Chemical Oxygen Demand (COD) is a measure of the amount of oxygen required to oxidize organic matter in water. It is a widely used indicator of water quality and can be used to assess the effectiveness of wastewater treatment and to monitor the health of aquatic ecosystems.
COD is measured by adding a strong oxidizing agent, such as potassium dichromate, to a water sample and heating it to a high temperature. The oxidizing agent reacts with the organic matter in the sample, consuming oxygen in the process. The amount of oxygen consumed is measured and expressed as COD.
COD levels can vary widely depending on the source of the water. Untreated wastewater typically has a COD of 100-1,000 mg/L. Treated wastewater typically has a COD of 20-50 mg/L. Surface water bodies, such as rivers and lakes, typically have a COD of 1-10 mg/L.
High levels of COD in water can have a number of negative impacts. It can deplete the oxygen levels in the water, which can suffocate fish and other aquatic life. It can also promote the growth of harmful algae blooms. Additionally, COD can contribute to the formation of toxic disinfection byproducts when drinking water is treated with chlorine.
COD is an important parameter to monitor in a variety of settings, including:
- Wastewater treatment plants
- Water treatment plants
- Industrial facilities
- Environmental monitoring programs
- Food processing facilities
- Agricultural facilities
There are a variety of methods available for measuring COD. The most common method is the closed reflux method, which is described in the American Public Health Association (APHA) Standard Methods for the Examination of Water and Wastewater. Other methods include the dichromate digestion method and the permanganate oxidation method.
COD is a valuable tool for assessing water quality and for monitoring the effectiveness of wastewater treatment and pollution prevention programs. By regularly monitoring COD levels, we can help to protect our aquatic ecosystems and ensure the safety of our drinking water.
All our units to measure COD can be found here: https://www.gas-sensing.com/support/gas-information/cod.html
