pH对MAP沉淀法去除尿液中氮磷的影响

Research on Affecting of pH in Nitrogen—Phosphorus Removal and Recovery from Human Urine with MAP Crystallization

目的研究不同pH值对MAP沉淀法处理预反应尿液中氮磷污染物的影响,并得出反应过程最佳pH值.方法以MgCl2.6H2O为投加镁盐,Na2HPO4.12H2O为外加磷源,在最佳反应条件下,即n(Mg)∶n(P)∶n(N)=1.4∶1∶0.9,搅拌速度100 r/min,反应时间15 min,沉降时间30 min,温度20～25℃,调节pH值,考察氮磷去除效果以及反应过程的变化.结果 pH=10时氨氮去除率最高,达到92.5%;pH>10时,氨氮去除率降低.pH=10时,PO34-的去除率最高,在90%以上,pH大于10以后将不再是磷酸铵镁结晶反应,而副反应使PO34-消耗,导致去除率增加.综上所述,最佳pH值仍取10.结论 pH为MAP沉淀法处理尿液中氨氮的重要影响因素,随着pH值的增加,氨氮的去除率先增大后减小,PO34-去除率随pH的上升而增加,过高的pH会有副产物产生,pH还对反应中沉淀快慢,沉淀颗粒大小和沉淀量都有一定影响.

Fresh urine used to be handling object in this experiment,the effect that pH for the recovery and removal nitrogen and phosphorus of urine and reaction process was researched in MAP sedimentation process after pretreatment.Adopting MgCl2·6H2O as adding Magmesium,Na2HPO4·12H2O as plusing Phosphorus source,we researched the effect that different pH for the recovery and removal nitrogen and phosphorus of urine and reaction process under the best conditions in the reaction（When the molar ratio of Mg/P/N was above 1.4：1：0.9,of reaction time,precipitation time,temperature and mixing speed could be set at 15 min,30 min and 100 r/min,20～25 ℃,respectively.）pH is the important influencing factors for the reaction of MAP precipitation.Taking the lead in the removal ratio of ammonia increased and then decreased with the increase in pH,the highest removal rate reached 92.5%.And the removal ratio of PO3-4increases with the pH increasing.However,high pH will produce by-products.In addition,the reaction speed of the process of sedimentation,sedimentation particle size and amount of precipitation are derived from the pH.pH is the significant influencing factors for MAP precipitation treatment of ammonia nitrogen in the urine.The experiment results show that the optimal pH is 10 in the recovery and removal process.