Wastewater math
Pounds Loading Formula for Wastewater Operators
Pounds per day from flow in MGD, concentration in mg/L and 8.34 lb/gal.
The formula
Formula
Find pounds per day
lb/day = MGD × mg/L × 8.34WPI Formula/Conversion Table (2023), Printed page 4 of 10, Loading Rate, lb/day: Flow, MGD × Concentration, mg/L × 8.34 lb/gal
Worked example
Step by Step
Waste activated sludge flows at 0.08 MGD and contains 6,000 mg/L of solids. What is the solids loading in lb/day?
What Do We Know?
Flow is 0.08 MGD and waste activated sludge solids concentration is 6,000 mg/L.
What Are We Finding?
Find the waste activated sludge solids loading in pounds per day.
Are the Units Compatible?
Flow is in MGD and concentration is in mg/L, matching the governed US-unit loading relationship.
Choose the Relationship
Loading = flow × concentration × 8.34.
Put In the Values
0.08 × 6,000 × 8.34
Perform the Calculation
480 × 8.34 = 4,003.2.
Check the Units
MGD × mg/L × 8.34 leaves pounds per day (lb/day).
Answer
4,003.2 lb/day
Answer: 4,003.2 lb/day
Practice
Try It Yourself
Practice this math in the Math Center, with hints and worked steps.
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