Water/Wastewater Laboratory Calculations - Basic Mathematics for Water and Wastewater Operators - page 254

Find pounds per day of alum solution:

147 lb/day ÷ 0.18 = 817 lb/day

Find gallons per day of alum:

817 lb/day solution ÷ 8.34 lb/gal = 98 gpd

Change gallons per day to milliliters per minute:

98 gpd × 2.6 = 255 mL/min

LABORATORY EXAMPLES
■ Example 16.32
Problem: A laboratory solution is made using 50 mg of sodium chloride (NaCl) dis-
solved in a 1-L volumetric flask filled to the mark. What is the milligram per liter
concentration of the solution?

Solution:

50 mg ÷ 1 L = 50 mg/L

■ Example 16.33
Problem: If 35 lb of a chemical are added to 146 lb of water, what is the percent
strength by weight?

Solution:

Weight of chemical
Weight of wate

%Strength = × 100

r + Weight of chemical

35 lb
146 lb

= ××= 100 19 3.%

+ 35 lb

■ Example 16.34
Problem: If 1 L of 0.1- N HCL is required but 12- N HCL is on hand, how many mil-
liliters of the 12- N HCL are required to make the 1 L?

Solution:

NV = NV

11 22

01 . N × 1 000 mL = 12 N × V

2

01 . N × 1

12

000 mL =

V

2

N

8.33 mL = V

2