Abstract: A process for treating frac flowback that contains barium, naturally occurring radioactive materials (NORM) and hardness for minimizing the amount of sludge produced that contains hazardous levels of NORM by employing a dual stage precipitation process. In the first stage a sulfate source is mixed with the frac flowback and barium sulfate and NORM is precipitated, the frac flowback is subjected to a solids-liquid separation process to produce a first effluent and a first sludge. In the second stage hardness is precipitated from the first effluent by addition of an alkali reagent, said first effluent is also subjected to solids-liquid separation producing a second effluent and a second sludge. The first sludge is recycled and mixed with the frac flowback and the sulfate source in a sufficient amount to maintain the NORM concentration in the second sludge at or below a threshold level.

Abstract: The present invention entails a method of treating an ion exchange regenerant stream containing selenate and removing the selenate from the regenerant stream through an oxidation-reduction process where selenate is reduced to selenite and the selenite is adsorbed onto an adsorbent which, in one embodiment, comprises iron oxide or iron oxyhydroxide. In particular, the method includes catalytically reducing the selenate to selenite in a selenate reduction reactor by reacting iron powder with the selenate in the presence of a nickel powder, which functions as a catalyst, to form selenite which is then adsorbed onto the iron oxide or iron oxyhydroxide.

Abstract: A process for treating frac flowback that contains barium, naturally occurring radioactive materials (NORM) and hardness for minimizing the amount of sludge produced that contains hazardous levels of NORM by employing a dual stage precipitation process. In the first stage a sulfate source is mixed with the frac flowback and barium sulfate and NORM is precipitated, the frac flowback is subjected to a solids-liquid separation process to produce a first effluent and a first sludge. In the second stage hardness is precipitated from the first effluent by addition of an alkali reagent, said first effluent is also subjected to solids-liquid separation producing a second effluent and a second sludge. The first sludge is recycled and mixed with the frac flowback and the sulfate source in a sufficient amount to maintain the NORM concentration in the second sludge at or below a threshold level.

Abstract: The instant application is directed towards methods for removing sulfide from a wastewater stream. The pH of the wastewater stream is adjusted to between 7.0 and 8.0. A first oxidizing agent is mixed with the wastewater stream, oxidizing the sulfide to elemental sulfur. The wastewater stream is then softened by mixing lime with the wastewater stream. The addition of lime further raises the pH of the wastewater stream to 10.0 or higher, and converts the elemental sulfur to soluble sulfide (S2-) and/or thio-sulfate. Calcium carbonate is precipitated and sulfide (S2-) and/or thio-sulfate is adsorbed thereon. Thereafter, the wastewater stream is directed to a solids-liquid separation process, which separates the calcium carbonate and adsorbed sulfide (S2-) and/or thio-sulfate from the wastewater stream. The solids-liquid separator produces an effluent that includes residual elemental sulfur.

Abstract: The present invention relates to a process for producing sodium bicarbonate crystals. Sodium carbonate derived from TRONA ore is mixed with a treated mother liquor produced in a downstream process to form a sodium carbonate solution. The sodium carbonate solution is subjected to a crystallization process that produces sodium bicarbonate crystals. The sodium bicarbonate crystals are separated from the sodium carbonate solution to form a mother liquor that includes silica. To remove the silica in the mother liquor, the mother liquor is directed to a reactor where an aluminum salt is mixed with the mother liquor to precipitate hydrous aluminum oxide which adsorbs silica thereon. The hydrous aluminum oxide with adsorbed silica is removed from the mother liquor. This produces the treated mother liquor that is mixed with the sodium carbonate and which forms the sodium carbonate solutions.

Abstract: The instant application is directed towards methods for removing sulfide from a wastewater stream. The pH of the wastewater stream is adjusted to between 7.0 and 8.0. A first oxidizing agent is mixed with the wastewater stream, oxidizing the sulfide to elemental sulfur. The wastewater stream is then softened by mixing lime with the wastewater stream. The addition of lime further raises the pH of the wastewater stream to 10.0 or higher, and converts the elemental sulfur to soluble sulfide (S2-) and/or thio-sulfate. Calcium carbonate is precipitated and sulfide (S2-) and/or thio-sulfate is adsorbed thereon. Thereafter, the wastewater stream is directed to a solids-liquid separation process, which separates the calcium carbonate and adsorbed sulfide (S2-) and/or thio-sulfate from the wastewater stream. The solids-liquid separator produces an effluent that includes residual elemental sulfur.

Abstract: The present invention relates to a process for producing sodium bicarbonate crystals. Sodium carbonate derived from TRONA ore is mixed with a treated mother liquor produced in a downstream process to form a sodium carbonate solution. The sodium carbonate solution is subjected to a crystallization process that produces sodium bicarbonate crystals. The sodium bicarbonate crystals are separated from the sodium carbonate solution to form a mother liquor that includes silica. To remove the silica in the mother liquor, the mother liquor is directed to a reactor where an aluminum salt is mixed with the mother liquor to precipitate hydrous aluminum oxide which adsorbs silica thereon. The hydrous aluminum oxide with adsorbed silica is removed from the mother liquor. This produces the treated mother liquor that is mixed with the sodium carbonate and which forms the sodium carbonate solutions.

Abstract: A method for removing sulfate from a wastewater stream includes mixing gibbsite and a calcium source to precipitate Ettringite from the wastewater stream and produce an effluent with a reduced sulfate concentration. The gibbsite in the precipitated Ettringite is regenerated by mixing an acid with the Ettringite and precipitating gibbsite particles, after which the gibbsite particles are subjected to a crystallization process to increase the size of the gibbsite particles which are recycled back to the main stream.

Abstract: A process is disclosed for recovering cyanide used to leach gold or silver from ore. In the course of leaching gold or silver from ore, a barren solution is generated. A portion of the barren solution containing sodium cyanide is recycled to the cyanidation process while blowdown from the barren solution is subjected to pre-treatment, UV photodissociation and pH adjustment. Ultimately, a volatile hydrocyanic acid is formed and is absorbed into a sodium hydroxide solution through the employment of a gas-filled membrane. This forms sodium cyanide that can be recycled and used in the cyanidation process to leach gold or silver from ore.

Abstract: A method of removing barium, calcium, strontium, and magnesium from frac flowback. A sulfate reagent and carbonate reagent are mixed with the frac flowback, causing barium, calcium, strontium, and magnesium to precipitate. The precipitants are crystallized and the resulting frac flowback and crystals are separated into relatively heavy solids and a stream of relatively light solids. The stream of relatively light solids is subjected to a further separation process that produces sludge that is recycled to aid in the crystallization process and a treated effluent which is recycled to the fracking operation or collected and used in another fracking operation.

Abstract: A method or process is provided for removing selenate from an ion-exchange or an adsorption media regenerant stream. The regenerant stream is processed in a nanofiltration membrane which produces a permeate and a reject stream containing the selenate. A reducing agent, such as iron, is mixed with the reject stream and this gives rise to an oxidation-reduction reaction that reduces the selenate to selenite. Thereafter, the method includes adsorbing the selenate onto an adsorbent, such as hydrous iron oxide. The adsorbent and adsorbed selenite is removed from the reject stream via a solids-liquid separation process.

Abstract: A process is disclosed for recovering cyanide used to leach gold or silver from ore. In the course of leaching gold or silver from ore, a barren solution is generated. A portion of the barren solution containing sodium cyanide is recycled to the cyanidation process while blowdown from the barren solution is subjected to pre-treatment, UV photodissociation and pH adjustment. Ultimately, a volatile hydrocyanic acid is formed and is absorbed into a sodium hydroxide solution through the employment of a gas-filled membrane. This forms sodium cyanide that can be recycled and used in the cyanidation process to leach gold or silver from ore.

Abstract: A method for removing sulfate from a wastewater stream includes mixing gibbsite and a calcium source to precipitate Ettringite from the wastewater stream and produce an effluent with a reduced sulfate concentration. The gibbsite in the precipitated Ettringite is regenerated by mixing an acid with the Ettringite and precipitating gibbsite particles, after which the gibbsite particles are subjected to a crystallization process to increase the size of the gibbsite particles which are recycled back to the main stream.

Abstract: A method for removing sulfate from a wastewater stream includes mixing gibbsite and a calcium source to precipitate Ettringite from the wastewater stream and produce an effluent with a reduced sulfate concentration. The gibbsite in the precipitated Ettringite is regenerated by mixing an acid with the Ettringite and precipitating gibbsite particles, after which the gibbsite particles are subjected to a crystallization process to increase the size of the gibbsite particles which are recycled back to the main stream.

Abstract: A method of reducing a sulfate concentration in wastewater comprises directing the wastewater stream to a precipitation reactor and mixing the wastewater stream with a calcium source and a calcium salt seed material to precipitate calcium sulfate. The precipitated calcium sulfate is then separated from a treated effluent and directed to a settling tank where the precipitated calcium sulfate is separated into heavier calcium sulfate precipitants and lighter calcium sulfate precipitants. The heavier calcium sulfate precipitants and the lighter calcium sulfate precipitants are separately recirculated to the precipitation reactor. A predetermined mass ratio of solids is maintained in the precipitation reactor.

Abstract: A method or process for removing perchlorate ions from water includes mixing water containing perchlorate ions with a reducing agent such that the perchlorate ions and the reducing agent undergo an oxidation-reduction reaction. During the oxidation-reduction reaction, perchlorate ions are reduced to chloride ions and the reducing agent is oxidized. The oxidized reducing agent is separated from the water containing chloride ions and the oxidized reducing agent is regenerated and reused in the reduction of the perchlorate ions.

Abstract: A method for removing sulfate from a wastewater stream includes mixing gibbsite and a calcium source to precipitate Ettringite from the wastewater stream and produce an effluent with a reduced sulfate concentration. The gibbsite in the precipitated Ettringite is regenerated by mixing an acid with the Ettringite and precipitating gibbsite particles, after which the gibbsite particles are subjected to a crystallization process to increase the size of the gibbsite particles which are recycled back to the main stream.

Abstract: A method of removing barium, calcium, strontium, and magnesium from frac flowback. A sulfate reagent and carbonate reagent are mixed with the frac flowback, causing barium, calcium, strontium, and magnesium to precipitate. The precipitants are crystallized and the resulting frac flowback and crystals are separated into relatively heavy solids and a stream of relatively light solids. The stream of relatively light solids is subjected to a further separation process that produces sludge that is recycled to aid in the crystallization process and a treated effluent which is recycled to the fracking operation or collected and used in another fracking operation.

Abstract: A method for treating wastewater comprises biologically treating the wastewater in a fixed-biomass biological reactor and then treating the wastewater in a ballasted flocculation system. The ballasted flocculation system produces a clarified effluent and sludge containing inert granular material having biomass accumulated thereon and suspended solids. The inert granular material having biomass accumulated thereon is separated from the suspended solids and then cleaned with a cleaning solution. After separating the biomass from the cleaned inert granular material, the cleaned inert granular material is recycled for use in the ballasted flocculation system.

Abstract: A method or process for removing perchlorate ions from water includes mixing water containing perchlorate ions with a reducing agent such that the perchlorate ions and the reducing agent undergo an oxidation-reduction reaction. During the oxidation-reduction reaction, perchlorate ions are reduced to chloride ions and the reducing agent is oxidized. The oxidized reducing agent is separated from the water containing chloride ions and the oxidized reducing agent is regenerated and reused in the reduction of the perchlorate ions.