Steam stripping, adsorption

Chemical precipitation Chemical oxidation/re duction Air and/or steam stripping Activated carbon adsorption Resin adsorption Ion exchange Ultrafiltra-tion and/or reverse osmosis Flo atation / ph ase separation... 

The energy requirements for desorbing 1,1-dichloroethane from activated carbon in a stripping—adsorption process for water purification have been calculated at 112 kj/kg (14). Chlorinated hydrocarbons such as 1,1-dichloroethane may easily be removed from water by air or steam stripping. 

Liquid-liquid extraction is used primarily when distillation is imprac-tic or too costly to use. It may be more practical than distillation when the relative volatility for two components falls between 1.0 and 1.2. Likewise, liquid-liquid extraction may be more economical than distillation or steam-stripping a dissolved impurity from wastewater when the relative volatility or the solute to water is less than 4. In one case discussed by Robbins [Chem. Eng. Prog., 76 (10), 58 (1980)], liquid-liquid extraction was economically more attractive than carbon-bed or resin-bed adsorption as a pretreatment process for wastewater detoxification before biotreatment. 

Three mass-exchange operations are considered steam stripping, air stripping and adsorption using granular activated carbon. The stream data ate given in Table 6.13. 

Steam stripping Air stripping Biological nitrification Chemical oxidation Ion exchange Solvent extraction Biological oxidation (aerobic) Wet oxidation Activated carbon Chemical oxidation Chemical precipitation Ion exchange Adsorption Nano-filtration Reverse osmosis Electrodialysis... 

PuraSiv HR A process for removing solvent vapors from air by adsorption on beaded activated carbon contained in a combined fluidized moving bed. For water-soluble solvents, the gas used for desorption is nitrogen and the process is known as PuraSiv HR, Type N (not to be confused with PuraSiv N) for chlorinated hydrocarbons, steam stripping is used and the process is known as PuraSiv HR, Type S. Developed by Kureha Chemical Company and now marketed by the Union Carbide Corporation. The process was originally known as GASTAK because it was developed by the Taiyo Kaken Company, subsequently acquired by Kureha Chemical Company. It is also marketed by Daikin Industries under the name Soldacs. 

There are six primary in-plant control methods for removal of priority pollutants and pesticides in pesticide manufacturing plants. These methods include steam-stripping, activated carbon adsorption, chemical oxidation, resin adsorption, hydrolysis, and heavy metals separation. Steam-stripping can remove volatile organic compounds (VOCs) activated carbon can remove semi volatile organic compounds and many pesticides and resin adsorption, chemical oxidation, and hydrolysis can treat selected pesticides [7]. Heavy metals separation can reduce toxicity to downstream biological treatment systems. Discussion of each of these methods follows. 

Radio frequency heating, 500 Steam stripping, 500 Vacuum extraction, 500 Aeration, 501 Bioremediation, 501 Soil flushing/washing, 502 Surfactant enhancements, 502 Cosolvents, 502 Electrokinetics, 503 Hydraulic and pneumatic fracturing, 503 Treatment walls, 505 Supercritical Water Oxidation, 507 Solid Solution Theory, 202 Solubility products, 48-53 Metal carbonates, 433-434 Metal hydroxides, 429-433 Metal sulfides, 437 Sorption, 167 See Adsorption Specific adsorption, 167 See Chemisorption Stem Layer, 152-154 Sulfate, 261... 

The environmental technology section includes reviews of waste water treatment and air and waste minimization/pollution prevention. Waste water treatment procedures discussed include biological treatment, activated carbon adsorption, air and steam stripping, chemical precipitation, ion exchange, and membrane separation. 

Pervaporation is a membrane process in which a liquid is maintained on the feed side of a membrane and permeate is removed as a vapor on the downstream side of the membrane. Pervaporation is used, because of its low energy consumption and low cost, to separate dissolved organics from water, purify waste water or volatile chemicals, and break azeotropes. Pervaporation plants range from processing a few grams per hour up to thousands of tons per year. For waste water treatment flow of less than 76 L min pervaporation is more cost-effective than other treatment options, such as chemical oxidation, ultraviolet destruction, air stripping followed by carbon adsorption, steam stripping, or distillation/incineration [262]. 

The EMB technology was also compared with other competing technologies. Data for steam stripping, activated carbon adsorption, and air stripping were obtained for year 1998... 

TREATABILITY/REMOVABILITY Process, Removable Range (%), Avg. Achievable Cone. (pg/L)) FUtration, 0, negative removal Sedimentation >70, <10 Sedimentation with chemical addition (alum, polymer), 30->60, <50 Sedimentation with chemical addition (alum , U, negative removal Steam stripping, 97->99, 33000 Solvent extraction, 87->99, 84000 Powdered activated carbon adsorption, 81, 190000 Granular activated carbon adsorption, >86->99, 230000... 

DISPOSAL AND STORAGE METHODS solutions of 1% phenol may be recovered by steam stripping, distillation, or carbon adsorption dilute large amounts with flooding quantities of water and feed to sewage organisms cautiously ignite small amounts store in a cool, dry location separate from oxidizers and acute fire hazards. 

A mixture of ethylene, high purity oxygen, and recycle gas is reacted in a vertical multitubular reactor filled with silver oxide catalyst. The exothermic heat of reaction is removed by the generation of steam in the reactor shell. The ethylene oxide product is absorbed from the reactor effluent gas with water. It is then recovered from the water stream by steam stripping, partial condensation, and adsorption to form a concentrated aqueous solution. The aqueous solution is further concentrated in a two-stage distillation system. The first-stage separates water and the second removes light ends. 

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