounds from, phosphate-containing wastewater. The method includes the steps of: (a) removing fluoride from the wastewater; (b) recovering a phosphate compound from the wastewater by maintaining supersaturation conditions for the phosphate compound; and (c) polishing the wastewater. A silica removal step may be optionally performed after step (a) and before step (b).

Abstract: Apparatus and methods for removing solutes from wastewater are disclosed. An embodiment provides a reactor tank having a manifold located at or near an interface between a lower (upstream) section having a first cross-section and a higher (downstream) section having a second cross-section smaller than the first cross section. An inlet for wastewater to enter the reactor tank is located in or below the first cross-section. A recycling path is provided for removing wastewater from the manifold and recycling at least part of the removed wastewater into the reactor tank. An outlet for water to exit the reactor tank is located downstream from the manifold.

Abstract: A method for treating, and recovering phosphate compounds from, phosphate-containing wastewater. The method includes the steps of: (a) removing fluoride from the wastewater; (b) recovering a phosphate compound from the wastewater by maintaining super saturation conditions for the phosphate compound; and (c) polishing the wastewater. A silica removal step may be optionally performed after step (a) and before step (b).

Abstract: A homogeneous fertilizer granule comprises slow-release (e.g. struvite) and fast release sources of phosphorus (P). The homogeneous fertilizer granule may further contain other essential nutrients and micronutrients required by plants. A number of methods may be used to make such granules. One method includes introducing a struvite slurry or fines and a liquid supply of water soluble P into a granulator. Alternatively, dry raw materials can be mixed with water/steam and/or another binder prior to being fed into a granulator. In another embodiment, pre-mixed dry raw materials are mechanically compacted and crushed to yield homogeneous fertilizer particles.

Abstract: Methods and apparatus for precipitating dissolved materials from a solution involve reduction of fines. In an embodiment, the method comprises: introducing a solution into a reactor, causing the dissolved materials in the solution to precipitate into crystals under a first reaction condition, adjusting the reaction condition from the first reaction condition to a second reaction condition, maintaining the reaction condition in the second reaction condition to cause a sub-population of the crystals to dissolve, and adjusting the reaction condition from the second reaction condition to the first reaction condition. In an embodiment, the apparatus comprises a reaction tank, a recycling path and at least an acid injector which is configured for dosing an acid into solution flow in the recycling path.

Abstract: Apparatus and methods for removing solutes from wastewater are disclosed. An embodiment provides a reactor tank having a manifold located at or near an interface between a lower (upstream) section having a first cross-section and a higher (downstream) section having a second cross-section smaller than the first cross section. An inlet for wastewater to enter the reactor tank is located in or below the first cross-section. A recycling path is provided for removing wastewater from the manifold and recycling at least part of the removed wastewater into the reactor tank. An outlet for water to exit the reactor tank is located downstream from the manifold.

Abstract: A method for treating, and recovering phosphate compounds from, phosphate-containing wastewater. The method includes the steps of: (a) removing fluoride from the wastewater; (b) recovering a phosphate compound from the wastewater by maintaining super saturation conditions for the phosphate compound; and (c) polishing the wastewater. A silica removal step may be optionally performed after step (a) and before step (b).

Abstract: A reaction tank useful for precipitating struvite from aqueous solutions such as wastewater comprises an aeration system. The aeration system includes air diffusers in the reaction tank. The air diffusers are located at a level below an outlet of the reaction tank. The airflow control mechanism comprises means for automatically controlling the flow of the stripping gas from the diffusers. The airflow control mechanism may be configured to automatically control the flow of stripping gas in response to a signal from a sensor measuring the pH of the aqueous solution the alkalinity of the aqueous solution or the concentration of dissolved carbon dioxide in the aqueous solution.