CIVL 1112 - Assignment #2

 Name: ________________________

 

"I am always ready to learn, but I do not always like being taught."  Winston Churchill

Part 1: Solve the following three problems (you are not required to use an Excel spreadsheet)

Carbon Dioxide Removal #1

  • A groundwater containing 30 mg/l of carbon dioxide is to be degasified using a multiple-tray aerator with six trays. In this water treatment facility ten aerators operating in parallel. For maintenance reasons, only nine of the aerators are available at any one time. The design population is 50,000 persons, and the maximum day demand is 150 gal/person-day. The k value is 0.33, and the hydraulic loading is 3 gpm/ft2. Determine:

  1. The carbon dioxide content of the product water.

  2. The size of the trays if the length-to-width ratio is 2:1 and the trays are made to 1 inch increments.

Carbon Dioxide Removal #2

  • A groundwater containing 25 mg/l of carbon dioxide is to be degasified using a multiple-tray aerator. The design population is 250,000 persons, and the maximum day demand is 150 gal/person-day. The k value is 0.32, and the hydraulic loading is 4 gpm/ft2. Determine:

  1. Determine the total number of trays in an aerator required to reduce the product water's carbon dioxide content by 90%.

  2. 2. Determine the number of aerators, operated in parallel, required for the water treatment facility if each tray's size is 1,000 ft2.

Disinfection

  • The following is actual data for a virus exposed to an experimental disinfectant. Estimate the contact time required to obtain a reduction of the 1/40,000 of the original number of virus.  
     

Time, seconds

1

2

4

8

N/N0

4,270/10,000

1,830/10,000

332/10,000

11/10,000

 

Part 2:  Use Excel to develop a table containing the removal of carbon dioxide in a water treatment process using the aeration model we described in class.
       

Develop a spreadsheet where the number of aeration trays, n, varies with the row, and the rate constant, k, varies with the column.  Also, allow the initial effluent concentration to be a parameter in your calculations.  In other words, store the value of C0 in a cell outside the table.

Part 3. Read the Chapters 3 and 4 in the "A Mind for Numbers" by Barbara Oakley.