I'm exploring leachate treatment and I see pH during aerobic digestion increase.
There is a lot of ammonium in the solution and nitrification should decrease pH, but it goes the other way. My only guess is that this happens because of aerobic digestion of organic matter (is that true?), but I would like it described with a sum equation (so I could see how much H+ is spent / or how much OH- is created).
If it isn't possible to describe it with a equation, is there any other description of pH change?
Thank you
@Bayan Hussein, so respiration of organic matter should not change pH value? If we assume there is no iron, manganese and sulfur compounds, pH should increase only because of denitrification, according to the equations.
Does that mean that I have anoxic zones in my reactor of 10 L?
Maybe denitrification is happening in the center of active sludge particles?
Do you have a lot amount of organic nitrogen ?. If yes, the ammonification process (First step of nitrogen degradation) raise the pH. What is your pH value? and ammonia concentration?
Also, I've just read in your explanation that you work with leachate. Leachate normally are very rich in CO2, than aeration strip out the CO2 and raise your pH, It's a usual effect.
Yann
Yann Le Bihan organic nitrogen (I designate it as R-NH2 - N) is anywhere between 250 mg/L and 10 mg/L. And that is surely one of the reasons - ammonification.
AND HERE IS ANOTHER QESTION - Is ammonification better in aerobic or anaerobic conditions? I can't seem to find a lot of info about that in the literature.
pH rose from 6,32 to 7,8 in 4 hours. O2 was controlled at 3 mg/L
NH4 - N is 1000-1500 mg/L.
CO2 stripping is interesting! Haven't thought of that.
Both, ammonification occur in aerobic and anaerobic conditions. In anaerobic reactor I convert more than 70% of organic nitrogen in ammonia. In swine manure aerobic treatment we reach 80-90% of organic nitrogen convert in ammonia.
You write 4 hours, is it the HRT of your reactor ?? Is is a biofilm reactor or a CSTR. Did you measure NO2 or NO3 at the outlet??
Yann
Yann Le Bihan does that mean that ammonification is not a bacterial reaction but just ordinary hidrolysis? Do bacteria have any impact on ammonification?
nono, 4 hours was just the duration of the experiment. NO2, NO3, NH4 were measured but the data wasn't reliable, sorry.
Stjepan Džalto , in your conditions, ammonification is mainly a biological process aerobic bacteria, fungi, anaerobic bacteria can do ammonification during a normal biodegradation process.
Yann
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