Abstract: Blow-off method was used to treat rare-earth ammonia chloride waste water and the optimal process parameters achieved in the experiment include a pH value of 12, blow-off temperature of 30 ℃, blow-off time of 3h and gas-liquid ratio of 6000. At these conditions, an ammonia-nitrogen removal rate of 97.20% can be obtained and its concentration in the waste water can be reduced from 12017.6mg/L to 336mg/L. A further application of the combination of secondary blow-off and reverse osmosis can make the waste water reach the state standard for discharge.

Key words: Rare-earth waste water, Ammonia chloride, Blow-off method, Ammonia-nitrogen.