Biochemical Oxygen Demand and Coliform

Biochemical Oxygen Demand:
  • It is the amount of dissolved oxygen needed by aerobic biological organisms in a water body to break down organic material present in a given water sample (at certain temperature in a specific time period).
  • It is not a precise quantitative test, although it is widely used as an indication of the organic quality of water.
  • BOD directly affects the amount of dissolved oxygen in rivers and streams.
  • The greater the BOD, the more rapidly oxygen is depleted in the stream.
  • This means less oxygen is available to higher forms of aquatic life.
Applications of the BOD Method:
  • To check the aerobic decomposition of environmental chemicals
  • To determine the respiration of soils, sludge, sediment, garbage and liquids
  • To test the toxicity in soils, sludge, sediment, garbage and liquids
  • To determine bio-activity in various environmental compartments
  • To check performance in a sewage treatment plant
  • To determine the respiration rates of living beings
  • Total coliform bacteria are a collection of relatively harmless microorganisms that live in large numbers in the intestines of man and warm- and cold-blooded animals.
  • They aid in the digestion of food.
Faecal coliform:
  • A specific subgroup of this collection is the faecal coliform bacteria, the most common member being Escherichia coli.
  • These organisms may be separated from the total coliform group by their ability to grow at elevated temperatures and are associated only with the faecal material of warm-blooded animals.
Faecal coliform- as a pollutin indicator:
  • The presence of faecal coliform bacteria in aquatic environments indicates that the water has been contaminated with the faecal material of man or other animals.
  • The source water may be contaminated by pathogens or disease producing bacteria or viruses which can also exist in faecal material.
  • Some waterborne pathogenic diseases include typhoid fever, viral and bacterial gastroenteritis and hepatitis A.
  • The presence of faecal contamination is an indicator that a potential health risk exists for individuals exposed to this water.
  • Faecal coliform bacteria may occur in ambient water as a result of the overflow of domestic sewage or non-point sources of human and animal waste.

One comment

  • You guys are doing great job. Simple and crisp 2 article per day in email is awesome thing one can get. Please add modern history, ethics, governance articles as well. Newsletter is very helpful as one don’t need to visit site.