Capture and recycling of ammonium by dolomite-aided struvite precipitation and thermolysis
Capture and recycling of ammonium by dolomite-aided struvite precipitation and thermolysis
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DOI：
10.1016/j.chemosphere.2017.08.065
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发表时间：
2017-11-01
期刊：
影响因子：
8.8
通讯作者：
Chu, Mao Quan
中科院分区：
文献类型：
--
作者：
Chen, Liang;Zhou, Chun Hui;Chu, Mao Quan
NH 4+的捕集和再利用是处理含NH 4+废水的理想方法。捕获和再利用过程需要清洁且具有成本效益。然而，目前存在许多障碍，特别是在所需化学源的可获得性、成本和回收方面。在这里，我们展示了一种清洁和有效的方法来捕获和回收NH 4+的沸石辅助鸟粪石沉淀过程。以CO2气氛下煅烧的白云石为镁源，在模拟废水（2000 mg L-1 NH 4+）中与PO 43-（KH 2 PO 4）和NH 4+反应。在nMg（2+）：nNH（4）（+）：nPO（4）（3-）= 1：1：1.2和pH = 8.0的条件下进行沉淀2 h，89.7%的NH 4+以鸟粪石沉淀的形式回收。模拟废水中K+和NH 4+的竞争导致了磷酸钾镁中心点6 H（2）O和磷酸铵镁中心点6 H（2）O的形成。鸟粪石的形成导致NH 4+去除率下降。鸟粪石在110 ℃下加热4 h时，其NH 4+释放率可达75.7%。在MgNH_4PO_4中心点6 H（2）O和CaCO_3的混合物中，容易形成不稳定的Ca ~（2+）-CO_3 ~（2-）-NH_4 ~+体系。鸟粪石沉淀-热处理-再沉淀过程中得到的Mg、P元素可重复利用。在pH = 9.0、nMg（2+）：nNH（4）（+）：nPO（4）（3-）=1：1：1、反应时间2 h的条件下，经过6次循环后，模型废水中NH 4+的去除率可达783%。(C)2017爱思唯尔有限公司版权所有
The capture and reuse of NH4+ is an ideal solution to treat NH4+-containing wastewater. The capture and reuse process needs to be clean and cost-effective. Currently, however, there are many obstacles, particularly in the availability, cost, and recovery of the chemical sources required. Here, we demonstrate a clean and efficient method to capture and recycle NH4+ by a dolomite-aided struvite precipitation process. Dolomite calcined carefully in CO2 atmosphere was used as a Mg source to react with PO43-(KH2PO4) and NH4+ in model wastewater (2000 mg L-1 NH4+). The precipitation was performed at nMg(2+):nNH(4)(+):nPO(4)(3-) = 1:1:1.2 and pH = 8.0 for 2 h; 89.7% of NH4+ was recovered in the form of struvite precipitate. The competition between K+ and NH4+ in the model wastewater led to the formation of K-struvite (MgKPO4 center dot 6H(2)O) and struvite (MgNH4PO4 center dot 6H(2)O). The formation of K-struvite resulted in a decrease in the NH4+ removal rate. When struvite was heated at 110 degrees C for 4 h, the NH4+ release rate from the thermolysis reached 75.7%. Thermolysis readily occurred as an unstable Ca2+-CO32--NH4+ system formed in the mixture of MgNH4PO4 center dot 6H(2)O and CaCO3. The elements Mg and P that were obtained during the struvite precipitation-thermolysis-reprecipitation process can be repeatedly used. After 6 cycles, under the conditions pH = 9.0, nMg(2+):nNH(4)(+):nPO(4)(3-) =1:1:1 and reaction time of 2 h, up to 783% of NH4+ was removed from the model wastewater. (C) 2017 Elsevier Ltd. All rights reserved.