Difference Between BOD and COD
The table below lists all the major differences between BOD and COD:
|
Features |
BOD |
COD |
|---|---|---|
|
Definition |
It estimates the quantity of oxygen needed by the aerobic microbes to breakdown organic matter. |
It estimates the oxygen needed to breakdown organic as well as inorganic constituents present in the wastewater by chemical reaction. |
|
Decomposition |
It is a biological oxidation process. |
It is a chemical oxidation process. |
|
Agents |
It is performed by aerobic organisms. |
It is performed by chemical reagents. |
|
Time Taken for Determination |
BOD value is determined in 5 days. |
COD is estimated within few days. |
|
Values of Measurement |
BOD value is lesser than COD always. |
COD value is always greater than BOD which means that more organic material can be oxidized through the COD test. |
|
Test Procedure |
BOD is measured by keeping a sealed water sample for incubation for a period of 5 days at 20°C. The difference in the amount of dissolved oxygen tells us the quantity of oxygen used by the aerobic microbes. |
For COD test, the water sample is subjected to incubation with boiling sulfuric acid and a potent oxidant for a specific amount of time and temperature. |
|
Permissible Limit of Test |
The permissible limit is 30 mg/L for BOD test. |
The permissible limit is 250-500 ppm for COD test. |
|
Oxidation Ability |
Organic waste and naturally occurring organic residues in water can be oxidized by biological oxidation. |
Industrial sewage is only degraded by COD. But, it is noteworthy to mention that COD does not measure the oxygen consumption of acetate. |
|
Analysis |
BOD analysis is slower and less accurate than COD analysis. |
COD analysis is far more accurate and faster than BOD . |
Difference Between Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand(COD)
The difference between BOD and COD is that BOD measures the quantity of oxygen consumed by aerobic microorganisms to break down organic matter in water whereas COD measures the amount of oxygen needed to chemically oxidize all organic and inorganic contaminants in water without the aid of microbes. A potent oxidizing agent is needed for COD. Unlike BOD, it completely oxidizes contaminants into CO2 and H2O. Furthermore, BOD tests take longer to complete than COD testing, which can be finished in a few hours. This article provides detailed information on the differences between BOD and COD.
Table of Content
- Difference Between BOD and COD
- Full form of BOD and COD
- What is Biochemical Oxygen Demand (BOD)?
- What is Chemical Oxygen Demand (COD)?
- FAQ’s – BOD and COD