Study On Removing Chlorine Ammonia Wastewater From Rare-earth Smelting

This paper introduces the experimental research on removing ammonia- nitrogen in chlorine ammonia wastewater from rare-earth smelting plant by the method combing chemical precipitation and ion-exchange-absorption under different reaction conditions.1. On the removal of high concentration ammonia-nitrogen in wastewater by chemical precipitation, the efficiency of removal is 60 ～ 90 % when pH=9.0, t=1.5h, m(Mg):m(N):m(P)=1.3:1.0:1.1 and C₀=500～10000mg/L.2. The ammonia-nitrogen wastewater is treated by fine zeolite. When t=1.0h, pH=7.0, T=20℃ and C₀= 100～300mg/L, the removal rate of ammonia-nitrogen is η%=80～95%.3. The formula of NH₄⁺ adsorbed by zeolite is isothermal formula. When the ammonia-nitrogen waterwater of 250mg/L concentration is treated by fine zeolite, the treated wastewater capacity is 7BV.4. When the 500ml ammonia-nitrogen waterwater of 250mg/L concentration treated by the 125g zeolite, the effluent anmmonia-nitrogen concentration is under 25mg/L.5. One of the best zeolite regenerated medicament is the intermixture of NaCl and NaOH (NaCl: NaOH=3:7), and the longevity of the regenerated zeolite is shortened about an hour when it is regenerated once more.6. When the influent ammonia-nitrogen concentration of 9000mg/L is treated by two series of chemical precipitation and one ion-exchange-absorption, the effluent anmmonia-nitrogen concentration is under 25mg/L, which reaches the secondary effluent standard.