【作者】 暴瑞玲；

【导师】 于水利；

【作者基本信息】 哈尔滨工业大学 ， 市政工程， 2009， 博士

【摘要】 水体富营养化问题的日益突出,为控制污水氮磷的排放提出了迫切的任务。传统的生物脱氮除磷系统尤其在低温时污泥性能与处理效果差,并存在不同程度的污泥膨胀等问题而影响系统的正常运行。好氧颗粒污泥作为一种特殊的生物膜结构,其具有独特的优点而倍受关注。然而,好氧颗粒污泥反应器的启动与稳定运行仍然是制约其工程应用的关键问题,在低温时由于微生物的活性受到抑制而使反应器的启动与运行问题更为突出。本文探索研究了好氧颗粒污泥的低温启动过程,并系统研究了低温好氧颗粒污泥的同步脱氮除磷的效能与过程以及颗粒污泥运行的稳定性。以乙酸钠和葡萄糖混合基质为碳源,研究了低温好氧颗粒污泥的启动特性。在10±1℃时成功实现了污泥的颗粒化。成熟的颗粒具有清晰光滑的轮廓,结构密实,平均粒径为2.8mm,湿密度为1.036g/mL,SVI为37mL/g。启动初期的前35天内污泥亚硝化活性增强而硝酸菌活性减小,出水亚硝化率为46%。通过PCR-DGGE和微生物群落演替分析,低温好氧颗粒内部富积了具有贮存PHB和反硝化功能的菌属,为颗粒污泥的同步硝化反硝化和反硝化除磷提供了基础。同时研究了温度对颗粒污泥脱氮除磷性能的影响,温度的大幅升高(△T>6℃),导致了颗粒污泥的解体。通过低温好氧颗粒SBAR反应器运行参数的优化研究表明,当进水COD/N/P为100/5/1时,出水氨氮浓度较高,单独增加反应器的运行周期并不能明显增加低温好氧颗粒污泥反应器对氨氮的去除效果。而减小进水COD/N比有利于低温颗粒污泥内部硝化菌的积累,从而发挥颗粒污泥反应器内较大的生物量的优势实现低温较好的硝化效果。另一方面,进水COD由1120mg/L降低至560mg/L后,颗粒污泥粒径由3.4mm降低到2.6mm;反应器污泥浓度也由11.0g/L降低到8.0g/L。曝气量是控制颗粒内部厌氧区域与好氧区域比例以实现同步硝化反硝化的重要参数,并对颗粒污泥的稳定运行影响显著。当Vobs小于0.58cm/s(曝气量小于0.05m3/h,溶解氧饱和度为36%)时,颗粒污泥反应器对氮磷有较好的同步去除效果,但是颗粒表面过量繁殖的丝状菌降低了颗粒污泥运行的稳定性。而Vobs小于1.17cm/s(曝气量小于0.10m3/h)时,混合液溶解氧浓度接近饱和,曝气量的增加颗粒内部的厌氧缺氧区域被压缩而反硝化效果受到抑制,并增加动力消耗。反应器运行参数优化后的低温好氧颗粒污泥单级反应器具有较好的同步碳氮磷的去除性能,其COD,NH4+-N和PO43--P去除率分别为89.5%,98.9%和95.5%。同时,颗粒污泥反应器10±1℃时具有较好的同步硝化反硝化性能,出水亚硝酸盐氮和硝酸盐浓度分别为3.2mg/L和小于0.5mg/L,同步硝化反硝化效率为83.3%。通过静态试验研究了10±1℃时好氧颗粒污泥反硝化除磷性能与过程。结果表明:厌氧阶段不同的碳源类型对颗粒污泥聚磷菌合成胞内PHAs的组成影响显著,并影响颗粒污泥的厌氧释磷与缺氧吸磷,即PHAs中PHV比例的增加提高了反硝化聚磷菌对硝态氮电子受体的利用效率。厌氧段初始COD浓度小于300mg/L时,可有效控制有机物流入到缺氧段而影响反硝化吸磷效果。好氧颗粒污泥的生物膜生长方式有效降低了亚硝酸盐氮对反硝化除磷的抑制作用,当亚硝酸盐氮浓度大于60mg/L时出现亚硝酸盐的抑制作用,远大于亚硝酸盐氮对絮状反硝化除磷污泥的抑制浓度。通过不同类型电子受体的反硝化除磷试验表明,颗粒污泥内部反硝化聚磷菌占总聚磷菌的58.7%,远大于厌氧—好氧条件下絮状污泥中的比例。为缩短和简化好氧颗粒污泥反应器的启动过程,研究了好氧颗粒污泥的储存对颗粒的影响,不同的氨氮负荷条件下脱氮除磷活性的恢复。两个月时间的保存后,颗粒污泥SVI由32mL/g增加到61mL/g,湿密度由1.036降低为1.017。在进水氨氮和磷浓度为40mg/L和12mg/L时,颗粒污泥的硝化与除磷活性分别在11d和42d后得到恢复。在进水氮氨浓度为80mg/L时,反应器运行27天后,进水氨氮可以被完全转化。由于混合液中较高的pH,颗粒表层发生磷的化学沉淀,使颗粒内基质的传输受限,而在试验中除磷活性并没有得到有效的恢复,出水磷浓度大于6.1mg/L,因此在颗粒污泥的活性恢复阶段应保持pH小于8.0。更多还原

【Abstract】 The problem of water eutrophication increasingly outstanding puts forward urgent task for controlling N and P discharge. There are many problems such as the worse sludge performance and treatment effect at low temperature. In addition, sludge bulking affects the stable operation of the system to some extant. The aerobic granular sludge process, which is considered as a special biological membrane structure, has received much attention due to the unique merits of aerobic granular sludge. However, the quickly start-up and stable operation of aerobic granular sludge reactor, especially at low temperature, is still the key problem that restricts its engineering application. In this work, start-up process of aerobic granular sludge at low temperature was investigated, and simultaneous nitrogen and phosphorus removal processes, the operating stability of aerobic granular reactor at low temperature were studied systematically.The start-up properties of aerobic granular sludge reactor at low temperature were studied, in which the mixture of acetate sodium and glucose served as carbon source. The granules were obtained at 10±1℃. The obtained granules exhibited clear and slippy surface, compact structure and better sedimentation feature. In the first 35 days during the start-up stage, nitrosation activity increased and nitrification activity decreased with the effluent nitrosation ratio of 46%. The results of PCR-DGGE and microbial community ecological succession showed that the bacteria genus which had the function of PHB synthesization and denitrification. This provided foundation of the simultaneously nitrification-denitrification and denitrifying phosphorus removal inside aerobic granules at low temperature. Effect of temperature on the removal properties of ammonia and phosphorus were also studied. The results showed that the stability of granules was affected when the operating temperature increased from 20±1℃to 26±1℃. The nitrite of effluent was accumulated as the temperature increased and its nitrosation ratio was 93.9%. As a result of increased temperature (△T>6℃), the granules grandually disintegrated during the operation period of 47d after the change of temperature.The operating parameters optimization of aerobic granular SBAR at low temperature was investigated. It was found that the effluent ammonia concentration was higher when COD/N/P was 100/5/1, and the removal efficiency of ammonia was not improved obviously only by extending the cycle time. A decline of COD/N ratio was benefit to the accumulation of nitrosation bacterial inside the granular sludge at low temperature. Furthermore, it took full advantage of higher MLSS in the reactor to achieve better nitrification effect at low temperature. When the influent concentration of COD decreased from 1120mg/L to 560mg/L, the diameter of stable granules decreased from 3.4mm to 2.6mm, and MLSS also reduced from 11.0g/L to 8.0 g/L. The aeration rate is the key parameter in controlling the ratio of anaerobic and aerobic area inside granules to achieve simultaneous nitrification and denitrification, and remarkably affects the stability operation of granular reactor. In the case of Vobs lower than 0.58cm/s, the effect of N and P removal by the granular sludge reactor was better. But the excessive propagation of filamentous organisms and then decreased operating stability of granular sludge reactor. In the case of Vobs higher than 0.58cm/s, the dissolve oxygen concentration in the mixture approached to saturation. And anaerobic area inside granule was compressed and denitrification effect was restrained and dynamic consumption increased as the aeration rate increased. It behaved better simultaneous N and P removal effect in the parameters optimized single grade reactor of aerobic granule sludge and the removal coefficiency for COD,NH4+-N and PO43--P were 89.5%,98.9% and 95.5%, respectively. Meanwhile, the reactor exhibited better performance of simultaneous nitrification and denitrification at 10±1℃. The experimental data showed that nitrite and nitrate concentration in effluent were 3.2mg/L and lower than 0.5mg/L, the nitrification and denitrification efficecy was 83.3%.The denitrifying phosphorus removal proformance and processes were studied through static experiments at 10±1℃. The results showed that the PHAs components synthesized by phosphorus accumulating organisms (PAOs) in granule sludge were affected by different types of carbon source in anaerobic period, and the release and uptake of phosphate were also affected. It was indicated that the increased ratio of PHV to PHAs led to the increase of the utilization efficiency of nitrate nitrogen by denitrification PAOs. When initial COD concentration in anaerobic period was lower than 300mg/L, it can effectively keep organic substrates from flowing into the following anoxic period which influenced the efficiency of denitrifying phosphorus removal. Inhibition of nitrite to denitrifying phosphorus removal was decreased due to biology film growth manner of aerobic granular sludge. The inhibitory concentration of intrite to denitrifying PAOs was 60 mg/L. Denitrifying phosphorus removal experiments with different types of electric acceptor showed that denitrifying PAOs inside granules obtained in aerobic-anaerobic condition was 58.7% to the total PAOs, which was much bigger than that in floc sludge existed in the same operation way.In order to shorten and simplify the start-up process of aerobic granular sludge reactor, the effects of aerobic granules storation on the granule properties were studied. The recovery of removal activity for ammonia and phosphorus by granular sludge.after a longer storage period was also investigated. After 2 monthes storation, SVI increased from 32mL/g to 61mL/g, and wet density decreased from 1.036 to 1.017. When inffluent concentration of NH4+-N and phosphate were 40mg/L and 12 mg/L, respectivily, the activity for nitrification and phosphorus removal of granular sludge recovered after 11 day and 42 day cultivation in aerobic-anaerobic condition. When inffluent concentration of NH4+-N was 80mg/L, the NH4+-N can be converted completely after 27 days operation. Due to the higher pH of mixture, chemical sedimentation happened in the surface layer of granules, which limited the transmission of the substrates into granules, and the phosphorus removal activity of the granules cannot be recovered effectively, and the effluent phosphorus concentration was higher than 6.1 mg/L. Thus, pH should be kept lower than 8.0 in the activity recovery processes of granule sludge.更多还原