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人工湿地是一种集生态和景观性于一体的高效低耗的废水生态处理技术。随着人工湿地越来越广泛的应用于处理垃圾渗滤液、畜禽养殖废水厌氧消化液和食品废水等高氮低碳废水,有机碳源的匮乏已成为制约人工湿地高效脱氮的瓶颈,特别是针对总氮(TN)的高效去除[1-2]。长期以来,反硝化作用被人们一直认为是将活性氮转化为氮气(N2)的唯一途径,然而在实际运行的湿地中,针对高氮低碳废水的传统硝化和反硝化脱氮能力被限制在一定水平,且由于传统厌氧反硝化过程需要大量碳源,往往需要外加碳源以补充其不足,从而导致其处理废水成本较高[1, 3]。
近年来日益成熟的厌氧氨氧化处理工艺为解决此问题提供了新的途径。厌氧氨氧化(anaerobic ammonia oxidation, anammox)过程是指在厌氧条件下分别以氨盐(NH4+)和亚硝酸盐(NO2−)为电子供体和电子受体的高效生物脱氮过程,该过程无需碳源,且伴随硝酸盐(NO3−)的生成[4-5]。随着分子生物学技术的发展,荧光定量PCR和高通量测序已被用于人工湿地中厌氧氨氧化菌的研究[5-7]。厌氧氨氧化过程已经被证明可以成为人工湿地中主要的脱氮过程,发挥高效的脱氮作用[1, 6, 8]。同时有研究表明,在人工湿地中厌氧氨氧化菌呈现出种群多样性[6, 8];C/N比、植物等环境因子和反硝化作用等脱氮过程对厌氧氨氧化菌的群落、丰度有着重要的影响[5, 9-10]。
目前虽然有学者对不同C/N条件下厌氧氨氧化菌在人工湿地的存在特征有少量研究,但在不同C/N和湿地植物多重耦合作用下针对处理高氮低碳废水的人工湿地中厌氧氨氧化菌的存在特征却尚乏报道。基于此,本文通过不同C/N比和植物配置,构建4组垂直流人工湿地处理高氮低碳废水,考察各湿地中氮污染物的去除差异;利用荧光定量PCR和高通量测序技术,对比研究各湿地的微生物群落、主要功能微生物及厌氧氨氧化菌的存在特征,进一步探讨C/N和湿地植物多重耦合作用下对湿地中厌氧氨氧化菌的影响特征。
处理高氮低碳废水的垂直流人工湿地中厌氧氨氧化菌分布特征
Distribution characteristics of anammox bacteria in vertical flow constructed wetlands for treating high-nitrogen wastewater with low carbon
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摘要: 为探明C/N和湿地植物对湿地中厌氧氨氧化菌的影响特征,基于不同C/N比和植物配置,构建4组垂直流人工湿地处理高氮低碳废水,研究其对氮污染物的去除特征差异,并利用荧光定量PCR技术和高通量测序技术对湿地中的主要功能微生物及厌氧氨氧化菌的分布特征进行分析。结果表明,在进水TN浓度为779.33 mg·L−1时,各湿地的TN平均去除率分别为75.48%、84.90%、77.94%和80.16%。整体来看,无碳源有植物湿地的脱氮效果最佳;有碳源湿地的脱氮效果优于无碳源无植物湿地;且有植物湿地的脱氮效果优于无植物湿地。各湿地中微生物群落结构在门上平上存在显著差异,且厌氧氨氧化菌属结构存在显著差异。 各湿地中均检出4种厌氧氨氧化菌属,其中Candidatus Kuenenia属在各湿地中占比最高(> 90%)。无碳源有植物湿地中厌氧氨氧化菌属相对丰度最高,且有植物湿地均高于无植物湿地,表明有植物无碳源的湿地系统更加有利于厌氧氨氧化的生长繁殖,而碳源的添加会对其起抑制作用,但植物在一定程度上可缓解碳源对厌氧氨氧化菌生长的抑制。各人工湿地系统的主要脱氮途径为厌氧氨氧化过程,且在不同程度上存在厌氧氨氧化与反硝化的协同耦合脱氮。Abstract: Based on different C/N ratio and plant configurations, four sets of vertical flow constructed wetlands (CWs) were constructed to treat high-nitrogen wastewater with low-carbon. The differences in characteristics of nitrogen pollutants treatment were studied, and the distribution characteristics of the main functional microorganisms and anaerobic ammonia oxidation (anammox) bacteria were analyzed. The results showed that when the influent TN concentration was 779.33 mg·L−1, the average removal efficiencies of TN in each CWs were 75.48%, 84.90%, 77.94% and 80.16%, respectively. By comparison, the CW treatment with plants and no carbon source showed the best nitrogen removal performance, and the CW treatment with carbon sources attained better nitrogen treatment performance than CW treatment with no carbon sources and no plants. Meantime, the CWs treatment with plants nitrogen treatment performance was better in than CWs without plants. At phylum level, there were significant differences in the microbial community structure in each CWs. Besides, there were significant differences in the structure of anammox bacteria among CWs. Four anammox bacteria genera were detected in each CWs, in which Candidatus Kuenenia accounted for the highest proportion (> 90%). The relative abundance of anammox bacteria genera in CW with plants and no carbon sources was the highest, and CWs with plants are higher than CWS without plants, indicating that CW system with plants and no carbon sources are more conducive to the growth and reproduction of anammox bacteria. The addition of carbon source inhibited the growth and reproduction of anammox bacteria, but plants could alleviate the inhibition of carbon source on the growth of anammox bacteria to a certain extent. The main nitrogen removal pathway of each CWs system was anammox process. And to varying degrees, there was synergistic coupling of anammox process and denitrification process for nitrogen removal.
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表 1 目标基因定量引物序列及退火温度
Table 1. Primer sequences and annealing temperature for target genes of q-PCR
目标基因
Target gene引物
Primers引物序列 (5′-3′)
Primer sequences退火温度/℃
Annealing temperature引物长度/bp
Primer length参考文献
ReferenceAnammox 16S rRNA Amx368f TTCGCAATGCCCGAAAGG 56 470 [12] Amx820r AAAACCCCTCTACTAGTGCCC 表 2 硝化-反硝化相关菌属存在特征
Table 2. Characteristics of nitrification-denitrification bacteria related genus
菌属
Bacterial genera相对丰度/%
Relative abundanceT1 T2 T3 T4 反硝化相关菌属 Flavobacterium 2.01 4.06 7.01 8.06 Thermomonas 0.10 1.47 1.17 1.79 Enterobacter 0.00 0.00 0.00 0.00 Pseudomonas 0.16 0.17 0.17 0.20 Hydrogenophaga 0.07 0.02 0.07 0.02 Aeromonas 0.00 0.01 0.00 0.01 Janthinobacterium 0.02 0.01 0.01 0.02 Acidovorax 0.12 0.09 0.19 0.06 总计 2.48 5.83 8.63 10.17 硝化相关菌属 Nitrosomonas 0.12 0.13 0.23 0.70 Nitrosovibrio 0.00 0.01 0.01 0.01 Nitrospira 0.04 0.03 0.05 0.05 Nitrosococcus 0.03 0.03 0.01 0.01 Nitrolancea 0.08 0.08 0.04 0.03 Nitrobacter 0.17 0.28 0.07 0.08 总计 0.44 0.56 0.42 0.89 -
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