Aqueous wastes

Waste aqueous metalworking fluids may be successfully treated by conventional means for removal of tramp oil, surfactants, and other chemical agents to provide suitable effluent water quaUty (78). 

Van Ness, G.F., J.G. Solch, M.L. Taylor, and T.O. Tieman. 1980. Tetrachlorodibenzo-p-dioxins in chemical wastes, aqueous effluents and soils. Chemosphere 9 553-563. 

The removal of metal ions from waste aqueous solutions is of importance to many countries of the world both environmentally and for water re-use. The application of low-cost sorbents including carbonacceous materials, agricultural products and waste by-products has been investigated [1], Several researchers employing wide variety techniques have attempted removal of metal ions from contaminated water bodies. Majorities of these are adsorption on various surfaces. In recent years, agricultured by products have been widely studied for metal removal from water. These include peat [2], pine bark [3], banana peat [4], peanut shells [5], sawdust [6] and leaves [7]. 

The crude paclitaxel is recovered from the rich aqueous fermentation broth by liquid/liquid extraction with a mixture of isobutyl acetate (IBA) and isopropanol (IPA), both class 3 solvents. The waste aqueous phase is stripped to remove residual organic solvents (IBA/IPA), treated with sodium hydroxide to deactivate any paclitaxel residues, and processed through a standard wastewater treatment facility. The amount of solid waste biomass generated in the process is negligible. 

Chlorine and calcium hydroxide (slaked lime), used to ensure high pH conditions to avoid generation of extremely toxic hydrogen cyanide gas, are used in combination to chemically neutralize waste aqueous solutions of sodium cyanide. In this way the much less toxic cyanate ion (CNO ) is produced for discharge by oxidation of the cyanide ion. 

Microfiltration applies when particulate materials above 50 nm diameter are to be separated from an aqueous phase or from macromolecules. Thus, microfiltration can be used for cell concentration. On the other hand, the same unit operation can be viewed as a fractionation procedure in processes where products are produced extracellularly. Although the first research on microfiltration was carried out in Germany in the early 1900s (55, 56), the technology didn t find major application until after World War II when it was used for the analysis of waste aqueous streams (57). In the late 1970s, applications for cell separation appeared as a substitute for centrifugation in the separation of plasma from whole blood (58). Thus, a significant data base... 

Process waste (aqueous solutions, slurries, ion-exchange resins, organic liquids)... 

Traditionally, most industrial chemical processes were targeted toward meeting required product specifications at competitive prices without much regard to emissions from hazardous chemicals and their by-products. Recently, however, these considerations, especially process emissions such as solid waste, aqueous discharges, and air emissions, have dominated process development because of the regulatory and permit requirements of the... 

The most frequently applied adsorbent for the removal of organic pollutants in wastewaters is currently activated carbon, which is an expensive material. Mounting apprehension about environmental issues has prompted the textile industry to investigate appropriate and environment-friendly treatment technologies for waste aqueous effluent containing color and heavy metals. Dubey and Rao [24] evaluated a number of alternative and cheaper adsorbents. Results... 

When triethylamine is used as an amine solvent or as a reagent, its relatively high water solubility (5.5% w/w at 20°C) leads to significant losses into waste aqueous streams and consequent higher costs for waste water treatment. Hiinig s Base, AT AT-diisopropylethylamine, on the other hand has relatively low water solubility (0.4% w/w at 20°C) and only dissolves 0.2% w/w of water in itself at 20°C. Hence mixtures of diisopropylethyla-mine and water readily separate into two layers yielding relatively dry amine for recycle. The waste water can be treated in normal effluent treatment plants without further handling. 

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