1. Estimate the concentration in mg/L, ppm, M, and Mole Fraction. Given: Compound: Toluene; Mol. Formula: C7H8; Mass: 0.015 mg (of toluene); Volume: 700 mL (of solution); Density: 0.999 Kg/L (of solution)

2. Estimate the concentration in mg/L, M and N (use Table 11.2). Given: Compound: Ferric Hydroxide; Mol. Formula: Fe(OH)3; Mass: 0.06 mg (of ferric hydroxide); Volume: 1200 mL (of solution);

3. Check the electroneutrality. Given: Ion Conc. (mg/L): Calcium 45; Magnesium 11; Sodium 200; Potassium 15; Carbonate 11; Bicarbonate 450; Sulfate 80; Chloride 120.

4. As appropriate, estimate pH and pOH and molar concetration of hydrogen and hydroxide ions. Given: a) pH = 3.4; b) [H] = 0.000025; c) pOH = 11.2

5. Check electroneutrality and determine alkalinity, total hardness, carbonate hardness, noncarbonate hardness, and total dissolved solids. Given: Ion Conc. (mg/L): Calcium 65; Magnesium 12; Sodium 100; Potassium 11; Carbonate 6; Bicarbonate 210; Sulfate 180; Chloride 50.

6. Water Treatment plants measure the flow of water through the plant to maintain efficient control and to ensure that sufficient water is generated. A venturi meter is one method for measuring flow in pressure conduits. Estimate the flow of water in a Venturi Meter like the one discussed in class. Given: Pressure at Pt 1 = 26 psig; Pressure at Pr 2 =20 psig; Diameter of Constriction =6 in; C =0.97; Temperature = 60 F. Make sure your units are consistent!

7. Determine the hydraulic residence time of a plug flow reactor. Plot the expected behavior of pulse and step tracers in the reactor. Volume, V: 950 L; Flow Rate, Q: 155 L/min; Pulse Tracer Mass, M: 3 kg; Step Tracer Conc., Co: 3 g/L.

8. Determine the hydraulic residence time of a completely mixed flow reactor. Plot the expected behavior of pulse and step tracers in the reactor. Volume, V: 1000 L; Flow Rate, Q: 150 L/min; Pulse Tracer Mass, M: 3 kg; Step Tracer Conc., Co: 3 g/L.

9. Determine effluent concentrations from a tank divided into multiple CMF reactors. A tank with volume V can be divided into as many as 100 (equal size) CMFs using baffles. Assume each CMF, no matter what size, is completely mixed. Four experiments are conducted with the tank divided into different numbers of CMFs. Each time, M kg of tracer is added to the first CMF at time zero (Pulse Tracer). On one graph, plot the effluent concentration (from the last CMF) versus theta (time relative to the residence time of the entire tank) . V = 1000 L; M =1 kg; Exp 1: 1 CMF; Exp 2: 4 CMFs; Exp 3: 20 CMFs; Exp 4: 70 CMFs.

10. Determine concentrations at different points in a tank divided into multiple CMF reactors. A tank with volume V can be divided into as many as 100 (equal size) CMFs using baffles. Assume each CMF, no matter what size, is completely mixed. M kg of tracer is added to the first CMF at time zero (Pulse Tracer). On one graph, plot the concentration versus t/tR (time relative to the residence time of a single CMF reactor in the tank) in four CMFs, a, b, c, and d. V = 1000 L; Co = 75 g/L; M = 1 kg; N = 75; CMFs a = 1; b = 25; c = 50; d = 75. In others words, CMF a is the first reactor, CMF b is the 25th reactor, etc.

11. From a step tracer experiment, determine a number of parameters for a reactor, including: measured mean residence time ; variance of the step tracer versus time curve; the reactor dispersion number; times for 10, 50, and 90 % of the step tracer to leave the reactor; and indicate where the reactor lies on a contimum from plug to completely mixed (use Figure 10.9) Get the time versus concentration data from this Word file.

12. Determine the power input and velocity gradient caused by a paddle flocculator. Given: Width of tank: 55 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: 3 ft; Paddle Radius 2: 4.5 ft; Paddle Radius 3: Not Applicable (only two paddles per arm!); Shaft Rotation: 0.06 rev/s; Vw/Vp: 0.3; Drag coefficient: 1.8; Water Temp: 50 F.

13. Evaluate the performance of an ideal clarifier. 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%.

14. The settling velocity of an alum floc is given below. Calculate the equivalent overflow rate in gpd/sq-ft. What is the minimum detention time in 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. Hint: You don't need the water temperature.

15. Two rectangular clarifiers are as described below. Calculate the overflow rate, detention time, horizontal velocity of flow, and weir loading. Are they acceptable? (Taken from Water Supply and Pollution Control). Given: Length (each) = 40 ft; Width (each) = 15 ft; Depth (each) = 12 ft; Flow rate (Total) = 0.5 mgd; Weir Length (Total) = 60 ft.

16. Calculate the required diameter and depth of a circular sedimentation basin. Will a single weir, with the overflow into the weir set 1.5 ft 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.

17. Determine the required dimensions of a single rectangular sedimentation basin. Design the weir. (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.

18. Determine the reaction order and the reaction constants. Given: Time (min) / Concentration (mg/L): 0 / 203; 1 / 191; 2 / 177; 3 / 169; 4 / 162; 5 / 151; 6 / 143; 7 / 127; 8 / 120; 9 / 109; 10 / 101; 11 / 92; 12 / 81; 13 / 70; 14 / 62; 15 / 51.

19. Determine the reaction order and the reaction constants. Given: Time (min) / Concentration (mg/L): 0 / 151; 1 / 129; 2 / 112; 3 / 96; 4 / 83; 5 / 69; 6 / 62; 7 / 54; 8 / 46; 9 / 37; 10 / 32; 11 / 29; 12 / 27; 13 / 23; 14 / 19; 15 / 16.

20. 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 = 38 mg/L; Natural Alkalinity = 12 mg/L as CaCO3 (assume it is HCO3)

21. Determine the quick lime and soda ash dosages needed for excess lime softening. Determine the total amount of carbon dioxide needed for recarbonation if 75% of the carbonate left after the first recarbonation step is to be converted to bicarbonate. Draw a bar chart for each step of the process. Draw a schematic of the process. Given: Ion Conc. (mg/L) Calcium (45) Magnesium (11) Sodium (200) Potassium (15) Carbonate (11) Bicarbonate (450) Sulfate (80) Chloride (120). Note: Cation and Anion equivalent concentrations are not equal.

22. Determine the quick lime and soda ash dosages needed for selective calcium removal. Determine the amount of carbon dioxide needed for recarbonation if 75% of the carbonate left after selective calcium removal is to be converted to bicarbonate. Draw a bar chart for each step of the process. Draw a schematic of the process. Given: Ion Conc. (mg/L) Calcium (45) Magnesium (11) Sodium (200) Potassium (15) Carbonate (11) Bicarbonate (450) Sulfate (80) Chloride (120). Note: Cation and Anion equivalent concentrations are not equal.

23. You conduct a series of batch adsorption experiments with equal volume and GAC mass. You vary the initial concentration of adsorbate and measure the final (equilibrium) concentration. Determine the coefficients for the Linear Freundlich, Freundlich, and Langmuir Isotherms. Which appears to best describe the data? Over what range of data? Be sure to plot all observed & predicted x/m values vs Ce on an arithmetic graph as a final check. Also, use R2 and the F statistic to check. Given: GAC = 10 g; Volume of solution = 1 L. Results of Batch Experiments - Init. Conc., mg/L / Final Conc., mg/L: 3.3 / 0.85; 2.5 / 0.62; 2.3 / 0.39; 1.5 / 0.2; 1.2 / 0.11.

24. The synthetic resin "Gorbachov" is used to reduce the concentration of the organic chemical "Yelstin". 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 = 0.09; b = 5.7 L/mg. Treatment method = Batch; Volume to be treated = 5000 L/d; Initial Conc. = 5 mg/L; Final Conc. = 0.1 mg/L.

25. The synthetic resin "Gorbachov" is used to reduce the concentration of the organic chemical "Yelstin". 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 = 0.09; b = 5.7 L/mg; Treatment method = Counter current, Continuous flow; Volume to be treated = 5000 L/d; Initial Conc. = 5 mg/L; Final Conc. = 0.1 mg/L.