Chapter 9.3, Problem 5MP

Repeat Example 5 if water is released from the tank at the rate of 75 gallons per hour.

Pollution Control A company has a 1,000-gallon holding tank that is used to control the release of pollutants into a sewage system. Initially, the tank contains 500 gallons of water. Each gallon of water contains 2 pounds of pollutants. Additional polluted water containing 5 pounds of pollutants per gallon is pumped into the tank at the rate of 100 gallons per hour and is thoroughly mixed with the water already present in the tank. At the same time, the uniformly mixed water in the tank is released into the sewage system at a rate of 50 gallons per hour (Fig. 2). This process continues for 5 hours. At the end of this 5-hour period, determine

(A)    The total amount of pollutants in the tank

(B)    The rate (in pounds per gallon) at which pollutants are being released into the sewage system