This study aimed to analyze the optimal conditions for simultaneous ammonium adsorption and biological nitrate denitrification and to determine the cation adsorption capacity of zeolite in contaminated salt water. We also attempted to quantify the effect of physical regeneration viathe stirring of zeolite to desorb the biofilm. Biological analysis showed that Nitrosomonas maria and Nitrosomonas europe were the dominant halophilic ammonia-oxidizing bacteria, while Hyphomicrobium, a facultative anaerobe, was the dominant denitrifying bacterium. When the biofilm was partially desorbed by stirring the zeolite, the ammonium in the water was more rapidly removed than when not stirred. When the hydraulic retention time was 60 minor longer, the zeolite was stirred to improve the ammonium adsorption capacity. Witha hydraulic retention time of 120 min, the ammonium removal rate was highest (76.3%) when stirred twice a day, while the nitrate removal rate was highest (43.2%) when stirred once a day. In conclusion, moderatedesorption was more effective than excessive desorption in terms of maintaining appropriate levels of nitrifying and denitrifying microorganisms.