The ability for removing ammonia-nitrogen of biomembrane cultured in fresh water decreased gradually with increases in salinity and its rise velocity.When the salinity rose to 13.3,23.9 and 31.3 from 0.6 respectively and was steadied for 48 h,the removing rates of the ammonia-nitrogen of biomembrane were 100%,93.0% and 86.9% respectively.When the salinity reduced to 0.6 from 31.3 with different velocity,the ability of removing ammonia-nitrogen of biomembrane resumed basically to normal,and removing rate of ammonia-nitrogen reached over 90%.The ability for removing ammonia-nitrogen of zeolite by absorption for 24-36 h was stronger than that of porcelain biochemical ring.But by absorption for 48 h,removing rate(95.1%) of ammonia-nitrogen of the porcelain biochemical ring was close to that(100.0%) of zeolite.The removing rate(99.2%) of ammonia-nitrogen of biological zeolite for 48 h was slightly higher than that(95.2%) of natural zeolite.