This paper focuses on the study of high ammonium concentrated wastewater with SBR reactors. Four type of wastewaters, landfill leachates (T=20°C) and the reject water (T=35°C) coming from mesophilic anaerobic digesters of sewage sludge, pig slurry and organic fraction of municipal solid waste (OFMSW), were studied in four SBR during 6 months. The removal of nitrogen was done in all the cases with nitrification/denitrification via nitrite obtaining high removal nitrogen conversions for the three types of reject water (0.75–0.85 kg N day−1 m−3) and lower for landfill leachates due to temperature requirements (0.3 kg N day−1 m−3).