Patent ID: 6383390
Filing Date: 2002-05-07
Classification: C02F

Abstract:
An improved method of treating ammonia-comprising waste water, wherein in a first step ammonia-comprising waste water is subjected to a nitrification treatment by using a nitrifying microorganism and by addition of oxygen, yielding a solution comprising an oxidation product of ammonia, and in a second step the oxidation product of ammonia together with ammonia is converted into nitrogen, through influence of a denitrifying microorganism, wherein the improvement comprises using bicarbonate-containing waste water which is substantially stripped of bicarbonate by supplying air, and in the first step said ammonia-comprising waste water is fed to a nitrification reactor in an amount such that the nitrification reactor operates without sludge retention and pH is maintained at less than or equal to approximately 7.2 by controlling the aeration, thereby automatically limiting conversion of the ammonia present in the waste water into nitrite as the oxidation product of ammonia to up to fifty percent of said ammonia and substantially preventing conversion of said ammonia to nitrate, yielding a both ammonia and nitrite-containing solution, and in the second step the denitrifying microorganism uses the thus formed nitrite as oxidant for the remaining ammonia.