The invention pertains to a finishing process for urea-comprising material, a plant for finishing urea-comprising material, a method of modifying an existing plant, and a use. Methods are disclosed for preventing the clogging of the conduit for off-gas between the finishing section and the treatment section.

The invention discloses a preparation method and application of in-situ high-efficiency degradation carbon based material of VOCs in landfill based on waste regeneration, which comprises the following steps: air drying the agricultural and forestry wastes to a moisture content of 0.001 wt % 20 wt %, and the agricultural and forestry wastes mainly include: straw, wheat straw, leaves, branches, weeds, crushing them to a particle size of 0-50 mm with a grinder, and then using urea or amide as modifier The nitrogen enriched biochar was prepared by mixing the crushed agricultural and forestry wastes with a mass ratio of 1:50-1:10; the nitrogen enriched biochar was prepared by retorting the nitrogen doped agricultural and forestry wastes at 300-600 C. for 20-60 min, and then cooling them rapidly; the nitrogen enriched biochar was mixed with the sewage sludge with a moisture content of 90-98 wt. % with a weight ratio of 20:1-10:1 to get the nitrogen enriched microorganism The degradation efficiency of TVOCs in landfill is 96.74%99.70%.

Disclosed are methods and systems for removing submicron particles from a gas stream, in particular from urea prilling off-gas, wherein a Venturi ejector is used. A method comprises contacting a gas stream containing submicron particles in a Venturi ejector with an injected high velocity scrubbing liquid to provide a pumping action, wherein the scrubbing liquid has an initial velocity of at least 25 m/s and wherein the ratio of scrubbing liquid and gas flow is between 0.0005 and 0.0015 (m.sup.3/h)/(m.sup.3/h).

A treatment process for remediating H.sub.2S and other contaminants in liquids includes: partially filling a closed vessel with a contaminated liquid containing 5 ppm H.sub.2S with a head space above the liquid within the vessel where gasses released from the liquid from the liquid collect; separately providing a treatment composition in the head space so that the gasses from the liquid may contact the treatment composition; and permitting the contact between the vapors from the liquid and the treatment composition to continue until a collective concentration of H.sub.2S in the liquid and in the head space is <5 ppm. The treatment composition includes an aqueous solution containing at least one hydroxide compound, a collective concentration of the at least one hydroxide compound in the aqueous solution is in a range of 35-55 weight %, and the aqueous solution constitutes at least 80 weight % of the treatment composition.

Disclosed are methods and systems for removing submicron particles from a gas stream, in particular from urea prilling off-gas, wherein a Venturi ejector is used. A method comprises contacting a gas stream containing submicron particles in a Venturi ejector with an injected high velocity scrubbing liquid to provide a pumping action, wherein the scrubbing liquid has an initial velocity of at least 25 m/s and wherein the ratio of scrubbing liquid and gas flow is between 0.0005 and 0.0015 (m.sup.3/h)/(m.sup.3/h).

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.

A device for the destruction of biohazardous waste converts harmful waste products into environmentally friendly discharge in compliance with environmental protection agency (EPA) standards. The device includes a waste disposal chamber where a crucible resides. The crucible contains a basket for holding the waste which is heated through induction coils that surround the crucible. The waste is vaporized and ionized in a vacuum forming a waste gas and drawn through a catalytic converter and a hot plasma jet via vacuum suction. The waste gas is then exhausted via a discharge duct where is it condensed by a heat exchanger further refining the waste gas into environmentally friendly molecules such as carbon dioxide. The waste destruction device further includes a programmable logic controller and user interface to control the device. Once the waste destruction process is completed, a compressor passes compressed air over the crucible to rapidly cool the crucible.

Calcium hydroxide-containing compositions can be manufactured by slaking quicklime, and subsequently drying and milling the slaked product. The resulting calcium hydroxide-containing composition can have a size, steepness, pore volume, and/or other features that render the compositions suitable for treatment of exhaust gases and/or removal of contaminants. In some embodiments, the calcium hydroxide-containing compositions can include a D.sub.10 from about 0.5 microns to about 4 microns, a D.sub.90 less than about 30 microns, and a ratio of D.sub.90 to D.sub.10 from about 8 to about 20, wherein individual particles include a surface area greater than or equal to about 25 m.sup.2/g.

A process is disclosed for removing nitrous components from a raw liquid nitric acid stream to produce a bleached nitric acid product (55). The raw liquid nitric acid stream (37) is from an absorber (19) of a nitric acid process. The process comprises contacting the raw nitric acid liquid stream with an oxidising gas (12) in a bleaching stage (52). At least some of the gas effluent (12c) from the bleaching stage enters (12d) a combustion stage (15) of the nitric acid process. The oxidising gas (12) entering the bleaching stage (52) may comprise at least about one-third of an oxidising gas feed (12) to the nitric acid process. At least about one-tenth of the bleaching stage gas effluent (12c) may enter (12d) the combustion stage (15).

A system and process for the recovery of at least one halogenated hydrocarbon from a gas stream. The recovery includes adsorption by exposing the gas stream to an adsorbent with a lattice structure having pore diameters with an average pore opening of between about 5 and about 50 angstroms. The adsorbent is then regenerated by exposing the adsorbent to a purge gas under conditions which efficiently desorb the at least one adsorbed halogenated hydrocarbon from the adsorbent. The at least one halogenated hydrocarbon (and impurities or reaction products) can be condensed from the purge gas and subjected to fractional distillation to provide a recovered halogenated hydrocarbon.