Abstract: Sulphuric acid plants, separators for separating entrainment for process gas, and gas treatment processes for generating sulphuric acid are provided. The sulphuric acid plant comprises a source of process gas, an entrainment eliminator, a gas rotator located downstream of the gas-liquid contactor, and a separator located downstream of the entrainment eliminator and upstream of the gas rotator. The separator comprises a plurality of passages. Each passage comprises a vane extending longitudinally along the passage, wherein each vane rotates a process gas flowing through the separator. The process comprises transferring process gas from an entrainment eliminator to a separator located downstream of the entrainment eliminator, rotating the process gas through the separator to separate entrainment, and transferring the separated process gas from the separator to rotating equipment located downstream of the separator.

Abstract: Gas treatment systems and processes for reducing tail gas emissions such as SO2, SO3, H2SO4, NOx, HC, CO, and other pollutants are provided. The processes include transferring tail gas from at least one source of tail gas to at least one destination sulphuric acid plant via a tail gas transfer system, wherein the tail gas replaces or supplements one or more of the combustion gas, air feed, dilution gas, and quench gas used by the destination sulphuric acid plant. The systems include at least one destination sulphuric acid plant and a tail gas transfer system for transferring tail gas from at least one source of tail gas to the at least one destination sulphuric acid plant. The systems and processes described herein may be used to eliminate start-up emissions and/or convert sulphur-containing species present in tail gas emissions into commercial H2SO4.

Abstract: A method and apparatus for contacting and reacting fine cellulosic material with acid to produce partly-hydrolyzed cellulose, in which the cellulose is compressed to form higher density material, resulting in reduced consumption of acid and increased uniformity of reaction times. Cellulosic material, such as ground wood pulp, is compressed to reduce the interstitial spaces therein. The compressed material is contacted with an acid, such as sulfuric acid, which is allowed to wick into the interstitial spaces and react with the cellulose to produce partly-hydrolyzed cellulose.

Abstract: A process for cleaning process gas removes sulfur oxides (SOx), nitrogen oxides (NOx), and particulate matter (PM) to produce a tail gas substantially free of these pollutants. The process oxidizes and absorbs SOx and NOx for storage as liquid acids. In some embodiments a PM removal stage and/or a SOx removal stage are provided in a close-coupled higher-pressure environment upstream from a turbocharger turbine. The process has example application in cleaning exhaust gases from industrial processes and large diesel engines such as ship engines.

Abstract: A method of recovering purified partly-hydrolyzed cellulose particles from a composition comprising agglomerated partly-hydrolyzed cellulose particles and an acid, using electrodialysis. The invention addresses the problem of reducing the acid to very low levels while avoiding the high capital and operating costs, high water usage and large filtration surface area or dilution time requirements of the prior art processes. Following dilution, concentration by centrifuging or settling, and/or dialysis of the composition, the composition is treated in an electrodialysis cell to remove ions, such as free sulfate from sulfuric acid. The method may include having an anion exchange resin in the feed compartment of the electrodialysis cell, adding a base to the receiving solution in the electrodialysis cell, and a second step of electrodialysis of the purified partly-hydrolyzed cellulose particles.

Abstract: A method of recovering purified partly-hydrolyzed cellulose (36) from a composition (14) comprising partly-hydrolyzed cellulose and an acid, such as sulfuric acid. A base (28) having a cation that forms a precipitate with the anion of the acid is added to the composition. For example, a base such as barium hydroxide is added to form a sulfate precipitate. The precipitate (38) is then separated from the partly-hydrolyzed cellulose (36), thus reducing its acid content. The method may include additional steps of centrifugation (18) of the composition, breaking-up agglomerations (44) in the composition after precipitation, and dialysis (42).

Abstract: A method of recovering purified partly-hydrolyzed cellulose particles from a composition comprising agglomerated partly-hydrolyzed cellulose particles and an acid, using electrodialysis. The invention addresses the problem of reducing the acid to very low levels while avoiding the high capital and operating costs, high water usage and large filtration surface area or dilution time requirements of the prior art processes. Following dilution, concentration by centrifuging or settling, and/or dialysis of the composition, the composition is treated in an electrodialysis cell to remove ions, such as free sulfate from sulfuric acid. The method may include having an anion exchange resin in the feed compartment of the electrodialysis cell, adding a base to the receiving solution in the electrodialysis cell, and a second step of electrodialysis of the purified partly-hydrolyzed cellulose particles.

Abstract: A method and apparatus for contacting and reacting fine cellulosic material with acid to produce partly-hydrolyzed cellulose, in which the cellulose is compressed to form higher density material, resulting in reduced consumption of acid and increased uniformity of reaction times. Cellulosic material, such as ground wood pulp, is compressed to reduce the interstitial spaces therein. The compressed material is contacted with an acid, such as sulfuric acid, which is allowed to wick into the interstitial spaces and react with the cellulose to produce partly-hydrolyzed cellulose.

Abstract: A method of recovering purified partly-hydrolyzed cellulose (36) from a composition (14) comprising partly-hydrolyzed cellulose and an acid, such as sulfuric acid. A base (28) having a cation that forms a precipitate with the anion of the acid is added to the composition. For example, a base such as barium hydroxide is added to form a sulfate precipitate. The precipitate (38) is then separated from the partly-hydrolyzed cellulose (36), thus reducing its acid content. The method may include additional steps of centrifugation (18) of the composition, breaking-up agglomerations (44) in the composition after precipitation, and dialysis (42).

Abstract: An electroless plating Ru bath for the deposition of Ru on the surface of a substrate comprises a Ru stock solution and hydrazine as a reducing reagent. Ru layers may be applied, for example, for use in membranes for the separation of hydrogen gas from mixtures of gases or to protect materials from corrosion. An example Ru stock solution comprises Ru chloride, hydrochloric acid, ammonia, nitrite salt, alkali hydroxide, and deionized water. The electroless plating bath may be applied to deposit ruthenium layers onto palladium layers to prepare Pd—Ru composite or alloy membranes or multilayer Pd—Ru composite or alloy membranes. Such membranes have example application to the separation of hydrogen from mixtures of gases.

Abstract: Methods and apparatus for maintaining sulfur concentration in the chemical recovery cycle of a Kraft pulping process. A portion of the recovery boiler ash is dissolved, treated to remove solids, and combined with an acid to provide a solution. The recovery boiler ash may be dissolved directly in the acid. The acid may be effluent from a chlorine dioxide generator. The resulting solution is maintained in a fully dissolved state and subjected to an acid separation step to provide a sodium sulfate enriched phase, which may be used to maintain sulfur concentration in the Kraft pulping process, and a sulfuric acid phase. Chlorine ions can be separated with the sulfuric acid phase. The sulfuric acid phase can be recycled to the chlorine dioxide generator.

Abstract: A method for removing metals from metal-containing acidic mine wastewater uses a basic sludge produced by the method for treating the wastewater. The wastewater is mixed with a lime slurry and with the basic sludge. This mixture is allowed to separate into an aqueous effluent and an acidic sludge. The effluent is mixed with the lime slurry and with a composition containing an iron compound, to produce a mixture. This mixture is allowed to separate into an aqueous effluent and the basic sludge. Lignin derivatives, such as calcium lignosulfonate, may be included in the treatment mixture.

Abstract: An apparatus for installing and removing candles from a packed tower comprises a rail or series of rails attached to the inside of the top of the vessel. The rail(s) may be supported from either the roof or walls of the tower. A traveler assembly is supported on the rail(s). The traveler assembly supports a hoist puller that in turn raises and lowers the candles. The rail(s) may be located such that they extend over the centerlines of each of the candle locations, and each such that a portion of each rail passes under the candle installation port. Multiple traveler assemblies may be used to increase the speed of installation. The traveler assembly may be configured to be removed when not in use, to ensure it is not exposed to the harsh environment in the tower. Alternatively, the traveler assembly may be constructed from corrosion-resistant materials, so that the traveler assembly may be left in the tower.

Abstract: A method for removing metal contaminants from water uses lignin derivatives, such as lignosulfonates and kraft lignin, a coagulant, such as a metal salt, and a pH-increasing composition. The lignin derivative is dispersed in the contaminated water, the coagulant is added and the pH is adjusted as required to cause flocculation. A sludge is formed that contains the metals and that is separated from the treated water by filtration. Related methods are used to reduce the leachable metal content of contaminated soils. The invention also provides a composition for stabilizing the metal contaminants in soil, comprising lignin derivatives, a coagulant and a composition for increasing the pH. The mixture is blended with the contaminated soil, reducing its leachable metal content.

Abstract: This application relates to a circular clarifier for separating and removing separable matter, such as suspended solids, from a liquid. The invention may be used, for example, for separating return activated sludge from clarified liquor using a gas flotation process. The clarifier includes a plurality of fluid feed ports for introducing influent into selected treatment cells of the clarifier in a timed sequence, thereby achieving batch flotation of solids or other separable matter in a continuous infeed process. A plurality of spaced-apart, rotating flocculent handling assemblies traverse the treatment cells for sequentially conveying flocculent into spaced-apart, radially extending collection troughs. All of the flocculent handling assemblies may be driven by a single drive means. Each flocculent handling assembly includes a submerged beach and a scraper assembly including a scraper blade which extends upwardly from the beach. The beaches provide a shear plane underneath the surface layer of flocculent.

Abstract: A method for removing metal contaminants from water uses lignin derivatives, such as lignosulfonates and kraft lignin, a coagulant, such as a metal salt, and a pH-increasing composition. The lignin derivative is dispersed in the contaminated water, the coagulant is added and the pH is adjusted as required to cause flocculation. A sludge is formed that contains the metals and that is separated from the treated water by filtration. Related methods are used to reduce the leachable metal content of contaminated soils. The invention also provides a composition for stabilizing the metal contaminants in soil, comprising lignin derivatives, a coagulant and a composition for increasing the pH. The mixture is blended with the contaminated soil, reducing its leachable metal content.

Abstract: A method for removing metal contaminants from acidic mine wastewater using lignin derivatives, such as lignosulfonates and kraft lignin, an alkali coagulant, such as a lime compound, and an alkaline composition for increasing the pH. The lignin derivatives are dispersed in the wastewater and the coagulant is added, increasing the pH to about 4.5–8.5 and causing the formation of a floc. The alkaline composition is then added to bring the pH to about 9 to 10, causing the further formation of a floc. Optionally, air oxidation is carried out, reducing the pH to about 8.1–8.6. Optionally, a ferric or ferrous salt may also be added. The flocs comprise metal-lignin colloids, metal hydroxides and metal salts. The flocs coagulate to form a sludge. Optionally, fly ash or diatomaceous earth may be added to increase the density and stability of the sludge. The sludge that is formed contains the metals and is separated from the treated water by filtration.

Abstract: An apparatus for installing and removing candles from a packed tower comprises a rail or series of rails attached to the inside of the top of the vessel. The rail(s) may be supported from either the roof or walls of the tower. A traveler assembly is supported on the rail(s). The traveler assembly supports a hoist puller that in turn raises and lowers the candles. The rail(s) may be located such that they extend over the centerlines of each of the candle locations, and each such that a portion of each rail passes under the candle installation port. Multiple traveler assemblies may be used to increase the speed of installation. The traveler assembly may be configured to be removed when not in use, to ensure it is not exposed to the harsh environment in the tower. Alternatively, the traveler assembly may be constructed from corrosion-resistant materials, so that the traveler assembly may be left in the tower.

Abstract: This application relates to improvements to long vertical shaft bioreactors for the aerobic biological treatment of wastewater and aerobic digestion of biodegradable sludges. The invention comprises a flow control device and method which improves hydraulic flow, inter-zonal mixing and gas transfer in such bioreactors. The flow control device includes a ported upper plate which is mounted in an upflow chamber of the bioreactor and a lower plate located below the upper plate at the juncture between mix and plug flow zones of the bioreactor which are in fluid communication. At least some of the ports in the upper plate are fitted with adjustable valves for regulating the flow of liquor therethrough and hence the size of a hydraulic head loss imposed by the flow control device. Preferably the upper plate is mounted at a location in the upflow chamber upstream from the inlet where influent is discharged into the bioreactor.

Abstract: An integrated process for treating alkaline wash water effluent from nitroaromatic manufacture, principally containing nitro-hydroxy-aromatic compounds is described. The integrated process concentrates the alkaline wash water to recover chemicals and water prior to treating the concentrate through supercritical water oxidation. The supercritical water oxidation step consists of treating the concentrate in the presence of an oxygen source at conditions, which are supercritical for water to cause a substantial portion of the organic component of the concentrate to oxidize. The product effluent includes a gaseous component and a clean water component, and in the event that insoluble ash is formed, an ash component. The new integrated process results in reduced chemical and water consumption compared to existing processes. In addition, the treated wash water effluent can be recycled to process or directly discharged.