【作者】 吴蕾；

【导师】 彭永臻；

【作者基本信息】 北京工业大学 ， 环境工程， 2012， 博士

【摘要】 好氧颗粒污泥技术、短程硝化技术与反硝化除磷技术是目前国内外水污染控制研究关注的热点技术。基于以上理论，本论文研究了如何从传统的活性污泥培养成具有硝化功能和除磷功能的颗粒污泥，并考察了不同环境条件对其性能的影响。在此基础上，本论文还提出了一种以颗粒污泥为介质的反硝化除磷新工艺。该工艺将颗粒污泥技术和反硝化脱氮除磷技术相耦合，由两个交替运行的厌\缺氧SBR和好氧硝化SBR组成，具有以下特点：(1)发挥了颗粒污泥沉降性能好，生物量大，脱氮除磷效率高的优势；(2)解决了硝化菌和聚磷菌污泥龄不同的矛盾且不需污泥回流，简化了系统装置；(3)节省耗氧量，减少污泥产量。本文包括3部分研究内容：(1)短程硝化颗粒污泥SBR的研究①短程硝化颗粒污泥的培养：采用SBR反应器，在温度28C，溶解氧(DO)2.0mg/L，污泥龄(SRT)为15d的运行工况下，缩短沉降时间为2min，通过以pH作为氨氧化过程的控制参数，优化曝气时间，防止过曝气，经过80周期(19d)成功实现短程硝化絮状污泥的颗粒化，并维持稳定。形成的颗粒污泥粒径在1.5-2.0mm之间，对COD和氨氮的去除率分别达到80%和95%，亚硝酸盐积累率(NO2--N/NOx--N)平均达到95%。分子生物学FISH技术对颗粒污泥种群结构的定量分析表明，氨氧化细菌(AOB)依旧是优势菌群，约占17.8%左右，亚硝酸盐氧化菌(NOB)占0.6%。曝气初期FA的抑制和实时控制是启动和维持颗粒污泥短程硝化性能的主要原因。②亚硝酸盐氧化菌颗粒污泥的培养及反应动力学研究，采用SBR反应器，在温度25C，曝气量0.2m3/h，DO2.0mg/L，沉降时间为2min的条件下，经过130d成功培养出亚硝酸盐氧化菌颗粒污泥，平均粒径在0.72mm。长期监测发现，颗粒污泥具有良好的亚硝酸盐氧化能力且出水中硝酸盐几乎检测不到。FISH定量分析表明，Nitrospira为优势菌群。利用莫诺特方程测定亚硝酸盐底物，动力学参数Vs为30.94mg/(g VSS·h)，Ks为8.19mg/L。③C/N比对硝化颗粒污泥形成和微生物群落迁移变化的影响，采用4个完全相同的SBR系统R1、R2、R3和R4，分别在进水COD/N比为0/200，200/200，400/200，800/200的条件下培养硝化颗粒污泥，结果表明，在R2和R3反应器中，颗粒污泥培养成功。但是发现，R2中的低负荷下培养的颗粒污泥，形态规则，颗粒污泥强度高，粒径较小，硝化活性强，且硝化菌群的数量较高。④温度和游离氨的协同作用对硝化颗粒污泥和絮状污泥氨氧化特性的影响，结果表明，氨氧化速率随着温度的升高逐渐增大，在相同温度下，颗粒污泥的氨氮去除率是絮状污泥的2-3倍。同时还发现，当游离氨升高到90mg/L，温度降低到10C时，两系统的氨氧化都受到明显抑制。随着温度高到30C，氨氧化反应速率增加，这说明高温有利于减轻游离氨的毒害作用。相同条件下，颗粒污泥似乎有着更强的抗FA抑制能力。主要原因是颗粒污泥相对于絮状污泥结氨氧化菌种群数量较高，且游离氨进入颗粒内部传质受到限制，从而表现出抗高氨氮负荷冲击的优势。(2)除磷颗粒污泥SBR的研究①除磷颗粒污泥的培养与丝状菌膨胀控制，在SBR反应器中接种普通活性污泥，通过厌氧\好氧交替的运行方式，以沉降时间作为选择要素，经过人工配水快速实现污泥颗粒化、实际生活污水稳定维持以及提高P/COD比强化富集聚磷菌3个阶段，成功培养出聚磷能力良好的好氧颗粒污泥，并稳定运行360周期。模拟废水水质成份单一且易降解是好氧颗粒污泥发生丝状菌膨胀的主要原因，变换水质为实际生活污水可有效控制丝状菌的过度生长。成熟的好氧颗粒污泥平均粒径0.8mm，SVI在17~30ml/g，平均除磷效率在90%以上。FISH定量分析表明，聚磷菌约占总菌的51.48%。②缺氧环境对颗粒污泥强化除磷系统释磷的影响，在厌氧起始阶段投加不同浓度的NO3--N和NO2--N，结果表明，硝态氮的投加对聚磷菌释磷无明显抑制，系统中VFA的吸收、磷的释放和硝态氮的反硝化同时发生，VFA吸收速率增大，比释磷速率降低，主要原因是反硝化菌与聚磷菌竞争碳源。但是在颗粒污泥系统中有明显的亚硝酸盐积累。不同pH和不同浓度的NO2--N批次试验表明，游离亚硝酸(FNA)对磷的释放有明显刺激作用。当FNA增加到0.004mg HNO2-N/L，比磷释放速率增加了4倍。另外，FNA对VFA的吸收和PHA的合成均有明显抑制，分别减少了53%和70%。FNA刺激磷释放的机理是聚磷菌需要释放更多的能量来保持足够的质子驱动力。(3)以颗粒污泥为介质的双污泥工艺氮磷去除性能研究本研究考察了HRT对双污泥系统脱氮除磷的影响，发现HRT的变化对COD的去除率影响较小，出水COD浓度平均为35.2mg/L。增加好氧硝化SBR的HRT，可实现氨氮的全部氧化，降低出水总氮浓度。增加缺氧SBR的HRT，可增大系统的反硝化除磷能力。本研究同时考察了进水C/P/N对双污泥系统脱氮除磷的影响，随着进水C/P比的逐渐增大，磷的释放能力逐渐增大。进水C/P比为20/1时，磷的去除能力维持在90%，出水磷浓度平均为0.75mg/L，当C/P比增加到40/1时，出水磷浓度较高，平均为3.8mg/L。通过探索影响双污泥工艺的关键因素，优化系统运行工况，实现了以颗粒污泥为介质的双污泥系统完成短程硝化反硝化除磷脱氮，最大程度的优化同步生物脱氮处理工艺。更多还原

【Abstract】 Aerobic granular sludge technology, partial nitrification technology anddenitrifying phosphorus removal technology are the hot spots for wastewatertreatment at home and abroad. In this study, the cultivation of aerobic granules fornitrogen and phosphorus removal by seeding conventional activated sludge werestudied and the effect of environmental factor on the performance of granules werealso studied. On this basis, a new process called granular two-sludge system wasestablished in this paper which is fundamentally based on the technique ofdenitrifying phosphorus removal. The two-sludge system with simultaneous nitrogenand phosphorus removal consists of sequencing batch reactors (SBR) is workingunder alternating anaerobic/anoxic conditions and an aerobic SBR using granularsludge. This process realizes a combination of granulation technology, denitrifyingphosphorus and nitrogen removal technology and has the characteristics described asfollows:(1) aerobic granules exhibit advantages of excellent settleability, highbiomass and high efficiency of nitrogen and phosphorus removal;(2) the system issimplified without sludge return and solves the contradiction of different SRT ofnitrifying bacteria and PAOs;(3) anoxic stage saves oxygen consumption and reducessludge production.There are three parts in this paper:(1) Study of partial nitrifying granular sludge in SBR①Cultivation of partial nitrifying granular sludge: Conventional partialfloccular activated sludge were successfully achieved granulation in80cycles (19days) under the conditions of temperature30C, dissolved oxygen (DO)2.0mg/L,sludge retention time (SRT)15days by increase of the settling time and optimizationof aerobic duration in SBR. pH was monitored and used to control aeration in order toavoid excess aeration. Average diameter of the aerobic granular sludge was between1.5-2.0mm. The nitrite accumulation ratio (NO2--N/NOx--N) was over95%as theshort-cut process was operated stably. The granules showed very good capability ofCOD removal with80%and ammonia removal with95%. Enrichment of ammoniaoxidizing bacteria was quantified by fluorescence in situ hybridization (FISH)analysis as17.8%of the total bacteria，on the contrary, the density of NOB decreasedto be0.6%. FA inhibition effect and real-time control were the main factors for stablepartial short-cut nitrification.②Cultivation of granules with nitrite oxidizing bacteria and reaction dynamicsstudy: In this study, a sequencing batch reactor (SBR) was developed to enrich nitriteoxidizing bacteria granular sludge fed with nitrite inorganic wastewater in SBR continuously under the condition of temperature25C, dissolved oxygen (DO)2.0mg/L, settling-time2mins. After130-day operation, sludge flocs becamegranulated with an average diameter of0.72mm. Long-term monitoring of the reactorperformance revealed that steady nitrite oxidation was achieved with the nitrite levelin the effluent almost undetectable. FISH results reported that Nitrospira is thedomitant bacteria. The Monod equation was used to describe their nitrite utilizationrate and the kinetic coefficients were calculated to be Vs=30.94mg/(g VSS h) and Ks=8.19mg/L.③Effect of COD/N ratio on the granulation process and microbial populationsuccession: Four identical sequencing batch reactors, R1, R2, R3and R4wereoperated with various initial COD/N ratios ranging from0/200,200/200,400/200and800/200. Aerobic granules were successfully cultivated in R2and R3. Differently,granules in R2had compact structure, regular shape, strong intensity and high specificnitritation rate and nitrifying bacteria population.④Short-term effects of temperature and free ammonia (FA) on ammoniumoxidization in granular and flocculent system: The results showed that the rate ofammonium oxidation in both cultures increased significantly as temperatureincreasing. The specific ammonium oxidation rate with the granules was2-3timeshigher than that with flocs at the same temperature. Nitrification at various FAconcentrations and temperatures combination exhibited obvious inhibition inammonium oxidation rate when FA was90mg/L and temperature dropped to10C inthe two systems. However, the increase in substrate oxidation rate of ammonia at30Cwas observed. The results suggested that higher reaction temperature was helpful toreduce the toxicity of FA. Granules appeared to be more tolerant to FA attributed tothe much fraction of ammonia oxidizing bacteria (AOB) and higher resistance to thetransfer of ammonia into the bacterial aggregates.(2) Study of aerobic granular sludge enriched with phosphorus accumulatingorganisms for phosphorus removal in SBR①Cultivation of aerobic granular sludge enriched with phosphorusaccumulating organisms and filamentous overgrowth controlling: By decreasing thesettling time，aerobic granules enriched with phosphorus accumulating organisms(PAOs) are cultivated under alternate anaerobic/aerobic conditions in a SBRinoculated with conventional activated sludge. The system underwent three phases:rapid start-up with synthetic wastewater, stabilization with real domestic wastewaterand enrichment of PAOs by increasing P/COD and stabilized during the next360cycles. Filamentous sludge bulking happened during start-up phase and readilybiodegradable organics in synthetic wastewater was considered to be the main reasonfor filamentous overgrowth in aerobic granules. It was ultimately controlled through changing the substrate from synthetic wastewater to real domestic wastewater. Thematured aerobic granules had an approximately spherical shape with a size of0.8mm,SVI of17-30ml/g. The average PO43--P removal efficiency was above90%. FISHanalysis showed that PAOs accounted for about51.48%of the total bacteria.②Effects of anoxic condition on phosphorus release of the phosphorusaccumulating microbial granules: It was investigated in batch testes using acetate andpropionate as carbon source by adding different levels of NO3--N and NO2--N in theinitial anaerobic stage. The results showed that nitrate addition had no obviousinhibition effect on phosphorus release. Phosphorus release and denitrificationsimultaneously occurred in the presence of nitrate accompanying VFAs increased andphosphorus release rate decreased. This phenomenon demonstrated a competition fororganic substrate under an anoxic condition between PAOs and ordinary heterotrophicdenitrifying bacteria with equal opportunities. Nitrite accumulation was observed ingranular system. Batch tests of NO2--N with different pH value showed that FNA,rather nitrite, had a strong stimulation effect on P-release. The P-release rate exhibited4times increase when FNA concentration was higher than0.004mg HNO2-N/L. And,VFA uptake rate and PHA synthesis mass were observed to decrease by53%and70%.The mechanism of nitrite toxicity associated with its effect on bacterial membranesand energy generation was that PAOs need release more energy to provide adequateproton motive force.③Nitrogen and phosphorus removal performance of granular two-sludgesystem: In this study, the effect of HRT on nitrogen and phosphorus removal wasinvestigated in the two-sludge system. The results found that COD removal rate wasless affected; the average COD effluent concentration was35.2mg/L. The increaseingHRT of aerobic nitrifying SBR can achieve complete ammonia oxidation and reducetotal nitrogen concentration in effluent. Similarly, a corresponding reduction ofphosphorus in effluent can be attained by increasing the HRT of anoxic stage. Theeffect of influent C/P/N ratio on the two-sludge system was also studied. With theinfluent C/P ratio gradually increasing, the phosphorus release capacity increased.When influent C/P ratio was at20/1, phosphorus removal capacity remained at90%and average effluent phosphorus concentration of0.75mg/L. But when the C/P ratioincreased to40/1, the effluent phosphorus concentration was higher to3.8mg/L. In all,it is expected that this study can optimize simultaneous biological nitrogen andphosphorus removal process to the greatest extent via the aerobic granular media.更多还原