1. Estimate the concentration in mg/L, ppm, M, and Mole Fraction.

Given: Compound: Toluene; Mol. Formula: C7H8; Mass: 0.02 mg (of toluene)
Volume: 800 mL (of solution); Density: 0.95 kg/L (of solution)

2. Estimate the concentration in mg/L, M and N

Given: Compound: Ferric Hydroxide; Mol. Formula: Fe(OH)3; Mass: 0.1 mg (of ferric hydroxide)
Volume: 1100 mL (of solution)

3. Check electroneutrality and determine alkalinity, total hardness,
carbonate hardness, noncarbonate hardness, and total dissolved solids

Ion / Conc. (mg/L)
Calcium / 85
Magnesium / 20
Sodium / 100
Potassium / 11
Carbonate / 8
Bicarbonate / 190
Sulfate / 180
Chloride / 100

1. Use the decreasing rate of return method to estimate the 2005 and 2020 populations (initial and design year, respectively), given the following data. Be sure to include the equation and a graph.

Year/Population: 1970/30,000; 1980/40,000; 1990/62,000; 2000/67,000 (data from Qasim et al.)

2. The per capita water demand during drought years is predicted to be 700 LPCD. The maximum day peak factor is estimated to be 1.9, while the peak hour factor is 1.5. Estimate the Annual Average Day, Maximum Day, and Peak Hour demand during the design year (all in cubic meters per day).

3. Estimate the fire demand during the design year using the same equation we used in class. Report it in cubic meters per day. Use Table 4-13 to estimate the required duration of the fire demand. What is the total amount of water needed to supply the fire flow over the required duration?

4. Determine the design flow for the distribution system.

5. Determine the design flow for the water treatment plant.

Given:

Volume: 1200 L
Flow Rate: 150 L/min
Pulse Tracer Mass: 3 kg
Step Tracer Conc.: 3 g/L

2. What is the hydraulic residence time of the completely mixed flow reactor?
Plot the expected behavior of pulse and step tracers in the reactor (using Excel).

Given:

Volume: 1200 L
Flow Rate: 150 L/min
Pulse Tracer Mass: 3 kg
Step Tracer Conc.: 3 g/L

3. For the data given below, determine the actual mean residence time and three tracer flush times (t10, t50, and t90).

Given: Time (min) / Conc (kg/m3)
0/0; 15/0; 30/0; 45/3; 60/16; 75/47; 90/72; 105/89; 120/95; 135/88; 150/78; 165/65; 180/55; 195/43; 210/33; 225/25; 240/20; 255/15; 270/12; 285/9; 300/7; 315/6; 330/4; 345/3; 360/2; 375/1; 390/0;405/0

4. Determine the power input and velocity gradient caused by a paddle flocculator.

Given:

Width of tank: 50 ft
Length of tank: 80 ft
Depth of tank: 15 ft
No. horizontal shafts: 3
No. arms per shaft: 4
No. paddles per arm: 2
Paddle width: 6 in
Paddle Length: 45 ft
Paddle Radius 1: 4 ft
Paddle Radius 2: 5.5 ft
Shaft Rotation: 0.06 rev/s
k: 0.3
Drag coefficient: 1.8
Water Temp: 50 F

1. A surface water is to be coagulated with ferric chloride. Determine the lb/million gallons of ferric chloride needed. Determine the lb/million gallons of ferric hydroxide produced. Determine the alkalinity deficit or surplus, in mg/L as CaO.

Given:

Reaction: 2FeCl3 + 3Ca(HCO3)2 --> 2Fe(OH)3 + 3CaCl2 + 6CO2
Ferric Chloride Dose = 30 mg/L
Natural Alkalinity = 50 mg/L as CaCO3 (assume it is HCO3)

2. Determine the quick lime and soda ash dosages needed for excess lime softening. Determine the total amount of carbon dioxide needed if, in the second recarbonation step, 75% of the carbonate is to be converted to bicarbonate. Draw a bar chart for each step of the process. Draw a schematic of the process.

Given: Calcium 45 mg/L; Magnesium 11 mg/L; Sodium 200 mg/L; Potassium 15 mg/L; Carbonate 11 mg/L; Bicarbonate 450 mg/L; Sulfate 80 mg/L; Chloride 120 mg/L.
Note: Cation and Anion equivalent concentrations are not exactly equal, which will effect your bar chart.

3. Determine the quick lime and soda ash dosages needed for selective calcium removal for the water described in problem 2. Determine the total amount of carbon dioxide needed if, in the recarbonation step, 75% of the carbonate is to be converted to bicarbonate. Draw a bar chart for each step of the process. Draw a schematic of the process. Remember, in selective calcium removal only the Ca is removed by precipiation, so determine your lime and soda ash dosages accordingly. Also, don't add excess lime!

14. Evaluate the performance of an ideal clarifier (Type I settling). Calculate the Overflow Rate.
Estimate the percentage of particles (total and each type) that will be removed.

Given: Surface Area = 2100 cu-ft
Flow rate = 2.7 mgd
Particles:
Settling Velocity, ft/s / % of total
0.003 / 11
0.002 / 34
0.0015 / 35
0.001 / 20

15. The settling velocity of an alum floc is given below. Calculate the equivalent overflow rate in gpd/sq-ft. Assume Type I settling. What is the detention time needed (hours) to settle the floc in an ideal basin of the given depth? (Taken from Water Supply and Pollution Control).

Given: Settling Velocity = 0.0016 fps
Water Temperature = 10 C
Depth = 10 ft

16. Two rectangular clarifiers are as described below. Flow is split evenly. Calculate the overflow rate, detention time, horizontal velocity of flow, and weir loading of one clarifier. Are they acceptable? (Taken from Water Supply and Pollution Control). Reference your check criteria!

Given: Length (each) = 40 ft
Width (each) = 15 ft
Depth (each) = 12 ft
Flow rate (Total) = 0.5 mgd
Weir Length (Total) = 60 ft

17. Calculate the required diameter and depth of a circular sedimentation basin. Will a single weir, 0.46 m from the inside of the basin wall, suffice? (Taken from Water Supply and Pollution Control).

Given: Flow rate = 3900 cu-m/d;
Overflow rate = 0.00024 m/s;
Detention time = 3 hr;
Weir loading = 350 cu-m/m.d

18. Determine the required dimensions of a single rectangular sedimentation basin. Design the weir (schematic with dimensions). (Taken from Water Supply and Pollution Control).

Given: Flow rate = 1.1 mgd
Length/width ratio = 2
Overflow rate = 0.00077 fps
Detention time = 3 hr
Weir loading = 20,000 gpd/ft

1. Design a rapid filtration unit operation. Indicate the number of filters and the dimensions of each (in plan view only).
Make all of the filters identical squares. Typically, plants have at least three filters. The flow handled by each filter ranges from 350 to 3500 gpm/filter (small plants and large plants, respectively).

Given: Flowrate = 10 mgd
Design loading = 5 gpm/sq-ft

2. You conduct a series of adsorption experiments with equal volume and GAC mass. Determine the coefficients for the Linear Freundlich, Freundlich, and Langmuir Isotherms. Which appears to best describe the data? Over what range of data? Use R2 and the F statistic to check. Plot all observed & predicted x/m data vs Ce on an arithmetic graph as a final check.

Given: GAC = 10 g
Volume of solution = 1 L
Results of Batch Experiments:
Init. Conc., mg/L / Final Conc., mg/L
3.3 / 0.83
2.5 / 0.59
2.3 / 0.39
1.5 / 0.22
1.2 / 0.12

3. The synthetic resin XA-1 is used to reduce the concentration of the organic chemical HL-2. Determine the amount of Gorbochov needed. "Initial Conc." = concentration of water to be treated. "Final Conc." = target concentration for treated water.

Given: Isotherm = Langmuir
Applicable range, Ce = 0.06 to 6 mg/L
a = 0.1
b = 5.8 L/mg
Treatment method = Batch
Volume to be treated = 5000 L/d
Initial Conc. = 5 mg/L
Final Conc. = 0.2 mg/L

4. The synthetic resin XA-1 is used to reduce the concentration of the organic chemical HL-2. Determine the amount of Gorbochov needed. "Initial Conc." = concentration of water to be treated. "Final Conc." = target concentration for treated water.

Given: Isotherm = Langmuir
Applicable range, Ce = 0.06 to 6 mg/L
a = 0.1
b = 5.8 L/mg
Treatment method = Counter current, Continuous flow
Volume to be treated = 5000 L/d
Initial Conc. = 5 mg/L
Final Conc. = 0.2 mg/L

1. Check the design of a disinfection tank for a surface water treatment plant
with just coagulation and filtration (This is a direct filtration plant).

Given: Water Temp = 10 C
pH = 8
Design microbe = G. Lamblia
free chlorine = 1 mg/L (at end of tank)
Peak hourly flow rate = 3.5 mgd
Results of t10 tracer tests on tank
t10, minutes /hourly flow rate, mgd: 200 / 1; 100 / 2.5; 70 / 4; 40 / 5.5

Determine the following:

• Required N Logs destruction/removal (total)
• N logs from treatment processes other than disinfection
• N logs that must be provided by disinfection
• Required C.t
• Contact time for tank (plot tracer test results)
• Actual C.t. Is it Acceptable?

2. Design a chlorination tank for a groundwater treatment plant (a) in a 12 " pipe.
(b) in a baffled chlorination tank with t10 = 0.4 tR.

Given: Water Temp = 10 C
pH = 7.5
Design microbe = viruses
Chlorine Dioxide = 0.35 mg/L (end of pipe or tank)
Required N Logs = 4 (from disinfection)
Flow rate = 5000 gpm

Determine the following:

• Required C.t
• Required Contact Time
• Length of Pipe
• Size of Baffled chlorination tank (cu-ft). If the tank is square and 10 ft deep, how long is each side?