【作者】 张秀红；

【导师】 周集体；

【作者基本信息】 大连理工大学 ， 环境工程， 2008， 博士

【摘要】 传统的生物脱氮工艺所包括的硝化和反硝化反应是在两个或多个独立的反应器中进行，或是在时间上造成交替缺氧和好氧环境的同一个反应器中进行，脱氮过程所需的硝化液的回流需要外加动力泵来实现。这样的工艺投资和运行费用较高，占地面积大。针对这些问题，本课题组设计制作了新型一体化气动内循环生物膜反应器，用于生活污水的脱氮和脱碳处理，硝化反应和反硝化反应分别在反应器不同分区内完成，曝气不但提供了硝化过程所需的溶解氧，而且还利用曝气作用实现了硝化液在反应器内的循环，节约了脱氮过程中所需的能耗。本论文首先研究了一体化气动内循环生物膜反应器不同分区结构对脱氮性能的影响，确定了反应器较优的结构形式为二区结构；在此基础上研究了运行温度、曝气量、进水COD／TN等运行条件对反应器脱氮性能的影响；并对反应器内实现短程硝化反硝化脱氮的可行性进行了研究；最后对本反应器的脱氮机理进行了特性分析。主要研究内容和研究结果如下。（1）论文首先研究比较了不同分区形式的反应器的脱氮效率。结果表明三区和二区结构形式的一体化生物膜反应器均可以在水平方向实现溶解氧的梯度分布，在单体反应器内同时实现了硝化和反硝化过程。在一定的运行条件下，由于硝化区容积的相对增加二区反应器比三区反应器的TN去除效率由所增加。二区反应器对模拟生活污水的TN去除负荷可达到0．080 kgTN／（m³·d），有机物的去除负荷可达到0．53 kgCOD／（m³·d）。荧光原位杂交实验表明，二区反应器的缓冲区内亚硝酸细菌丰度有所增加。以上实验说明二区结构反应器的脱氮性能优于三区结构反应器的脱氮性能。故此，本论文确定了反应器较优的结构形式为二区结构。（2）研究了进水COD／TN和曝气量对反应器硝化反硝化的联合影响。在进水COD／TN值（2．0）较小的情况下，反硝化是脱氮的限制步骤，TN去除负荷为0．052kgTN／（m³·d）。当进水COD／TN值为3．5，通过调整曝气量，TN去除负荷可达到0．069kgTN／（m³·d）。当进水COD／TN值为6．2时，TN去除负荷达到0．080 kgTN／（m³·d）。在一定的进水COD／TN下，曝气量的增加一方面会使缺氧区中的溶解氧升高，不利于反硝化；另一方面也会促进硝化液的回流，有利于更多的NO₃^--N完成反硝化。曝气量由850L/h增大到1100 L／h时对反硝化的综合影响不大，正反两方面作用趋于平衡。但曝气量达到一定量（1400 L/h）之后会不利于反硝化反应的进行，进而不利于TN的脱除。（3）反应器缓冲区和缺氧区之间的控制板高度决定了两区之间反应液流通截面积，而反应液流通截面积直接影响反应器内液体的循环量和缺氧区内的溶解氧浓度。本论文研究了反应液流通截面积对脱氮效率的影响。结果表明，在一定的曝气量下，通过增大反应液流通截面积可以增加反应器内的液体循环量，提高脱氮效率。当曝气量为850 L／h，反应液流通截面积由150cm²增大到300cm²时，TN去除负荷由0．059提高至0．065kgTN／（m³·d）。而当曝气量较高为1100 L／h时，流通截面积的增大使缺氧区中的溶解氧浓度增加，不利于反硝化，进而不利于TN的去除。（4）研究了运行温度和有机碳源对反应器脱氮性能的联合影响。结果表明，在一定的进水有机负荷下，随着运行温度的升高，NH₄⁺-N和TN去除率都有所升高。在一定的运行温度下，随着进水有机负荷的增加，硝化率下降，反硝化率升高。运行温度为8℃，进水中不加有机碳源时，NH₄⁺-N去除率可达到95％，去除负荷为0．086 kgNH₄⁺-N／（m³·d），TN去除率仅为10％左右。（5）对反应器能否以短程硝化反硝化原理脱氮进行了研究。结果表明运行温度为8℃，进水TN浓度为68-80 mg／L时，通过调整进水碱度反应器内可以实现短程硝化。亚硝酸盐积累率达到80％，NH₄⁺-N去除率达到88％，NH₄⁺-N去除负荷为0．075kgNH₄⁺-N／（m³·d）。硝酸菌属的荧光原位杂交实验表明在8℃下反应器实现短程硝化，很可能是硝酸细菌的活性被抑制了。运行温度为29℃时，进水TN浓度为114-146 mg／L时，通过调整进水碱度和曝气量，反应器可以以短程硝化反硝化的原理进行脱氮。好氧区和缓冲区中亚硝酸盐积累率分别为77％，79％。TN去除率达到72％，TN去除负荷为0．130 kgTN／（m³·d）。荧光原位杂交实验表明在29℃下反应器内实现稳定的短程硝化反硝化是由于硝酸细菌的活性长时间受到游离氨的抑制，在污泥中所占的丰度下降所致。（6）通过测定反应器各区各态氮浓度及各区污泥的硝化及反硝化活性研究了本反应器的脱氮机理。硝化反应主要在好氧区内完成，反硝化反应主要在缺氧区内完成。不同分区的污泥都同时具有硝化活性和反硝化活性。本反应器的脱氮过程，一方面是基于不同分区内发生的硝化反应和反硝化反应以达到脱氮的目的；另一方面，由于反应器各区内液体混合形态不均匀以及各区溶解氧分布不均，在每一个分区内都可能同时发生硝化反应和反硝化反应。更多还原

【Abstract】 For conventional nitrogen removal processes, nitrification and denitrification are carried out in separated tanks or in a single reactor where aerobic and anoxic conditions are formed sequentially. Such processes need power pump to realize the recirculation of nitrified wastewater that is needed in nitrogen removal. The investment and operation cost is high, and the land occupied is large. As to these problems, a novel incorporate airlift inner circular biofilm reactor is designed and fabricated which is applied as a single treatment unit for carbon and nitrogen removal of domestic wastewater. Nitrification and denitrification are accomplished respectively in different zones of the reactor. Aeration not only supplies dissolved oxygen needed in nitrification but also impulses the recirculation of nitrified wastewater, which economizes energy needed in nitrogen removal.This paper studied the influence of different configurations of the reactor on nitrogen removal firstly. According to the above results a preferable two zones configuration reactor was selected. Secondly the influence of operation temperature、aeration rate and influent COD/TN on nitrogen removal was studied. The feasibility of nitrogen removal via short-cut nitrification and denitrification principle in this reactor was studied. The nitrogen removal mechanism of the reactor was analysed lastly. The main content and results are as follows.（1） Nitrogen removal efficiencies of the reactor under different configuration forms were studied and compared firstly in this paper. The results demonstrate that DO distributing is different in level direction in the three zones reactor and in the two zones reactor that makes nitrification and denitrification carrying out in one reactor simultaneously. TN removal efficiency of the two zones reactor is higher than that of the three zones reactor at a certain operational conditions because of the increasing nitrifying zone volume. 0.080 kgTN/（m³·d） of TN removal loading and 0.53 kgCOD/（m³·d） of COD removal loading are attained in the two zones reactor treating simulated domestic wastewater. Fluorescence in situ hybridization analysis indicates that ammonia oxidizing bacteria percentage of buffering sludge increases which is the main reason for higher nitrifying efficiency of the two zones reactor. The above experiment results show that nitrogen removal performance of the two zones reactor is better than that of the three zones reactor. Therefore two zones configuration form is the preferable form of the reactor. （2） The influence of influent COD/TN and aeration rate on nitrogen removal was studied. Denitrification is the restrictive process and nitrogen removal loading is 0.052 kgTN/（m³·d） under lower COD/TN （2.0）. When the influent COD/TN is 3.5 0.069 kgTN/（m³·d） removal loading is achieved through adjusting aeration rate. Under a higher influent COD/TN 6.2, TN removal loading is 0.080 kgTN/（m³·d）. Under a definite influent COD/TN the increasing aeration rate not only results in the increasing of DO concentration in anoxic zone that is adverse for denitrification but also accelerates the recirculation of nitrified wastewater that is favorable for more NO₃^--N to accomplish denitrification. When aeration rate increases from 850 L/h to1100 L/h, the total influence is not high and positive and negative effect keep balanced. When aeration rate increases to a definite quantity （1400 L/h）, denitrification and nitrogen removal are both influenced adversely.（3） The baffle height between buffering zone and anoxic zone determines circulation area of nitrified wastewater. The circulation area influences the circulation quantity of nitrified wastewater and DO concentration of anoxic zone. So the influence of the circulation area between buffering zone and anoxic zone on nitrogen removal was researched. The circulation quantity of nitrified wastewater increases through increasing the circulation area under a certain aeration rate, which is favorable for nitrogen removal. But DO concentration of anoxic zone may increase which is disadvantage for denitrification and nitrogen removal. Under a definite aeration rate （850 L/h） when the circulation area increases from 150cm² to 300 cm², denitrification is accelerated, TN removal loading increases from 0.059 to 0.065kgTN/（m³·d）. But when the aeration rate is higher （1100 L/h） the increasing of the circulation area makes DO concentration of anoxic zone increasing that is adverse for denitrification and nitrogen removal.（4） The united influence of temperature and organic carbon on nitrogen removal performance of the reactor was researched. Under a definite influent organic loading NH₄⁺-N and TN removal efficiencies increase with operational temperature increasing. Under a definite operational temperature nitrification efficiency decreases and denitrification efficiency increases with influent organic loading increasing. At a lower temperture （8℃）, 95% NH₄⁺-N removal efficiency and 0.086 kgNH₄⁺-N/（m³·d） removal loading are attained with no organic carbon in influent. But TN removal efficiency is low which was only 10% because of no organic carbon in influent used for denitrification.（5） Nitrogen removal via Short-cut nitrification denitrification in this reactor was studied. Short-cut nitrification is realized through adjusting influent alkalinity at lower temperature （8 ℃） when the influent TN is 68⁸0 mg/L in this reactor. 80% of nitrite accumulating rate is attained. The average NH₄⁺-N removal efficiency is 88% and removal loading is 0.075 kgNH₄⁺-N/（m³·d）. Fluorescence in situ hybridization of nitrite oxidizing bacteria indicates that the activity of nitrite oxidizing bacteria is restrained and the percentage of nitrite oxidizing bacteria does not decreased a lot when short-cut nitrification carrying out in the reactor. When the influent TN is 114-146 mg/L nitrogen removal via short-cut nitrification denitrification is realized through adjusting influent alkalinity and aeration rate at 29℃in this reactor. NO₂^--N/NO_x^--N of the aerobic and buffering zone are 77% and 79% respectively. TN removal efficiency is 72% and removal loading is 0.130 kgTN/（m³·d）. Fluorescence in situ hybridization analysis indicates that the reason of short-cut nitrification denitrification carrying out in the reactor at 29℃is the decreasing of nitrite oxidizing bacteria percentage resulted from the restrained activity of nitrite oxidizing bacteria by free ammonia for a long time.（6） The nitrogen removal mechanism of the reactor was studied through measuring various forms nitrogen concentrations and the nitrification and denitrification activities of sludge from different zones. Nitrification prevails in the aerobic zone of the reactor, which results in lower concentration of NH₄⁺-N and COD and higher concentration of NO₃^--N in this zone. On the contrary, denitrification prevails in the anoxic zone, which results in higher concentration of NH₄⁺-N and lower concentration of NO₃^--N in this zone. Sludges from different zones of the reactor have both the ability of nitrifying and that of denitrifying. The nitrification activity of sludge from aerobic zone is higher and the denitrification activity of sludge from anoxic zone is higher. Nitrogen removal process of the reactor is realized by the nitrification and denitrification that predominated in different zones of the reactor and simultaneous nitrification and denitrification that occur in each zone resulted from the disproportion of wastewater and DO.更多还原