Chemical Oxygen Demand
Chemical oxygen demand (COD) is a measure of the capacity of water to consume oxygen during the decomposition of organic matter and the oxidation of inorganic chemicals such as ammonia and nitrite. COD measurements are commonly made on samples of waste waters or of natural waters contaminated by domestic or industrial wastes. Chemical oxygen demand is measured as a standardized laboratory assay in which a closed water sample is incubated with a strong chemical oxidant under specific conditions of temperature and for a particular period of time. A commonly used oxidant in COD assays is potassium dichromate (K2Cr2O7) which is used in combination with boiling sulfuric acid (H2SO4). Because this chemical oxidant is not specific to oxygen-consuming chemicals that are organic or inorganic, both of these sources of oxygen demand are measured in a COD assay.
Chemical oxygen demand is related to biochemical oxygen demand (BOD), another standard test for assaying the oxygen-demanding strength of waste waters. However, biochemicaloxygen demand only measures the amount of oxygen consumed by microbial oxidation and is most relevant to waters rich in organic matter. It is important to understand that COD and BOD do not necessarily measure the same types of oxygen consumption. For example, COD does not measure the oxygen-consuming potential associated with certain dissolved organic compounds such as acetate. However, acetate can be metabolized by microorganisms and would therefore be detected in an assay of BOD. In contrast, the oxygen-consuming potential of cellulose is not measured during a short-term BOD assay, but it is measured during a COD test.
User Comments Add a comment…
about 1 month ago
dianarra zamora
what is the samling protocl in getting the COD???
3 months ago
Elhashmi M Abujaafar
Are There any Expriment ran on Lab-on-Chip
3 months ago
malvika
why one has to perform a COD or BOD or DO test
3 months ago
mandy » waiman0204 ((at)) hotmail dot com
may i know what is the reason that cause the measured COD reading is overange or underange? tahnks>
6 months ago
margaret » margsnoda ((at)) gmail dot com
Is there any other method to calculate the COD without using the formula.
8000(b-a)n/vol. sample
6 months ago
Sultan » sultan dot alrubkhi ((at)) orpc dot co dot om
Sir,
we use sulphuric acid to neutralize spend caustic but stil we found high COD.
Did you have any way to reduce the COD?
6 months ago
priya » manas_priya2002 ((at)) gmail dot com
Sir,recently we are doing a project by performing cod test on effluents coming out of some famous industries...could you please help us by cleary giving the details of the chemicals and reagents to carry out this test?
7 months ago
shafia leghari
Respected Sir can you tell how oxygen can be detected in laboratory by simple chemical test in organic compounds.
7 months ago
fred paras » utek102001 ((at)) yahoo dot com
Good day. We have analyzed our BOD and COD content on our effluent. How come our BOD passed the regulatory limit while the COD failed? How can I reduced COD on our effluent?
8 months ago
gs nagender » gsn ((at)) indochem dot in
dear sir, can you give some information , if cooling tower water contains COD 296 mg/lt and BOD 90 mg/lt. is there any corrosion problem [small pinholes in return water lines].what is the reason kindly mail me .gsn@indochem.in
8 months ago
M.fahim » fahim_ric01 ((at)) yahoo dot com
How can you differentiate between the COD and BOD?
11 months ago
priya » padu dot sweety ((at)) gmail dot com
Dear Sir/Madam, Good day! can you please tell me whether the COD value should increase or decrease when a microbe degrades waste inoculated along with it. please reply me.its urgent..
11 months ago
gugu zulu » gugu ((at)) tigerbrands dot com
I working for food company, we are having a problem with our COD and BOD, please help ,how can we solve it, but our effuent results, in term of pH and Tss are good.please help me urgently.
12 months ago
Zinnah » zoozim22 ((at)) yahoo dot com
Hi,
Thanks for such an excellent publication. After reading it, i realized that my doubts about the difference between COD and BOD were cleared.However, please include some quantitative analysis and laboratory procedures.
12 months ago
Ran Sarun » ran dot sarun ((at)) yahoo dot com
i want to know the effect of the Biological Oxygen Demand, Chemical Oxygen Demand and the Disolved Oxygen when it has high concentration.
about 1 year ago
manisha roy » manisha_roy85 ((at)) rediffmail dot com
Hello sir
I want to know that how calculate COD and BOD? pls help me.
about 1 year ago
chay » reachem_industries ((at)) yahoo dot com
Dear Sir,
Good day could you help me on what are the procedure on how to calculate hte COD and the reagents to be used.We have a product an acidic liquid soap and a basic liquid soap which we must test the COD.Thank you! God bless!
about 1 year ago
Andre » and_xool ((at)) yahoo dot co dot id
Good day sir...
Sir,i want to know how to reduce or decrease COD and BOD levels at industrial waste water or effluent...? In my company COD and BOD levels are very high, up to 1000 ppm. Please help me..
I'm waiting for your answer.! Thank's...
about 1 year ago
R.Jayapal » appliedco ((at)) vsnl dot net
Dear sir,
Please tell me How to calculate COD and BOD and Procedure.
over 1 year ago
bernard seneki » bernard_seneki ((at)) colpal dot com
I work for a processing industry. Please tell me ways I can reduce COD/BOD levels in industrial waste water.
over 1 year ago
philotsh » phitush2004 ((at)) yahoo dot com
thanks in advance. whats the relationship between COD and BOD- Is it possible to use biological means to reduce cod.
over 1 year ago
hetal mehta » hetal dot mehta23 ((at)) yahoo dot com
Hello sir, I want to measure H acid degradation by white rot fungi. I want to know is it possible to measure its degradation by COD? Can I determine its degradation using COD?
over 1 year ago
RENAN SADICON » sadicon_renan ((at)) yahoo dot com
Good Day, I would like to know why do we add minerals in dilution water like MnSo4, FeCl3. What are the effects of this compound to the dilution water? What is the purpose of Glutamic acid or GGA that we used in our standard? And most important the purpose of SEED in the analysis. I was just curious in the addition of dilution water that we used to fill up the BOD bottle to 300 ml. Thanks...
over 1 year ago
sangeeta dhote » sangeetadhote ((at)) yahoo dot com
Plz tell me in a lake eco-system for poluuting the lake how COD contributes?
I also want to know is there any relation ship between BOD and COD?
over 1 year ago
Shahaji Arun Mane » shahaji_mane7578 ((at)) yahoo dot co dot in
Rescepted sir,
Please sir tell me can we increase the COD of perticular organic material and how?
over 1 year ago
JOYDEB BOSE » j_bose27 ((at)) rediffmail dot com
Iwant to know that, is the process said above (cod test process)recognised by APHA?
over 1 year ago
N.celin manoj » celinmanoj24 ((at)) gmail dot com
Dear Sir, Plz tell me how to reduce the cod in paint effluent what vare the treatments and methods
almost 2 years ago
sagar » royaltyunlimited ((at)) gmail dot com
plz tell me the standard procedure 2 calculate the cod that means i want 2 know the materials required, reagents
requered,procedure, observation table, formula, precaution etc related with during cod measurement during lab
about 2 years ago
vipin » vipin dot bhagat ((at)) yahoomail dot com
Give the information how to calculate %oxygen consume.i mean formulas