How do you calculate biological oxygen demand?

Measuring biochemical oxygen demand requires taking two measurements. One is measured immediately for dissolved oxygen (initial), and the second is incubated in the lab for 5 days and then tested for the amount of dissolved oxygen remaining (final).

How do you calculate BOD of wastewater?

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 BOD and How Is It Measured?

Biochemical oxygen demand, or BOD, measures the amount of oxygen consumed by microorganisms in decomposing organic matter in stream water. BOD also measures the chemical oxidation of inorganic matter (i.e., the extraction of oxygen from water via chemical reaction).

Why BOD is calculated for 5 days?

The BOD is an empirical test to determine the molecular oxygen used during a specified incubation period (usually five days), for the biochemical degradation of organic matter (carbonaceous demand) and the oxygen used to oxidise inorganic matter (e.g., sulphides and ferrous iron).

What is the ratio of BOD and COD?

Typical values for the ratio of BOD/COD for untreated municipal wastewater are in the range from 0.3 to 0.8 (see in table 3). If the BOD/COD ratio for untreated wastewater is 0.5 or greater, the waste is considered to be easily treatable by biological means.

How is seeded BOD calculated?

#2 Seed BOD = (DO depletion x 300)/Seed dilution, mL The calculated seed BOD represents the BOD exerted by 300 mL of undiluted seed material. The ratio of the seed BOD to 300 mL will be used to calculate the seed correction for seeded samples.

What does the 5 day BOD test measure?

The test for biochemical oxygen demand (BOD) is a bioassay procedure that measures the oxygen consumed by bacteria from the decomposition of organic matter (Sawyer and McCarty, 1978). The change in DO concentration is measured over a given period of time in water samples at a specified temperature.

Why are BOD bottles kept in dark?

Incubation in the dark ensures that no additional oxygen is produced in the samples from photosynthesis. After 5 days, the dissolved oxygen is measured again. The difference between the initial and final oxygen concentrations corrected for BOD of the seed and dilution factor is the BOD.

What is BOD value of water?

BOD is a measure of the amount of oxygen required to remove waste organic matter from water in the process of decomposition by aerobic bacteria (those bacteria that live only in an environment containing oxygen).

Is BOD higher than COD?

COD is normally higher than BOD because more organic compounds can be chemically oxidised than biologically oxidised. This includes chemicals toxic to biological life, which can make COD tests very useful when testing industrial sewage as they will not be captured by BOD testing.

How do you calculate biochemical oxygen demand?

How to calculate biological oxygen demand ( BOD ) It is determined experimentally by measuring the oxygen concentration in a sealed sample before and after a 5-day incubation period. The standard titration procedure reacts the oxygen in the sample with manganese (II) sulfate in basic solution. Manganese (IV) oxide is precipitated,…

How is the biological oxygen demand determined?

Biological oxygen demand is affected by the same factors that affect dissolved oxygen. Measuring biochemical oxygen demand requires taking two measurements . One is measured immediately for dissolved oxygen (initial), and the second is incubated in the lab for 5 days and then tested for the amount of dissolved oxygen remaining (final).

What is the biological oxygen demand?

Biochemical Oxygen Demand (BOD, also called Biological Oxygen Demand) is the amount of dissolved oxygen needed (i.e. demanded) by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period.

What does biological oxygen demand mean?

Biological oxygen demand ( BOD ) refers to the amount of dissolved oxygen (DO) that aerobic organisms need in order to break down organic material in water over time.