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传统污水处理技术多为“以能耗换水质”。国际污水处理行业正形成污染物削减功能进一步强化、低碳处理和能源开发技术收到重视、实现处理过程与资源回收同步等3个明显的发展态势[1]。我国已明确提出“碳达峰”和“碳中和”战略目标,在节能低碳和资源能源回收的污水处理新需求下,也面临污水处理技术的革新。
厌氧消化能将有机污染物转化为清洁能源甲烷,具有运行能耗低、能源回收效率高、占地面积小等优势,可为主流城市污水处理实现可持续发展提供新思路[2]。然而,在厌氧消化过程中,有机物含有的氮最终被转化为氨氮(
${\rm{NH}}_4^{+} $ -N),还需进一步脱氮处理以实现污水的达标排放[3]。厌氧氨氧化(anaerobic ammonium oxidation,anammox)是一种资源节约、环境友好的污水脱氮技术。厌氧氨氧化菌(anaerobic ammonium oxidation bacteria,AnAOB)能在厌氧条件下,以亚硝氮(${\rm{NO}}_2^{-} $ -N)为电子受体将${\rm{NH}}_4^{+} $ -N转化为N2,而无需曝气和外加碳源[4]。主流城市污水经厌氧消化处理后其出水C/N低,与anammox耦合可充分发挥二者的技术优势[5]。在实际应用中,anammox工艺已成功实现对污泥消化液[6]、垃圾渗滤液[7]等废水的处理。然而,对于氨氮较低(C/N比亦较低)的主流城市污水处理的研究则较少,这是由于在该反应体系内反应基质${\rm{NO}}_2^{-} $ -N很难稳定获取。目前,普遍采用短程硝化(partial nitrification,PN)过程来获取
${\rm{NO}}_2^{-} $ -N。然而,anammox工艺的理论最高脱氮效率仅为89%[8],且PN难以稳定控制亚硝酸盐氧化菌(nitrite oxidizing bacteria,NOB),导致出水硝氮(NO3−-N)质量浓度偏高,这也进一步限制了该过程的脱氮效果[9]。基于此,本研究拟通过外加人工合成城市污水来提供碳源,在移动床生物膜反应器(moving bed biofilm reactor,MBBR)中,通过调控运行参数,将短程反硝化(partial denitritation,PD)与PN/A进行耦合,从而强化其对主流厌氧消化出水的脱氮效果,以期为类似低C/N比污水的处理提供参考。
一段式短程反硝化耦合厌氧氨氧化工艺处理厌氧膜生物反应器出水
Treatment of effluent from anaerobic membrane bioreactor by one-stage partial denitrification coupled with an am mox
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摘要: 采用移动床生物膜反应器,通过一段式短程硝化-厌氧氨氧化耦合短程反硝化工艺处理主流厌氧消化出水。在溶解氧浓度(DO)维持在(1.45 ± 0.15)mg·L−1的条件下,出水TN低至(10.7 ± 2.4)mg·L−1、
${{\rm{NH}}_4^{+}} $ -N转化率达到(86.8 ± 4.5)%,平均TN去除率为(78.9 ± 4.9)% (最高达84.0%)、TN去除负荷为0.38 kg·(m3·d)−1。分析氮的去除路径表明,低浓度有机物诱导反硝化菌主要发生短程反硝化,耦合系统脱氮贡献主要来源于厌氧氨氧化。在载体上,生物膜实现了厌氧氨氧化菌的有效富集,其中菌的活性为873.9 mg·(g·d)−1;而氨氧化细菌主要存在于絮体污泥中,占总菌比例为(38.7 ± 5.9)%;亚硝酸盐氧化细菌则仅占(7.8 ± 2.8)%,说明其受到一定程度抑制。本研究结果可为anammox在主流厌氧消化出水深度处理中的应用提供参考。Abstract: In this study, the mainstream anaerobic digestion effluent was treated through integrated partial denitrification with one-stage partial nitrification-anaerobic ammonium oxidation in a moving-bed biofilm reactor. When the concentration of dissolved oxygen (DO) remained at (1.45 ± 0.15) mg·L-1, the total nitrogen (TN) concentration in the effluent was as low as (10.7 ± 2.4) mg·L-1, and the NH4+-N conversion rate reached (86.8 ± 4.5) %. The average TN removal efficiency reached (86.8 ± 4.5)% (up to 84.0%), and the TN removal load was 0.38 kg·(m3·d)-1. Nitrogen removal pathway analysis revealed that partial denitrification was induced by the low organic concentration, and nitrogen removal of coupling system was mainly contributed by anaerobic ammonium oxidation. The biofilm could effectively enrich anammox bacteria on the carrier, and the activity of the bacteria was 873.9 mg·(g·d)-1, while ammonia-oxidizing bacteria mainly existed in sludge flocs, accounting for (38.7 ± 5.9)% of the total bacteria. Nitrite oxidizing bacteria (NOB) only accounted for (7.8 ± 2.8)%, indicating that they were suppressed in the system. The results of this study can provide a reference for the application of anammox in mainstream anaerobic digestion effluent treatment. -
表 1 反应器运行工况
Table 1. Operational conditions of the reactor
运行阶段 时间/d 进水基质 调配策略 NH4+-N/
(mg·L−1)COD/
(mg·L−1)HRT/h 运行模式 Ⅰ 1~20 人工合成氨氮废水 — 200 — 6 进水10 min、曝气30 min、
厌氧搅拌10 min、沉淀30 min、出水10 minⅠ 21~33 人工合成氨氮废水 — 100 — 6 Ⅱ 34~53 人工合成氨氮废水 外加碳源 100 19.6~34.8 6 进水20 min、曝气40 min、厌氧
搅拌150 min、沉淀30 min、出水30 minⅡ 54~68 主流厌氧消化出水 外加碳源 51.0 ± 2.3 34.8~58.0 3 进水15 min、曝气20 min、
厌氧搅拌55min、沉淀30 min、出水15 min -
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