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厌氧氨氧化(anaerobic ammonium oxidation bacteria,anammox)自养生物脱氮工艺是以氨氮(NH4+-N)为电子供体,亚硝氮(NO2−-N)为电子受体的自养脱氮工艺[1],因其具有脱氮效率高、无需额外补充碳源等优点,在老龄垃圾渗滤液为代表的低C/N比污水脱氮处理中受到广泛关注[2, 3]。但anammox菌生长和富集速度缓慢,环境敏感性强[4],且垃圾渗滤液含有高浓度氨氮、有机物及重金属等污染物对anammox菌具有强烈抑制作用,使得anammox工艺在垃圾渗滤液脱氮应用中受到极大的制约。因此,寻找一种快速启动anammox的污泥接种策略,及实现anammox自养脱氮工艺在垃圾渗滤液处理过程中稳定运行的方法,对该自养工艺的工程化应用具有重大意义。
Anammox工艺的启动是淘汰劣势菌种,富集anammox菌的过程。有研究表明,混合接种反硝化污泥与anammox污泥能减少反应器启动所需时间,CHEN等[5]将接种反硝化污泥与接种Anammox污泥:反硝化污泥=1:3的混合污泥启动效果进行比较,发现接种反硝化污泥反应器氮去除速率达0.54 kg·(m3·d)−1需98 d,而后者氮去除速率达到0.55 kg·(m3·d)−1仅需40 d。但WANG等[6]接种厌氧颗粒污泥:anammox污泥=20:1启动反应器却未能成功,这可能与anammox污泥接种比例有关。因此,其他污泥与anammox污泥混合接种的比例对anammox反应器启动影响还有待深入探究。本研究将垃圾渗滤液常规处理中的短程硝化污泥、反硝化污泥以及实验室前期培养的anammox污泥为接种对象,探究一种最优的污泥接种策略来减少anammox工艺启动时间。此外,由于anammox工艺在实际处理垃圾渗滤液时,往往受到渗滤液中NH4+-N,NO2−-N和有机污染物浓度变化影响,导致anammox脱氮效果降低[7, 8]。其中,垃圾渗滤液中NH4+-N对anammox活性的影响主要源于游离氨(free ammonium,FA),JUNG等[9]a研究中发现当进水FA达到1.7 mg·L−1以上时开始对anammox产生抑制,当FA达到32 mg·L−1时anammox会完全停止反应。而垃圾渗滤液中NO2−-N本身具有一定的生物毒性,STROUS等[10]发现当NO2−-N质量浓度超过100 mg·L−1时anammox反应会受到抑制,且在该浓度下持续12 h会完全失活。高浓度有机污染物会造成反应器anammox种群丰度下降,TANG等[11]探究有机物对anammox长期运行影响中发现当进水中COD达800 mg·L−1时,有机环境中的anammox活性仅为无机环境的1/4,反应器内异养菌丰度大幅度提高。因此,在anammox自养脱氮工艺实际应用中,需要一种能维持anammox高效脱氮性能,保证anammox菌在反应器中始终占据主导地位的方法。联氨(N2H4)是anammox反应过程的中间产物,可在联氨脱氢酶的作用下转化为N2,该过程中释放的部分电子会用于ATP的合成[12],适量投加N2H4可强化anammox脱氮性能[13],但N2H4也是一种强还原剂,具有生物毒性,过量投加反而会抑制Anammox反应[14]。目前对N2H4研究主要集中在污染物浓度较低的水体(如模拟废水或城市污水)中anammox的反应过程和活性恢复方面。如MIODONSKI等[15]在污泥消化废水中通过投加N2H4促进Anammox活性,投加N2H4反应器的氮去速率较未添加N2H4的对照组高出0.256 kg·(m3·d)−1。而如何通过N2H4促进anammox菌快速适应高污染及生物抑制性强的垃圾渗滤液,以及其对渗滤液中脱氮菌群活性变化的影响研究却鲜有报道。
鉴于此,本研究在选择出anammox工艺最优污泥接种启动策略的基础上,讨论N2H4在anammox工艺中对垃圾渗滤液脱氮的影响,通过对比运行中的脱氮性能、比厌氧氨氧化活性、胞外聚合物以及微生物群落结构变化等,以确定促进anammox运行的最适N2H4浓度。结合最优污泥接种策略与适合的N2H4浓度实现anammox在垃圾渗滤液中的快速启动以及长期稳定运行,解决anammox工艺受垃圾渗滤液抑制脱氮性能不佳的困扰,为该工艺在实际工程运用中提供科学的技术支持。
污泥接种策略与联氨促进垃圾渗滤液厌氧氨氧化工艺快速启动及其运行效果
Sludge inoculation strategy and hydrazine promoting rapid start-up and operational effectiveness of anaerobic ammonia oxidation process for landfill leachate
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摘要: 针对厌氧氨氧化工艺启动速度慢及在垃圾渗滤液中脱氮效率低的问题,探究了厌氧氨氧化工艺在处理高氨氮、低C/N比垃圾渗滤液中的快速启动及稳定运行策略。结果表明,厌氧氨氧化工艺接种反硝化污泥:anammox颗粒污泥=9:1的启动效果最佳,100 d时TN去除率可达75.1%。但由于垃圾渗滤液中COD较高,异养反硝化菌生长迅速且严重影响厌氧氨氧化菌活性。通过投加6 mg·L−1的N2H4之后,异养反硝化菌活性受到抑制,反应器内厌氧氨氧菌占据主导地位,Candidatus Kuenenia菌相对丰度由0.2%提升到10.6%,TN去除率及氮去除速率分别达90.6%和0.143 kg·(kg·d)−1以上。在厌氧氨氧化工艺中投加适量N2H4可实现垃圾渗滤液的稳定高效自养脱氮。Abstract: Aiming at the problems of slow start-up and low denitrification efficiency of anammox process in landfill leachate, the strategy of rapid start-up and steady operation of anammox process in treating landfill leachate with high ammonia nitrogen and low C/N ratio was investigated. The results showed that the anammox process inoculated with denitrifying sludge: anammox granular sludge = 9:1 had the optimal start-up effect, and TN removal rate could reach 75.1% at 100 d. However, due to the high COD in landfill leachate, heterotrophic denitrifying bacteria grew rapidly and seriously affected the activity of anammox bacteria. After the addition of 6 mg·L−1 N2H4, the activity of heterotrophic denitrifying bacteria was inhibited and the abundance of anammox bacteria dominated. The relative abundance of Candidatus Kuenenia increased from 0.2% to 10.6%, and TN removal rate and nitrogen removal rate reached over 90.6% and 0.143 kg·(kg·d)−1, respectively. The stable and efficient autotrophic denitrification of landfill leachate could be achieved by adding an appropriate amount of N2H4 to the anammox process.
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Key words:
- autotrophic denitrification /
- anammox /
- landfill leachate /
- N2H4
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表 1 B1~B5反应器各阶段进水水质
Table 1. Influent water quality of B1~B5 reactors during different phases.
阶段 渗滤液占比/% COD/(mg·L−1) NH4+-N/(mg·L−1) NO2−-N/(mg·L−1) NO3−-N/(mg·L−1) Ⅰ (第1~116天) 25 497~728 58.5~156.6 76.5~201.2 0~13.0 Ⅱ(第117~144天) 50 1 226~1 422 168.4~189.5 232.0~252.3 1.3~9.6 Ⅲ(第145~184天) 75 2 184~2 316 147.4~168.4 183.3~249.5 ND Ⅳ(第185~222天) 100 2 510~2 632 167.1~185.5 191.5~264.1 0~0.9 Ⅴ(第223~252天) 100 2 504~2 892 163.2~165.8 210.4~214.4 2.0~8.1 表 2 B1~B5反应器各阶段化学计量变化
Table 2. The stoichiometric change of B1~B5 reactors during different phases
反应器 阶段Ⅰ 阶段Ⅱ 阶段Ⅲ 阶段Ⅳ 阶段Ⅴ ΔNO2−-N/
ΔNH4+-NΔNO3−-N/
ΔNH4+-NΔNO2−-N/
ΔNH4+-NΔNO3−-N/
ΔNH4+-NΔNO2−-N/
ΔNH4+-NΔNO3−-N/
ΔNH4+-NΔNO2−-N/
ΔNH4+-NΔNO3−-N/
ΔNH4+-NΔNO2−-N/
ΔNH4+-NΔNO3−-N/
ΔNH4+-NB1 1.37 0.13 1.53 0.24 1.44 0.26 1.40 0.08 1.43 0.05 B2 1.31 0.12 1.46 0.18 1.27 0.17 1.28 0.10 1.37 0.08 B3 1.32 0.11 1.44 0.21 1.24 0.20 1.20 0.13 1.34 0.11 B4 1.31 0.11 1.46 0.18 1.21 0.15 1.08 0.10 1.34 0.13 B5 1.30 0.04 1.44 0.22 1.20 0.02 1.21 0.11 1.28 0 表 3 接种污泥及阶段Ⅴ B1~B5的Alpha多样性指数
Table 3. Alpha diversity index of inoculation sludge and B1~B5 reactors in phase Ⅴ
样品 OTUs Shannon Simpson Ace Chao 1 谱系多样性 覆盖率 接种污泥 86 2.933 0.770 5 126.224 3 119.214 3 10.862 0.996 8 B1 310 4.753 7 0.889 4 432.124 9 419 31.7412 0.985 9 B2 460 5.516 3 0.927 7 579.214 7 568.370 4 40.487 8 0.986 1 B3 375 4.954 6 0.918 2 521.858 9 537.018 2 36.746 8 0.988 8 B4 500 5.57 3 0.923 5 602.091 5 603.2 42.287 2 0.988 4 B5 366 4.621 7 0.878 2 489.403 9 467.283 6 33.491 0.989 0 -
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