Page 349 - Water and wastewater engineering

8-18 WATER AND WASTEWATER ENGINEERING

Qtreated treated Qbypass bypass Qblended bleended
C
C
C
With no leakage C treated 0.0 mg/L and material balance equation is

3
Q treated ()0 Q bypass (328 6. mg/L as CaCO 3 ) (2775 m /d)( 80 mg/L as CaCO )
3
3
d
( 275 m /d)(80 mg/L as CaCO )
3
Q bypass
328 6 . mg/L as CaCO 3
3
66..95 m /d
f. The flow rate passing through the ion exchange column is
3
275 m /d 66 95 m /d . 3 208 05 m /d. 3
g. The meq/L of hardness to be removed is

⎛ 1 ⎞
(328 6 mg/L as CaCO 3 ) ⎜ ⎝ 50 meq/mg⎠ ⎟ 6 572 meq/L
.
.
where 50 meq/mg is the equivalent weight of CaCO 3 .
h. The meq of hardness to be removed in one day is

3
.
,
1d
.
1
(6 572 meq/L )(208 05 m /d )(1 000 L/m 3 )( ) 1 3710. 6 meq
i. The mass of dry resin required is
⎛ 1 g ⎞ 3
6

⎟
.
(1 3710 meq ) ⎜ ⎝ 489 meq⎠ (10 kg g / ) 2279 61. or 280 kg
.
j. The mass of resin on a moist basis is
⎛ 1 ⎞
(280 kg ) 500 kg
⎝ 10 44 ⎠

.
k. To account for the manufacturer’s operating capacity to breakthrough, increase the
mount of resin to
1
)
.
( 500 kg 746 27 or 750 kg
067
.
Comments:
1. The estimated resin was given in meq hardness/g of dry resin. This estimate could also be
made as meq of hardness/mL of moist resin. The resin is shipped and installed moist. The