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Xinxiang Juxinglong Water Treatment Co.,Ltd. Contact：Mr. Xu Mobile：13653905177 Tel：0373-5651158、0373-5651855 Fax：0373-5651866、0373-5762666 Addrerss：Hongqi District, Dong Guan township government breakwater 500 meters,Xinxiang City, Henan Province
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Several methods of water softening
Softening method
Lime softening method is usually used for water with high hardness and high alkalinity; The water with high hardness and low alkalinity is softened by lime soda ash; The negative hard water with low hardness and high alkalinity is treated with lime gypsum.
1. Lime softening method
In order to avoid dust pollution caused by adding quicklime (CAO), quicklime is usually made into hydrated lime Ca (OH) 2 (i.e. hydrated lime) for use. The reaction is as follows
CaO+H2O====Ca(OH)2
When hydrated lime is put into high hard water, the following reactions will occur
Ca(OH)2+CO2====CaCO3$+H2O
Ca(OH)2+Ca(HCO3)2====2CaCO3$+2H2O
2Ca(OH)2+Mg(HCO3)2====2CaCO3$+Mg(OH)2+2H2O
CaCO3 and Mg (OH) 2 are insoluble compounds, which can be precipitated from water.
However, the permanent hardness and negative hardness in water cannot be removed by lime treatment, because the permanent hardness of magnesium, negative hardness and hydrated lime will produce the following reactions
MgSO4+Ca(OH)2====Mg(OH)2$+CaSO4
MgCl2+Ca(OH)2====Mg(OH)2$+CaCl2
NaHCO3+Ca(OH)2====CaCO3$+NaOH+H2O
It can be seen from the reaction formula that the permanent hardness of magnesium is all transformed into the permanent hardness of calcium with great solubility, while the negative hardness is transformed into the same amount of sodium hydroxide and alkalinity, so the alkalinity in water is not removed.
The amount of lime can be estimated according to the following formula
[CaO]=28/Z1{[CO2]+[Ca(HCO3)2]+2[Mg(HCO3)2+B]}
Where [Cao] - amount of industrial lime to be added, mg / L;
[CO2] - concentration of CO2 in raw water (1 / 2co2), mmol / L;
[Ca (HCO3) 2] - concentration of Ca (HCO3) 2 in raw water [1 / 2ca (HCO3) 2], mmol / L
[Mg (HCO3) 2] - concentration of Mg (HCO3) 2 in raw water [1 / 2mg (HCO3) 2] mmol / L;
Z1 -- purity of industrial lime,%;
28 -- molar mass of 1 / 2CaO, g / mol;
B - excess lime (1 / 2CaO), mmol / L (generally 0.2-0.4mmol/l).
2. Lime soda softening method
Lime softening method is only applicable to water treatment with high temporary hardness and low permanent hardness. For water with high hardness, low alkalinity and high permanent hardness, lime soda softening method can be adopted, that is, add lime and then add an appropriate amount of soda (NaCO3, also known as soda). The reaction is as follows
CaSO4+Na2CO3====CaCO3$+Na2SO4
CaC12+Na2CO3====CaCO3$+2NaC1
MgSO4+Na2CO3====MgCO3$+Na2SO4
MgC12+Na2CO3====MgCO3$+2Na<spanstyle="margin:0px；padding:0px；border:0px；outline:0px；vertical-align:baseline；background:tra
