以农田高盐排水为替代镁源回收养殖废水中的磷素

Recovery of phosphorus from livestock wastewater using high salt drainage of farmland as an alternative magnesium source

为解决新疆南疆地区养殖废水高浓度氮磷和农田排水中的高浓度盐分的协同污染问题,以农田高盐排水为镁源对模拟养殖废水中的磷进行了回收实验,对比了高盐排水和常规镁源的磷回收效率,探讨了影响其回收的主要因素,并通过正交试验获得了高盐排水回收磷的最优反应条件。与常规MgCl_(2)镁源的磷回收对比分析结果表明,pH=10时高盐排水回收磷的效率最高,比MgCl_(2)镁源达最大回收率所需的反应pH略高;利用L^(4)_(3)正交试验探究了pH(8、9、10、11)、Mg∶P摩尔比(1.0、1.5、2.0、2.5)、N∶P摩尔比(1.0、1.5、2.0、4.0)对高盐排水镁源回收磷的影响,并结合SPSS统计分析得到高盐排水回收磷的最优反应条件为pH=10、n(Mg)∶n(P)=2.5,n(N)∶n(P)=4;高盐排水中的HCO_(3)^(−)和SO_(4)^(2−)离子对磷回收有抑制作用,而Ca^(2+)离子对磷回收有促进作用;XRD和SEM-EDS分析表明,高盐排水回收磷的产物以鸟粪石为主,并夹杂着磷灰石和粘土矿物等杂质。整体上,以高盐排水作为替代镁源回收磷的效果较好,本研究为解决鸟粪石沉淀法的镁源问题提供了一种新思路。

In order to solve the synergistic pollution problem of high concentration nitrogen and phosphorus in livestock wastewater and high salt concentration in farmland drainage in southern Xinjiang.In this paper,the recovery experiment of phosphorus from simulated livestock wastewater was conducted with high salt drainage from agricultural soil as magnesium source.The phosphorus recovery efficiency between high salt drainage and conventional magnesium source was compared,and the main factors affecting the phosphorus recovery efficiency were also discussed.The optimal reaction conditions for phosphorus recovery by high salt drainage were determined through orthogonal test.In comparison with MgCl_(2)magnesium source,the maximum phosphorus recovery rate occurred at pH=10 by the high salt drainage,which was slightly higher than the reaction pH required by MgCl_(2)magnesium source.L_(3)^(4) orthogonal test combined with SPSS statistical analysis were conducted to study the effects of pH(8,9,10,11),Mg∶P molar ratio(1.0,1.5,2.0,2.5),and N∶P molar ratio(1.0,1.5,2.0,4.0)on phosphorus recovery by high salt drainage magnesium source.The optimum reaction conditions for phosphorus recovery were pH=10,n(Mg)∶n(P)=2.5,n(N)∶n(P)=4.HCO_(3)^(−),and SO_(4)^(2−) in high salt drainage inhibited the phosphorus recovery,while Ca^(2+) promoted P recovery.XRD and SEM-EDS revealed that the precipitation products were mainly guanite and mixed with impurity minerals of apatite and clay.Overall,high salt drainage as a substitute for magnesium source has a good effect on phosphorus recovery,which provided a new strategy to solve the magnesium source problem of struvite precipitation method.