What changes does evaporation losses cause in organic and inorganic concentrations of aerobic reactor?
I think the evaporation itself does not affect COD concentration because organic matter charge is the same in, for example, 900 ml suspension after evaporation as it is in 1000 ml. But this is for a static process, while in aerobic reactor the process is dynamic, oxidation reactions occur, therefore COD will normally decrease in time. In case of ammonium, nitrate, bicarbonate initially present in suspension, the evaporation loss leads to an increase in the concentration of such ions but also the biochemical decomposition processes have an cumulative effect on this increase.
I suggest it is well known that ammonia strip from water and it is in pH dependant equilibrium with ammonium. Therefor some loss can be expected depending on the pH.
Biarbonate and nitrate are ionic so they don't evaporate.
Any loss of COD depends on the organic matter that constitute the COD. If it is large and/or ionic molecules it will not evaporate. If some of the COD comes from small molecules such as volatile organic acids(VFA), ethanol some evaporation can be expected.
This is likely understood and not what you asked, but obviosuly water loss through evaporation in the system will cause an increase in relative concentrations of organics and inorganics. It is somewhat common to run laboratory scale reactors with fixed volumes that can be augmented with DI water to account for this or track water loss in your experiments to account for this.
I agree with Mr. Flannery, the question is not quite well defined. I supposed the question is related to water evaporation that occurs in lab experiments. Even that evaporation of any other organics (volatile acids, aldehides, cetones, alcohols), besides ammonia is very likely too....
Thank you @ Carmen Mateescu ; @ Henrik Rasmus Andersen ;@ Md Iftakharul Muhib ; @ Christopher C Flannery for your answers.
In my experiments, i have observed that both bicarbonate and ammonium ions from black wastewater (source : toilets) escape to air. I am testing for nitrification of wastewater with natural aeration.
If I compensate evaporation loss with DI water, does it cause dilution effect on COD value and also changes pH value?
Is there any other way to compensate evaporation loss in batch reactor?
How do we find out ammonia volatilisation and bicarbonate losses to air to prepare mass balance for ammonium?
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