The paper describes some recent and exciting work in the use of biotrickling filters for the treatment of waste gases containing high loads of ammonia. This works explores a range of operational conditions that open up further technological possibilities for this technology such as the retroffiting of chemical scrubbers at waste treatment facilities into biological reactors. Limits and capacities of biotrickling filtration as a technique to compete with chemical scrubbing for the treatment of ammonia loads above 40 gN m-3 h-1 are investigated. Long-term operation of a lab-scale biotrickling filter under different inlet NH3 concentrations (100 to 1400 ppmv) and gas contact times (2 to 46 sec) was performed to study the influence of operating parameters such as the make-up water flowrate and to assess biological and mass transfer limitations. The effect of the ammonia load over nitritation and nitratation rates was analyzed. Microbial diversity was compared between low and high-ammonia load conditions through tag-encoded FLX amplicon pyrosequencing showing that accumulation of FA and FNA promoted the growth of nitrifiers. Also, a large fraction of denitrifying species was found demonstrating that denitrification occurs also in aerobic biotrickling filters.