Nitrification in extreme conditions was studied in a gas/liquid bioreactor treating gaseous ammonia (NH3) emissions. As autotrophic bacteria can use simple inorganic compounds to supplement their energy requirements (i.e., NH$_3$ and carbon dioxide CO$_2$ from air), no nutrients or carbon sources were introduced into the water to support biomass growth. Furthermore, the continuous recirculation of water in a closed-loop within the bioreactor resulted in the accumulation of ammonium (NH$_4^+$), nitrite (NO$_2^–$), and nitrate (NO$_3^–$) concentrations in the water reaching levels in the order of several thousand milligrams per liter (mg/L). The bioreactor underwent continuous monitoring throughout four experiments, spanning a total duration of two years. The results unveil that unexplained yet reproducible phenomena occurred during the nitrification process: (1) once NH$_4^+$ and NO$_2^–$ accumulated in the water, significant losses of these two nitrogen forms occurred simultaneously while maintaining the mass transfer of ammonia from the gas phase to the water; (2) continuous production of NO$_3^–$ was observed despite the absence of nitrite oxidizing bacteria (NOB) due to inhibition phenomena induced by elevated concentrations of free ammonia (FA) and free nitrous acid (FNA); (3) sudden unidentified inputs of ionized nitrogen forms NH$_4^+$, NO$_2^–$, and NO$_3^–$ occurred in the bioreactor. The findings and microbial analysis indicate that simultaneous nitrification denitrification (SND) process could occur in the bioreactor. However, this assumption is constrained by the unfavorable carbon to nitrogen ratio (C/N < 1) and the negligible production of N$_2$O. To date, the surprising phenomena recorded in the bioreactor remain unresolved, indicating that certain mechanisms within the nitrogen cycle in challenging environments are still unknown.