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针对现有流化床鸟粪石造粒法回收废水中氮磷时缺乏有效的方法定量描述颗粒的形貌及对应的组分含量,综合图像法、FTIR、XRD、元素组成分析和物料衡算等方法,分析了分段式流化床不同区域的颗粒形貌及对应的组分情况。研究结果表明,流化床不同区域内上升流速分别为15.0、30.6和60.0mm/s,对应鸟粪石颗粒平均粒度分别为703、963和1747μm,相应的颗粒形貌为絮团、团聚式颗粒和包层式颗粒。颗粒的主要成分为鸟粪石(MgNH_4PO_4·6H_2O,MAP)、钾型鸟粪石(MgKPO_4·6H_2O,MKP)、无定型磷酸钙(Ca_3(PO_4)_2·xH_2O,ACP)其中MAP含量均大于92%,ACP1.26%~1.75%,MKP含量为3.75%~3.91%,有机物含量低于0.4%。回收的颗粒中Cr、As、Cd和Pb等重金属含量低于现行的化肥重金属控制标准(GB/T23349-2009)限值,有效降低了重金属污染的风险,提高了回收颗粒的品质。
In view of the lack of an effective method to quantitatively describe the particle morphology and the corresponding component content when the existing fluidized bed struvite granulation method is used to recover nitrogen and phosphorus in waste water, the integrated image method, FTIR, XRD, elemental composition analysis and material balance And other methods, analysis of different parts of the fluidized bed particle morphology and the corresponding components. The results show that the upflow velocities in different regions of the fluidized bed are respectively 15.0, 30.6 and 60.0 mm / s, and the corresponding mean particle sizes of struvite are 703, 963 and 1747 μm, respectively. The corresponding particle morphology is flocs, agglomerated particles And clad particles. The main components of the particles were struvite (MgNH 4 PO 4 · 6H 2 O, MAP), potassium type struvite (MgKPO 4 · 6H 2 O, MKP) and amorphous calcium phosphate (Ca 3 PO 4 · xH 2 O, ACP) %, ACP 1.26% ~ 1.75%, MKP 3.75% ~ 3.91%, and organic content less than 0.4%. The content of heavy metals such as Cr, As, Cd and Pb in the recycled particles is lower than the limit of the current control standard for heavy metal fertilizers (GB / T23349-2009), effectively reducing the risk of heavy metal pollution and improving the quality of recovered particles.