Nitrogen　removal　by　anaerobic　ammonia　oxidation　(anammox)　of　granular　sludge　is　a　globally　important　emerging　technology.　The　ammonium　adsorption　properties　of　anammox　granular　sludge　were　studied　at　varying　initial　ammonium　concentration　and　sludge　concentration.　Factors　affecting　the　absorption　process　as　temperature,　pH,　salinity,　and　metal　cations　were　also　examined.　The　experimental　results　indicated　that　ammonium　adsorption　by　anammox　granular　sludge　occurred　quickly　(in　about　20　min).　The　optimal　pH　was　7.0　and　the　ammonium　adsorption　process　was　significantly　affected　by　temperature,　salinity,　and　metal　cations.　The　experimental　data　were　modeled　using　Langmuir,　Freundlich,　and　Temkin　adsorption　isotherms　and　the　ammonium　adsorption　process　was　fit　to　the　Freundlich　isotherm.　The　kinetic　results　indicated　that　the　experimental　data　fit　well　to　a　pseudo-secondorder　model.　Both　intraparticle　diffusion　and　boundary　layer　diffusion　could　affect　the　ammonium　adsorption　rate.　The　thermodynamic　parameters　Delta　G(0),　Delta　H-0,　and　Delta　S-0　were　evaluated　and　suggested　that　ammonium　adsorption　was　spontaneous　and　exothermic.　These　findings　indicate　that　the　adsorption　of　ammonium　should　be　incorporated　into　models　for　nitrogen　removal,　particularly　for　the　use　of　anammox　granular　sludge.