Five million gallons per day (mgd) of wastewater, with a concentration of 10.0 mg/l of a
conservative pollutant, is released into a stream having an upstream flow of 10 mgd and
pollutant concentration of 3.0 mg/l.
(a) what is the concentration in ppm just downstream?
(b) how many pounds of substance per day pass a given spot downstream? (you may want the
conversions 3.785 l/gal and 2.2 kg/lbm from appendix a.)

(c) draw a diagram showing the streams with flow rates and concentrations