The ammonia nitrogen level in the effluent from the AO tank does not meet the standards
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Recently, the ammonia nitrogen level in the effluent from the AO tank did not meet the required standards; therefore, we reduced the water inflow rate, while leaving everything else unchanged. As a result, the ammonia nitrogen level in the effluent gradually decreased. We would like to understand the principle behind this. Does an increase in retention time lead to a higher ammonia nitrogen removal rate, or is it an increase in the internal recirculation ratio that results in a better ammonia nitrogen removal rate? Solve
What water is being treated? Specific process parameters?
The conditions for biological nitrogen removal are sufficient dissolved oxygen, a long sludge age to ensure the growth and reproduction of nitrifying bacteria, and low organic matter concentrations.
The water inflow was reduced, which in turn increased DO and sludge age and lowered the organic matter concentration; all these are conditions favorable for biological nitrogen removal, as a result of which ammonia nitrogen levels decreased； Furthermore, by reducing the water inflow volume, the total amount of ammonia nitrogen entering also decreases; with the removal rate remaining unchanged, the ammonia nitrogen level in the effluent will as well decrease.