【作者】 叶杰旭；

【导师】 孙德智；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2012， 博士

【摘要】 垃圾焚烧发电技术可以实现城市生活垃圾的减量化、无害化和资源化，但是垃圾焚烧发电厂也面临着垃圾渗沥液的合理处置问题。城市生活垃圾焚烧厂渗沥液产生于垃圾焚烧前的堆酵过程，具有成分复杂、有机污染物和氨氮浓度高、毒性大、可生化性好等特点，是目前废水处理领域中的热点和难点。本文以北京某生活垃圾焚烧发电厂的垃圾渗沥液为研究对象，在比较不同工艺运行效能的基础上，确定了适用于渗沥液处理的厌氧-好氧生物组合工艺，分析探讨了渗沥液中有机污染物在组合工艺处理过程中的降解特性和规律。对比研究了UASB和EGSB反应器对城市生活垃圾焚烧厂渗沥液的处理效果。实验结果表明，EGSB反应器具有更高的处理效率，更适用于渗沥液的处理。当渗沥液COD为72000mg/L左右时，UASB反应器的最大有机容积负荷（Organic loading rate，OLR）为12.5kgCOD/（m³·d），此时COD去除率为82.4%，所需的水力停留时间（Hydraulic retention time，HRT）为5.8d。而EGSB在OLR约为18.2kgCOD/（m³·d）、液体上升流速(Velocity liquid，V_up)为2m/h和HRT为4d的条件下，COD平均去除率达90.3%，且呈酸性的渗沥液可以不经pH调节直接进入反应器。EGSB反应器在OLR≤18.2kgCOD/（m³·d）的条件下稳定运行时，去除的COD中有85.7%转化成了甲烷，颗粒污泥中的古菌菌群主要为属于甲烷鬃毛菌属、甲烷杆菌属和甲烷螺菌属的产甲烷菌。高浓度的渗沥液具有厌氧抑制性，采用Haldane模型对厌氧污泥降解渗沥液时的基质抑制动力学进行了模拟，拟合结果表明，最大比基质反应速率q_max为3.45gCOD/（gVSS·d），半饱和常数K_s和基质抑制系数K_i分别为19.265g/L和130.996g/L。城市生活垃圾焚烧厂渗沥液中含有高浓度的氨氮，且经厌氧生物处理后氨氮浓度升高，必须进行脱氮处理。首先研究了缺氧/两级好氧MBBR系统对渗沥液厌氧出水的处理效果，结果表明：当回流比为300%，总停留时间为3.75d，进水氨氮浓度为850mg/L左右，好氧MBBR中溶解氧大于3mg/L时，NH₄⁺-N和TN去除率分别达到84.1%和69.8%。当进水氨氮浓度增加至1000mg/L时，即使总停留时间延长至4.8d，氨氮去除率仍下降至70%左右。因此，本文进一步提出并采用缺氧/两级好氧MBBR-MBR双回流系统对渗沥液厌氧处理出水进行处理。结果表明：在进水pH约为7.0，好氧段DO>3mg/L，总停留时间为6.8d和总回流比为400%的条件下，即使渗沥液中氨氮浓度高约1650mg/L，COD约为6500mg/L，COD、NH₄⁺-N和TN的去除率仍达到80%、99%和81%左右，但COD浓度过高会导致系统硝化效果变差，应小于8000mg/L。与此同时，还发现二级好氧MBBR和MBR中的亚硝酸盐积累率分别达到90%和80%左右。最大可能计数法测定结果表明，这两个反应器中亚硝酸菌的数量远多于硝酸菌的数量。在较高的pH条件下，反应器中高浓度的游离氨对硝酸菌活性的抑制作用是短程硝化实现和维持的主要原因。以Haldane模型拟合得出反硝化的最大比基质反应速率q_max为2062mgNO₂--N/（gVSS·d），半饱和常数K_s和基质抑制系数K_i分别为140.2mg/L和836.3mg/L；一级好氧MBBR、二级好氧MBBR和MBR中污泥硝化的最大比基质反应速率q_max分别为172.8mgNH₄⁺-N/（gVSS·d）、261.8mgNH₄⁺-N/（gVSS·d）和782.6mgNH₄⁺-N/（gVSS·d），半饱和常数K_s分别为57.9mg/L、82.3mg/L和148.9mg/L，基质抑制系数K_i分别为339.7mg/L、600.7mg/L和601.4mg/L。EGSB-缺氧/两级好氧MBBR-MBR组合工艺处理城市生活垃圾焚烧厂渗沥液时运行稳定，COD、BOD₅、NH₄⁺-N、TN和TP的总去除率分别达到98.4%、99.7%、98.9%，81.8%和91.8%。EGSB对有机污染物的去除起主要贡献，去除的COD占总去除量的91.5%，去除的BOD₅占总去除量的95.6%。NH₄⁺-N和TN的去除主要发生在缺氧/两级好氧MBBR-MBR单元，占各自总去除量的100%和84.3%。实验结果还表明，渗沥液经组合工艺处理后生物毒性降低。组合工艺对整个分子量区间的溶解性有机物都有很好的处理效果，>100kDa、50k¹00kDa、10k⁵0kDa、4k¹0kDa和<4kDa的有机物去除率分别达100%、100%、96.88%、98.90%和98.67%。组合工艺能显著降解渗沥液中的蛋白质、氨基酸、羧酸类化合物、脂肪族碳氢化合物等有机质，但新生成的富里酸类物质较难降解，并导致渗沥液经生物处理后芳香化程度增大。更多还原

【Abstract】 Waste incineration for power generation is an effective technology for itsadvantages in reducing the volume and mass of municipal solid waste （MSW）,detoxification and energy production. However, a considerable amount ofleachate can be generated during the period of MSW stored in the storage bunkerbefore incineration. The leachate contains various contaminants such as organics,refractory compounds, ammonia nitrogen （NH₄⁺-N）, etc. It is a difficulty and afocus of wastewater treatment to treat the leachate from MSW incineration plant. Inthis dissertation, a new anaerobic-aerobic combined process was adopted andoptimized for treating the leachate from an incineration plant in Beijing and thecharacteristics of the organics in the leachate degraded by the combined processwas discussed.The treatment efficiencies of the leachate from MSW incineration plant by theup-flow anaerobic sludge blanket （UASB） reactor and the expanded granular sludgebed （EGSB） reactor were compared. The results showed that the EGSB reactor hadhigher operation loading and higher COD removal efficiency than the UASB reactor.When the influent COD concentration was around72000mg/L, the maximumorganic loading rate （OLR） of the UASB reactor was12.5kgCOD/（m³·d）, and thecorresponding COD removal efficiency and hydraulic retention time （HRT） were82.4%and5.8d, respectively. With HRT of4d and velocity liquid (V_up) of2m/h,OLR of the EGSB reactor reached18.2kgCOD/（m³·d）, and the COD removalefficiency reached90.3%. Furthermore, the leachate could be treated by the EGSBreactor without pH adjustment. When OLR≤18.2kgCOD/（m³·d）,85.7%of theremoved COD was converted to methane in the EGSB reactor. Methanogens in thegranular sludge mainly included Methanosaeta sp., Methanobacterium sp. andMethanosarcina sp. The anaerobic degradation kinetic of the leachate was studied,and the results indicated that the leachate was inhibitive to the anaerobicbiodegradation. The maximal specific degrading rate (q_max) of organics reckoned bythe Haldane model was3.45gCOD/（gVSS·d）, and the half-saturation constant（K_s）and the substrate inhibition coefficient （K_i） were19.265g/L and130.996g/L, respectively.The effluents from EGSB reactor need to be further treated as it contains highconcentrations of ammonia nitrogen. A system comprised of anoxic moving bedbiofilm reactor （MBBR） and two-stage aerobic MBBR was used to treat theanaerobic effluents. NH₄⁺-N removal and total nitrogen （TN） removal efficiencieswere84.1%and69.8%with total HRT of3.75d, influent NH₄⁺-N concentration of850mg/L, reflux ratio of300%and DO of above3mg/L. However, when theinfluent NH₄⁺-N concentration increased to1000mg/L, the NH₄⁺-N removalefficiency declined to around70%even though total HRT was extended to4.8d.Therefore, an anoxic/two-stage aerobic MBBR-MBR system was proposed andadopted to treat the anaerobic effluents of the leachate. The results showed that theanoxic/two-stage aerobic MBBR-MBR system was effective for nitrogen removal.Under the following conditions as influent pH of about7, total HRT of6.8d andtotal reflux ratio of400%, the removal efficiencies of COD, NH₄⁺-N and TNreached around80%,99%and81%, respectively, even though the influent NH₄⁺-Nconcentration increased to around1650mg/L and the influent COD concentrationwas around6500mg/L. However, the influent COD concentration should be <8000mg/L to avoid being detrimental to nitrification. Furthermore, short-cut nitrificationwith about90%and80%of nitrite accumulation efficiency took place in the secondstage of aerobic MBBR and MBR. The most probable number （MPN） measurementshowed that the amount of ammonia-oxidizing bacteria was much more than that ofthe nitrite-oxidizing bacteria in the second stage aerobic MBBR and MBR. And thehigh pH and high concentration of free ammonia in the reactors were critical forshort-cut nitrification. q_maxof denitrification for the sludge in the anoxic MBBRfitted by Haldane model was2062mgNO₂--N/（gVSS·d）, K_sand K_iwere140.2mg/Land836.3mg/L, respectively. And q_maxof nitrification for the sludge in the firststage aerobic MBBR, the second stage aerobic MBBR and MBR were172.8mgNH₄⁺-N/（gVSS·d）,261.8mgNH₄⁺-N/（gVSS·d） and782.6mgNH₄⁺-N/（gVSS·d）, respectively; K_swere57.9mg/L,82.3mg/L and148.9mg/L, respectively; and K_iwere339.7mg/L,600.7mg/L and601.4mg/L,respectively.The organic pollutants in the leachate from MSW incineration plant could be effectively removed by EGSB-anoxic/two-stage aerobic MBBR-MBR combinedprocess. The removal efficiencies of COD, BOD₅, NH₄⁺-N, TN and TP were98.4%,99.7%,98.9%,81.8%and91.8%, respectively. Most organic pollutants wereremoved in EGSB reactor. COD and BOD₅removal by the EGSB reactor took91.5%and95.6%of each of their total removal by the combined process,respectively. NH₄⁺-N and TN were mainly removed in the anoxic/two-stage aerobicMBBR-MBR system as NH₄⁺-N and TN removal by the system took100%and84.3%of each of their total removal by the combined process, respectively. Besides,experimental results showed that after treated by the combined process, thebiological toxicity of the leachate decreased. The dissolved organic matter （DOM）was effectively removed by the combined process. TOC removal efficienciesreached to100%,100%,96.88%,98.90%and98.67%, corresponding to DOM withmolecular weight of>100kDa,50k-100kDa,10k-50kDa,4k-10kDa and <4kDa,respectively. Protein, amino acid, carboxylic acids compounds and aliphaticcompounds were obviously removed. However, fulvic acid substrates was generatedafter the leachate treated by the combined process, which lead to the increase ofaromatic degree.更多还原