鸟粪石法沉淀去除氨氮的平衡体系模拟预测

Modeling and prediction for ammonium nitrogen removal in the struvite precipitation equilibrium system

使用化学平衡软件Visual MINTEQ计算拟合鸟粪石(磷酸镁铵,MgNH4PO4·6H2O,MAP)沉淀去除氨氮的平衡体系在不同pH值条件下Mg2+、NH4+和PO34-各组分的变化及饱和指数(SI)的变化.实验和预测结果表明,模型对MAP沉淀平衡体系拟合良好.在本研究的pH值范围内(8.0—11.0),化学平衡模型VisualMINTEQ能预测敞开体系氨氮废水中通过磷酸铵镁沉淀去除的NH4+-N,但不能用来预测敞开体系中所有氨氮的去除,即预测结果中不包括由于氨气挥发而去除的氨氮.

Visual MINTEQ, an useful chemical equilibrium model, was proposed to calculate the equilibrium speciation of MAP （MgNH4POa.6H20）, saturation index （SI）, as Well as to model the availability of Mg2＋ , NH4＋ and PO3/4- ions as a function of pH for ammonium nitrogen removal. The predicted and experimental data suggested that the model described the experiments well. The results showed that the chemical thermodynamics equilibrium model could be used to preetermine the concentration of ammonium precipitated by struvite. Within the ranges of the investigated factors, Visual MINTEQ program can be proposed to pre-determine the concentration of ammonium precipitated volatilization from the investigated system by struvite, but not to predict the NH4-N removal by ammonia open to the atmosphere.