Heterogeneous fluidized-bed Fenton process: Factors affecting iron removal and tertiary treatment application
Heterogeneous fluidized-bed Fenton process: Factors affecting iron removal and tertiary treatment application
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DOI：
10.1016/j.cej.2018.07.037
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发表时间：
2018-11-15
影响因子：
15.1
通讯作者：
Boonrattanakij, Nonglak
中科院分区：
文献类型：
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作者：
Anotai, Jin;Wasukran, Naruemol;Boonrattanakij, Nonglak
研究了以建筑砂为介质的流化床Fenton反应器除铁的影响因素。在最佳条件下，流化床Fenton法可以去除大部分颗粒铁。流体化介质非均相成核可使铁结晶的表面积和水力停留时间是控制除铁效率的关键因素。床层膨胀50%足以达到满意的除铁效果。进一步的床层膨胀对除铁效果没有明显的改善，而且会通过冲刷效应使除铁性能变差，增加能耗。甲酸是有机污染物与羟基自由基氧化产生的羧基中间体之一，其除铁性能明显下降。这是因为它不仅通过络合增加了铁的溶解度，而且还阻碍了氢氧化铁在流化材料上的非均相成核。因此，在除铁方面，流化床Fenton工艺应用于处理低强度废水或作为抛光单元，以限制Fe3+螯合中间体的形成。流化床Fenton反应器作为三级处理单元，可以成功地将制浆造纸二级出水的COD和颜色分别降至120 mg/L和300 ADMI以下。根据水的特性，在最佳保留时间下，总铁去除率可达53 ~ 81%。
In this research, the factors affecting iron removal were determined for a fluidized-bed Fenton reactor using construction sand as the medium. Most of the particulate iron could be removed by the fluidized-bed Fenton process under optimum conditions. The surface area of the fluidized media available for iron crystallization via heterogeneous nucleation and hydraulic retention time were found to be the key factors controlling the iron removal efficiency. Bed expansion of 50% was sufficient for satisfactory iron removal. Further bed expansion did not provide any significant improvement, and could deteriorate the iron removal performance through scouring effect and increase energy consumption. Formic acid, one of the carboxylic intermediates from organic pollutant oxidation with hydroxyl radicals, remarkably deteriorated the iron removal performance. This is because it not only increased iron solubility through complexation but also hindered heterogeneous nucleation of ferric hydroxide onto the fluidized material. Therefore, in terms of iron removal, the fluidized-bed Fenton process should be applied to treat low-strength wastewater or to serve as a polishing unit to limit the formation of Fe3+-chelating intermediates. As a tertiary treatment unit, the fluidized-bed Fenton reactor could successfully and consistently reduce the COD and color of secondary effluents from pulp and paper mills to below the new and more stringent standards of 120 mg/L and 300 ADMI, respectively. Depending on the water characteristics, total iron removal of 53-81% could be achieved at the optimum retention time.