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A Bipolar Membrane-Integrated Electrochlorination Process for Highly Efficient Ammonium Removal in Mature Landfill Leachate: The Importance of ClO• Generation
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2022-10-14 , DOI: 10.1021/acs.est.2c05735
Wenjie Kuang 1 , Zhang Yan 1 , Jinxiu Chen 2 , Xiaotang Ling 2 , Wenxiao Zheng 1 , Weijun Huang 1 , Chunhua Feng 1
Affiliation  

Electrochemical oxidation has been demonstrated to be a useful method for removing biorefractory organic pollutants in mature landfill leachate but suffers from low efficiency in eliminating ammonium because of its resistance to being oxidized by HO or free chlorine (FC) at decreased pH. Here, we propose a new bipolar membrane-electrochlorination (BPM-EC) process to address this issue. We found that the BPM-EC system was significantly superior to both the undivided and divided reactors with monopolar membranes in terms of elevated rate of ammonium removal, attenuated generation of byproducts (e.g., nitrate and chloramines), increased Faradaic efficiency, and decreased energy consumption. Mechanistic studies revealed that the integration of BPM was helpful in creating alkaline environments in the vicinity of the anode, which facilitated production of surface-bound HO and FC and eventually promoted in situ generation of ClO, a crucial reactive species mainly responsible for accelerating ammonium oxidation and selective transformation to nitrogen. The efficacy of BPM-EC in treating landfill leachates with different ammonium concentrations was verified under batch and continuous-flow conditions. A kinetic model that incorporates the key parameters was developed, which can successfully predict the optimal number of BPM-EC reactors (e.g., 2 and 5 for leachates containing 589.4 ± 5.5 and 1258.1 ± 9.6 mg L–1 NH4+-N, respectively) necessary for complete removal of ammonium. These findings reveal that the BPM-EC process shows promise in treating ammonium-containing wastewater, with advantages that include effectiveness, adaptability, and flexibility.

中文翻译:

双极膜集成电氯化工艺可高效去除成熟垃圾渗滤液中的氨:ClO• 生成的重要性

电化学氧化已被证明是去除成熟垃圾渗滤液中难生物降解有机污染物的有效方法,但由于其在 pH 值降低时难以被H2O或游离氯 (FC)氧化,因此消除铵的效率较低。在这里,我们提出了一种新的双极膜电氯化(BPM-EC)工艺来解决这个问题。我们发现,BPM-EC 系统在提高氨去除率、减少副产物(例如硝酸盐和氯胺)的产生、提高法拉第效率和降低能耗方面均明显优于带有单极膜的非分隔式反应器和分隔式反应器。 。机理研究表明,BPM的集成有助于在阳极附近创造碱性环境,促进表面结合的H2O ·和FC的产生,并最终促进ClO·的原位生成,ClO ·是一种关键的反应物种,主要负责加速氨氧化和选择性转化为氮。在间歇和连续流条件下验证了BPM-EC处理不同铵浓度的垃圾渗滤液的效果。开发了包含关键参数的动力学模型,可以成功预测 BPM-EC 反应器的最佳数量(例如,对于含有 589.4 ± 5.5 和 1258.1 ± 9.6 mg L –1 NH 4 + -N 的渗滤液,分别为2 和 5 个) )是完全去除铵所必需的。这些发现表明,BPM-EC 工艺在处理含铵废水方面显示出前景,具有有效性、适应性和灵活性等优势。
更新日期:2022-10-14
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