Softening Calculations

ate *eine*  the ollowing anali i to e otene*  ee lime teatment. !ume that the patial limit o ha*ne emoval o CaCO3 i 30 mg/l5 an* that o Mg,O)-2 i 10 mg/l CaCO3. CO2 % 8.8 mg/l Ca2+ % 40.0 mg/l Mg2+ % 14.7 mg/l Na+ % 13.7 mg/l  !l" ,)CO3'- % 13# mg/l a CaCO3 CaCO3 $O4% % 2&.0 mg/l Cl' % 17.8 mg/l

Comp Compon onen entt mg/L mg/L CO2 Ca2+ Mg2+ Na+  !l" $O4% Cl'

8.8 40 14.7 13.7 13# 2& 17.8

Equi Equiva vale lent nt meq meq/l weight 22 0. 0.40 20 2. 2.00 12.2 1.20 23 0.0 #0 2.70 48 0.0 3# 0. 0.#1

$"eth a meq/l a gaph an* lit the hpothetial omination o hemial ompoun* in olution

Component meq/l total meq/l CO2 '0.40 Ca 2.00 2.00 Mg 1.20 3.20 Na 0.0 3.80

meq/l CO2 )CO3 $O4% Cl'

0.40 2.70 0.0 0.#1

)pothetial omination omination o hemial ompoun* in olution ae Ca,)CO3-25 Mg$O45 Na2$O45 an* NaCl Calium ha*ne % 2.00  #0 % 100 mg/l a CaCO3 Magneium ha*ne % 1.21  #0 % 0 mg/l

Calulate the otening otening hemial quie* quie* epeing lime *oage a CaO an* o*a ah a Na2CO3 Component meq/l CO2 Ca,)CO3-2 Mg,)CO3-2 Mg$O4

Lime meq/l 0.4 2 0.7 0.#0

0.40 2.00 1.40 0.#0 4.30

$o*a ah meq/l 0 0 0 0.#0 0.#0

6equie* lime *oage equal the amount nee*e* o the

total meq/l 0.40 2.70 3.30 3.81

peipitate the magneium. :oage % 4.31  28 + 3# % 1# mg/l CaO :oage o o*a ah % 0.#1  #3 % 27 mg/l Na2CO3

:aw a a gaph o the otene* wate eoe an* ate eaonation. !ume that one hal the al"alinit in the otene* wate i the iaonate om. eoe Component meq/l total meq/l CO2 '0.40 0.00 Ca 2.00 2.00 )CO3 Mg 1.20 3.20 $O4% Na 0.0 3.80 Cl'  !te  Component meq/l total meq/l Ca '1.2# '1.2# Ca 0.0 0.0 Mg 0.20 0.80 Na 1.10 1.&0

6eaonation Component meq/l

meq/l

total meq/l 2.70 0.0 0.#1

2.70 3.30 3.81

'0.4

'0.80 '0.40 '1.00 '0.0 '0.2

O)' O)' CO3% $O4% Cl'

total meq/l

meq/l total meq/l '1.2# 0.20 0.20 0.0 0.80 0.0 1.40 0.#1 1.&1

meq/l

1.2# 0. 0.2 1.10

'0.80 '0.40 '1.00 '0.0 '0.2

total meq/l '1.

Ca Mg Na

0.0 0.20 1.10

0.0 )CO3' 0.80 CO3% 1.&0 $O4% Cl'

0.20 0.0 0.0 0.#1

0.20 0.80 1.40 1.&1

'1.00 '1.00 '0.80 '0.80

'0.0 '0.0

'1.

$plit eatment eatment with 409 o low 'pae*. Compute the hemial equie* an* ha*ne o inihe* wate 

'1.00 '1.00 '0.80 '0.80

'0.0 '0.0

'1.00 '1.00

'0.8 '0.80 0

'0.0 '0.0

'1.00 '1.00

'0.8 '0.80 0

'0.0 '0.0

Lime :oage $o*a ah

0.  1# % 0.  27 %

&3. mg/L CaO 1.2 mg/l Na2CO3

$ee initial aw a gaph an* teate* wate a gaph Hydroxide Ee lime ;om teate* wate
1.2# 0.20 1.4# 0.87 .87

In by-passed water  CO2  pae* wate CC)

409 409

meq/L meq/L meq/L meq/L eq/L

0.40 meq/L % 2.00 meq/L %

0.1 meq/L 0.80 meq/L

Carbon dioxide eliminated by excess lime ee ee  h* h*o oi* i*e e in tea teate te* * wate wate 0.87 0.87 meq/ meq/L L a aon on *io *ioi* i*e e in 'p 'pa ae e* * wate wate 0.1 0.1 meq/ meq/L L 0.71 meq/L after Carbon dioxide eliminated --> [OH-] = Balance hydroxide ion reacts with CH  pae* wate CC) 0.80 meq/L =O)'> 0.71 meq/L ;inal CC) 0.0& meq/L Ca Hardness Limit on o emoval 0. meq/L total 0.& meq/L a CaCO3 ,  #034.# mg/L CaCO3 Mg Hardness
409 09

1.21 meq/L 0.2 meq/L

0.484 0.12 0.0 30.2

meq/L meq/L meq/L mg/L CaCO3 CaCO3

4.7 mg/L CaCO3

Na

Mg

Ca

C O2

2.00

1.20

0.00 0.40 0.80 1.20 1.0 2.00 2.40 2.80 3.20 3.0 4.00 0 0.20 0.0 1.00 1.40 1.80 2.20 2.0 3.00 3.40 3.80 4.20 C l'

$O4%

) C O3

2.70

0.0

0.#1

0.00 0.40 0.80 1.20 1.0 2.00 2.40 2.80 3.20 3.0 4.00 0.20 0.0 1.00 1.40 1.80 2.20 2.0 3.00 3.40 3.80 4.20

Na

Mg

2#

' 0. 0.40

0.0

' 0. 0.20

0.00

C l'

0.20

' 0. 0.20

0.00

0.0

C O3%

0.20

0.20

0.40

0.0

0.00

' 0. 0.20

0.00

1.40

1.0

1.80

2.00

0.20

0.20

1.00

1.20

1.40

1.0

1.80

2.00

1.40

1.0

1.80

2.00

1.40

1.0

1.80

2.00

Ca

0.20

0.40

$O4%

0.20

' 0. 0.40

1.20

O) '

0.80

Mg

C l'

1.00

O) '

0.0

' 0. 0.20

0.80

0.0

Na

' 0. 0.40

Ca

0.20

0.40

$O4%

2#

' 0. 0.40

Ca

0.0

0.80

C O3%

0.0

1.00

1.20

) C O3'

0.0

0.40

1.10

0.0

0.80

1.00

1.20

From water analysis : ?aamete :$ Calium Magneium $o*ium ?otaium iaonate $ulate Chloi*e p)

Ca Mg Na @ )CO3 $O $O4 Cl

Conentation mg/l 373 70 22 14 2 187 118 17 7.#

Construct an equialent table !or the chemical species o! interest ?aamete

mole wt

Ca Mg Na @ )CO3 $O4 Cl

no.eq/mole

Conentation mmole/l meq/l

mg/l 40 24.3 23 2&.1 1 &.1 3#.3

2 2 1 1 1 2 1

70 22 14 2 187 118 17

1.7# 0. 0.&1 0.1 0.07 3.07 1.23 0. 0.48

3.#0 1. 1.81 0.1 0.07 3.07 2.4 0. 0.48

Construct an equialent diagram !or the cationic and anionic chemical sp Cation Ca Mg Na @

3.#0 1.81 0.1 0.07

3.#0 )CO3 #.31 $O4 #.&2 Cl #. # .&&

!nion 3.07 2.4 0.48

3.07 #.#2 .00

"etermine the types o! hardness present in the water  pe o )a*ne Calium aonate Magneium aonate Calium nonaonate Magneium nonaonate

Conentation eq/l 3.07 0 0.43 1.81

Based on the chemical requirement indicated by the so!tening reactions compute the lime and soda ash dose Contituent

amount to e

Ca,O)-2

Na2CO3

to e emove*

emove* meq/l

Calium aonate ha*ne Magneium aonate ha*ne Calium nonaonate ha*ne Magneium nonaonate ha*ne

equie* meq/l

3.07 0.00 0.43 1.81

1 2 0 1

otal hemial equiement

3.07 0.00 0.00 1.81

equie* meq/l 0 0 1 1

4.88

Convet the lime an* o*a ah equiement int mg/l o wate teate* Ca,O)-2 Ca,O)-2 %

meq/l  mmol/ mmol/meq meq  mg/mmole mg/mmole % %

4. 4.88  180 mg/L

0.#



74

0.#



10

%

2.2#  11& mg/L

Na2CO3 %

o aeleate the ate o otening eation5 a # to 109 ee o the toihiometi lime an* o*a ah i oten a**e*. 6ega*ing that alulation have een ae* on pue hemial ompoun*5 to otain the atual hemial *oe5 the alulate* equiement houl* e *evi*e*  the ational puit o hemial ue*. Lime $o*a $o*a ah ah

0'709 at lea leatt &89 &89 *oe

Ca,O)-2 % Na2CO3 %

ee 180 11&

ee puit *oe *oe 109 1&8 #9 30# 109 131 &89 134

0 0 0.43 1.81 2.2#

 

cies

Contituent

amount to e

NaO)

Na2CO3

to e emove*

CC) MC) CN) MN)

emove* meq/l 3.07 0.00 0.43 1.81

equie* meq/l 1 2 0 1

otal auti o*a equiement otal o*a ah equiement $o*a ah po*ue* Net o*a ah equiement

otal auti o*a equiement Ee auti o*a equiement

3.07 0.00 0.00 1.81

equie* meq/l 0 0 1 0

0 0 0.43 0.00

4.88 0.43 2.3

4.88  40 %

1&# mg/l 21# mg/l

 !*vantage in man ae onl one hemial ee* tem i equie* it i eaie to han*le an* ee* the lime it *oe not *eteioate in the toage le lu*ge po*ue* Choie o hemial A ot o equipment o hemial ee* *elive ot ot o lu*ge han*ling an* *ipoal

1 2 0 0

$lu*ge

Na2CO3

Lime o*a otening

Cauti o*a otening

po*ue* meq/l 3.07 0 0 0

3.07

CaCO3 ome* meq/L 2 1 0 1

CaCO3 ome* meq/L .13 0.00 0.00 1.81

otal 7.&4 lu*ge mg/l teate* wate ,05# B 1003&7

1 1

3.07 0.00

3.07

1#3