Described herein are membrane processes for separating CO.sub.2 from flue gas. An exemplary process involves passing a fluid stream including the flue gas across a membrane permeable to CO.sub.2 and H.sub.2O, removing treated gas from a feed side of the membrane that has less CO.sub.2 than the flue gas, and removing permeate from a permeate side of the membrane comprising CO.sub.2 and H.sub.2O. Suitably, the permeate is removed at a sub-atmospheric vacuum pressure. The permeate is then cooled to remove at least some of the H.sub.2O from the permeate and form a smaller volume of H.sub.2O-depleted, CO.sub.2 enriched permeate.

The invention provides for the optimal utilization of gas by a fermentation process, whereby the various components within the gas stream are separated to increase the efficiency of the microorganisms. The invention is capable of tailoring the composition of the gas being used by the fermentation process so as to enhance the production of various products. The invention is capable of applying such controlled separation and utilization of gas to produce different products in two parallel fermentation processes. The invention is also capable of applying such controlled separation and utilization of gas to produce one product in a first fermentation process, which may be converted to a different product in a second fermentation process. The invention is additionally capable of mitigating culture inhibition.

An automatic control system (ACS) for capturing and utilizing carbon dioxide (CO.sub.2) of one or more gases from one or more plants may receive, from one or more sensors, one or more parameters of at least one gas of one or more gases through a system gas flow inlet channel, a first volumetric flow rate of the one or more gases through a plug flow reactor (PFR), a second volumetric flow rate of the one or more gases through a bypass channel that bypasses the PFR, the CO.sub.2 flowing into the CO.sub.2 capture unit, or the syngas flowing into the CO.sub.2 capture unit. The ACS may also command one or more flow controllers to modulate at least one of the first volumetric flow rate of the one or more gases through PFR or the second volumetric flow rate of the one or more gases through the bypass channel based on the one or more parameters.

Provided herein are methods of removing carbon dioxide from an aqueous stream or gaseous stream by: contacting the gaseous stream comprising carbon dioxide, when present, with an aqueous solution comprising ions capable of forming an insoluble carbonate salt; contacting the aqueous solution comprising carbon dioxide with an electroactive mesh that induces its alkalinization thereby forcing the precipitation of a carbonate solid from the solution and thereby the removal of dissolved inorganic carbon by electrolysis; and removing the precipitated carbonate solids from the solution, or the surface of the mesh where they may deposit. Also provided herein are flow-through electrolytic reactors comprising an intake device in fluid connection with a rotating cylinder comprising an electroactive mesh, and a scraping device and/or liquid-spray based device for separating a solid from the mesh surface.

To provide a carbon dioxide separation composition which is excellent in carbon dioxide desorption efficiency (desorption amount/absorption amount) and durability to nitrogen oxides, and a method for separating carbon dioxide.

A carbon dioxide separation composition, containing at least one amine compound selected from the group consisting of an amine compound represented by the following formula (1):

##STR00001## wherein R.sup.1 to R.sup.3 each independently represent a hydrogen atom or a C.sub.1-4 alkyl group, and an amine compound represented by the following formula (2):

##STR00002## wherein R.sup.10, R.sup.11, R.sup.12, R.sup.13 and R.sup.14 each independently represent a hydrogen atom, a C.sub.1-4 alkyl group, a hydroxy group, a hydroxymethyl group, a 2-hydroxyethyl group or a C.sub.1-4 alkoxy group, a and b are each independently 0 or 1 and satisfy the relation a+b=1, and R.sup.15 is a hydrogen atom, a C.sub.1-4 alkyl group, a methoxymethyl group, a methoxyethoxymethyl group or a 2-hydroxyethyl group.

Described herein are membrane processes for separating CO.sub.2 from flue gas. An exemplary process involves passing a fluid stream including the flue gas across a membrane permeable to CO.sub.2 and H.sub.2O, removing treated gas from a feed side of the membrane that has less CO.sub.2 than the flue gas, and removing permeate from a permeate side of the membrane comprising CO.sub.2 and H.sub.2O. Suitably, the permeate is removed at a sub-atmospheric vacuum pressure. The permeate is then cooled to remove at least some of the H.sub.2O from the permeate and form a smaller volume of H.sub.2O-depleted, CO.sub.2 enriched permeate.

The invention relates to a method of reducing carbon dioxide and metal-containing dust and, more particularly, to a method of simultaneously reducing carbon dioxide and metal-containing dust by passing an off-gas, which contains carbon dioxide or carbon dioxide and metal-containing dust, through a reactor in which a sulfur-oxidizing microorganism is grown using carbon dioxide as a carbon source to produce sulfuric acid, and producing metal sulfates (MeSO.sub.4) by reaction of the produced sulfur acid with metal components present in the off-gas.

According to one embodiment, a gas processing equipment includes an oxygen remover 2 that removes oxygen contained in exhaust gas G, and a gas processing device 3 that processes pretreated exhaust gas G (P), from which the oxygen has been removed by the oxygen remover 2, with a carbon dioxide absorbent solvent S as a treatment agent.

The present invention provides a method for treating a gas, comprising: step (A): collecting a gas comprising carbon dioxide and fine particulate matter; step (B): rinsing the gas with water to obtain a rinsed gas; and step (C): contacting the rinsed gas with a basic solution in a way of co-current flow to absorb the carbon dioxide in the rinsed gas by the basic solution to obtain a treated gas and a weak basic solution; wherein the pH value of the basic solution is between 9 and 14, and the pH value of the weak basic solution is between 8 and 8.5. The method can reduce the content of both fine particulate matter and carbon dioxide.

Provided herein are methods of removing carbon dioxide from an aqueous stream or gaseous stream by: contacting the gaseous stream comprising carbon dioxide, when present, with an aqueous solution comprising ions capable of forming an insoluble carbonate salt; contacting the aqueous solution comprising carbon dioxide with an electroactive mesh that induces its alkalinization thereby forcing the precipitation of a carbonate solid from the solution and thereby the removal of dissolved inorganic carbon by electrolysis; and removing the precipitated carbonate solids from the solution, or the surface of the mesh where they may deposit. Also provided herein are flow-through electrolytic reactors comprising an intake device in fluid connection with a rotating cylinder comprising an electroactive mesh, and a scraping device and/or liquid-spray based device for separating a solid from the mesh surface.