Liquid wastes caustic

Spent caustic solutions from petroleum refining. Petrochemical refineries use caustics to remove acidic compounds such as mercaptans from liquid petroleum streams to reduce produced odor and corrosivity as well as to meet product sulfur specifications. Spent liquid treating caustics from petroleum refineries are excluded from the definition of solid waste if they are used as a feedstock in the manufacture of napthenic and cresylic acid products. U.S. EPA believes that spent caustic, when used in this manner, is a valuable commercial feedstock in the production of these particular products, and is therefore eligible for exclusion. 

Corrosivity. A liquid waste that has a pH of less than or equal to 2 or greater than or equal to 12.5 is considered to be a corrosive hazardous waste (40 CFR 261.22). Sodium hydroxide, a caustic solution with a high pH, is often used... 

Some aluminosilicate minerals appear to meet the above criteria rather well, especially with regard to low leachability and chemical and physical stability 1, 2). A low-temperature process for converting the wastes to aluminosilicates with low leachability has now been found (3). Aqueous waste solutions containing NaOH, NaNOa, NaN02, NaAl02, mixed fission products, and minor amounts of other salts are mixed with powdered clays (kaolin, bentonite, halloysite, or dickite) and allowed to react at 30°-100°C to form small crystals of the mineral cancrinite. The sodium aluminosilicate crystal lattice of cancrinite contains large amounts of trapped salts and radioactive fission products. The process is applicable to caustic radioactive liquids such as neutralized Purex wastes or to salts or oxides produced by evaporation or calcination of these liquid wastes. 

The components of most refinery liquid waste streams are recovered and reused, whenever feasible. Unfortunately, some of these, such as aqueous caustic phenolic or caustic sulfidic wastes, do not lend themselves readily to reuse. Deep well disposal, incineration, or precipitation in some manner and landfilling of the separated solids are the measures used in these instances. Raising the concentration of brine streams by reverse osmosis before discharge can help decrease final disposal costs by decreasing the waste volume [78]. 

There are mass transfer tasks in the G/L systems, which require special reactor designs. Such tasks include absorption processes, in which strongly diluted gases necessarily participate and the liquid phase consists of liquids which are inmiscible or contain an readily precipitating solid. Examples are oxidation reactions with an ozone-air (3 vol.-% O3) or an ozone-oxygen mixture (6 vol.-% O3), flue gas scrubbing of 6-8 vol.-% CO2 with waste caustic soda, whereupon sodium carbonate is formed and upon exceeding its solubUity precipitates out, etc. 

This is almost certainly due to the very low defect density of the SCCO2 deposited monolayers the caustic solution has no breach to attack. Since much of the high level liquid radioactive waste in the US is held at extremely alkaline conditions, this feature might allow processing of the liquid wastes without the need to drastically modify the pH of the stream before sorption of the target ions. 

N Process Water 163-N Liquid 200 to 300 gal/fflin 1324-N/NA Acid and Caustic liquid waste... 

In early designs, the reaction heat typically was removed by cooling water. Crude dichloroethane was withdrawn from the reactor as a liquid, acid-washed to remove ferric chloride, then neutralized with dilute caustic, and purified by distillation. The material used for separation of the ferric chloride can be recycled up to a point, but a purge must be done. This creates waste streams contaminated with chlorinated hydrocarbons which must be treated prior to disposal. 

Several units are used for sulfite-paper-mill waste-liquor disposal. At least six units are used for oil-refinery wastes, whicdi sometimes include a mixture of liquid sludges, emulsions, and caustic waste... 

Figure 14 Incineration system flow diagram. Waste is incinerated in the presence of air and supplemental fuel the incinerator can be multiple hearth, fluidized bed, liquid injection, rotary kiln, or other types caustic or lime scrubbers are used to remove gaseous pollutants from exhaust gases (from Ref. 11).

The liquid from spent caustic soda baths must be disposed of or treated as a hazardous waste. The finish residue may contain heavy metals as well as caustic thus requiring treatment as a hazardous waste,... 

The cracked gas stream is cooled and purified in the primary fractionator (3) and quench water tower (5). Waste heat is recovered by a circulating oil cycle, generating dilution steam (4) and by a water cycle (5) to provide heat to reboilers and process heaters. The cracked gas from the quench tower is compressed (6) in a 4- or 5-stage compressor and dried in gas and liquid adsorbers (8). C02 and H2S are removed in a caustic-wash system located before the final compressor stage. 

Historically, a classic example of an evaporation process is the production of table salt. Maple syrup has traditionally been produced by evaporation of sap. Concentration of black liquor from pulp and paper processing constitutes a large-volume present application. Evaporators are also employed in such disparate uses as desalination of seawater, nuclear fuel reprocessing, radioactive waste treatment,preparation of boiler feed waters, and production of sodium hydroxide. They are used to concentrate stillage waste in fermentation processes, waste brines, inorganic salts in fertilizer production, and rinse liquids used in metal finishing, as well as in the production of sugar, vitamin C, caustic soda, dyes, and juice concentrates, and for solvent recovery in pharmaceutical processes. 

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