Novel methods for pretreating a rare-gas-containing stream exiting an etch chamber followed by recovering the rare gas from the pre-treated, rare-gas containing stream are disclosed. More particularly, the invention relates to the pretreatment and recovery of a rare gas, such as xenon or krypton, from a nitrogen-based exhaust stream with specific gaseous impurities generated during an etch process that is performed as part of a semiconductor fabrication process.

A fossil fuel fired power plant exhaust gas clean-up system is provided to remove detrimental compounds/elements from the exhaust gas emitting from the power plant to protect the environment. This is accomplished primarily by directing the exhaust gas from a fossil fuel fired power plant through both a reaction chamber containing a chemically produced compound and a catalytic converter. The final exhaust gas can now be safely exhausted to the atmosphere and only contains nitrogen gas, oxygen, water and a trace amount of carbon dioxide.

A fossil fuel fired power plant exhaust gas clean-up system is provided to remove detrimental compounds/elements from the exhaust gas emitting from the power plant to protect the environment. This is accomplished primarily by directing the exhaust gas from a fossil fuel fired power plant through both a reaction chamber containing a chemically produced compound and a catalytic converter. The final exhaust gas can now be safely exhausted to the atmosphere and only contains nitrogen gas, oxygen, water and a trace amount of carbon dioxide.

A wet desulfurization apparatus which removes sulfur oxides in flue gas from a boiler 11 includes a mist collection/agglomeration apparatus which is provided on a downstream side of the desulfurization apparatus and forms agglomerated SO.sub.3 mist by causing particles of SO.sub.3 mist contained in flue gas 12B from the wet desulfurization apparatus to be bonded together and have bloated particle sizes; a CO.sub.2 recovery apparatus constituted by a CO.sub.2 absorption tower having a CO.sub.2 absorption unit which removes CO.sub.2 contained in flue gas by being brought into contact with a CO.sub.2 absorbent and an absorbent regeneration tower which recovers CO.sub.2 by releasing CO.sub.2 from the CO.sub.2 absorbent having absorbed CO.sub.2 and regenerates the CO.sub.2 absorbent; and a mist collection unit which collects CO.sub.2 absorbent bloated mist bloated by the CO.sub.2 absorbent being absorbed by the agglomerated SO.sub.3 mist in the CO.sub.2 absorption unit.

A method of selectively catalysing the reduction of oxides of nitrogen (NO.sub.x) including nitrogen monoxide in an exhaust gas of a stationary source of NO.sub.x emissions also containing oxides of sulfur (SO.sub.x) comprising the steps of passively oxidising nitrogen monoxide to nitrogen dioxide (NO.sub.2) over an oxidation catalyst comprising a platinum group metal so that a NO.sub.2/NO.sub.x content is from 40-60%; introducing a nitrogenous reductant into the exhaust gas; and contacting exhaust gas having the 40-60% NO.sub.2/NO.sub.x content and containing the nitrogenous reductant with a selective catalytic reduction (SCR) catalyst comprising an aluminosilicate zeolite promoted with copper.

A method of selectively catalysing the reduction of oxides of nitrogen (NO.sub.x) including nitrogen monoxide in an exhaust gas of a stationary source of NO.sub.x emissions also containing oxides of sulfur (SO.sub.x) comprising the steps of passively oxidising nitrogen monoxide to nitrogen dioxide (NO.sub.2) over an oxidation catalyst comprising a platinum group metal so that a NO.sub.2/NO.sub.x content is from 40-60%; introducing a nitrogenous reductant into the exhaust gas; and contacting exhaust gas having the 40-60% NO.sub.2/NO.sub.x content and containing the nitrogenous reductant with a selective catalytic reduction (SCR) catalyst comprising an aluminosilicate zeolite promoted with copper.

Methods and systems for bioremediation of heavy metal contaminants in waste materials (e.g., sludge and combustion wastes from a coal-fixed power plant). The systems described in the present application include at least one waste treatment unit (e.g., a flue gas cleaner or a waste lagoon) that includes one or more selected bacterial strains disposed therein consume and/or reclaim at least a portion of the heavy metal in the combustion wastes. Methods include inoculating a waste treatment unit with one or more selected bacteria that consume and/or reclaim at least a portion of the heavy metal in the combustion wastes. Methods may include periodic reinoculation of the waste treatment unit with fresh bacteria and period recovery of the bacteria from the waste treatment unit.

A method for removing hydrogen sulfide (H.sub.2S) from an acid gas comprises feeding the gas to a membrane separation unit, collecting the product gas from the membrane unit, heating the permeate stream to the necessary inlet temperature for catalytic oxidation of H.sub.2S and feeding the heated permeate stream to a catalytic oxidation unit, where H.sub.2S is oxidized to SO.sub.2. The heating of the permeate stream is accomplished by using a fraction of the feed gas to heat the permeate stream in a separate heater or by using a steam-fired heater. The method is especially suited for use on an off-shore facility.

A method for removing hydrogen sulfide (H.sub.2S) from an acid gas comprises feeding the gas to a membrane separation unit, collecting the product gas from the membrane unit, heating the permeate stream to the necessary inlet temperature for catalytic oxidation of H.sub.2S and feeding the heated permeate stream to a catalytic oxidation unit, where H.sub.2S is oxidized to SO.sub.2. The heating of the permeate stream is accomplished by using a fraction of the feed gas to heat the permeate stream in a separate heater or by using a steam-fired heater. The method is especially suited for use on an off-shore facility.

An active wet scrubbing filtration system for decontamination of a gas stream comprises components including one or more of: a) a vortexing apparatus which induces a contaminant-bearing gas into a helical flow; b) an initial scrubbing fluid spray section configured so as to project a spray of scrubbing fluid into the contaminant-bearing gas stream; c) an absorption structure; d) a condenser; and e) first and second scrubbing fluid decontamination systems that may be engaged or disengaged independently of each other. In some embodiments, the worksite comprises a clean room or one or more a semiconductor processing tools, which may include photolithography tools or photolithography tool clusters. In some embodiments, the active wet scrubbing filtration system may be useful in cleaning and recycling air or other process gasses for use in clean rooms or semiconductor processing tools.