Question

Calculate the lime and soda ash requirements to achieve the practical limits of hardness removal, given 3

Answer 1

HCO^-_3 = 185 mg/L as CaCO_3 Ca^2 + = 60 mg/L Mg^2 + = 15.8 mg/L solution: Total Alkalinity = 185 mg/L as CaCO_3 (mglc as CaCO_2) Total Hardness = Ca^2 + times Eq^wt of CaCo_3/Eq^wt of Ca^2 + + mg^2 + _(mglc) times Eq^wt of CaCo?_3/Eq^wt of mg^2 + = 60 times 50/20 + 15.8 times 50/12 Total Hardness = 215.83 mg/L as CaCo_3 mg/c as CaCo_3\r\n TH > T.A rightdblarrow T.A = CH NCH = TH - CH rightdblarrow carbonate Hardness = 185 mg/L as CaCo_3 Non-carbonate Hardness = 215.8 - 185 = 30.83 mg/L as CaCo_3 Line Requirement: Dose of line = 56/100 times TH(mg/L) rightdblarrow Dose of line = 56/100 times 215.83 Dose of line as Cao = 120.86 mg/L Given Purity of line is 85% rightdblarrow Dose of line required as Cao = 120.86/0.85 = 142.193 mg/L Soda Requirements: \r\n rightdblarrow Dose of Soda = 106/100 times 30.83 = 32.68\r\n