Can pH neutralization process reduce COD levels? Can high or low pH and temperature contribute to high COD levels? This is a liquor manufacturing industry with an activated sludge treatment process.

Both pH and temp can impact COD depending on the processes involved.  For example, temp can have a big impact on COD removal by coagulation.  Some chemicals are better food for bacteria at certain pHs.

Tom said "Finally, you say that this is a "liquor" manufacturing industry,... what type of liquor are you manufacturing?"

He forgot the ".....and do you have samples if it is the drinkable type?"

Thanks for the reply sir Tom and Dr. Henry, the liquor manufacturing company produces alcoholic beverages like rum and brandy. Their activated sludge treatment process has a neutralization tank before aeration tank. The influent or untreated water goes first to the neutralization tank before it passes to the aeration tank. The scenario is that we would like to minimize the COD from neutralization tank before it goes to aeration tank so we could minimize aeration energy and chemicals involved to enhance sludge performance. Would it be possible to minimize COD from neutralization tank by neutralization process? How can you minimize COD, with a low pH or a high pH?

But is it possible to minimize COD with the use of pH neutralization process?

As Tom said, you have to do the bench tests.  It can happen, but it usually takes a drastic pH adjustment.  For example, I had a latex that would solidify 90%, but at pH 2.  So then you have to raise it back up after solids removal.  pH changes can aid coagulants and flocs.

You use the term "minimize".  A better term would be separate since the COD is not going away, just being put in a different form.  To eliminate COD with acid takes intense treatment with high strength sulfuric or nitric acid and is really just not practical.