1. EG-CE 441 Environmental Engineering
Homework #3
(Due 10/15/13)
(Show your calculations)
1. A wastewater stream has a BOD5 of 150 mg/L, and the BOD rate constant is 0.20/day (base e).
The BODultimate of this wastewater = 237 mg/L.
The BOD7 of this wastewater =179 mg/L.
2. Calculate the theoretical oxygen demand of 10-4M ethanol, CH3CH2OH.
ThOD = 9.6mg/L.
3. Use the information given in the following table to answer the question:
Compound
Sodium chloride
Sand and clay
Coffee grounds
Alcohol
Concentration
(mg/L)
10
90
30
80
Dissolves?
Burns or volatilizes at 550 oC?
Yes
No
No
Yes
No
No
Yes
Yes
TSS = 120 mg/L.
VSS = 30 mg/L.
TDS =10mg/L.
FDS = 10 mg/L.
4. A wastewater stream is being discharged into a river that has a temperature of 15 oC. What
fraction of the maximum oxygen consumption has occurred in five days if the BOD rate constant
determined in the laboratory under standard condition is 0.25/day (base e)? 48.6%
5. A constant volume batch reactor was operated to provide data for determination of reaction rate
constant for ultraviolet enhanced ozonation of a synthetic organic compound. The duration of the
batch reaction was 1 hr and the concentration of the organic compound was reduced from 200
”g/L to 10 ”g/L. If the reaction is assumed to be first-order with respect to this synthetic
compound, then determine the rate constant for the oxidation reaction in 1/hr. 3.0 hr-1
6. What would be the âhalf-lifeâ of the compound in the reactor in question #5? 0.231hr
7. The chlorine dose for a 10 MGD water treatment plant is 8 mg/L. The peak factor is 1.8.
Determine the monthly usage of chlorine at this plant. 2.0x104 lbs/mo