The invention is in the field of landfill leachate, in particular the invention is directed to a method for purifying landfill leachate comprising water, dissociated ions and organic compounds, wherein the method comprises providing the leachate in a eutectic freeze crystallization (EFC) crystallizer and carrying out eutectic freeze crystallization by reducing the temperature of the leachate to a first eutectic point to obtain a first mixture comprising ice and a first crystalline salt. Further the ice and the first crystalline salt are separated into an ice stream and a crystalline salt stream.

A process and a system allow producing sodium hydrosulfite crystals. A suspension containing sodium hydrosulfite is provided. The sodium hydrosulfite crystals are separated from a remainder of the suspension. The separated sodium hydrosulfite crystals are cooled to a stable temperature. The suspension may be obtained by raising a pH and lowering a temperature of a solution containing sodium hydrosulfite. A partial precipitation of the sodium hydrosulfite to form the crystals may be facilitated by addition of a nucleating agent to the suspension.

This specification discloses a system and method for treating process water from a starch process, and more specifically, recycling a concentrated sodium sulfate solution, obtained from the process water to the starch process.

This specification discloses a system and method for treating process water from a starch process, and more specifically, recycling a concentrated sodium sulfate solution, obtained from the process water to the starch process.

A process for treating wastewater or waste brines that include sodium and chloride ions. The waste brine is concentrated and thereafter directed to a Mirabilite crystallizer that produces hydrated sulfate salt crystals and a first solution. The hydrated crystals are melted to form an aqueous sulfate solution that is directed to a sodium sulfate crystallizer which produces sodium sulfate salt crystals. The first solution produced by the Mirabilite crystallizer is directed to a nanofiltration device which produces a permeate stream and a reject stream containing sulfate removed by the nanofiltration device. The permeate stream is directed to a sodium chloride crystallizer that produces sodium chloride salt crystals. The reject stream is recycled to the Mirabilite crystallizer.

A process for treating wastewater or waste brines that include sodium and chloride ions. The waste brine is concentrated and thereafter directed to a Mirabilite crystallizer that produces hydrated sulfate salt crystals and a first solution. The hydrated crystals are melted to form an aqueous sulfate solution that is directed to a sodium sulfate crystallizer which produces sodium sulfate salt crystals. The first solution produced by the Mirabilite crystallizer is directed to a nanofiltration device which produces a permeate stream and a reject stream containing sulfate removed by the nanofiltration device. The permeate stream is directed to a sodium chloride crystallizer that produces sodium chloride salt crystals. The reject stream is recycled to the Mirabilite crystallizer.

Method for producing soluble potassium sulfate by recrystallization of crude potassium sulfate wherein the crude potassium sulfate contains an amount of potassium, calculated as K.sub.2O, of about 15 wt % or higher, and the resulting potassium sulfate crystalline material conforms with the following characteristics: the amount of insoluble material is less than about 0.05 wt %, a 1 wt % solution of the potassium sulfate has a pH below about 6, and/or 1 pH unit lower than the pH of the crude potassium sulfate, the fraction obtained after crystallization has an average particle size within the following parameters: (i) d90<about 0.6 mm, (ii) d10>about 0.02 mm, and (iii) dust amounts to about 0.4 wt % or less, whereby the resulting potassium sulfate contains more than 51% potassium, calculated as K.sub.2O.

Method for producing soluble potassium sulfate by recrystallization of crude potassium sulfate wherein the crude potassium sulfate contains an amount of potassium, calculated as K.sub.2O, of about 15 wt % or higher, and the resulting potassium sulfate crystalline material conforms with the following characteristics: the amount of insoluble material is less than about 0.05 wt %, a 1 wt % solution of the potassium sulfate has a pH below about 6, and/or 1 pH unit lower than the pH of the crude potassium sulfate, the fraction obtained after crystallization has an average particle size within the following parameters: (i) d90<about 0.6 mm, (ii) d10>about 0.02 mm, and (iii) dust amounts to about 0.4 wt % or less, whereby the resulting potassium sulfate contains more than 51% potassium, calculated as K.sub.2O.

Systems and processes for producing potassium sulfate that include providing an industrial waste material that includes at least sodium sulfate, reacting the sodium sulfate with potassium chloride to produce a byproduct comprising potassium sulfate and a chloride-containing brine, and reacting the chloride-containing brine with barium chloride to produce barium sulfate and sodium chloride.

Systems and processes for producing potassium sulfate that include providing an industrial waste material that includes at least sodium sulfate, reacting the sodium sulfate with potassium chloride to produce a byproduct comprising potassium sulfate and a chloride-containing brine, and reacting the chloride-containing brine with barium chloride to produce barium sulfate and sodium chloride.