Problem

The rolling mill in a large steel plant generates two types of water wastes: pickling wast...

The rolling mill in a large steel plant generates two types of water wastes: pickling waste and process water. If these wastes are discharged directly into the local city sewer without treatment, they are subject to an effluent tax. Alternatively, the plant operates a treatment facility capable of removing 90% of the pollutants from the waste streams. In this case the pickling wastes require pre-treatment (neutralization) before being processed thro ugh the plant's treatment facility.

The local municipality controls the effluent tax on untreated wastes entering city sewers; the higher the effluent tax, the more wastes the steel mill will treat on site. How-ever, this could cause a decrease in the plant’s productivity that could directly affect the economy of the community. The lower the effluent tax, the less waste the plant will treat and production will be higher. But this in turn means that the community will be subsidizing the mill's waste treatment at the city sewage treatment plant.

Let: x1 = tons of steel to be manufactured per day

x2 = volume of pickle waste (gallons) treated per day

x3 = volume of process water (gallons) treated per day

Income from the production of steel = $25/ton

Pickle waste generated = 100 gallons/ton of steel

Process water generated = 1000 gallons/ton of steel

Pre-treatment cost = $.02/thousand gallons treated

Treatment cost = $.10/thousand gallons treated

Pre-treatment capacity = 2,000,000 gallons/day

Treatment capacity = 50,000,000 gallons/day

Treatment efficiency = 90% (both wastes)

Tax all untreated pickle waste = $0.15/thousand gallons

Tax on untreated process water = $0.05/thousand gallons

Limit on pickle waste discharge to city sewer = 500,000 gallons/day

Limit on process water discharge to city sewer = 10,000,000 gallons/day.

Step-by-Step Solution

Request Professional Solution

Request Solution!

We need at least 10 more requests to produce the solution.

0 / 10 have requested this problem solution

The more requests, the faster the answer.

Request! (Login Required)


All students who have requested the solution will be notified once they are available.
Add your Solution
Textbook Solutions and Answers Search
Solutions For Problems in Chapter 5