A water plant operates at 5.00 MGD. Jar testing determines the optimum coagulant dose is 16.0 mg/L of dry alum. If the plant feeds liquid alum containing 48.0% dry alum by weight, how many pounds of commercial liquid alum must be fed per day?

Formula Used: Liquid Alum (lbs/day) = [Flow (MGD) × Dose (mg/L) × 8.34] ÷ [Dry Fraction (0.48)]

Step-by-Step Mathematical Derivation:

1. Calculate pure dry alum requirement: 5.00 MGD × 16.0 mg/L × 8.34 = 667.2 lbs dry alum/day.
2. Divide by 48% (0.48) liquid concentration: 667.2 ÷ 0.48 = 1,390.0 lbs/day.

⚠️ Common Exam Trap: Always divide dry chemical requirement by liquid active fraction when commercial chemical slurries are used.