Calculate the quantities if Lime and Soda required for softening 50,000 litres of water,

 Given-:

Ca(HCO₃)₂ = 8.1mg ; Mg(HCO₃)₂  = 7.5 mg ; CaSO₄ = 13.6 mg ;  MgSO₄ = 12mg ; MgCL₂ = 2 mg. 

Solution -: 

Calculation of CaCO₃ equivalents:

  

Constituent	Amount	Multiplication factor	CaCO3 Equivalents	Need
	A(mg/L)	M	A*M(mg/L)	Lime = L Soda = S
Ca(HCO3)2	8.1	100/162	8.1*100/162 = 5	L
Mg(HCO3)2	7.5	100/146	7.5*100/146 = 5.14	2L
CaSO4	13.6	100/136	13.6*100/136 = 10	S
MgSO4	12	100/120	12*100/120  = 10	L+S
MgCL2	2	100/95	2*100/95      = 2.1	L-S

 

Lime requirement ={74/100[ Ca(HCO₃)₂ +2Mg(HCO₃)₂ + MgSO₄ + MgCL₂ ]*volume/10⁶ } kg

= { 74/100 [5+2*5.14+10+2.1]* 5*10⁴ /10⁶ }kg

=1.013kg 

Soda requirement = {106/100[CaSO₄ + MgSO₄ + MgCL₂ ]*volume/10⁶ } kg

={106/100[10+10+2.1]* 5*10⁴ /10⁶ }kg

=1.17kg