NOVELTY - Anaerobic digestion of wastewater with a high concentration of ammonia nitrogen, organic nitrogen, or proteins, in an upflow anaerobic digester and sludge blanket (UASB), with immobilization of microorganisms and inhibition controlled ammonium, comprises: e.g. (a) inoculating well digested sludge wastewater with a high concentration of nitrogen or of proteins that are contained in the digester; and (b) adding to the resultant of the step (a), zeolite-clinoptilolite having an average particle size of 0.5-2 mm, at 15-23 vol.% of zeolite based on the total volume of sludge.    USE - The method is useful for anaerobic digestion of wastewater with a high concentration of ammonia nitrogen, organic nitrogen, or proteins, in an UASB, with immobilization of microorganisms and inhibition controlled ammonium.    ADVANTAGE - The method: provides sludge with improved density and settling properties; increases the efficiency of the removal of organic material and the production of biogas (60-70% methane) in more than 20% over the same type reactor used without zeolite; utilizes zeolite-clinoptilolite that has high capacity to remove ammonia nitrogen due to its properties as ion exchanger, and prevents the accumulation of nitrogen, which is toxic to the process; prevents the development of filamentous bacteria; utilizes the UASB reactor that operates at lower retention time, thus reducing the required volume of the digester and is cost effective; and produces sludge having high concentration of nutrients.    DETAILED DESCRIPTION - Anaerobic digestion of wastewater with a high concentration of ammonia nitrogen, organic nitrogen, or proteins, in an upflow anaerobic digester and sludge blanket (UASB), with immobilization of microorganisms and inhibition controlled ammonium, comprises: (a) inoculating well digested sludge wastewater with a high concentration of nitrogen or of proteins that are contained in the digester; (b) adding to residual inoculated wastewater from step (a), zeolite-clinoptilolite having an average particle size of 0.5-2 mm, at 15-23 vol.% of zeolite based on the total volume of sludge; (c) adding to granular activated sludge resulting from step (b), increasing volumes of wastewater with a high concentration of nitrogen or protein to reach stable predetermined operating conditions; (d) monitoring the operation of the digester under predetermined stable operating conditions of step (c), to quantify the removal of organic matter and ammonia nitrogen in the digesters effluent, the concentration of nitrogen in the digester, the biogas production in the effluent digester and the methane concentration in the biogas; (e) adding zeolite in the accumulation of granular activated sludge of the digester, to detect at least an increase in concentration of ammonium nitrogen in the effluent of the digester, a decrease in removal efficiency, a decrease in removal efficiency of organic material or a decrease in biogas production, where the the volume of sludge in the digester is kept constant, in a proportion of 20% based on the total volume of the digester; and (f) optionally removing the excess sludge produced from the bottom of the digester, and subjecting it to dehydration by using sunlight or an alternative method so that a high concentration material is obtained with nutrients with a moisture concentration of 20-30%, which can be used as a biofertilizer or slow release fertilizer nutrients.