Science of Water : Concepts and Applications

Water Treatment Calculations 359
Example 10.61
Problem:
The lime dose for a raw water has been calculated to be 15.2 mg/L. If the fl ow to be treated is 2.4 MGD,
how many lb/day lime will be required?
Solution:
Example 10.62
Lime, lbday (lime, mgL)(flow, MGD)(8.34 lbgal) (15.2 mg L)(2.4
MGD)(8.34 lbgal) 304 lb day lime
Problem:
The fl ow to a solids contact clarifi er is 2,650,000 gpd. If the lime dose required is determined to be
12.6 mg/L, how many lb/day lime will be required?
Solution:
DETERMINING LIME DOSAGE, g/min
Lime, lbday (lime, mgL)(flow, MGD)(8.34 lbgal) (12.6 mgL)(2.65
MGD)(8.34 lbsgal) 278 lb day lime
In converting mg/L lime into grams/min (g/min) lime, use Equation 10.58.
Key Point: 1 lb = 453.6 g.
(lime, lbday)(453.6 glb) Lime, gmin
1440 minday Example 10.63
Problem:
A total of 275 lb/day lime will be required to raise the alkalinity of the water passing through a solidscontact
clarifi cation process. How many g/min lime does this represent?
Solution:
(lbday)(453.6 glb) Lime, gmin
1440 minday (275 lbday)(453.6 glb)
1440 minday 86.6 gmin lime
(10.58)