homework_5_v3 (1)

# homework_5_v3 (1) - Introduction to Computers and...

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Introduction to Computers and Engineering Problem Solving Spring 2005 Problem Set 5: Water quality Due: 12 noon, Session 19 1. Problem statement Wastewater and storm runoff discharges from small and large population centers degrade water quality in rivers and lakes. An example watershed with four population centers is shown below: Each of the four towns produces pollutants at a loading rate of P i milligrams per day. Each town has a wastewater and stormwater treatment plant that removes a fraction x i of the pollutants, so that (1- x i ) P i milligrams per day of pollutants are discharged into the rivers next to the plants. When the pollutants enter the river, they mix with pollution from upstream towns. The concentration of pollutants downstream of the plant is given by flow conservation: C out = ((1- x i ) P i + F in C in ) / F out Where C out = pollutant concentration (mg/L) downstream of plant 1.00 Spring 2005 1/4 Problem Set 5

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C in = pollutant concentration (mg/L) upstream of plant F in = flow (L/day) upstream of plant F out = flow (L/day) downstream of plant After treatment from the plant, natural biological processes further reduce the pollution level; this is modeled as fraction r i of pollutants removed. If we assume that the pollution levels are small above Boxboro and Sudbury, we have the following equations for pollution concentration below each plant (see diagram on previous page): C 0 = ((1- x 0 ) P 0 ) / F 0 (Boxboro) C 1 = ((1- x 1 ) P 1 ) / F 1 (Sudbury) C 2 = (F 0 (1-r 0 )C 0 + F 1 (1-r 1 )C 1 + (1-x 2 )P 2 )/ F 2 (Acton) C 3 = (F 2 (1-r 2 )C 2 + (1-x 3 )P 3 )/ F 3 (Concord) There are three types of treatment plant: Type 1 Type 2 Type 3 Unit cost(\$/mg
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## This note was uploaded on 11/29/2011 for the course CIVIL 1.00 taught by Professor Georgekocur during the Spring '05 term at MIT.

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homework_5_v3 (1) - Introduction to Computers and...

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