In SBR treatment of wastewater, is there any priority regarding the treatment of COD and ammonia nitrogen?
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In other words, does the ammonia nitrogen need to be treated to a certain extent before treatment of COD can yield significant results?
There is no such statement; rather, it is said that COD should be dealt with first, followed by the reduction of ammonia nitrogen, especially in the CASS process.
In principle, it first involves carbon oxidation, that is, the removal of COD, followed by nitrification, which is the removal of ammonia nitrogen. However, in terms of operation, the two processes occur simultaneously; at this stage, microorganisms need nitrogen for synthesis, so it is oxidized to nitrate nitrogen to form organic nitrogen.
Theoretically, carbonization should occur before nitration, but this COD value is inaccurate; BOD should be used to represent a more reliable figure； The main reason is that there is a significant difference in the time it takes for aerobic bacteria and nitrifying bacteria to reproduce; therefore, once BOD becomes a bottleneck, nitrifying bacteria can multiply in large numbers, allowing for substantial degradation of ammonia nitrogen. This depends mainly on which species are dominant