Hi, It depends of what is your raw matter. I don't know wich COD test you are using but possibly that the COD of the raw matter are underestimated (we observed it with lipidic solid substrate). With the hydrolysis step of the organic particulate matter, more soluble substrate is released and convert to acid before CH4 etc.. production. This hydrolysis step could generate more soluble fraction that is high COD value and that your COD test respond.

In your case, are you sure that you generate real biogaz or you stop at the hydrolysis or acidification step. Normally COD decrease with the Biogaz production but not strongly as aerobic process.

Yann

hi, Yann Le Bihan ...

i am working on CODcr..

Hi, try a TOC analysis if you can (Total organic carbon).

Yann

ok

Oh ok It's a SBR, did you try soluble COD?. Possibly the suspended biomass concentration is not the same in the SBR anaerobic vs aerobic...follow also suspended solids (SS raise COD).

Yann

@ Yann Le Bihan i think biomass remain same in both situations

Abdul Rehman no the settling properties could vary between aerobic and anaerobic process. But some information is missing for your reactor operation and sampling. Be sure that the Suspended solids dont affect your COD value.nt

Thank you Yann Le Bihan .. you are right .. i shall monitor every content and cause..

actually its should be decreasing in both conditions( anaerobic & aerobic ). However, in aerobic condition the results can get faster. In your case I do believe you need to settle your suspended solid first by serving your sample centrifuge for a while then try to test COD.

Hello dear Mustafa wajid wajid,

i centrifuged samples before testin.COD while revealing both situation but some times COD remains nearly same and infact effluent doesnot show a major change.. so i am Little confused with situation... however nutrient removal is more than 90%

how do you estimate the nutrient removal of 90% if COD remains the same?

in terms of N and P..