Problem 2 (40 points) Assume that there are two sites along a stream, i=1, 2, at which industrial
waste is discharged to the river. Current discharge levels are W; and W2 at these sites.
Industrial waste significantly deteriorates water quality in the river, and water quality is being
monitored in sites 2 and 3. Currently, without any wastewater treatment, the water quality at
each of sites 2 and 3 (q: and qg) is less than the minimum desired, Q2, Q3, respectively. At each
site i, there is a waste treatment option available. R i is the fi'acrion of waste discharge (WE)
being treated at site 1'. The cost per unit of waste treated is 6:. For each unit of waste treated at
site i upstream of site j, the quality improves by Ag. W1 Stream W2 Part 2-1) Formulate a linear
programming model to determine how much treatment is required at sites 1 and 2 that meets the
standards at a minimum total cost. Specify the objective function, decision variable(s) and the