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随着我国大量城镇污水处理厂的建成运行,排入水环境容量小的敏感受纳水体的城镇污水厂尾水排放量日益增加,北京、昆明、河北、浙江[1]等地相继提出了《城镇污水处理厂污染物排放标准》地方排放标准,这些标准中的高标准要求出水
${\rm{NH}}_4^{+} $ -N、TN、TP限值分别为1.0~1.5、5~10、0.05~0.3 mg·L−1,比现行国家《城镇污水处理厂污染物排放标准》(GB 18918-2002)中一级标准A标准更严格。因此,对城镇污水进行高标准深度除磷脱氮成为当务之急。传统A2O工艺的脱氮和除磷过程均需要碳源[2],对于C/N较低的城市污水难以实现氮、磷同步高标准深度去除。为解决传统A2O工艺中碳源不足的问题,曹贵华采用分段多点进水方式降低碳源损耗,以提高A2/O工艺的碳源利用率[3]。此外,有研究者提出通过新的脱氮除磷路径减少对碳源的需求。如短程硝化反硝化脱氮可节省40%的碳源,但短程硝化反硝化效能易受DO、温度、泥龄影响[4-5],不能实现稳定的短程硝化。而反硝化除磷技术则利用反硝化聚磷菌,以硝态氮为电子受体分解胞内储存的PHAs,利用产生的能量吸磷,通过“一碳两用”同时脱氮和除磷[6],可节省碳源50%。因此,罗亚红在A2O工艺末端进行间歇曝气构建了反硝化除磷系统,在除磷脱氮的同时可减少碳耗及能耗[7],但该系统对氮、磷去除效能的提升有限。陈永志[8]构建了A2O-BAF工艺,利用反硝化除磷路径减少碳源消耗,但仍然难以实现高标准除磷脱氮。此外,好氧反硝化是一种新型脱氮途径,在好氧过程中进行好氧反硝化脱氮,可以减少好氧过程中的碳源损耗[9]。
针对城镇污水AAO工艺进行高标准除磷脱氮存在的碳源不足问题,本研究构建了城镇污水厌氧/缺氧/好氧/缺氧(anaerobic-anoxic-aerobic-anoxic,简称AAOA)的除磷脱氮技术,在不补充碳源条件下,通过多路径耦合的城镇污水脱氮除磷技术实现城镇污水的高标准除磷脱氮。重点探究了在进水C/N对城镇污水AAOA系统深度除磷脱氮效能的影响,确定了AAOA系统实现高标准脱氮需要的C/N;解析了污染物沿程去除规律,并利用16S rRNA高通量测序技术探究了系统微生物种群结构及微生物作用机制。在此基础上,开展了实际城镇污水AAOA处理实验,在不补充碳源条件下,通过构建多路径除磷脱氮的AAOA系统,实现城镇污水高标准脱氮除磷。本研究结果可为城镇污水高标准除磷脱氮以及传统A2O工艺的城镇污水厂的提标改造提供参考。
城镇污水AAOA高标准除磷脱氮技术开发与应用
Development and application of AAOA high-standard phosphorus and nitrogen removal technology for urban sewage
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摘要: 针对城镇污水在高标准除磷脱氮过程中碳源不足的问题,提出了基于多路径协同的AAOA除磷脱氮技术,探究了AAOA系统实现高标准除磷脱氮对进水C/N的要求,并对实际城镇污水处理进行了实验研究。结果表明:当进水C/N分别为6、7.5、9时,系统TN去除率分别为74.12%、84.90%、90.05%,TP去除率分别为48.29%、97.68%、98.50%;当进水C/N≥7.5时,系统可以实现高标准脱氮除磷。16S rRNA高通量测序结果表明:系统中脱氮除磷功能菌属主要有Aeromonas、Nitrospira、Aeromonas、Comamonadaceae_unclassified、Uliginosibacterium、Saccharibacteria_norank、Candidatus_Accumulibacter、Aeromonas、Pseudomonas、Dechloromonas,系统通过自养硝化、异养硝化、异养反硝化、反硝化聚磷、好氧反硝化等多条路径协同作用实现了高标准除磷脱氮。同时,采用AAOA系统处理城镇污水,当城镇污水进水C/N为7.5时,系统出水
${\rm{NH}}_4^{+} $ -N、TN和PO43--P平均质量浓度分别为0.40、3.57、0.21 mg·L−1,平均去除率分别达到98.76%、89.03%和95.55%,即无需外加碳源可实现城镇污水的高标准除磷脱氮。Abstract: Aiming at the problem of insufficient carbon source in the process of high standard phosphorus and nitrogen removal in urban sewage, an AAOA phosphorus and nitrogen removal technology based on multi-path coordination was proposed. The requirements of influent C/N in AAOA system for high standard phosphorus and nitrogen removal and the actual urban sewage treatment were studied. The results showed that when the influent COD/TN were 6, 7.5 and 9, the TN removal rates were 74.12%, 84.90% and 90.05%, respectively, and the TP removal rates were 48.29%, 97.68% and 98.50%, respectively; when the influent C/N increased to 7.5 and higher values, the system could realize the high-standard removal of phosphorus and nitrogen. The results of 16SrRNA high-throughput sequencing indicated that the functional bacteria for nitrogen and phosphorus removal in the system mainly included Aeromonas, Nitrospira, Aeromonas, Comamonadaceae _ unclassified, Uliginosibacterium, Saccharibacteria_norank, Candidatus_Accumulibacter, Aeromonas,Pseudomonas and Dechloromonas. The system realized high-standard removal of nitrogen and phosphorus through autotrophic nitrification, heterotrophic nitrification, synergistic action of denitrifying phosphorus accumulation, heterotrophic denitrification and aerobic denitrification. At the same time, when AAOA was used to treat municipal wastewater with the influent C/N of 7.5, the average concentrations of${\rm{NH}}_4^{+} $ -N, TN and PO43--P in the effluent of AAOA system were 0.40, 3.57, 0.21 mg·L-1, and the average removal rates were 98.76%, 89.03% and 95.55%, respectively. High standard phosphorus and nitrogen removal of urban sewage can be achieved without additional carbon source.-
Key words:
- urban sewage /
- AAOA /
- phosphorus and nitrogen removal /
- C/N /
- high standard
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表 1 小试实验水质
Table 1. Quality of wastewater in lab test
C/N COD和氮磷质量浓度/(mg·L−1) COD -N${\rm{NH}}_4^{+} $ TN PO43--P 6 254±4 38.52±0.37 40.50±0.57 5.40±0.34 7.5 318±5 38.83±0.78 40.56±1.05 5.13±0.26 9 371±5 39.55±1.36 40.85±1.62 5.30±0.34 表 2 城镇污水实验水质
Table 2. Experimental water quality of urban sewage
统计
值pH COD和氮磷质量浓度/(mg·L−1) COD -N${\rm{NH}}_4^{+} $ TN PO43--P 范围 7.00~8.00 148~306 19.00~43.00 21.00~44.00 2.10~5.60 均值 7.45 224 31.00 33.00 3.60 表 3 实际城镇污水AAOA脱氮除磷效能
Table 3. Nitrogen and phosphorus removal efficiency of AAOA treating actual urban sewage
检测指标 进水检测值/(mg·L−1) 出水检测值/(mg·L−1) 平均去除率/% 范围 平均值 范围 平均值 -N${\rm{NH}}_4^{+} $ 24.10~39.29 32.37±3.78 0.16~0.68 0.40±0.15 98.76 TN 24.81~39.65 32.92±3.71 2.44~4.91 3.57±0.61 89.03 PO43--P 3.21~5.63 4.85±0.58 0.05~0.36 0.21±0.07 95.55 -
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