Low water technology

The high solubility of the salt and resultant low water vapor pressure (58) of its aqueous solutions ate usehil ia absorption air conditioning (qv) systems. Lithium bromide absorption air conditioning technology efficiencies can surpass that of reciprocal technology usiag fluorochlorocarbon refrigerants. 

Extraction. Traditionally tea leaf is extracted with hot water either in columns or ketdes (88,89), although continuous Hquid soHd-type extractors have also been employed. To maintain a relatively low water-to-leaf ratio and achieve full extraction (35—45%), a countercurrent system is commonly used. The volatile aroma components are vacuum-stripped from the extract (90) or steam-distilled from the leaf before extraction (91). The diluted aroma (volatile constituents) is typically concentrated by distillation and retained for davoring products. Technology has been developed to employ enzymatic treatments prior to extraction to increase the yield of soHds (92) and induce cold water solubiUty (93,94). 

Low-temperature (<500 °C) reforming technologies are also under investigation. The advantages of low-temperature technologies are reduced energy intensity, compatibility with membrane separation, favorable conditions for the water-gas shift reaction, and minimization of undesirable decomposition reactions typically encountered when carbohydrates are heated to high temperatures [44]. 

The technology, available from a number of vendors, is portable and uses a single pump to extract free product, groundwater, and soil gas from multiple wells. Groundwater and soil gas may require treatment before being discharged. Bioslurping is used at petroleum spill sites and has proven most effective in fine-to-medium textured soils or fractured rock in areas with a low water table. 

VOCs), uranium, and heavy metals. There has been extensive research on various materials for use in PRBs. Metal-based PRBs are common because the reactive material is commercially available at low costs and has been effective on a variety of contaminants. Metal-based PRBs act as selective filters to contaminants and are being developed in response to the need for effective, low-cost technologies to remediate contaminated subsurface environments. The barriers are permeable to water and nontargeted groundwater constituents and impermeable or destructive to the target contaminant(s). 

Polymer encapsulation technology (PET) was designed to stabilize radioactive materials and wastes. Polymer encapsulation uses nonvolatile polymers with excellent heat resistance, low water solubility, chemical stability, and excellent radiation resistance. Once materials have been mixed with the encapsulant, the mixture expands and hardens. This process prevents radioactivity from escaping and confines radioactive particles to the polymer structure. 

Microencapsulation using extrusion is mainly described for glassy carbohydrate matrices [14-16, 28-29]. The glassy carbohydrates, such as starch and maltodextrins, are melted at elevated temperature and low water contents and are intensively mixed with the active in the extrusion barrel. Extrusion has been used for volatile and unstable flavours. The shelf life of flavour oils could be extended from several months to 5 years, compared with 1 year for spray-dried materials. The main drawbacks of the technology are the high investments costs and the formation of rather large particles (500-1,000 pm). 

The decontamination of polluted waters by photocatalytic treatment has been suggested as a viable, low-cost, and environmental friendly technique. The possibility of using solar energy as well as low-cost technology pushed to develop solar plants based on this process. The field results are very encouraging [1]. 

Currently, most mature dissolution controlled release systems/ technologies are applicable for water-soluble and low-water-solubility compounds (with low doses). For very poorly water-soluble compounds, dissolution controlled release systems/technologies may not be applicable because these compounds have intrinsically slow dissolution/release rates. Recently, several new technologies such as solid dispersions and self-emulsifying drug delivery systems (SEDDS) have been developed to deliver poorly water-soluble compounds at reasonable doses through enhancement of dissolution rate. These technologies have created new potentials for controlled release of poorly water-soluble compounds, often... 

Litter, M.I. (Ed.), Prospect of Rural Latin American Communities for application of Low-cost Technologies for Water Potabilization, ASO Project AE141/2001. Digital Grafic, La Plata, (2002), http //www.cnea.gov.ar/xxi/ambiental/agua-pura/default.htm. 

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