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榨菜是中国的特色产品之一,深受广大群众的欢迎。然而,榨菜产业在蓬勃发展的同时,大量高盐榨菜废水的散排和直排等也带来了许多环境问题[1]。高盐榨菜废水具有盐度高、有机物浓度高和氮磷浓度高的特点,如何实现废水的有效处理以及达标排放是亟待解决的难题。目前,榨菜废水的处理工艺主要有SBR工艺、UASB-好氧-混凝工艺、ASBBR工艺等。刘欢逸[2]采用SBR处理某榨菜生产企业所排放的榨菜废水,在将废水稀释至COD<2000 mg·L−1、氨氮<60 mg·L−1、盐度为2%后,该工艺的COD去除率和氨氮去除率分别能达到94%和98%。许劲等[3]采用厌氧-接触氧化工艺处理COD值为3 000 mg·L−1、氨氮为80 mg·L−1、盐度为1.5%的榨菜废水,其稳定运行的最佳负荷为0.5~0.6 kg·(m³·d)−1,出水COD值和氨氮浓度分别可达到100 mg·L−1和15 mg·L−1以下。由此可见,榨菜废水经过稀释等手段将污染物浓度和盐度控制在一定范围内时,可以得到较为有效的处理。但稀释原水不仅提高了处理成本,同时污水量大幅增加,此外,传统的处理方法存在污泥流失严重、抗冲击能力差、有机负荷低等问题[4, 5]。本课题组在前期研究中采用厌氧膜生物反应器(Anaerobic Membrane Bioreactor,AnMBR)有效解决了高盐高污染物榨菜废水厌氧生物处理耐盐微生物截留富集及污染物的去除,取得了较好的处理效果[6]。但厌氧工艺对于氮、磷等元素的去除效果有限,并且厌氧膜出水的有机物浓度也难以满足排放要求。因此,寻找合适的好氧工艺对厌氧膜出水进一步处理十分必要。
缺氧/好氧/缺氧-膜生物反应器(anacrobic/oxic -membrane bioreactor,AOA-MBR)是由硝化反硝化工艺与膜分离技术耦合而成的脱氮除磷工艺,该工艺不仅能够提升污泥浓度、强化脱氮效率、提升出水水质,还能节约用地面积,方便城镇污水厂的改建[7-8]。潘懿等[7]在处理生活污水的中试研究中发现,AO-MBR工艺不仅对COD、氨氮等具有较高的去除效率,并且对总氮的去除率也远高于传统的A/O工艺。贾国江[9]等采用AO-MBR处理含盐制药废水,在盐度为4 000 mg·L−1、HRT为16 h的条件下,反应器的出水COD值平均为为178 mg·L−1,COD去除率为95.8%;出水氨氮平均为12 mg·L−1,氨氮去除率为93.7%;出水总氮为48 mg·L−1,总氮去除率为78.9%。这说明,采用AO-MBR工艺来处理高盐有机废水具有较高的可行性,可以考虑将其作为厌氧出水的深度处理和脱氮除磷工艺,以达到废水达标排放的目的。
在本课题组前期研究中[6],榨菜废水厌氧膜出水COD值仍有1 200 mg·L−1左右,总氮和总磷质量浓度分别为500 mg·L−1和55 mg·L−1左右,需要进一步处理以实现达标排放。基于此,本研究采用缺氧/好氧/缺氧-膜生物反应器(anacrobic/oxic/anacrobic-membrane bioreactor,AOA-MBR)强化工艺对高盐榨菜废水的厌氧膜工艺出水进行了进一步处理,通过低负荷耐盐性驯化启动、缩短HRT、调整Ro等方式探索最佳运行参数,考察了AOA-MBR在不同HRT和不同Ro下的脱氮除磷效果,并对其污泥性质变化进行了研究,以期为高盐榨菜废水处理工艺的工业化应用提供参考。
AOA-MBR处理高盐榨菜废水厌氧膜生物反应器出水的效能
Operation performance of an AOA-MBR treating the effluent from an anaerobic membrane bioreactor dealing with high-salt mustard tuber wastewater
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摘要: 为了解决高盐榨菜废水厌氧膜生物反应器出水的处理问题,考察了缺氧/好氧/缺氧-膜生物反应器(anacrobic/oxic/anacrobic-membrane bioreactor,AOA-MBR)在不同水力停留时间(Hydraulic Retention Time, HRT)下对高盐榨菜废水厌氧膜生物反应器出水的处理效果,并通过调整硝化液回流比(nitrification liquid reflux ratio, Ro)优化了反应器的运行参数。在进水COD值为3 200 mg·L−1、氨氮为400 mg·L−1、盐度为35 g·L−1、溶解氧(dissolved oxygen,DO)浓度为2~4 mg·L−1、温度为25 ℃左右的条件下,AOA-MBR的最佳运行工况为HRT=4 d、Ro=200%。在此工况下,AOA-MBR的COD去除率为85.4%、氨氮去除率为96.4%,总氮去除率为89.1%。此外,仅依靠AOA-MBR无法实现出水总磷的达标排放,还需要与化学除磷相结合。在运行过程中,污泥浓度在初始高盐冲击下会出现短暂下降现象,随后在逐渐适应了高盐环境后再缓慢上升。长期的高盐环境驯化使体系内可溶性微生物产物(Soluble Microbial Products,SMP)和胞外聚合物(Boud Extracellular Polymeric Substances,BEPS)的质量浓度由5.1 mg·g−1和36.9 mg·g−1(以MLVSS计)上升到18.3 mg·g−1和62.5 mg·g−1,这可能有利于微生物在高盐环境下的生存。在AOA-MBR的运行过程中,膜组件共进行了5次清洗,而物理清洗+化学清洗的组合清洗方式对于膜污染有更好的清洗效果。
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关键词:
- 缺氧/好氧/缺氧-好氧膜生物反应器 /
- 污水处理 /
- 高盐废水 /
- 污泥性质
Abstract: The treatment efficiency of the effluent from an anaerobic membrane bioreactor (AnMBR) dealing with high-salt mustard tuber wastewater by the anacrobic/oxic/anacrobic-membrane bioreactor (AOA-MBR) was investigated under different Hydraulic Retention Time (HRT), and the operation parameters of the reactor were optimized by adjusting the Nitrification Liquid Reflux Ratio(Ro). When the influent COD was 3 200 mg·L−1, ammonia nitrogen was 400 mg·L−1, salinity was 35 g·L−1, dissolved Oxygen(DO) concentration was 2~4 mg·L−1, temperature was 25 ℃, the optimal operation parameters of AOA-MBR were HRT=4 d and Ro=200%. Under this condition, the removal efficiencies of COD, ammonia nitrogen and total nitrogen by AOA-MBR were 85.4%, 96.4% and 89.1%, respectively. Furthermore, total phosphorus of the effluent could not meet the harge standard only by AOA-MBR. Thus, it was suggested to add a step of chemical phosphorus removal. During the operation period, the sludge concentration decreased briefly due to the impact of high salinity at the initial period and then gradually increased with the microbe adapting to the high salinity environment. After long-term acclimation, the concentrations of SMP and BEPS increased from 5.1 mg·g−1 and 36.9 mg·g−1 to 18.3 mg·g−1 and 62.5 mg·g−1, respectively, which may be beneficial to the survival of microorganisms in high salt environment. During the operation of AOA-MBR, the membrane modules were cleaned five times, and the physical and chemical combination cleaning could achieve better cleaning effect of membrane fouling.-
Key words:
- AOA-MBR /
- wastewater treatment /
- high-salinity wastewater /
- sludge properties
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表 1 水质参数
Table 1. water quality parameters
水样来源 COD/(mg·L−1) 氨氮/(mg·L−1) 总氮/(mg·L−1) 总磷/(mg·L−1) 盐度/(g·L−1) pH 厌氧膜出水 1 200±200 450±50 550±50 55±5 35±2 7.4±0.2 榨菜废水原水 7 500±1500 300±100 400±100 75±10 35±2 5.6±0.8 混合后好氧进水 3 200±300 400±100 500±100 65±10 35±2 7.0±0.5 -
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