In nitrification reaction processes, the degradation rate
of ammonia by the aerobic microbes was determined by
the rate of the nitrification reaction, which is controlled
by the substrate concentration of ammonia, the inside
and outside concentrations of ammonia on the oxygenenriched
biofilms, and the oxygen transfer processes from
water to the inside of the oxygen-enriched biofilms. Given
the high DO in the water and small thickness of the
oxygen-enriched biofilms, the mass transfer resistance was
smaller and the degradation rate was more rapid compared
to anaerobic conditions. Therefore, a high removal rate
for ammonia can be reached in a short hydraulic retention
time.