Hello Dears,
we take some samples of treated domestical wastewater coming out from small wwtp, in some cases we have ammonia higher than the influent in the treatment plant (example 60mg/l in the influent, 120-170mg/l in the effluent).
Of course is not possible that the plant "produce" ammonia, so I would like to ask you a suggestion about how can this happen.
The sample are taken from the surface of a small tank of 150 liters, maybe can be possible that ammonia stratifies on the surface because of the lower density of ammonia solution then water.
Waiting for your response.
Thank you very much.
Michele Marzi
It is a bit odd that you don't mention the nitrification in the treatment. Mostly sewage treatment plants nitrify ammonia.
If there is no nitrification capacity in the plant most municipal sewage treatment plants have a diurnal rhythm in the ammonia concentration. Usually there is a peak in concentrations late in the morning and and smaller peak with longer duration in the evening and quite low concentrations during the day. Thus if you sample in the middle of the day you might have the effect of the morning peak towards the end of the plant and a low influent concentration. Likely the retention time of your sewage treatment plants is less than 6 h because it appears not to be able to nitrify.
You might also have ammonification which produces ammonia from hydrolysis of organic nitrogen (TKN).
It is not possible that ammonia stratifies. This can only happen to particles and molecules that doesn't completely dissolve.
I'd first look to biomass. Filter the samples through a micron sieve washed with DI water, and compare results. Check the auto sampler line (Assuming 24-hour composite), and see if it is lined with biofilm.
You need to take samples at least in 24 hours (e.g. every 4 hours), then mix all samples properly. Afterwards, pick-up your sample, filter it, and measure the ammonia.
Denitrification converts nitrate to free nitrogen. Biologically denitrification doesn't make ammonia as it can with chemical reduction.
If there is no error on sampling and of ammonia, most likely the wastewater had very high concentration of protein which on anaerobic condition can generate very high concentration of ammonia.
If you system is high loaded and you influent has a high concentration of particular organic matter I support also the theory that you arrive at hydrolise organic matter with any nitrification taking place. I can though also be a consequence of making non time coordinated spot samples with large influent variations.
Hello there, continuin with the discussion here,
What you can do to give yourself a favorable explenation on this numbers is to change the measurement for Total Nitrogen. Additionally to this make sure you take at least a 24 mixed sample for each step in the process.
Cheers
Adrian
1st, might be due insufficient DO supply. a successful nitrification need enough oxygen since oxygen has to diffuse into the biofilm. 2nd, you need to check the biomass/biofilm value. excessive biofilm formation might reduce the ammonia removal ability in one oxidation tank.
If the protein concentration in the wastewater is high and due to lack of oxygen, the protein will be converted to ammonia under anaerobic conditions and this could the cause for higher ammonia concentration,
If the protein concentration in the wastewater is high and due to lack of oxygen, the protein will be converted to ammonia under anaerobic conditions and this could be the cause for higher ammonia concentration in the effluent.
I agree with Henrik Rasmus Andersen. Additionally, TKN measurements show the NH3 coming from hydrolysis of organic compounds. Also aerobic conditions must be controled.
Anaerobic Supernatant can be a high ammonia concentration in the internal recycle that drains from the digester and anaerobic condition. So, along with the factors that other friends have said, you should also control the amount of ammonia entering the internal flow.
Salam all, there are 2 ways to create Ammonia in wastewater, first with enough oxygen may organic nitrogen transfer to Ammonia by Ammonification. Second with Unsufficient oxygen the nitrogen become Ammonia by Nitrogen Fixation. Some times worms and pH increase also as well as temperature.
https://www.epa.gov/sites/production/files/2015-06/documents/Wastewater-Sampling.pdf
In order to verify the result, consider sampling procedure taking flow factor at time of ww sampling into account. Composited samples are preferred to grab samples to avoid errors in wwtp performance studies. Check influent loading and or characterize influent ww to establish constituents for possible presence of inhibitor that can affect nitrification and lead to observed trend particularly if such inhibitor lose effect along the ww treatment unit operations.
Hi
I agree with Jamal Ali Kawan Ammonia in wastewater, first with enough oxygen may organic nitrogen transfer to Ammonia by Ammonification. Second with Unsufficient oxygen the nitrogen become Ammonia by Nitrogen Fixation. Some times worms and pH increase also as well as temperature.
I disagree with Jamal Ali Kawan and Marzieh Vahid Dastjerdi. There is no way "nitrogen become Ammonia by Nitrogen Fixation" in a sewage treatment plant.
Nitrogen fixation is an energy demanding process performed by bacteria lacking nitrogen for growth. In wastewater there is plenty of ammonia and nitrate. The process that makes ammonia in a sewage treatment plant is ammonification which is conversion of organic nitrogen (proteins/amino acids and urea) to ammonia. This occur both anaerobically and anaerobically.
https://en.wikipedia.org/wiki/Nitrogen_cycle#Nitrogen_fixation
https://en.wikipedia.org/wiki/Nitrogen_cycle#Ammonification
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