Why after 5 days the measurement of BOD is not usually reliable?

Why after 5 days the measurement of BOD is not usually reliable?

If the sample is not diluted, the biological activity of the microorganisms will use up the DO in the BOD bottle before the five day incubation time is up. If the final DO is too low, the BOD cannot be determined.

Why is the incubation period for BOD 5 days?

Five days period in BOD5 was chosen for the test because it was to estimate the longest travel time of river water from its source to the estuary in the United Kingdom in 1908 by Royal Commission on Sewage Disposal of Great Britain [5].

What is the mathematical expression of BOD?

Explanation: BOD = [(D1-D2)-(B1-B2) f]/P.

How is BOD of waste water calculated?

For example: 1.0 mL of a full strength wastewater sample added to 9.0 mL of DI water results in a 0.1 dilution of the wastewater. The DO concentration (mg/L) reduction must then be multiplied by 10 to determine the final BOD concentration.

What is the reason for taking 5 days BOD as standard?

The reason for taking 5 days BOD as standard is due to the following fact: The “Dissolved Oxygen” present in water gets used for the decomposition of organic matter as well as nitrogenous matter. From the combined BOD curve, we have two oxygen demands: 1. COD stands for ‘Chemical Oxygen Demand’ where BOD stands for Biochemical Oxygen Demand.

What is the BOD 5 value?

The standard oxidation (or incubation) test period for BOD is 5 days at 20 degrees Celsius (°C) (BOD 5). The BOD 5value has been used and reported for many applications, most commonly to indicate the effects of sewage and other organic wastes on dissolved oxygen in surface waters (see TECHNICAL NOTE).

How do you measure BOD value?

In Laboratory, The BOD value is measured by measuring the difference of dissolved oxygen (DO) of the sample after 5 days of incubation at 20 degrees centigrade. The answer to this question is among the basic building blocks of Environmental Engineering, Yet…

What is the significance of 5 day incubation period for BOD test?

Also for 5 days incubation period test results were close to onsite conditions and a safe margin error due to inclusion of oxygen required by nitrifying bacteria. Later this was widely adopted as a standard for carbonaceous oxygen demand i.e. BOD. Higher the BOD value higher is the water polluted.