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自厌氧氨氧化(anaerobic ammonium oxidation,Anammox)工艺诞生以来,凭借其经济、高效与可持续性而成为生物脱氮领域一大研究热点,并被公认为是时下最具有工程应用前景的新型生物脱氮工艺。然而受制于厌氧氨氧化菌(anaerobic ammonia oxidant,AnAOB)的生长速率较慢,世代周期较长等因素[1],导致厌氧氨氧化菌富集难,反应器启动慢,加上运行不稳定等问题较长,影响了厌氧氨氧化工艺规模化工程应用。此外AnAOB对pH、O2等生长环境因素极为敏感,易受到干扰物质的抑制。因此,学者们围绕厌氧氨氧化反应器的启动及稳定运行开展了相关研究[2]。
近些年来,研究发现Anammox中包含了大量以血红素和硫铁蛋白形式存在的细胞铁,并且铁元素也作为重要的辅助因子参与厌氧氨氧化脱氮的过程中[3]。袁欣眀等[4]利用Fe(Ⅲ)促进血红素的合成强化了Anammox工艺,任立峰等[5]利用铁元素历时84 d成功启动Anammox工艺。铁元素的存在会促进厌氧氨氧化菌的生长[6],而不同形态和价态的铁离子促进作用也不同。与其他形式的单质铁相比纳米零价铁 (nano zero valent iron,nZVI)具有更大的比表面积,更强的还原性,能够快速消耗溶解氧,从而降低氧化还原电位,有利于维持厌氧氨氧化需要的厌氧环境[7]。有研究表明,合适的nZVI投加有利于提高厌氧氨氧化微生物活性[8]。nZVI腐蚀产生的铁离子(Fe(II)/Fe(III)是包括在厌氧氨氧化酶分解代谢中起关键作用的细胞色素c蛋白、肼合酶和肼脱氢酶等血红素酶的重要成分[9]。
由于nZVI易氧化、团聚,难以液相中均匀分布,研究者提出碳基质-nZVI复合材料,有利于nZVI分散和腐蚀[10],使其在生物反应器体系中更好地与微生物接触。同时碳基质-nZVI可使Fe(0)与碳紧密接触,产生原电池反应,在反应器中产生微电流促进氧化还原反应,吸附沉淀等反应,有利于污染物去除,被应用于Anammox脱氮研究中[11]。
生物炭(biochar,BC)来源广泛,价格低廉,多为农林废弃物经加工产生的富碳、多孔的固体物质,并能长期停留在环境介质中[12],可通过物理吸附、离子交换等多种机制降解污染物,此外,适量的BC还能改善AnAOB性能,加速Anammox工艺的启动[13]。但单一的生物炭材料物理化学性能稳定,不能满足复杂污染物的处理。因此,目前有研究人员对纳米零价铁进行改性,将纳米零价铁负载在比表面积大、官能团丰富、孔隙率高和稳定性好的生物炭上,构建微电解体系,充分发挥两者的优势。但现有的研究通常将两种材料按照一定比例充分混合,仍存在铁碳负载不均匀的局限性。
基于以上研究现状,本研究改进负载方法,利用液相还原法将nZVI充分分散于生物炭孔隙表面,对所制备材料的表面形貌和结构进行了表征。并在EGSB反应器中,探究在BC-nZVI诱导下Anammox工艺的快速启动、长期运行特性,以及氮转化规律,研究不同pH条件下复合材料对厌氧氨氧化体系中氮元素转化的影响,分析微生物群落结构的变化特征,探索了BC-nZVI对厌氧氨氧化工艺的启动的影响,为Anammox工艺的工程应用提供理论支持和技术参数。
BC-nZVI诱导厌氧氨氧化工艺的快速启动及运行特性
Rapid start-up and the operation characteristics of Anammox process induced by BC-nZVI
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摘要: 厌氧氨氧化工艺的启动周期和稳定性已成为工程化应用的制约因素,铁元素可促进厌氧氨氧化菌的生长,BC-nZVI诱导下厌氧氨氧化工艺的启动与长期稳定运行特性是值得研究的课题。为此,采用液相还原法制备BC-nZVI复合材料,成功将粒径100~500 nm的nZVI负载于生物炭表面。在膨胀颗粒污泥床(expanded granular sludge bed,EGSB)中,BC-nZVI的投加大幅缩短了Anammox工艺的启动时间,提高了氮负荷冲击性能以及在弱酸性环境下的适应能力。通过投加30 mg·L−1 BC-nZVI,仅需43 d即可快速启动Anammox工艺,总氮去除负荷和去除率稳定在0.22 kg·d−1和80%以上。在BC-nZVI强化成熟的污泥体系中,浮霉菌门(Planctomycetota)和变形菌门(Proteobaxteria)占主导,其中 unclassified-Brocadiaceae作为AnAOB优势菌属相对丰度达22.3%,成为绝对的优势功能菌。Abstract: The start-up period and stability of the Anammox process have become the limiting factors of its engineering applications. Iron can promote the growth of Anammox bacteria. The start-up and long-term stable operation characteristics of the Anammox process induced by BC-nZVI are the topics worthy of study. In this study, BC-nZVI composites were prepared by a liquid-phase reduction method, and nZVI with particle size of 100-500 nm was successfully loaded on the surface of biochar. In EGSB(Expanded Granular Sludge Bed), the addition of BC-nZVI significantly shortened the start-up time of the Anammox process, and improved the resistance to the nitrogen shock loads, as well as the adaptability in weakly acidic environments. By adding 30 mg·L−1 BC-nZVI, the Anammox process could be quickly started only after 43 days, and the total nitrogen removal load and removal rate were stable at 0.22 kgTN·d−1 and above 80%, respectively. In the mature sludge system enhanced by BC-nZVI, Planctomycetota and Proteobaxteria dominated. Of them, unclassified_Brocadiaceae. as the dominant AnAOB genus, had a relative abundance of 22.3%, becoming the absolute dominant functional bacteria.
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Key words:
- EGSB /
- Anammox /
- Feammox /
- fast start-up /
- nano zero-valent iron(nZVI) /
- nitrogen removal efficiency.
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表 1 反应器运行工况
Table 1. Operating conditions of the reactor
运行阶段 时间/d 进水氨氮质量浓度/
(mg·L−1)进水亚硝质量浓度/
(mg·L−1)HRT/h 氮负荷/
(kg·d−1)阶段Ⅰ 1~30 50 66 26 0.11 阶段Ⅱ 30~60 100 132 26 0.22 阶段Ⅲ 60~90 100 132 13 0.42 表 2 铁促进厌氧氨氧化启动时间对比
Table 2. Comparison of the start-up time of iron-promoted Anammox
表 3 微生物物种多样性指数
Table 3. Microbial species diversity index
样品 物种丰度 群落多样性 覆盖率/% ACE指数 Chaol指数 Shannon指数 Simpson指数 R0 1 182 1 168 5.32 0.01 99.81 R1 1 172 1 161 4.75 0.05 99.63 -
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