Chemical oxygen demand and total organic carbon analysis of water from a bio-filter sample show increasing trend for chemical oxygen demand while total organic carbon shows a decreasing trend. what can be the reason for increasing COD value?
It may be due the presence of interfering agents like NH4+,NO3-, Cl-, in the sample. These got oxidised by the K2Cr2O7 in strongly acidic medium (H2SO4) and hence an alteration comes in the COD value (increased COD). The nitrogenous ions and chlorides are common in organic wastes. In industrial wastewater presence of H2O2 can also play a role in alteration of COD.
Maybe (1) the COD data is wrong, (2) the organic pollutants are hard to be oxidized by K2CrO4, but easier oxidized after bio-treatment, or (3) if some reductive materials such as Cl- was introduced during wastewater treatment might also cause an increase in COD.
I cannot see the logic in these comments:
Therefor neither of these factors can explain an increased COD over a biofilter.
Perhaps the filter is anaerobic and organic matter is mineralised (TOC decrease) while sulfate is reduced to sulfide (COD increase).
All the answers may be right. But first we have to know
a) the kind of the input water of the biofilter
b) the kind of the organic matter, which shall be disintegrated
c) the distribution of the nutrient for the biofilter
d) the amount of oxidisable inorganics
and last not least the amounts of COD and TOC.
Without the knowledge of these facts all is possible.
hello Arpan Sarkar . Your answer really answer my question. But is there any journal that can support this anwer? Thank you so much
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