Dear All,
I am now running a continuous aerobic MBBR system treating synthetic wastewater of TKN ~40 ppm and NH3-N ~30 ppm. Now I can acheive effluent NH3-N of 23 ppm) with only low levels of NO3-N (~6 ppm). The pH is 7.5-8.0 and the DO is always >7 ppm. Can anyone help me to suggest some reasons behinds and some solutions to enhance the NOB activity?
Thank you very much!
Dennis Tang
Hong Kong, China
Nitrification organisms that use TKN and ammonia for energy will convert TKN and ammonia nitrogen to nitrates. These reactions are quite natural. There are nitrification inhibitors, but these are not desirable in an effluent.
Is there any organic substrate present? The lack of organic substrate for heterotrophic nitrification can be a reason for NO2 accumulation.
Regards
Vit
Dear Vit,
The COD of synthetic wastewater is about 400 ppm and the effluent is 30-50 ppm.
Thank you very much!
Regards,
Dennis
Due to a bit outdated classical view nitrification is performed in 2 steps by 2 microorganisms. Modern data proved that some nitrifiers may perform both steps within 1 microorganisms. However, in this case both steps sometimes are not tightly coupled and sometimes significant part of nitrite is released into the medium and then later is oxidised to nitrate . That is my personal observation during cultivation the COMAMOX culture.
Thus, in your case 2 processes are incoupled. That could be that you lack nitrite-oxidising organisms.
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