How many pounds of chlorine gas are required per day to disinfect a water supply flowing at 1 MGD with a chlorine dose of 2 mg/L?

To determine the amount of chlorine gas required for disinfection in a water supply flowing at 1 Million Gallons Per Day (MGD) with a required chlorine dose of 2 mg/L, you start by converting the flow rate and the dosage into compatible units.

1 MGD is equivalent to 1,000,000 gallons. For chlorine dosing, it is essential to convert gallons to liters because the dosage is provided in milligrams per liter (mg/L). Since there are approximately 3.78541 liters in a gallon, 1 MGD equals about 3,785,410 liters per day.

The dosage of chlorine (2 mg/L) can be translated into total milligrams needed per day:

• Total chlorine needed = flow rate (in liters) × dosage (in mg/L)

• Total chlorine needed = 3,785,410 liters/day × 2 mg/L = 7,570,820 mg/day

Next, converting milligrams to pounds, you utilize the conversion factor that 1 pound equals 453,592 milligrams:

• Total chlorine needed in pounds = 7,570,820 mg/day ÷ 453,592 mg/lb ≈ 16.68 lbs/day

This calculation confirms