Your boss asked to analyze a system that initially contains 3,000 gallons of water that is contaminated with 53 lbs of arsenic. He wants you to reduce the concentration of the arsenic down to 10 mg/L, which is the standard that the US Environmental Protection requires for your company to be able to bottle and sell the water. You have a 1 hp pump that will allow you to move 17 gallons/minute of water into the well-mixed tank with the contaminated water. Unfortunately, the water you have coming in contains 3.5 mg/L of arsenic. An overflow valve releases water to a discharge at the same flowrate as the inlet to the tank.
Mohammed asked you to:
a) Identify the total amount of water you will have to pass through the tank to reach the standard in the tank using your pump, in gallons.
b) How long will it take to reach the final concentration before you can start to bottle and sell the water, in hours?
c) Predict what the concentration of arsenic is in the tank as a function of time, in mg/L.