Typically, the average BOD result is divided by the average COD result to find a “conversion factor” between the two parameters. One would then multiply their COD results by this factor to estimate BOD. COD values are almost always higher than BOD values for the same sample.
Can you calculate COD from BOD?
COD can test wastewater that is too toxic for the BOD test.
Can I use my COD results to predict my BOD?
| Sample 1: | COD = 2,150 mg/L | BOD = 1,100 mg/L |
|---|---|---|
| Sample 2: | COD = 1,990 mg/L | BOD = 1,050 mg/L |
| COD ÷ BOD = 1,990 ÷ 1,050 = 1.89 | ||
| Sample 3: | COD = 1,850 mg/L | BOD = 997 mg/L |
| COD ÷ BOD = 1,850 ÷ 997 = 1.86 |
What is the ratio of BOD to COD?
BOD : COD (Chemical oxygen demand) ratio using the formulated seed comes in the range of 0.7-0.8 whereas that using BODSEED comes in the ratio of 0.5-0.6.
Is BOD and COD value same?
Hence, the value of COD is greater than BOD.
Chemical Oxygen Demand (COD) v/s Biological Oxygen Demand (BOD)
| BOD | COD |
|---|---|
| BOD value is determined by 5 days. | COD can be measured within few days. |
What is the formula to calculate COD?
H2SO4 + 1 Ltr D.W.)
Why is COD always higher than BOD?
As such, COD will always be higher than BOD. Because the test for COD takes only a few hours (as opposed to the test for BOD, which takes 5 days), it can be used as an operational adjustment parameter in close to real time.
Is BOD higher than COD?
BOD can be higher than COD determined by dichromate oxidation in a few cases. The most common is a sample with very degradable organic matter and high organic nitrogen or ammonium such as wastewater from fish processing.
What is the ratio of COD BOD for fresh water?
For fresher water, as both BOD and COD should be negligible, hence the ratio can be equal to 1.
What is COD and BOD of water?
The biochemical oxygen demand (BOD) represents the amount of dissolved oxygen (DO) consumed by biological organisms when they decompose organic matter in water. The chemical oxygen demand (COD) is the amount of oxygen consumed when the water sample is chemically oxidised.
How do you determine COD in water samples?
Chemical oxygen demand (COD) is used to determine the quantity of pollution in water after wastewater treatment. The higher value of chemical oxygen demand indicates the higher organic pollution in the water sample. Only chemically digest able matter can be determined by the COD test.
How is COD measured in water sample?
This is usually done by titration, using an indicator solution. COD is expressed in mg/L, which indicates the mass of oxygen consumed per liter of solution. The COD test only requires 2-3 hours, while the Biochemical (or Biological) Oxygen Demand (BOD) test requires 5 days.
Why is BOD done for 5 days?
BOD occurs in 2 general stages. While calculating the oxygen demand, the carbonaceous stage is taken into account. This stage is almost completed in 5 days, which means that most of the organic content of the sewage is oxidized under aerobic conditions in 5 days. Hence ,BOD for 5 days is calculated.
What if COD is high in water?
When the COD levels are higher, there is a greater demand for oxygen. This means that there is likely more oxidizable organic material in water with high COD levels. This also means that there are reduced Dissolved Oxygen (DO) concentrations in wastewater with high COD levels.
What is the difference between BOD and COD in wastewater?
BOD measures the oxygen demand for the decomposition of organic material by the microbes in the wastewater. COD measures the oxygen demand for the decomposition of both organic and inorganic materials in wastewater. This is the main difference between BOD and COD.
What are the standard limits for BOD and COD?
According to standards of Central Pollution Control Board, permissible value of BOD is 30 mg/l and COD is 250 mg/l.
What is the permissible limit of COD in wastewater?
The chemical oxygen demand (COD) concentration in a treated effluent, if observed to be persistently greater than 250 mg/l before disposal to any receiving body (public sewer, land for irrigation, inland surface water and marine coastal areas), such industrial units are required to identify chemicals causing the same.
How is BOD calculated?
6.1 Take four 300 ml BOD bottles and add 10 ml of samples to two bottles and fill the remaining volume with dilution water.
Biological Oxygen Demand (BOD):
| Recommended sample volume for BOD determination | ||
|---|---|---|
| BOD range (mg/liter) | Sample volume (ml) | Dilution water (ml) |
| 0-10 | 300 | |
| 11-30 | 100 | 200 |
| 31-70 | 50 | 250 |
Why Sulphuric acid is used in COD?
Chemical Oxygen Demand (COD) 1% Silver Sulphate in Sulphuric Acid (conc.) provides the primary and secondary digestion catalysts for oxidation of carbon during chemical oxidation.
What is COD and How Is It measured?
COD is an indicative measure of the amount of oxygen that can be consumed by reactions in a measured solution. It is commonly expressed in mass of oxygen consumed over volume of solution, which in SI units is milligrams per liter (mg/L). A COD test can be used to easily quantify the amount of organics in water.
Why potassium dichromate is used in COD?
While the BOD test is performed by using a population of bacteria and other microorganisms to attempt to duplicate what would happen in a natural stream over a period of five days, the COD test uses a strong chemical oxidizing agent (potassium dichromate or potassium permanganate) to chemically oxidize the organic
Lorraine Wade is all about natural food. She loves to cook and bake, and she’s always experimenting with new recipes. Her friends and family are the lucky beneficiaries of her culinary skills! Lorraine also enjoys hiking and exploring nature. She’s a friendly person who loves to chat with others, and she’s always looking for ways to help out in her community.