化学沉淀法去除废水中高浓度氨氮研究

本文采用Mg SO4·7H2O和Na2HPO4·12H2O,使含有高浓度NH3-N废水中的氨生成Mg NH4PO4·6H2O结晶沉淀,以此回收废水中高浓度NH3-N.本研究考察了p H值、反应时间t、试剂用量配比对废水中NH3-N去除率的影响.研究结果表明,反应的适宜p H值为8-10之间,过高的p H会破坏形成的晶体结构,导致固定氨从Mg NH4PO4·6H2O中游离出来,对氨氮去除产生不利影响.在参数值p H值为8.0、反应时间t为20min、各试剂离子的量的比Mg^2＋∶NH4^＋∶PO4^3-=1.5∶1∶1.5的最佳条件下,废水总中NH3-N浓度由初始1 981mg/L降低至5mg/L,去除率达95%.化学沉淀法在回收废水中高浓度氨氮的同时,形成了鸟粪石结晶沉淀,是一种优良的缓释肥原料.

The Removal of High NH3-N Concentration in Wastewater by Chemical Precipitation

A lab-scale study was conducted to precipitate the ammonia from high NH3-N concentration wastewater in the form of magnesium ammonium phosphate（MAP）. The influences of p H value,reactive time and removal rate of ammonia nitrogen were tested. The result shows that the feasible p H values of crystallization and precipitation were from 8 to 10. The structure of structure crystallization was destroyed under high p H value condition that resulted in ammonia nitrogen dissociating from MAP,which reduced the removal rate of ammonia nitrogen. Results also demonstrated that ammonia nitrogen was effectively reduced from initial 1981 mg/L to final 5mg/L,which removal efficiency reached 99% with crystallization and precipitation method when the optimal p H, precipitation time mole ratio of Mg^2 ＋,NH4^＋,PO4^3-were 8. 0,20 min and 1. 5∶ 1∶ 1. 5 respectively.