How many pounds of lime must be fed daily to achieve a dosage of 9 mg/L if the plant treats 4 MGD?

To determine how many pounds of lime are necessary to achieve a dosage of 9 mg/L for a treatment plant processing 4 million gallons per day (MGD), you'll need to convert the flow rate to a pound per day basis using the dosage you need.

First, convert the flow rate from MGD to liters per day. There are approximately 3.78541 liters in a gallon:

[

4 \text{ MGD} \times 3.78541 \text{ L/gallon} \times 1,000,000 \text{ gallons} = 15,141,640 \text{ L/day}

]

Next, since you are looking to achieve a target concentration of 9 mg/L, you can calculate the total mass of lime needed per day:

[

\text{Total mass (mg)} = \text{Dosage (mg/L)} \times \text{Flow rate (L/day)}

]

[

= 9 \text{ mg/L} \times 15,141,640 \text{ L/day} = 136,274,760 \text{ mg/day}

]

To convert milligrams to pounds, note that there are approximately 453,