available upon request.
Biological Oxygen Demand Rod O'Connor Texas A & M University C o l l e ~ eStation, TX 77843
T h e total 0 2 concentration in the mixture is measured just after mixing and again after five days incubation a t 20°C. I t is the change in 0 2 concentration (A) over this period that is used to calculate the BOD. Calculate: a) the volume of oxygen (measured at 2 0 T and 150 tom) required
Many organic, and some inorganic, wastes are degraded in natural waters by oxidation processes. In some cases these involve direct reaction of chemical wastes with molecular oxygen dissolved in the water. More commonly, aerobic bacteria in the water degrade the chemicals while utilizing dissolved oxygen. In either case, oxygen is consumed and if waste degradation demands abnormally high amounts of 0 2 , fish and other aquatic life cannot survive in the oxygen-depleted waters. The hiological oxygen demand (ROD)is defined as A(no. mg 0 2 ) ROD = (in ppm 0 2 ) no. liters water and is determined hy mixing a measured sample of polluted water with a known volume of oxygen-saturated pure water.
is converted to COr
Answers (a) 7.2 X lo4 1
(b) 9.9 kg To obtain detailed solutions or to submit problems for "Brain Tinglers," write to Dr. Rod O'Connor, Department of Chemistry, Texas A & M University, College Station, TX 77843.
This problem was reprinted from O'Connor, Rod, "Fundamentals of Chemistrv." 2nd edition. Haroer and Row Publ.. New York.
Volume 57, Number 3. March 1980 1 209
