【作者】 魏燕杰；

【导师】 季民；

【作者基本信息】 天津大学 ， 市政工程， 2010， 博士

【摘要】 好氧颗粒污泥技术具有生物量大、泥龄长、耐冲击负荷能力强、能够同时实现脱氮除磷等特点,是一种具有良好发展潜力的工艺。目前将颗粒污泥SBR(GSBR)应用于垃圾渗滤液处理的研究较少。本文利用实验室规模的SBR反应器处理垃圾渗滤液,研究污泥颗粒化过程、颗粒污泥的耐盐性能及稳定性、进水氨氮浓度对脱氮性能的影响、以及污泥理化性状和微生物种群结构的变化。以絮状活性污泥为接种污泥,采用SBR处理垃圾渗滤液。通过逐渐增加反应器体积交换率,经过50天的运行污泥实现颗粒化;形成的好氧颗粒污泥具有优良的沉降性能、高生物活性及较高的耐盐性能。颗粒污泥形成过程中,污泥胞外蛋白(PN)浓度及表面疏水性(SRH)逐渐增加,表明PN及SRH与污泥颗粒化过程有密切的关系。处理垃圾渗滤液的GSBR稳定运行一段时间后大量颗粒污泥发生了解体现象,分析认为系统内水力选择压与基质选择压之间的平衡失调,是导致颗粒污泥解体、系统失稳内在诱因;并在此基础上提出了“投加粉末活性炭(PAC)强化好氧颗粒污泥稳定性”的调控措施。通过投加PAC可以强化系统内水力选择压,提高污泥的比重和强度(湿密度达1.070g/cm3),降低污泥生长速率和产率(成熟的颗粒污泥表观产率Yobs仅为0.103mgVSS/mgCOD),调节污泥浓度和粒径大小(平均粒径为0.36~0.60 mm)、降低粒径分布分散化的趋势,避免因传质阻力引起的颗粒内部分裂,保证GSBR持久维持稳定。GSBR进水氨氮浓度升高会导致反应器内游离氨(FA)浓度的增加,从而抑制部分污染物降解功能菌,特别是硝化细菌(NOB)的活性,导致系统内亚硝酸盐大量积累;若进水氨氮浓度处于788mg/L左右时,积累的NO2-通过短程反硝化转化为N2,再加上周期进水段进行的厌氧氨氧化反应,周期总氮(TN)的总去除率达58.1%;当氨氮浓度更高时(1165mg/L左右),AOB、NOB的活性均受到抑制,反应器TN和氨氮的去除率仅为35.0和39.3%。通过化学沉淀法对高氨氮垃圾渗滤液进行预处理,预处理后TN和氨氮浓度为399和366mg/L时,GSBR脱氮方式以完全硝化反应为主,还包括短程硝化、反硝化等多种脱氮途径;TN和氨氮的去除率达75.4%和95.6%。在稳定运行时,处理垃圾渗滤液GSBR中的颗粒污泥结构密实;细菌以杆菌为主,颗粒表面发现少量钟虫;粒径以0.20~0.60mm的小粒径颗粒为主;污泥SVI5min为38mL/g左右,污泥层区域平均沉降速度(ZSV)为24m/h;污泥密度为28gVSS/L;颗粒污泥强度(以完整性系数计)为96.3%;含水率为97%。污泥内元素分析表明:颗粒状污泥更倾向于选择性结合Ca、Fe、Cu等二价或三价金属,特别是Ca元素以CaCO3化合物的形式在好氧颗粒污泥内核大量沉积。污泥EPS中Na、K和Mg成为了主要的阳离子,Ca所占的比例相对较少。通过(Nested)PCR-DGGE技术对处理垃圾渗滤液SBR的污泥颗粒化阶段及不同氨氮负荷运行阶段微生物群落结构演变进行研究。结果表明:在反应器启动初期,总细菌、AOB、NOB的种群多样性较低,反硝化细菌未检出;随着污泥沉降性能的稳定以及颗粒污泥的形成,反硝化细菌出现,且各细菌种群多样性稳步上升,特别是AOB种群多样性的增加以及DGGE图谱中条带f所代表的AOB的出现及大量繁殖对反应器内氨氮转化为亚硝酸盐、保证氨氮的高去除率起着极其重要的作用;当处理高氨氮垃圾渗滤液时,系统内产生的高浓度FA会抑制功能菌的繁殖和活性,各细菌种群多样性有所降低,其中DGGE图谱表明NOB受到的抑制作用最为明显,这与反应器相应阶段的“短程硝化”表现相对应;当对高氨氮垃圾渗滤液进行预处理、GSBR进水氨氮浓度降低后,系统内种群多样性进入较长的稳定期,这为反应器对污染物高效、稳定地去除提供了保证。细菌克隆测序结果表明:总细菌优势菌大部分为未经培养菌种(Uncultured bacterium),部分菌种与弓形杆菌属、苯酚降解菌、降解芳香族污染的功能菌、影响活性污泥沉降性能的菌种等的同源性达91%以上;AOB中的优势菌群主要为β-变形菌纲(Beta-proteobacterium)、亚硝化单胞菌属(Nitrosomonas);NOB的大部分优势菌为未经培养菌种和根瘤菌(Rhizobium sp.),其中某些NOB与已知的耐盐硝酸菌、脱氮除磷菌、商用硝化菌等的同源性高达98%以上;测得的两株反硝化优势菌为Brachymonas denitrificans不动球杆菌。更多还原

【Abstract】 The technology of aerobic granular sludge has the advantages of high biomass content, high biomass retention, strogent ability to withstand shockloadings, and capacity of simultaneous nitrogent and phosphorus removal; it is a promising option for efficient wastewater treatment. Information on the aerobic granulation with landfill leachate is very limited. Lab-scale SBRs, fed with landfill leachate, were used in this study to investigate the formation, salt-resistance performance, stability of granules, as well as nitrogen removal performance under different influent NH4+-N concentrations. Moreover, the variations of aerobic granule properties and microbial population structure were paid more attention.Conventional activated sludge was inoculated in the SBR treating landfill leachate. Through step-rising of volumentic exchange ration from 30% to 50%, granules were cultivated successively in 50 days, and showed excellent settleability, high microbial activity and salt-resistance ability. In addition, the aerobic granulation process was accompanied with increments of extracellular protein content (PN) and surface relative hydrophobicity (SRH), which revealed the close relationships between PN and SRH with aerobic granulation.After a while of stable operation period, due to the disorder of balance between hydraulic and substrate selection pressures, a great quantity of aerobic granules began to break down into flocculent sludge. PAC was used to regulate the hydraulic selection pressure and strengthen the stability of aerobic granules. Experimental results showed that PAC addition could enhance granule strength and specific gravity (wet density of mature granules with PAC addition was1.070g/cm3), slow down the sludge growth rate and yield rate (observed yield coefficient Yobs of mature granules was only 0.103mgVSS/mgCOD), moderate the sludge concentration and size (average diameter was 0.36~0.60 mm), and reduce the dispersed tread of size distribution, so as to avoid internal segmentation of granule.High concentration of influent NH4+-N led to high concentration of free ammonia (FA) in the GSBR, which could inhibit the activity of functional bacteria, especially nitrite oxidizing bacteria (NOB). It finally resulted in the accumulation of NO2-. When the influent NH4+-N was around 788mg/L, partial accumulated NO2- was transformed to N2. Considering the partial nitrification and denitrification (PND), as well as the anaerobic ammonium oxidation (ANAMMOX) process during feeding time, TN removal efficiency in the whole cycle was 58.1%. When the influent NH4+-N was 1165mg/L, high FA concentration inhibited the activities of both ammonium oxidizing bacteria (AOB) and NOB, TN and NH4+-N removal efficiencies were only 35.0 and 39.3%, repectively. Magnesium ammonium phosphate (MAP) sedimentation process was used as pre-treatment for ammonia-nitrogen removal, and influent TN and NH4+-N of GSBR was greatly reduced. When the influent TN and NH4+-N were 399 and 366mg/L, nitrogen was mainly removed in means of complete nitrification. Coupled with other nitrogen removal pathways, like partial nitrification and denitrification, the TN and NH4+-N removal efficiencies were 75.4% and 95.6%, respectively.During the stable period of GSBR treating landfill leachate, aerobic granules were stable with dense structure, SVI5min of 38mL/g, average Zone Settling Velocity (ZSV) of 24m/h, biomass density of 28gVSS/L, sludge strgenth (in terms of integrity coefficient) of 96.3%, and water content of 97%. The granules were mainly composed of bacillus, as well as some protozoa and metazoan, like vorticella. Granules with the size of 0.20~0.60mm were the main part of the sludge. Multi-valence Ca, Fe, and Cu were the main metal elements of granules. Especially, Ca in the form of CaCO3 largely accumulated in the core of granules. While Na, K, and Mg were the main cations in the extracellular polymer substance (EPS), in comparison with the low content of Ca.(Nested) PCR-DGGE technologies were used to investigate the microbial community structure of GSBR during granulation process and other operation periods under different influent nigtrogen. The results showed that the biodiversities of total bacteria, AOB and NOB were low during the start-up period, when dinitrfiers were not discovered. With the improvement of sludge settleability and formation of aerobic granules, dinitrfiers appeared, and the biodiversities of each sort of bacteria steadily rose up. Especially the increment of AOB biodiversity and reproduction of AOB represented by Band f in the DGGE profile had significant positive effects on NH4+-N removal. When influent NH4+-N concentration increased, corresponding high FA content in the GSBR inhibited the activity of most functional bacteria, especially NOB. This situation was connected with“partial nitrification”performance. After pre-treatment by MAP, influent NH4+-N concentration decreased, bacteria biodiversity in the GSBR was stable, contributing to the efficient and steady pollutants removal. Most predominant species in the system were uncultured bacteria, the homology of these bacteria were more than 91% compared with Arcobacter butzleri, phenol-degrading bacterium, bacterium response to aromatic contamination and comamonadaceae as determinants of activated sludge settling performance. The main AOB species were Nitrosomonas, Beta-proteobacterium. Most predominant NOB were uncultured bacterium and Rhizobium sp., the homology of these bacteria were more than 98% compared with the halotolerant nitrite oxidizing bacterium, commercial nitrifying inoculum, and bacterium response to simultaneous phosphorus and nitrogen removal. Two isolated denitrifier strains were Brachymonas denitrificans.更多还原