HOt Products
4) Excess lime-soda ash treatment i. The source water has high Ca and Mg hardness. ii. Under such conditions, usually, there is not enough alkalinity, so Na 2 CO 3 is added. iii. High Mg hardness requires excess lime to increase pH to 12-13 so that reaction kinetics is When soda ash is used to remove noncarbonate hardness, an even higher pH is required 10.0 to 10.5 for calcium compounds and 11.0 to 11.5 for magnesium compounds. Carbon Dioxide Demand The first step in lime softening is the addition of lime to water using a Hardness and pH levels of make-up water should be checked prior to addition of Soda Ash. When treating make-up water, pH ranges should be maintained between 8.5 9.5 Addition of Soda Ash should always be done prior to addition of bentonite or polymer to the fluid system. Equation (ix) indicates the chemical reaction between sodium carbonate (or soda ash) and magnesium chloride. A summary of the chemicals required for the removal of the different types of hardness is indicated in the following table: Lime used for water softening may be either quick lime CaO, or hydrated lime Ca(OH) 2. Quick lime is preferred When soda ash is used to remove noncarbonate hardness, an even higher pH is required 10.0 to 10.5 for calcium compounds and 11.0 to 11.5 for magnesium compounds. Carbon Dioxide Demand The first step in lime softening is the addition of lime to water using a 
REMOVAL OF HARDNESS BY PRECIPITATION
Lime Soda Ash Softening
Soda Ash Baroid
Removal of Permanent Hardness from Water Water Engineering
Lesson 18: Softening