FE Review for Environmental Engineering

1. FE Review for Environmental Engineering Problems, problems, problems Presented by L.R. Chevalier, Ph.D., P.E. Department of Civil and Environmental Engineering Southern Illinois University Carbondale

2. FE Review for Environmental Engineering biological Foundations

3. Given the following data, calculate BOD5 Initial DO of sample: 9.0 mg/L Volume of sample: 10 ml Final DO of bottle after 5 days: 1.8 mg/L Volume of BOD bottle: standard 300 ml

4. Review and understand the terms of the governing equation

5. Standard Bottle: 300 ml P = 10/300 =0.033

6. Typical Curve BOD (mg/L) BOD5 Time (days)

7. Further Discussion on BOD • Typical values • domestic sewage 250 mg/L • industrial waste as high as 30,000 mg/L • untreated dairy waste 20,000 mg/L • After 5 days, BOD curve may turn sharply upward • demand of oxygen by microorganisms that decompose nitrogeneous organic compounds into stable nitrate

8. nitrogenous BOD (mg/L) Lo carbonaceous BOD5 Time (days)

9. If the BOD3 of a waste is 75 mg/L and k=0.345 day-1, what is the ultimate BOD?

10. For some of you there may be a confusion as to which equation to use:

11. Recall the equation for BODt The amount of DO measured will decrease over time. Does BOD increase or decrease over time?

12. OXYGEN CONSUMED OXYGEN DEMAND REMAINING Want to use the equation that shows an increase with time!

14. Given: DOi = 9.0 mg/L DO = 3.0 mg/L after 5 days Dilution factor P = 0.030 Reaction rate, k = 0.22 day-1 a) What is the 5-day BOD? b) What is the ultimate BOD? c) What is the remaining oxygen demand after 5 days?

15. Review and understand the equations needed for the solution

16. a) What is the 5 day BOD?

17. b) What is the ultimate BOD?

18. c) What is the remaining oxygen demand after 5 days? 300 - 200 = 100 mg/L

19. Determine the ThOD of a 400 mg/L solution of glucose C6H12O6

20. Balance the equation • Determine the MW of compound and O2 • Calculate ThOD

21. 1. Balance the following equation

22. 2. Determine the MW of glucose and O2 MW C6H12O6 = 12(6) + 12 + 16(6) = 180 g/mol MW O2 = 2(16) = 32 g/mol 3. Calculate the ThOD

23. Ethanol, or ethyl, alcohol is used in beverages, as a gasoline additive, and in other industrial applications. Because small amounts of ethanol and sugar are used in the biological process to produce methanol, both of these compounds inevitable end up in the waste water of methanol plants. Calculate the ThOD demand for waste water containing 30 mg/L ethanol [CH3CH2OH] and 40 mg/L sucrose [C6H12O6]

24. Balance two equations • Determine the MW of both compounds • Calculate ThOD for both, then add

25. 1. Write the balanced equation for the oxidation of ethanol (often written EtOH) to the end products of CO2 and H2O. MW EtOH = 46 g/mol

26. 2. ThOD of EtOH is calculated as follows:

27. 3. Calculate the ThOD for wastewater containing 40 mg/L sucrose [C6H12O6] MW Sucrose = 180 mg/L

28. 4. To calculate ThOD for waste water containing both 30 mg/L ethanol [CH3CH2OH] and 40 mg/L sucrose [C6H12O6], you can add the ThOD of the individual compounds. ThOD tot = 62.6 mg/L O2 + 42.7 mg/L O2 = 105.3 mg/L O2 ... end of example

29. A chemical plant produces the amino acid glycine [C2H5O2N]. The wastewater from the facility contains approximately 25 mg/L of this acid. Calculate both the carbonaceous and nitrogenous ThOD for the wastewater.

30. 1. As in the previous example, write the balance equation, but include NH3 as an end product.

31. 2. Balanced equation: 3. The molecular weight of the acid is 75 g/mol. The amount of oxygen required to oxidize the carbonaceous portion is:

32. 4. One mole of ammonia is produced for each mole of acid oxidized. The equation for oxidation of the ammonia is: ammonia nitrate

33. 5. To determine the nitrogenous oxygen demand:

34. 6. The amount of oxygen required to oxidize the acid is the sum of both the carbonaceous and the nitrogenous oxygen demands. ThOD = 16 + 21.33 = 37.33 mg/L O2 .....end of example