Is COD always greater than BOD?

Is COD always greater than BOD?

COD, Chemical Oxygen Demand, is a measure of the total quantity of oxygen required to oxidize all organic material into carbon dioxide and water. COD values are always greater than BOD values, but COD measurements can be made in a few hours while BOD measurements take five days.

Why is COD value high?

1.1 Chemical Oxygen Demand. COD is an indicative measurement of the amount of oxygen that can be consumed by reactions in a measured solution. COD detection can be used to easily quantify the amount of organics in water. The higher the COD value, the more serious the pollution of organic matter by water.

How is the value of COD compared to BOD?

BOD measures the amount of oxygen required by the aerobic organisms to decompose organic matter and COD measures the oxygen required to decompose organic and inorganic constituents present in the wastewater by chemical reaction. Hence, the value of COD is greater than BOD.

What is BOD and differentiate it from COD?

COD is closely related to BOD or Biochemical Oxygen Demand, the difference being that BOD is a test of the level of organic matter that can be biologically oxidised while COD is a test of the amount of organic matter that can be chemically oxidised.

How is the value of COD compared to BOD Mcq?

COD value is always greater than BOD for every wastewater sample.

Why is high COD bad?

Higher COD levels mean a greater amount of oxidizable organic material in the sample, which will reduce dissolved oxygen (DO) levels. A reduction in DO can lead to anaerobic conditions, which is deleterious to higher aquatic life forms.

What happens if BOD is high?

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. The consequences of high BOD are the same as those for low dissolved oxygen: aquatic organisms become stressed, suffocate, and die.

Is BOD more accurate than COD?

There is a strong correlation between COD and BOD, however COD analysis is a much faster and more accurate method. BOD analysis is performed to determine what effect dirty water, containing bacteria and organic materials, will have on animal and plant life when released into a stream or lake.

Can COD be lower than BOD?

Simply BOD indicates the biodegradable organic matter (OM) while COD represents both biodegradable and non-biodegradable OM in water. If all OM is your sample is biodegradable, so BOD will approximately equal COD. Therefore, COD should be higher than or equal BOD but never be lower than BOD.

How is COD calculated *?

Chemical oxygen demand, or COD, is a test that measures the amount of organic compounds in water. Consider the formula for COD calculation: (a – b) X C X 8,000 / the volume of the sample in mL. Let “a” represent the titrant used for your sample expressed in mL.

When there is a decrease in BOD?

When mass of organic matter is used. When organic matter increases. Decrease in the water level. When there is an increase in the O2 quantity.

What is the ratio of BOD COD in untreated waste?

0.3-0.8
15. What is the ratio of BOD/COD in untreated waste? Explanation: The ratio of BOD/COD is 0.3-0.8 in untreated waste.

Why cod is greater than BOD?

Why cod is greater than bod. 1. Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period Chemical oxygen demand…

What is the difference between cod and BOD in a bioassay?

COD is the amount of oxygen required to chemically oxidize organic matter in your wastewater into inorganic matter. whereas BOD is the amount of oxygen required to biologically oxidize the organics in your sample, usually after 5 days or 21 days of incubation time, depending on the bioassay followed.

What is BOD5 and cod5?

BOD5 is a measure of, the amount of oxygen that require for the bacteria to degrade the organic components present in water / waste water. Thus BOD5 values should not be higher than COD value of the same water samples, however the ratio could varies depend on the origin of the waste water.

What is the relationship between CBOD and BOD?

The normal relationship between COD and BOD is such that COD will be typically double (or other multiples) of whatever BOD is unless a dramatic process change pushes a parameter. cBOD is always equal or less than COD.