Potable water hardness

The biological contamination and the hardness of underground water are the two very serious problems of water. Dissolved salts deteriorate water quality and may cause diseases related to joints and bones, while infected water may cause many water-borne diseases such as cholera, dysentery, typhoid etc. Ultrasound may disinfect the potable water by blasting off micro organisms such as zooplanktons, phytoplanktons, pathogenic bacteria and produce germ-free water in few minutes of... 

Pankaj DS, Manju C (2006) Sonochemical removal of hardness and sterilization of underground potable water. J Ind Council Chem 23( 1 ) 38—40... 

Similar small experiments, demonstrating the sterilization of potable water, reduction in the hardness of water, degradation of phenol, amines, potassium iodide and indicators, degradation of complexes, formation of complexes may still be added as found in the preceding chapters of this book. 

Potable water is hard to win because of the very properties that make it worth winning. Because of its unique properties, it exists as a liquid instead of a gas and as a liquid it penetrates into and interacts with living tissues to make possible the processes of life. Because it dissolves salts and nutrients, it is essential for the metabolism of all living cells. 

It was previously mentioned that PDADMAC (Cat-Floe) was the first commercial flocculant approved for potable water [26]. Since then, PDADMAC has been continuously used for coagulation/flocculation both in potable water and waste water treatment. A good example of the performance of PDADMAC in the coagulation of colloidal solids is the reduction of turbidity in fresh water of 150 mg L 1 of Ca(OH)2. A reduction of 82% in turbidity is observed with the addition of only 2 mg L 1 of branched PDADMAC [217]. In addition, PDADMAC and copolymers of DADMAC are reported to be effective in the removal of hard-to-elimi-nate impurities in the water treatment industry. Emulsified impurities from streams of a petroleum refinery waste water and an automotive oily effluent water have been removed by the use of water soluble copolymers consisting essentially of DADMAC and small amounts of anionic acrylic monomers [89]. 

The correct choice of membrane should be determined by the specific objective, such as the removal of particulates or dissolved solids, the reduction of hardness for the production of ultra pure water or the removal of specific gases/chemicals. The end use may also dictate the selection of membranes in industries such as potable water, effluent treatment, desalination, or water supply for electronic or pharmaceutical manufacturing. 

The recommended daily allowance (RDA) for an adult male is 420 mg of magnesium per day, and 320 mg for an adult female (Clinical Nutrition Service, NIH). Magnesium deficiency is rare if a well-balanced diet is consumed that is rich in fruits, vegetables, whole grains, and nuts. Potable water can also contribute significant amounts of Mg to the diet especially in hard-water areas however, softened water is depleted in magnesium. 

Chem. Descrip. Calcium carbonate CAS 471-34-1 EINECS/ELINCS 207439-9 Uses Filler for plastics, PVC, polyolefins, polyesters, BMC/SMC, paint, caulks, sealants, adhesives, paper, foam urethane, modified acrylics, filled thermosets/thermoplastics, and rubber Features Improves impact str., dimensional stability Regulatory NSF approved for potable water materials Properties Wh. powd. 2 avg. particle diam. 99.9% finer than 8 0.15% sol. in water sp.gr. 2.70-2.71 dens. 22.57 Ib/gal bulk dens. 38 Ib/tP (loose) oil absorp. 23 01 cc/100 g brightness (Hunter) 95 ref. index 1.6 pH 9.5 (sat.) hardness (Mohs) 3.0 Toxicobgy Nontoxic Camel-TEX [IMERYS]... 

The world primary energy consumption amounts to well over 300,000 Peta joules and over half of that is used as hot water, steam and heat. Only a few nuclear power plants are being used for heat applications (district heating, heat for industrial processes, and seawater desalination). Potential nuclear heat applications include enhanced oil recovery, petroleum refining, petrochemical industries, and methanol production from hard coal. The need for potable water in some parts of the world is large, vital for sustaining development, and ever increasing. Clearly nuclear heat and power production could play a major and important role. 

Potable water contains as additives sodium, calcium, magnesium, chloride and carbonate ions and a number of other ions in very low concentrations. The bivalent ions of calcium and magnesium are the cause of hardness in water. The hardness of water is specified as hardness degrees, see Table 23.7. 

The corrosion of metals and alloys in potable water varies greatly depending on the water s composition. Among the factors that are most influential are oxygen content, pH, temporary hardness, chloride, sulfate, toted dissolved solids (TDS), and conductivity. Temporary hardness is sometimes referred to as carbonate hardness and is romoved easily by boiling. 

Lime is the largest toimage chemical used in the treatment of potable and industrial water supplies. In conjunction with alum or iron salts it is used to congulate suspended solids and remove turbidity. It is also used in water softening to remove temporary (bicarbonate) hardness. Typical reactions are ... 

Polysilicates are effective in potable HW systems and provide threshold effect protection against hardness destabilization and red water. They also function by laying down a protective calcium silicate film. Polysilicates used for this type of application typically require a dose rate of 8 to 15 ppm Si02 above that of the natural orthosilicate found in the MU water. Where polysilicates are employed for dualtemperature and LPHW systems, however, the silicate reserve required is higher and ranges from 50 to 150 ppm. 

Industry accounts for about a quarter of all water consumption and there is hardly any industry that does not use large amounts of water. Much of the water used in industry is taken from public water supplies and has therefore been treated to potable standards. This means that it is often of a better quality with respect to... 

This case is taken from an actual analysis conducted for an O M contract for a facility in Venezuela. The system is to take potable well water from the city and generate boiler make-up water. The water has 77 ppm (as calcium carbonate) total hardness, with 60 ppm calcium and 17 ppm magnesium. The water contains 0.5 ppm iron and 0.4 ppm manganese. The remainder of the analysis is listed below (all species listed as ppm ion) ... 

Just as water is an integral part of any food, the supply, quality, and disposal of water is of prime consideration in the establishment and operation of all food processing. Potable (drinkable) water may be required for addition to the product, and will certainly be required for cleanup. Nonpotable water may be required for heat exchangers and cooling towers. Boiler feed water must be conditioned within close limits of pH and hardness. Brennan et al. (1990) in their book Food Engineering Operations list four types of water used in the food and beverage industries ... 

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