Desalination salts recovery

These features are likely to encourage further development of vacuum or solar evaporation salt recovery operations to work these brines in proximity to the desalination plants. In this way, various salts may be more profitably recovered from these artificially enriched seawaters for reasons similar to the present incentives to use the rich natural brine sources for sodium chloride production (Table 6.3). Similar energy savings should be obtained. 

Salts recovery from seawater desalination plants... 

R Macedonio and E. DrioU, Hydrophobic membranes for salts recovery from desalination plants, Desalination and Water Treatment, 18 (2010) 224-234. 

Bromley and co-workers (36) have calculated the minimal energy of separation of water from seawater containing 3.45 wt % salt, at 25°C, to be 2.55 kj/(kg fresh water) for the case of 2ero fresh water recovery (infinitesimal concentration change) and 2.91 kj/(kg fresh water) for the case of 25% fresh water recovery. is, however, severalfold smaller than the energy necessary for water desalination ia practice. 

The pressure to be used for reverse osmosis depends on the salinity of the feedwater, the type of membrane, and the desired product purity. It ranges from about 1.5 MPa for low feed concentrations or high flux membranes, through 2.5—4 MPa for brackish waters, and to 6—8.4 MPa for seawater desalination. In desalination of brackish or sea water, typical product water fluxes through spiral-wound membranes are about 600—800 kg/m /d at a recovery ratio RR of 15% and an average salt rejection of 99.5%, where... 

Evaporation. In most chemical industry evaporation systems, the objective is product recovery, although occasionally the objective is concentration of an organic waste from an aqueous solution, to facihtate incineration. Similar equipment is used extensively for desalination of salt or brackish water (see also Water, supply and desalination). 

Ni-Si recovery of HP Processes involving cone. H2SO4 processes. Sulphur stripping columns. Distillation columns containing acidic chlorides. Handling acid sludges processes impellers, propeller shafts, fasteners. Demisters in desalination plants refrigerating brines. Salt production. Evaporators steel... 

Mani KN, Chlanda FP, Byszewski CH (1988) Aquatech membrane technology for recovery of acid/base values from salt streams, Desalination 68 149 Chem Abstr 108 (1988) 189072n... 

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. 

Figure 5.16, adapted from Kurihara,79 80 shows a comparison of several types of commercial reverse osmosis membranes in terms of salt rejection and permeate flow rate under seawater test conditions (35,000 ppm, 800 psi, 25°C). This chart emphasizes the capability of PEC-1000 to provide complete single-stage seawater desalting. In a test at Toray s Ehime desalination test facility on 42,000 ppm seawater (equivalent to Red Sea salinity), PEC-1000 spiral elements operated at 35% recovery produced a permeate having an average salinity of only 220 ppm, well below WHO standards. Average salt rejection was 99.5%. 

Food industry and medical supplies Edible salt production from seawater,23 demineralization of whey,24 recovery of amino acids from fermentation liquor,25 separation of amino acids,26 preparation of lactic acid27, gluconic acid28 amino acids,29 etc. from their salts, stabilization of grape juice30 and pre-treatment of wine,31 deacidification of sour orange juice,32 desalination of soups, desalination of soybean sauce,33 continuous fermentation in the presence of electrodialysis,34 de-ionization of sugar solution.35... 

Serkiz and Perdue (1990) were the first to report the successful use of RO to isolate NOM from river water. Polyamide (PA) membranes on a polysulphone (PS) support were used. Freshwatcrs were pretreated with a cation exchange resin and, due to a low salt content, no further desalination was required. Concentrates were then freeze dried. Recoveries of about 90% were achieved. The method appears to be well suited for NOM removal with the possibility of subsequent use of XAD for separation of FA and HA from the NOM. The method can be applied to freshwatcrs containing DOC in the range of 3 to 40 mgL h Problems of the method include the presence of residual inorganics such as H2SO4 and Si(OH)4. 

Brackish Water Desalination Low-pressure membranes were used by Glueckstern et al. (1986) for brackish water desalination. With a feed water of 6000-6500 mg/1, recovery of 65%, and applied pressure of 14 bars (net driving pressure of 7 bars), a salt rejection of 95% was obtained. An energy saving of 33% was achieved. 

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