不同运行条件下硝化系统的硝化效果及微生物特性研究

发布时间：2018-05-22 10:47

本文选题：SBR + CSTR　；参考：《扬州大学》2017年硕士论文

【摘要】：本研究是以CSTR和SBR反应器的活性污泥硝化系统为研究对象,通过改变进水氨氮负荷和SRT,对比不同运行条件下的硝化效果、污泥絮体形态、污泥微生物特性和硝化细菌的动力学参数来研究不同运行条件对硝化系统的影响。同时考察了硝化细菌的选择机制和硝化细菌动力学参数的影响因素。通过对CSTR和SBR反应器的研究,得到以下结论:(1)CSTR反应系统在进水氨氮浓度为70mgN/L时,通过改变其SRT可以实现短程硝化,但是不能长期维持,并且在继续降低SRT时,也不能重新恢复短程硝化。因此在污水处理中,仅靠调整SRT来维持短程硝化是不现实的,必须还要结合其他因素共同控制条件,才可能实现短程硝化的长期稳定运行。(2)在SBR反应器中,通过提高进水氨氮浓度可以快速实现短程硝化,降低负荷后最终会导致NOB抑制解除,短程硝化被破坏,硝化类型向全程硝化转变。通过调节反应器的SRT可以实现短程硝化,从稳定持续的实现短程硝化的角度看,SRT=10d是最佳工况,这个阶段可以利用AOB和NOB的增长速率的差异淘洗NOB,并且不会导致污泥和AOB的大量流失。(3)在污泥培养的过程中,污泥絮体的尺寸大小会发生改变。污泥絮体的大小、形状可以反映污泥对污染物吸收与降解性能。长期的高负荷条件,细菌消耗大量底物进行生长繁殖,微生物的增殖和聚集导致了污泥絮体尺寸变大,絮体在聚集和解体过程中受到了挤压使絮体变得紧实。不同SRT运行条件下的SBR反应器的污泥絮体尺寸有很大差别,SRT越小,由于污泥排出较多使微生物不能大量聚集,因此污泥絮体的尺寸越小。(4)在短程硝化下主要的AOB和NOB是Nitrosomonas和Nitrospira,这两种细菌被普遍认为是可以在底物浓度较高的条件下快速降解底物的r-策略细菌。在全程硝化中检测到的 AOB 是 Nitrosomonas,NOB 主要是 Candidatus Nitrotoga。对 AOB,Nitrosomonas 的百分含量随着SRT的降低而减少,Nitrosomonadaceae的百分含量随着SRT的降低而增加,对于NOB,Nitrospira的百分含量随SRT的降低而减少,Candidatus Nitrotoga的百分含量随着SRT的降低而增加。系统中优势菌类型的转变与负荷和SRT有关,负荷的大小和SRT的高低是影响细菌生长繁殖的重要因素。在只有氨氮作为营养源的条件下的微生物群落特性会一直发生变化,时间间隔越小污泥群落差异性越小,不同负荷下污泥的微生物群落差异性比相同负荷的污泥差异性更加显著。不同的SRT会对污泥中微生物群落的差异性造成影响,SRT越接近,差异性越小。在整个污泥驯化过程中,微生物的丰富度和均匀度都在不断降低。(5)动力学参数的变化可以说明动力学参数是受多种因素共同影响的,其中底物的转化效率、氮的形式和污泥的絮体形态均是造成动力学参数改变的重要条件。r-AOB含量越高的样本AOB最大比增长速率μAOB.max越高;SRT对微生物动力学参数的变化起间接作用,Nitrosomonadaceae 的μAOB,max 比 Nitrosomonas 大。AOB 的氨氮半速度常数 KNH4 随着最大比增长速率μAOB.max增大而增大。溶解氧半速度常数KO,AOB随污泥絮体尺寸的增大而增大。NOB的最大比增长速率μNOB.max与细菌的种类有关,Nitrospira比CandidatusNitrotoga的值大。NOB的溶解氧半速度常数KO,NOB可能随絮体尺寸变大而变大,也可能是随优势NOB的改变而改变。NOB的KN02可能随污泥絮体尺寸的增大而增大。(6)在动力学参数的测定中,测得值可能与理论值有矛盾,这可以用污泥絮体尺寸的大小来解释。絮体内部生长的硝化细菌在利用底物时,需要克服扩散阻力,絮体尺寸越大需要克服的阻力越大。所以对于不同尺寸的污泥絮体进行动力学分析时,不仅要需要考虑扩散阻力的影响。传统的r-策略和K-策略经典理论应该把污泥絮体尺寸的大小划入需要研究的范围内。
[Abstract]:In this study, the nitrification system of activated sludge in CSTR and SBR reactors was studied. By changing the ammonia nitrogen load and SRT, the nitrification effect under different operating conditions, the morphology of the sludge floc, the microbial characteristics of the sludge and the kinetic parameters of the nitrifying bacteria were studied. The selection mechanism of nitrifying bacteria and the influencing factors of nitrifying bacteria kinetic parameters. Through the study of CSTR and SBR reactor, the following conclusions are obtained: (1) CSTR reaction system can achieve short nitrification by changing its SRT when the concentration of ammonia nitrogen is 70mgN/L, but it can not be maintained for a long period, and can not be reproduced when SRT is continued. Therefore, it is unrealistic to maintain short range nitrification by adjusting SRT only in sewage treatment. It is necessary to combine other factors together with other factors to realize the long-term stable operation of short range nitrification. (2) in the SBR reactor, short range nitrification can be realized quickly by increasing the concentration of ammonia nitrogen in the influent, and the load will eventually be reduced. NOB suppression, short range nitrification and nitrification change to whole nitrification. By adjusting the SRT of the reactor, short nitrification can be realized. From the point of view of stable and persistent nitrification, SRT=10d is the best working condition. This stage can use the difference in the growth rate of AOB and NOB to wash NOB, and does not lead to sludge and AOB (3) in the process of sludge culture, the size and size of sludge floc will change. The size and shape of the sludge floc can reflect the absorption and degradation performance of the sludge to pollutants. Long term high load conditions, the bacteria consume a large number of substrates to grow and reproduce, and the proliferation and aggregation of microorganism lead to the larger size of the sludge floc. The floc becomes tight in the process of aggregation and disintegration. The floc size of the sludge in the SBR reactor under different SRT operating conditions is very different. The smaller the SRT is, the smaller the sludge is discharged from the sludge, the smaller the size of the sludge floc. (4) the main AOB and NOB under short range nitrification are Nitrosomonas. And Nitrospira, these two kinds of bacteria are generally considered to be the r- strategy bacteria that can quickly degrade substrates at high substrate concentration. The AOB of the whole nitrification is Nitrosomonas, NOB is Candidatus Nitrotoga. to AOB, and the percentage of Nitrosomonas decreases with the decrease of SRT, and Nitrosomonadaceae percent With the decrease of SRT, the content of NOB, Nitrospira decreased with the decrease of SRT, and the percentage of Candidatus Nitrotoga increased with the decrease of SRT. The transformation of the dominant bacteria type in the system was related to the load and SRT. The size of the load and the level of SRT were the important factors affecting the growth and reproduction of bacteria. The microbial community characteristics will change under the condition of nitrogen as the source of nutrition. The smaller the time interval is, the smaller the diversity of the sludge community, the diversity of the microbial community under different loads is more significant than that of the same load. Different SRT will affect the diversity of the microorganism community in the sludge, the closer the SRT, the worse, the difference between the sludge community and the difference of the sludge community. The smaller the opposite sex is, the richness and uniformity of microorganism are decreasing during the whole sludge acclimation process. (5) the dynamic parameters can be influenced by various factors. The conversion efficiency of the substrate, the form of nitrogen and the floc form of the sludge are all important conditions for the change of kinetic parameters,.R- The higher the AOB content, the higher the maximum ratio of AOB to the growth rate, the higher the growth rate of AOB.max; the SRT has an indirect effect on the change of the microbial kinetic parameters, the Nitrosomonadaceae's mu AOB, the ammonia nitrogen half velocity constant KNH4 of Max is larger than Nitrosomonas, and the half velocity constant of the dissolved oxygen increases with the maximum specific growth rate mu AOB.max. The maximum specific growth rate of.NOB, which increases the maximum specific growth rate of.NOB, is related to the species of bacteria. The value of the dissolved oxygen half velocity constant of.NOB is KO, and NOB may become larger with the size of the floc, and the KN02 may also be the increase in the size of the floc with the change of the dominant NOB. (6) in the determination of the kinetic parameters, the measured value may contradict the theoretical value, which can be explained by the size of the sludge floc. The nitrifying bacteria within the floc need to overcome the diffusion resistance when using the substrate, and the larger the size of the floc, the greater the resistance to overcome. So the power of the sludge flocs of different sizes is driven. It is necessary to consider not only the influence of the diffusion resistance, but the traditional r- strategy and the classical K- strategy theory should draw the size of the sludge floc into the scope of the need to be studied.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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