Page 289 - Fair, Geyer, and Okun's Water and wastewater engineering : water supply and wastewater removal

JWCL344_ch07_230-264.qxd 8/2/10 8:44 PM Page 249

7.7 Automated Optimization 249

Create a Line-Series Graph from the New button in the Graphs dialog. Select the Age Analysis box
in the Scenarios field and Calculated Age, both under Tank and Junction in the Fields field in the
Graph Series Options window. Close the options window to look at the graph. Notice that the
water age in the junctions is much less (2 to 4 h) than the water in the tank while the pump is on and
feeding freshwater into the system. Then the water age in the junctions greatly increases when the
system is fed by the tank water after the pump turns off.

Water Quality Analysis
To analyze the behavior of chlorine in the network, the properties of chlorine must be defined in the
engineering library.

• From the Components menu, select Engineering Libraries. Double-click the Constituent
Libraries. Then right-click on the ConstituentLibrary.xlm to select Add Item.
• Rename the new constituent by right-clicking it and selecting Rename. Change the label
2
to “Chlorine.” Click on the Chlorine dialog. Enter the Diffusivity (l.l22e-010 m /s). Enter
the Bulk Reaction Order as 1 and the Bulk Reaction Rate as 0.5 (mg/L) 1 n /day.
1
Because n 1, the units of the rate constant are day . Close the Engineering Libraries.
• From the Analysis menu, select Scenarios. Create a new base scenario named “Chlorine
Analysis.”
• Click on the Calculation Options tab at the bottom of the window. Create a new
Calculation Option by clicking the New button and enter “Chlorine Analysis Calculation
Options” as the name. Double-click the calculation options you just created and select
Constituent in the Calculation Type field. The Duration is 168 h (7 days), and the
Hydraulic Time Step is 1.00 h.
• Go back to the Scenarios tab and right-click the Chlorine Analysis scenario and select
Make Current. The red check should now be on the Chlorine Analysis scenario. Double-
click on the Chlorine Analysis scenario and select the Chlorine Analysis Calculation
Options in the Calculation Options field.
• Go to the Alternatives tab. Double-click on the Constituent; right-click on Base
Constituent Alternative to select Open. Select the Constituent System Data tab
then click the ellipse button. Click the Synchronization Options button to select
Import from Library. Select Chlorine from the Constituent Libraries list. Close the
Constituents dialog. Select Chlorine in the Constituent field on the Constituents: Base
Constituents Alternative window. Close the Constituent Alternative window.
• Double-click the reservoir to define the loading of chlorine. Select True in the Is
Constituent Source? field. The Constituent Source Type is Concentration and the
baseline concentration is 1.0 mg/L. The constituent source pattern is fixed.
• The bulk reaction rate in the pipes can be adjusted using the Tables tool. Click the Flex Table
button, then select the Pipe Table. Add the Bulk Reaction Rate (Local) and Specify Local
Bulk Reaction Rate? to the table by clicking the Edit button in the toolbar at the top of the
table. Scroll to the Specify Local Bulk Reaction Rate? column to click the box for the pipe
you want to adjust. Now you can enter a reaction value for the pipe in the Bulk Reaction Rate
(local) column. In this case we will not change any of the default values so close the Pipe Table.
• Double-click the tank. Set the initial chlorine concentration to 0.000 mg/L, select True in
the Specify Local Bulk Rate? field, then enter the bulk reaction rate of 0.5 /day. Close
the editor dialog.
• From the Analysis menu, select Scenarios. Make sure Chlorine Analysis is the current
scenario then run the scenario by clicking the Compute button in the top row.
• Open the EPS Results Browser window by clicking the icon button. To create a con-
tour map of the chlorine concentration, click the Contour button. After clicking the New