Solid waste continued recovery from

Studies designed to improve the determination of environmental contaminants will continue to provide refinements and improvements in the determination of acrylonitrile. The current high level of activity in supercritical fluid extraction of solid and semisolid samples should yield improved recoveries and sensitivities for the determination of acrylonitrile in solid wastes, and the compound should be amenable to supercritical fluid chromatographic analysis. Immunoassay analysis is another area of intense current activity from which substantial advances in the determination of acrylonitrile in environmental samples can be anticipated (Vanderlaan et al. 1988). 

The recovery of heavy metals from solid waste poses more challenges. The Eastman Chemical Company process for the manufacture of acetic anhydride by the carbonylation of methyl acetate involves a proprietary process for the continuous recovery of rhodium and lithium from the process tar (see Section 4.6). 

Ultrasonic LSE is most applicable to the isolation of semivolatile and nonvolatile organic compounds from solid matrices such as soil, sediment, clays, sand, coal tar, and other related solid wastes. U-LSE is also very useful for the disruption of biological material such as serum or tissue. U-LSE can be coupled with solid-phase extraction (SPE) to give a very robust sample preparation method at relatively low cost in comparison to MAE and ASE approaches. The author has utilized U-LSE/SPE to isolate and recover 9,10-dimethyl-l,2-benzanthracene from animal bedding. A 89% recovery was obtained for bedding that was spiked with this polycyclic aromatic hydrocarbon (PAH) of interest to toxicologists (20). An ultrasonic horn and tip are immersed into a mixture of liquid extractant and solid sample and sonicated at some percent of full power for a finite length of time, either continuously or pulsed. 

Several investigations were carried out to remove toxic heavy metal ions from waste water by biosorption. Microbial cells loaded with heavy metals were recovered by flotation, e.g. Streptomyces griseus and S clavuUgerus loaded with Pb [108] and Streptomyces pilosus loaded with Cd [109]. In these flotation processes the microbial cells were dead therefore, they are not considered here. The removal of pyritic sulfur from coal slurries such as coal/water mixtures by Thiobacillus ferrooxidans and recovery of this iron-oxidizing bacterium by flotation is a special technique in the presence of high concentrations of solid particles (see e.g. [110]). The flotation of colloid gas aphrons was used for the recovery of yeast in continuous operation [ 111 ] for the recovery of micro algae, and in the presence of flocculants in batch operation [112]. These special techniques are not discussed here. 

Bomb calorimetry was applied to determine the energy contents of different species of undergrowth and their seasonal changes in Spain [84]. Forest residues from afforestation, forest clearing and firebreaks showed mean combustion heats near -19 MJ/kg similar to the value for solid municipal waste. The authors state that forest residues may be thus added to such wastes as further fuel in energy-recovery plants and - if continuously harvested - decrease the risk of forest fires. In two further publications different woodland species from the humid Atlantic zone and the dry continental hillside, plateau and high mountain zones were in-... 

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