Why is chemical oxygen demand greater than biological oxygen demand?

Posted on by Author

Why is chemical oxygen demand greater than biological oxygen demand?

COD is normally higher than BOD because more organic compounds can be chemically oxidised than biologically oxidised. This includes chemicals toxic to biological life, which can make COD tests very useful when testing industrial sewage as they will not be captured by BOD testing.

Which is greater COD or Tod?

Explanation: ThOD mostly greater than COD. BODu = 0.9ThOD, ThOD > BOD. BOD5 = 0.77 BODu , BODu > BOD.

What is the difference between chemical oxygen demand and biological oxygen demand?

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. COD analysis on the other hand is a measurement of the oxygen-depletion capacity of a water sample contaminated with organic waste matter.

READ:   How do I convert to Sikhism?

Is Tod greater than BOD?

∴ TOD > COD > BOD Other Important points: COD is also known as Di-chromate demand.

What is meant by 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).

Why is Chemical Oxygen Demand important?

In wastewater treatment, the Chemical Oxygen Demand (COD) is an important measurement for the amount of oxygen that is required to break down pollutants (organic substances) in water. Compared to off-line measurement this method is much quicker providing an easier way to analyse the chemical oxygen demand.

What does Chemical Oxygen Demand indicate?

3.3. Chemical oxygen demand is a parameter that indicates the total chemically oxidisable material in the sample and therefore indicates the energy content of a feedstock. In this analysis the sample is refluxed in a boiling mixture of sulphuric acid and a known excess of potassium dichromate (K2Cr2O7).

What does Chemical Oxygen Demand measure?

READ:   What are those things on plane wings?

The chemical oxygen demand (COD) test is commonly used to indirectly measure the amount of organic compounds in liquid waste. It is expressed in milligrams/grams per liter, which indicates the mass of oxygen consumed per liter of solution. Older references may express the units as parts per million (ppm).

Is TOC greater than COD?

COD testing is simple and less sensitive in lower concentrations, whereas TOC requires instrumental analysis but much more precise. Therefore, it is advisable to use TOC for following biodegradation reactions of compounds at low concentration (below COD 10-20 mg/L).

What causes chemical oxygen demand increase?

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.

What increases chemical oxygen demand?

Is chemical oxygen demand good?

COD is useful in terms of water quality by providing a metric to determine the effect an effluent will have on the receiving body, much like biochemical oxygen demand (BOD).

READ:   Is real estate a low risk business?

What is Theoretical oxygen demand (ThOD)?

Theoretical oxygen demand (ThOD) is the calculated amount of oxygen required to oxidize a compound to its final oxidation products.

What is chemical oxygen demand in organic chemistry?

Chemical Oxygen Demand. Chemical oxygen demand (COD) is the amount of oxygen necessary to oxidize all of the organic carbon completely to CO2 and H2O.

What is chemical oxygen demand (COD) test?

As Wikipedia put it: The chemical oxygen demand (COD) test is commonly used to indirectly measure the amount of organic compounds in water. Most applications of COD determine the amount of organic pollutants found in surface water (e.g. lakes and rivers) or wastewater, making COD a useful measure of water quality.

What is biochemical oxygen demand (BOD)?

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. The term also refers to a chemical procedure for determining this amount.