Highly Polluted Water could have a BOD value of :

  1. 17 ppm or more
  2. Less than 5 ppm
  3. Less than 4 ppm
  4. Less than 3 ppm
Monis Rasool Professor Asked on 25th August 2015 in Science.
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    17 ppm or more

    Highly Polluted Water could have a BOD value of 17 ppm or more. Biochemical Oxygen Demand (BOD) refers to the amount of oxygen that would be consumed if all the organics in one liter of water were oxidized by bacteria and protozoa.  The BOD test takes 5 days to complete and is performed using a dissolved oxygen test kit. The difference between the two DO levels represents the amount of oxygen required for the decomposition of any organic material in the sample and is a good approximation of the BOD level

    • Take a two differ sample of water
    • Record the DO level (ppm) of one immediately using the method described in the dissolved oxygen test.
    • Place the another water sample in an incubator in complete darkness at 20 degree C for 5 days.  If you don’t have an incubator, wrap the water sample bottle in aluminum foil or black electrical tape and store in a dark place at room temperature (20 degree C)
    • After 5 days, take another dissolved oxygen reading (ppm) using the dissolved oxygen test kit.
    • Subtract the Day 5 reading from the Day 1 reading to determine the BOD level. Note your final BOD result in ppm
    Monis Rasool Professor Answered on 5th September 2015.
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