A method and a system for sequestering carbon dioxide (CO.sub.2) while producing freshwater are provided. An exemplary method includes producing saline water from a saline aquifer, desalinating at least a portion of the saline water, producing freshwater and waste brine, mixing waste CO.sub.2 with the waste brine forming a brine/CO.sub.2 mixture, and injecting the brine/CO.sub.2 mixture into the saline aquifer.

The invention relates to a stirred tank reactor for gas-liquid mass transfer in a slurry. The reactor includes a reactor tank (1) having a first volume (V.sub.1), a drive shaft (2) that extends vertically in the reactor tank, a motor (3) for rotating the drive shaft (2), a main impeller (4) which is a downward pumping axial flow impeller attached to the drive shaft (2) to create a main flow pattern in the reactor tank, and a gas inlet (5) arranged to supply gas into the reactor tank (1) to be dispersed to the liquid. The reactor includes a mechanical gas sparging apparatus (6) comprising a dispersion chamber (7) having a second volume (V.sub.2) which is substantially smaller than the first volume (V.sub.1) of the reactor tank (1), the dispersion chamber being arranged coaxial with the drive shaft (2), and the gas inlet (5) being arranged to feed gas into the dispersion chamber (7), and mixing means (8, 9, 10, 11, 12) arranged within the dispersion chamber (7) for mixing the gas into liquid by dispersing the gas to fine bubbles before the bubbles enter the main flow pattern. The mixing power per unit volume inside the dispersion chamber (7) is significantly larger than the mixing power elsewhere in the reactor.

Provided is a method of producing an ultrafine bubble-containing liquid containing ultrafine bubbles generated by causing film boiling in a liquid with a heat generation member, including: detaching a solid present at a liquid contact surface of the heat generation member in a form of a microscopic substance by using the film boiling; and generating ultrafine bubbles with the detached microscopic substance as a core.

A method of removing carbon dioxide from flue gas is disclosed. The method comprises mixing the flue gas with ammonia; and contacting the gas mixture with calcium nitrate solution to produce calcium carbonate precipitates and ammonium nitrate solution; or contacting the gas mixture with sodium nitrate solution to produce sodium carbonate precipitates and ammonium nitrate solution. The carbonate/bicarbonate precipitates are recovered by separating the carbonate/bicarbonates (s) from said solutions. An apparatus for performing the above method is also disclosed. The apparatus comprises a reaction vessel with an inlet to receive said solution and an inlet to receive and deliver a flue gas-ammonia mixture to a gas-liquid contactor which is configured to diffuse said gas mixture into either calcium nitrate or sodium nitrate solution. The reaction vessel is also provided with an impellor and draft tube configured to circulate the diffused gas mixture throughout the calcium nitrate or sodium nitrate solution for a period of time sufficient to produce carbonate/bicarbonate precipitates locking the CO2 into a solid form.

Provided is a UFB generating apparatus that can achieve compactness, power saving, and low cost. To this end, a liquid containing unit for supplying a liquid to a UFB generating head is fluidly linked to the UFB generating head at a position higher than the UFB generating head in a direction of gravitational force.

Provided is a UFB-containing liquid production apparatus that can efficiently produce a UFB-containing liquid with a UFB generation unit. The UFB-containing liquid production apparatus includes: a gas dissolution unit that produces a gas-dissolved liquid by dissolving a gas into a liquid supplied from a liquid supply unit; a UFB generation unit that generates UFBs in the flowing-in gas-dissolved liquid; and a circulation path that supplies the gas-dissolved liquid to the UFB generation unit and supplies a UFB-containing liquid produced by the UFB generation unit to the liquid supply unit. In the circulation path, there is provided a micro-bubble reduction unit that reduces an amount of micro-bubbles contained in the gas-dissolved liquid to flow into the UFB generation unit.

Provided is a method of producing an ultrafine bubble-containing liquid containing ultrafine bubbles generated by causing film boiling in a liquid with a heat generation member, including: detaching a solid present at a liquid contact surface of the heat generation member in a form of a microscopic substance by using the film boiling; and generating ultrafine bubbles with the detached microscopic substance as a core.

A method of removing carbon dioxide from flue gas is disclosed. The method comprises mixing the flue gas with ammonia; and contacting the gas mixture with calcium nitrate solution to produce calcium carbonate precipitates and ammonium nitrate solution; or contacting the gas mixture with sodium nitrate solution to produce sodium carbonate precipitates and ammonium nitrate solution. The carbonate/bicarbonate precipitates are recovered by separating the carbonate/bicarbonates (s) from said solutions. An apparatus for performing the above method is also disclosed. The apparatus comprises a reaction vessel with an inlet to receive said solution and an inlet to receive and deliver a flue gas-ammonia mixture to a gas-liquid contactor which is configured to diffuse said gas mixture into either calcium nitrate or sodium nitrate solution. The reaction vessel is also provided with an impellor and draft tube configured to circulate the diffused gas mixture throughout the calcium nitrate or sodium nitrate solution for a period of time sufficient to produce carbonate/bicarbonate precipitates locking the CO2 into a solid form.

The abstract of the disclosure is a thermal-ultrafine bubble generation unit which is configured to generate thermal-ultrafine bubbles by bringing a liquid into film boiling. More specifically, the thermal-ultrafine bubble generation unit in the disclosure includes a temperature detection element that is configured to detect generation of the film boiling.

A rotary gas bubble ejector has a fluid reservoir chamber having at a bottom end a fluid discharge opening and a shaft extending through fluid reservoir chamber in connection with a rotor plate. The rotor plate has an outer dimension greater than the outer dimension of fluid discharge opening and is positioned proximate bottom end of fluid reservoir chamber such that a fluid acceleration gap is formed. Rotation of the shaft and rotor plate initiates a fluid flow thereby generating a low-pressure zone within the fluid acceleration gap, wherein gas is discharged from the fluid reservoir chamber into the fluid acceleration gap. As the gas is expelled from the fluid acceleration gap, fluids, gas and liquid, are brought into contact producing micro-sized gas bubbles that are ejected into the body of liquid.