化学沉淀法去除木薯制备酒精废水中氨氮的试验研究

针对NH_3-N质量浓度为500~900mg/L木薯制备酒精的废水,采用正交试验及单因素试验研究了用化学沉淀法去除废水中氨氮的工艺条件,结果表明:以MgCl_2·6H_2O和Na2HPO4·12H_2O为沉淀剂,在pH=9.0时废水溶液中PO_4~(3-)与Mg~(2+)和NH_4~+一起发生沉淀反应生成MgNH4PO4·6H_2O,从而达到去除废水中的氨氮的目的;影响废水中的氨氮去除率的因素依次为n(Mg~(2+):NH_4~+),反应时间,n(PO_4~(3-)∶NH_4~+)和pH值。最佳反应条件是当pH=9.0,n(Mg~(2+))∶n(NH_4~+)∶n(PO_4~(3-))=1.4∶1.0∶1.2,常温下反应30min,静置30min,该工艺条件下,对初始氨氮为644.5mg/L的木薯制备酒精的废水进行处理,其氨氮的去除率90%。

The Experimental Study on Chemical Precipitation to Remove Ammonia Nitrogen in Alcohol Wastewater Prepared from Cassava

According to the NH3-N alcohol wastewater prepared from cassava with the concentration of 500-900 mg·L-1.The orthogonal experiment and single factor test are used to study the removal of ammonia nitrogen from wastewater by chemical precipitation.The experimental results indicate that taking MgCI2·6H2O and Na2HPO4·12H2O as precipitants MgNH4PO4·6H2O has been gotten in the wastewater of pH =9.0,with PO3-4,Mg2+and NH+4 to precipitating together,in order to remove ammonia nitrogen in wastewater;the factors affecting the removal rate of ammonia nitrogen in wastewater are in the sequence of n(Mg2+∶NH+4),reaction time,n (PO3-4:NH+4)and pH value.The best reaction condition is pH=9.0,n(Mg2 +)∶n(NH+4)∶n(PO3-4) =1.4∶1.0∶1.2.The reaction at room temperature is for 30 min,and at standing state is for 30 min.Under this technique condition,the treatment to alcohol wastewater prepared from cassava with the initial ammonia nitrogen rate of 644.5 mg/L has been made,and the ammonia nitrogen removal rate is >90%.