Question

6.16 A water is analyzed and found to have the composition shown in the following table Component CO2 Ca Mg Nat Alkalinity Soi pH Concentration 6.0 mg/L 50.0 mg/L 20.0 mg/L 5.0 mg/L 3.1 millimole/L 85 mg/L 7.6 2+ (a) What concentrations (expressed as mg/L) of slaked lime [Ca(OH)2] and soda ash (Na2CO3) must be added to the water to remove the maximum practical hardness? (b) If the water shown in the table is the source water for a 15 MGD water softening plant, estimate the mass of sludge (in kg/day) produced by the softening process.

Answer 1

solutionる- -A oae s analyeed and foundhave he concenhah0 6.o mgl ro omgl 20 0 mglL Componet ca2+ 24 S:0m3ル Alkon' and solid geneiaed Calcu lah tm me soda as ai n sof entn g the walex ampontonsda as melyng (on) Soda as meeli Cos H) mealL ルMgIL 0.2729 | 0.2729 r00 0 600 ca2 0-2722 ca -CH S000 O 2150O | m3-CH |1.200 lo |тгоб| 0.600 200 0-6o0 CanNCH 0

2 meg IL meel 63 c 03 9 o 39 1. 019 11-039 0 400 excels 639 312 卜639 GHaly Concen hah'm.in/my.)usf'ng -for eavatm below Solving me mei, hy slacked Rme 55-1 mg onc. of Soda ash =

-tr mass of sludge i /g meh 292 mee kg/day au, bu 2 sludge generakkg da