【作者】 王强；

【导师】 马放； 杨基先；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2010， 博士

【摘要】 氮素污染控制是当今水污染防治领域的关注焦点。传统生物脱氮工艺在处理过程中存在弊端,亟待研发高效、稳定、节省占地的新型生物脱氮工艺。本论文将好氧反硝化和磁生物强化理论引入新型生物脱氮工艺的研发,研究高效好氧反硝化功能菌的筛选、鉴定、生理特性及脱氮效能;构建基于好氧反硝化菌的新型强化生物脱氮系统,探讨磁强化技术对功能菌效能和对SBR系统污水处理效果的强化作用;考察反应系统中的微生物群落结构演替规律,解析系统中的硝化功能菌群、反硝化功能菌群间的生态学关系及动态变化趋势,为现有污水处理系统的强化及同步脱氮机理提供进一步参考。定向筛选高效好氧反硝化菌,确定其最适生长和反应条件,结果表明:所筛选菌株T13(Pseudomonas sp.)为硝酸盐去除率97.75 %,总氮去除率89.74 %的高效好氧反硝化菌。其适宜生长和反硝化温度范围为25-35℃,μmax=0.3079 h-1,代时G =2.25 h。并在15℃的低温下仍具有脱氮能力;适宜的pH为中性偏碱;适宜的C/N为3-12;能够利用硝酸盐、亚硝酸盐为电子受体进行硝酸盐呼吸,并实现90 %以上的硝酸盐、亚硝酸盐去除率。结合菌株微生物特性,探讨磁场对好氧反硝化进程的影响与机制,结果表明:磁场强度和磁作用方式均对好氧反硝化功能菌的生理特性产生影响,当磁场强度150 mT时,T13的微生物生长量、硝氮去除率、脱氢酶活性最佳,其中硝氮去除率、脱氢酶活性分别较未加磁场时提高了7.2%和2.38倍;投加磁粉后T13生长显著,T13加磁粉的比生长速率μ明显高于其他两组。磁粉投加量为2g/L时,硝氮去除率达到100 %,经统计学差异显著分析,磁作用效果明显。将高效好氧反硝化菌T13接入SBR系统,可见磁作用对硝氮和COD去除的明显增强作用。功能菌蛋白凝胶分析推断,磁致生物效应主要为通过磁效应对微生物的酶活性产生影响,进而调控微生物反应的进行。考察磁作用对污染物去除及污泥性质的影响并优化磁作用参数,结果表明:常温条件下,综合考虑氨氮和COD的去除效果,60-90 mT磁场范围能达到对污染物去除较佳。磁作用可以使污泥颗粒zeta电位降低,促进了污泥的沉降速率的提高,活性污泥的脱氢酶活性随着磁场梯度的增加呈现出较明显的增加趋势。考察生物-磁复合强化技术的低温同步脱氮效能及稳定性,结果表明:磁效应可以缩短最佳停留时间,增大了SND稳定高效运行pH值的耐受范围,增强了处理系统的稳定性,实现污染物的高标准达标排放。低温运行期间,平均进水COD 377 mg/L、氨氮67 mg/L,MSBR-SND(Magnetic-SBR-SND)出水平均氨氮去除率为95.76 %,出水平均总氮去除率为60 %,COD去除率为82 %左右,出水氨氮浓度符合《城镇污水处理厂污染物排放标准》(2002)一级A标准,磁作用效果显著。基于PCR-DGGE技术,结合聚类分析与Shannon多样性指数分析,结果表明,磁效应导致适应磁环境的细菌生物活性增强,使系统更快形成稳定的群落结构。在系统HRT与DO改变时其微生物群落结构相对稳定,pH改变时群落结构变化相对激烈,但外界条件对加磁系统微生物多样性的影响均较小。系统中的反硝化菌群和硝化功能菌群结构与多样性的变化受上述条件影响,所筛选菌株T13有较强的适应能力,所代表的条带在整个运行期间的DGGE图谱上始终存在,为菌群中的优势种属之一,从而保证了系统硝氮的稳定去除。通过上述研究,可以确定:磁效应对好氧反硝化功能菌的生长代谢与生态优势地位具有显著促进与稳定作用,基于好氧反硝化菌的磁复合强化生物脱氮技术能够有效提高污水处理系统的处理能力和效率,并在低温条件下具备稳定性与高效性的优势,为完善城镇污水的生物脱氮工艺,尤其是北方低温环境下污水的高效稳定处理提供了有效的新途径。更多还原

【Abstract】 Recently, nitrogen removal which plays an important role in controlling water pollution has received more and more attention. Due to the disadvantage of traditional technologies for biological nitrogen removal, the research on novel technology which focuses on enhancing the efficiency and stabilization of biological nitrogen removal, as well as saving the consumption of construction and operation become an urgent need. With the development of aerobic denitrification and magnetic strengthening, in this paper, the aerobic denitrifier which having high potential of denitrification was isolated, the performance of magnetic strengthening on the denitrification characteristics of function microbe and the efficiency of biological nitrogen removal system was further investigated, meanwhile, under the magnetic condition, the microbial community structure in the system was detected, and the relationship and dynamic variation of nitrobacteria and denitrifying bacteria was analyzed.A high efficient aerobic denitrifying bacterium belonging to Pseudomonas sp. was isolated from activated sludge, named T13, having the excellent removal efficiency of nitrate and total nitrogen which achieved 97.75 % and 89.74 % respectively. The optimal temperature for the growth and denitrification of T13 ranged from 25 to 35℃, and a nitrogen removal ability of T13 could be found even at a lower temperature such as 15℃. The optimal pH was neutral and low alkali, and the optimal C/N was 3-12. Such a strain could utilize nitrate and nitrite as electron acceptors for nitrate respiration, achieving high-efficiency removal of nitrate and nitrite which were higher than 90 %.Both the intensity and modes of magnetic interaction had great effects upon the physiological characteristics of function microbe regarding aerobic denitrification. Strain T13 showed better performance at the magnetic intensity of 150 mT, the nitrate removal efficiency and dehydrogenase activity increased 7.2 % and 2.38 folders respectively compared to the control condition without magnetic interaction. And the removal of nitrate caused by T13 could reach 100 % when adding magnetic powder into the system. Further, the remarkable improvement of nitrate and COD removal by magnetic interaction was also found in SBR system incubated strain T13. It was presumed that magnetic field had a particular biological effect on the micro activity in order to regulate the reaction of biological nitrogen removal. Considered with the tendency of COD and nitrogen removal, the optimal range of magnetic field was 60-90 mT. Magnetic treatment could reduce the zeta potential of sludge particle and increase the sludge sedimentation rate correspondingly.Magnetic strengthening biological nitrogen removal based on aerobic denitrifiers was investigated at low temperature. It was found that magnetic field was beneficial for the operation of simultaneous nitrification and denitrification (SND) system including shortening the HRT, improving the stabilization and efficiency, enhancing the tolerance to pH and achieving the contamination removal with high standard. Under low temperature, the MSBR-SND (Magnetic-SBR-SND) fed with 377 mg/L of COD and 67 mg/L of ammoniac nitrogen showed a high degree of contamination removal, the average removal of ammoniac nitrogen, total nitrogen and COD was 95.76 %, 60 % and around 82 % respectively.Based on the PCR-DGGE (denaturing gradient gel electrophoresis of polymerase chain reaction) protocol, together with the cluster analysis and Shannon divergence, it was clear that magnetic interaction could induce to a better micro activity of bacterium which adapting the magnetic field and help for forming the stable community structure in the ecosystem rapidly. Under different HRT and DO, the total community structure was stable, while it changed much more intensely with the changed pH, but the effect of these operational parameters on microbial community diversity in the magnetic-added system of biological nitrogen removal was uniformly low. The community structure and microbial diversity of nitrification bacteria and denitrifiers were also affected by the above parameters, but the function microbe T13 which became the dominance strain in this ecosystem presented perfect tolerance to the variation in these conditions, indicating the stabilization of the magnetic-added system for nitrogen removal.Through the systemic research on performance and mechanism on magnetic strengthening biological nitrogen removal based on aerobic denitrifiers, it can be determined that magnetic effect could promote the growth and metabolism of aerobic denitrifiers and help for keeping their dominance state in ecosystem of nitrogen removal, and the technology of magnetic strengthening composite biological nitrogen removal have obvious advantages on improving treatment capable and efficiency of biological nitrogen removal system,especially under low temperature conditions. Therefore this investigation provides a new approach to novel technology of biological nitrogen removal and feasible application in the cold regions of north china.更多还原