Harvesting salts

Deposits of salt exist throughout the world, but there are many countries where salt deposits are absent. Sodium chloride also makes up 2.68 percent of seawater.4 As a result, sea salt is harvested in many countries that have a flat coastline and good weather conditions suitable for harvesting salt, i.e., warm breezes and plentiful sunlight. Pure sodium chloride is white-to-colorless, crystalline, and contains 60.663 wt% Cl and 39.337 wt% Na. Once the salt has been processed, it can exist as discrete cubic crystals of varying sizes. Readily dissolvable in water, the aqueous solution has a pH of 7.0. 

Sodium chloride occurs naturally as the mineral halite and abundantly in the oceans, where it is found in seawater at an average concentration of about 2.6 percent. There are several methods for harvesting salt, some of which date to ancient times. The earliest known method of production is also the simplest evaporation of seawater by the Sun. In this method, seawater is collected in large, shallow ponds and allowed to evaporate. The salts dissolved in the water crystallize on the bottom of the ponds and can be scraped off and the individual compounds present—including sodium chloride-separated from each other. 

The precipitated matter itself also helps to seal the ponds. A permanent salt floor of 200-250 mm acts as a seal and also prevents inclusions of dirt and clay in the harvested salt. Fresh salt then accumulates to a thickness of 100-200 mm before harvesting. 

Figure 1.59 Harvesting salts at SQM s solar ponds on the Salar de Atacama (SQM, 2001, courtesy of SQM SA).

An estimation of the amount of amino acid production and the production methods are shown ia Table 11. About 340,000 t/yr of L-glutamic acid, principally as its monosodium salt, are manufactured ia the world, about 85% ia the Asian area. The demand for DL-methionine and L-lysiae as feed supplements varies considerably depending on such factors as the soybean harvest ia the United States and the anchovy catch ia Pern. Because of the actions of D-amiao acid oxidase and i.-amino acid transamiaase ia the animal body (156), the D-form of methionine is as equally nutritive as the L-form, so that DL-methionine which is iaexpensively produced by chemical synthesis is primarily used as a feed supplement. In the United States the methionine hydroxy analogue is partially used ia place of methionine. The consumption of L-lysiae has iacreased ia recent years. The world consumption tripled from 35,000 t ia 1982 to 100,000 t ia 1987 (214). Current world consumption of L-tryptophan and i.-threonine are several tens to hundreds of tons. The demand for L-phenylalanine as the raw material for the synthesis of aspartame has been increasing markedly. 

Composition and Methods of Manufacture. Vaccine is produced from the Oka attenuated strain. Vacciae is produced in human diploid cells such as MRC-5. After growth in the cell substrate, the cells themselves are harvested into the growth medium and sonicated to release the cell-associated vims. Sucrose and buffering salts are generally in the medium to help stabiLize the vims. The vacciae is presented in a free2e-dried vial to be reconstituted with sterile distilled water before injection (27). 

Recovery. The principal purpose of recovery is to remove nonproteinaceous material from the enzyme preparation. Enzyme yields vary, sometimes exceeding 75%. Most industrial enzymes are secreted by a microorganism, and the first recovery step is often the removal of whole cells and other particulate matter (19) by centrifugation (20) or filtration (21). In the case of ceU-bound enzymes, the harvested cells can be used as is or dismpted by physical (eg, bead mills, high pressure homogenizer) and/or chemical (eg, solvent, detergent, lysozyme [9001 -63-2] or other lytic enzyme) techniques (22). Enzymes can be extracted from dismpted microbial cells, and ground animal (trypsin) or plant (papain) material by dilute salt solutions or aqueous two-phase systems (23). 

Natural rubber is harvested as latex by tapping trees in a manner similar to maple syrup. Tree latex contains about 35 wt% rubber solids, as well as small quantities of carbohydrates, resins, mineral salts and fatty acids. Ammonia should be immediately added to the latex to avoid coagulation by these other ingredients and to prevent bacterial degradation. After collection, the latex can be concentrated to 60-70% solids if the latex product is required for end-use. Otherwise, the latex is coagulated, washed, dried, and pressed into bales for use as dry rubber. 

Use of mild conditions was crucial and the development of diimide reduction of singlet oxygenates, silver-salt-assisted displacement of halide by peroxide nucleophiles, peroxymercuration and demercuration, peroxide transfer from organotin to alkyl triflates, and oxygen trapping of azoalkane-derived diradicals have all played a part in providing the rich harvest of new bicyclic peroxides described herein. 

Fantozzi et al. [73] presents the study of the carbon footprint of a typical food product in Central Italy truffle sauce. This is a mixture of vegetable oil and truffle in proportions of 33% and 67% respectively and minor components and spices (garlic, salt, pepper, etc.). Both truffles and olives are cultivated and harvested in a farm in Umbria (Italy). Olives are crushed in a mill that is situated few kilometers from the farm. Once it has been produced, the extra virgin oil, together with the truffle, is transported to another facility to produce bottled truffle sauce. The carbon footprint calculation is based on ISO 14076 technical standard. Product Category Rules (PCR) have been developed (see Table 7). 

Some extraneous constituents of plant tissues, such as alkali salts in many lignocellulosics and particularly resin in wood, oxidize at lower temperatures and faster than the regular constituents. Therefore some fires from self-heating have been attributed to extraneous constituents. Extrinsic substances added after harvesting may accelerate self-heating even more the additives and contaminants either catalyze oxidation and pyrolysis, or the extrinsics themselves oxidize, with fats and oils being examples (9). 

Nanoscale Metallics. Many of the metallization materials previously discussed, such as gold, can be developed into fine particles through either chemical reduction from a metal salt or from vaporization of the bulk metal.89 In fact, metals, such as gold, silver, palladium, and iron, can be harvested in elemental form from vegetation and grains that have been planted... 

More research and demonstration activity should be devoted to water harvesting, which can be considerably useful not only in reducing irrigation requirements but also in the reduction of overland flow and consequently in the protection of soils from water erosion, as well as in leaching soils from salts accumulated with irrigation water. The solution of tied ridges, or diked furrows, to be obtained either by animal energy or when possible with the use of mechanical equipment, has been... 

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