Jiangxi Key Laboratory of Mining & Metallurgy Environmental Pollution Control, Jiangxi University of Science and Technology, Ganzhou, 341000, PR China.
Sci Rep. 2020 May 6;10(1):7672. doi: 10.1038/s41598-020-64634-9.
Ammonium-nitrogen (NH-N) recovery from high concentration of NH-N-containing wastewater by struvite (MgNHPO·6HO, MAP) precipitation method has been realized, but whether NH-N recovery under different reagent adding sequence of NaOH, solid Mg salt and P salt can generate different effects, remains ambiguous. In view of the problem, four modes to add reagents were investigated in detail on the formation of struvite. The results show that the Mode IV (M-IV, i.e. using 50% NH-N wastewater to dissolve completely the Mg salt and the P salt, respectively and then simultaneously poured into a beaker to mix the solution evenly and adjust the pH to 9.5.) has the highest NH-N recovery efficiency (90.80%) and the maximum mass of precipitates (896 mg) because of the more amount of alkali and initial seed formation. From the morphology of the obtained precipitates, it can be seen that sample M-IV is more loose and porous than the others. XRD patterns show that the four products under the different modes basically agree with the standard MAP.
通过鸟粪石（MgNH4PO4·6H2O，MAP）沉淀法从高浓度含 NH-N 废水中回收氨氮（NH-N）已经实现，但在添加 NaOH、固体 Mg 盐和 P 盐的不同试剂添加顺序下，NH-N 回收是否会产生不同的效果，尚不清楚。针对这一问题，详细研究了在形成鸟粪石时四种加试剂的模式。结果表明，模式 IV（M-IV，即使用 50% NH-N 废水分别完全溶解 Mg 盐和 P 盐，然后同时倒入烧杯中混合均匀溶液并将 pH 值调节至 9.5）具有最高的 NH-N 回收效率（90.80%）和最大的沉淀物质量（896mg），因为有更多的碱和初始晶种形成。从获得的沉淀物的形态可以看出，与其他模式相比，样品 M-IV 更疏松多孔。XRD 图谱表明，在不同模式下得到的四种产物基本与标准 MAP 一致。
