Hello,Very good ...

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Hello,Very good question.Indirectly BOD means both 1 &2 and oxygen content,

Five-Day Biochemical Oxygen Demand (BOD5): BOD5 is defined as the amount of oxygen required by bacteria to decompose organic matter for a specified time (usually5 days) under aerobic conditions. The amount of oxygen reported with this method represents only the carbonaceous oxygen demand (CBOD) or the easily decomposed organic matter. BOD5 is commonly used to measure natural organic pollution

Chemical Oxygen Demand (COD): COD is defined as the oxygen equivalent of the organic portion of the sample that is susceptible to oxidation by a strong chemical oxidant potassium dichromate K2Cr2O7,

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So, can we conclude that high BOD shows High concentration of microorganisms and organic matter, both

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Not quite correct.  BOD5 is the amount of oxygen consumed by bacteria over exactly a 5-day incubation period at 20 deg C in the dark.  It represents both carbonaceous and nitrogenous (due to ammonia present) oxygen demand.  CBOD5 is the "Carbonaceous" component of BOD5.  Letting the test run for 20-days results in a greater oxygen demand and is referred to as Ultimate BOD; however, depending on the biodegradability of the organic matter present, aerobic biological decomposition may continue past 20 days.  It is an estimate of the amount of biodegradable organic matter and is used to determine the oxygen supply requirements for aerobic treatment, as well as the oxygen sag due to treated effluent discharged into a receiving water body. 

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