Chemical Oxygen Demand.
COD is defined as the amount of oxygen equivalents consumed in the chemical oxidation of organic matter by strong oxidant (e.g., potassium dichromate).
What is COD in chemistry class 11?
In environmental chemistry, the chemical oxygen demand (COD) test is commonly used to indirectly measure the amount of organic compounds in water.
What is COD in analytical chemistry?
Chemical Oxygen Demand (COD) analysis is a measurement of the oxygen-depletion capacity of a water sample contaminated with organic waste matter. Specifically, it measures the equivalent amount of oxygen required to chemically oxidize organic compounds in water.
What is BOD and COD in chemistry?
Biochemical oxygen demand (BOD) is the amount of oxygen required by the microorganisms to break down the organic materials, whereas chemical oxygen demand (COD) is the amount of oxygen required to break down the organic material via oxidation.
What is COD biochemistry?
Chemical Oxygen Demand (COD) is a test that measures the amount of oxygen required to chemically oxidize the organic material and inorganic nutrients, such as Ammonia or Nitrate, present in water.
Why do we measure BOD and COD?
Answer: Both COD and BOD test methods aim to give an indication of the amount of pollution in a water sample. COD is the amount of oxygen required to chemically breakdown the pollutants whereas BOD is the amount of oxygen required to do this biologically through micro-organisms.
How is COD calculated *?
There is a formula for calculating COD. 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. Let “b” represent the titrant used for your blank sample in mL.
What is COD in simple words?
COD is the oxygen demand that is consumed by both inorganic and organic matter present in the wastewater sample. The chemical oxygen demand is expressed as the mass of oxygen consumed over the volume of the solution. Its SI unit is milligrams per liter (mg/l).
What is the principle of COD?
OBJECTIVE: To measure Chemical Oxygen Demand. BACKGROUND AND PRINCIPLE: The chemical oxygen demand (COD) determines the amount of oxygen required for chemical oxidation of organic matter using a strong chemical oxidant, such as, potassium dichromate under reflux conditions.
What is the value of COD?
The COD value indicates the amount of oxygen which is needed for the oxidation of all organic substances in water in mg/l or g/m3. The COD (Chemical Oxygen Demand) is closely related to the laboratory standard method named Dichromate-Method.
What is BOD value?
Biochemical oxygen demand (BOD) represents the amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter under aerobic (oxygen is present) conditions at a specified temperature.
What is BOD full form?
BOD is abbreviated form of Biological Oxygen Demand. It is the amount of oxygen required by microbes to break down the organic matter present in a certain volume of a sample of water. The amount of BOD in the water is a measure of the amount of organic material in the water.
What is COD and its significance?
2)COD(chemical oxygen demand)- It is defined as the amount of oxygen required by organic matter in sample water for its oxidation by strong oxidizing agents (K2Cr2O7) in the hot conditions. It is a measure of both the biologically oxidisable & biologically inert organic matter.
What is COD in laboratory?
COD (chemical oxygen demand) COD is the most popular alternative test to BOD for establishing the concentration of organic matter in wastewater samples. The COD test only takes a few hours to complete, giving it a major advantage over the 5-day BOD test.
What is a high COD value?
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 is BOD test used for?
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.
What is difference between BOD and COD?
The main difference between BOD and COD is that BOD is the amount of oxygen which is consumed by bacteria while decomposing organic matter under aerobic conditions whereas COD is the amount of oxygen required for the chemical oxidation of total organic matter in water.
What is BOD water?
BOD is defined as the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down the organic material present in a water sample, at a specific temperature and specified period.
What is COD level in water?
COD is a measure of the oxygen equivalent of the organic matter in a water sample that is susceptible to oxidation by a strong chemical oxidant. COD is widely used as a measure of the susceptibility to oxidation of the organic and inorganic materials present in water bodies and in the municipal and industrial wastes.
How is COD measured in a lab?
The most common test method is the colorimetric analysis after oxidizing the COD with acid and using indicator compounds, such as hexavalent dichromate. In some instances, however, there are compounds that will interfere with the colorimetric analysis, and titration is required to determine COD levels.
What causes high COD in water?
COD increases as the concentration of organic material increases. It also increases if inorganic compounds susceptible to oxidation by the oxidant (typically dichromate) are present. Water with high COD typically contains high levels of decaying plant matter, human waste, or industrial effluent.
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