Research Centre for Environmental Health and Pollution Control, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China; Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong.
Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong.
Water Res. 2016 Mar 1;90:9-14. doi: 10.1016/j.watres.2015.12.014. Epub 2015 Dec 13.
Struvite (MgNH4PO4·6H2O) crystallization from wastewater can gain a great advantage for phosphorus recovery and recycling. Although the recovery process and reaction modeling have been investigated, few studies have been conducted to quantify the different phases in recovered phosphorus products. The quantitative X-ray diffraction (QXRD) technique was employed in the present study to quantitatively determine the crystal phases and amorphous content of recovered struvite-containing products. Substantial mixed phase samples (i.e. struvite, newberyite and amorphous phase) were prepared to perform quantitative analysis to calibrate against known phase composition information by Rietveld refinement on powder X-ray diffraction data. The results showed a high level of accuracy (mean error = ∼3%) in our quantification model and validated the use of the Rietveld method to quantify the amorphous and crystal phases in the struvite-containing products. In addition, the influence of N:P molar ratio on struvite crystallization suggested that the weight percentage of struvite increased from 52% to 93%, when the N:P molar ratio was elevated from 0.2:1 to 1.2:1. This finding suggested the effectiveness of QXRD in facilitating the recovery of quality struvite products from waste streams.
从废水中回收鸟粪石（MgNH4PO4·6H2O）结晶，可获得回收磷和循环利用的巨大优势。尽管已经研究了回收工艺和反应模型，但很少有研究定量分析回收磷产品中的不同相。本研究采用定量 X 射线衍射（QXRD）技术定量测定回收含鸟粪石产品中的晶体相和无定形含量。制备了大量的混合相样品（即鸟粪石、新水磷矿和无定形相），通过粉末 X 射线衍射数据的 Rietveld 精修对已知相组成信息进行校准，以进行定量分析。结果表明，我们的定量模型具有很高的准确性（平均误差约为 3%），验证了 Rietveld 方法可用于定量测定含鸟粪石产品中的无定形和晶体相。此外，N:P 摩尔比对鸟粪石结晶的影响表明，当 N:P 摩尔比从 0.2:1 升高到 1.2:1 时，鸟粪石的重量百分比从 52%增加到 93%。这一发现表明 QXRD 有助于从废水中回收高质量的鸟粪石产品。
