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厌氧消化技术可有效处理污泥并产生绿色能源“沼气”,已成为污泥处理的重要发展方向[1]。在2013年“水环境治理三年行动方案” [2]及产业升级政策的契机下,北京市借鉴国际上大城市污泥处理经验,采取“热水解+厌氧消化+板框压滤+土地利用”的技术路线[3]处理中心城区的污泥,开创了污泥处理处置新思路。热水解技术被广泛应用在厌氧消化预处理阶段,随之产生的热水解厌氧污泥消化液是一种典型的高氨氮废水。此类废水主要指污泥经过热水解预处理及厌氧消化过程后排放的废水,以污泥消化液主。经过热水解预处理后的消化液具有比传统厌氧消化液更加复杂的水质特征,其特点为低CON/N。因此,在其处理过程中,高氨氮浓度、碱度严重不足,以及难降解底物抑制等问题尤为突出[4]。若采取传统硝化反硝化脱氮技术对其进行处理,不仅处理费用高,且出水水质难以保证。
厌氧氨氧化菌(anaerobic ammonium oxidation bacteria, AnAOB)可利用亚硝酸盐作为电子受体将污水中的氨氮氧化为氮气。该脱氮过程仅需将50%的氨氮氧化为亚硝酸盐氮,可节省50%的曝气能耗、50%的碱度消耗及100%的有机碳源,且剩余污泥产量可降低约90%,温室气体排放量减少量大于90%[5-6]。目前,国外已有将厌氧氨氧化成功应用于污泥消化液、养殖废水、垃圾渗滤液等高氨氮废水处理工程的案例[7-12]。热水解厌氧消化液的氨氮高达2 000~3 000 mg·L−1,C/N低于1.5,温度约为30℃。这一水质特点使得其适合采用费用较低的厌氧氨氧化技术进行脱氮处理。然而,有学者通过小试实验发现热水解厌氧消化液中含有的可溶性有机物对氨氧化菌(ammonium oxidation bacteria, AOB)和厌氧氨氧化菌(anaerobic ammonia-oxidizing bacteria,AnAOB)具有较强的抑制作用,经过长期驯化也无法消除此抑制作用。另外,厌氧氨氧化技术应用于热水解厌氧消化液的处理难度更大[13-15],尚无成功案例。
本研究团队在前期研究和实践中已将厌氧氨氧化高效脱氮技术成功应用于城市污水处理厂,并实现了产业化。本研究拟通过启动并调试利用短程硝化厌氧氨氧化(partial nitritation-anammox,PN-ANA)工艺进行热水解厌氧消化液的旁侧脱氮处理工程,深入考察PN-ANA工艺处理热水解厌氧消化液的工艺运行效果,拟评价该技术对城市污水处理厂主流区的影响,并对反应系统内的功能菌群进行定量分析,考察系统菌群的生长情况,以期为该工艺处理高氨氮废水的工程应用提供参考。
Startup and operation of PN-ANA technology for treating anaerobic digestion liqui d treated by thermal hydrolysis
- Received Date: 18/02/2021
- Available Online: 10/06/2022
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Key words:
- sewage treatment /
- anammox /
- nitrogen removal /
- anaerobic digestion liquid treated by thermal hydrolysis
Abstract: A practical project of a sewage treatment plant in Beijing was taken as an example to investigate the effect of partial nitritation-anammox (PN-ANA) process on the dewatering liquid of anaerobic digestion pretreated with thermal hydrolysis (THP-AD), and the influence of sidestream PN-ANA technique on the mainstream was evaluated. The operation results showed that when the inoculation amount of biofilm was 5% and the proportion of anaerobic ammonia-oxidizing bacteria (AnAOB) on biofilm was more than 10%, after 6 months of commissioning and operation, the effluent of PN-ANA process reached the design index. The total nitrogen removal load was 0.3 kg·(m3·d)-1 and the total nitrogen removal rate reached 78%.It was estimated that the sidestream PN-ANA technique could reduce the total nitrogen by about 3 mg·L-1 in the eflluent of a water plant with a day capacity of 100×104 t. Meanwhile, the ammonia oxidizing bacteria (AOB) and anaerobic ammonia-oxidizing bacteria (AnAOB) showed a trend of slow growth during engineering commissioning by molecular biology detection, which was consistent with the improvement trend of the project treatment effect. In this project, anaerobic ammonium oxidation was successfully used to treat thermal hydrolysis anaerobic sludge digestion liquid, and the start-up time was only half a year, which can provide reference for the engineering application of this technology to treat high ammonia nitrogen wastewater.