生物膜对城市污水处理厂营养物去除系统硝化的强化效果

发布时间：2018-08-02 12:02

【摘要】：目前,城市污水处理厂生物脱氮除磷工艺多采用A2/O及其改进型活性污泥工艺,此类工艺的弊端在于功能菌对污泥龄的要求与实际运行的偏离。这种情况在低温条件下更为严重,由于硝化菌对温度更为敏感,生长速率更低,因此,二者的偏离更大,这是造成我国北方地区城市污水处理厂冬季脱氮效果差的主要原因。为了维持低温下的脱氮(硝化)效果,污水处理厂一般采取降低污泥负荷、延长污泥龄和增加污泥回流等措施,但这无疑会降低系统的处理能力和除磷效率、增加运行费用。通过在活性污泥系统中投加悬浮填料,形成附着态和悬浮态微生物共存体系,可在不延长污泥龄的条件下增加系统中硝化菌浓度,在维持除磷能力和效果的前提下,提高脱氮效果。近年来,这种方法已逐渐被应用于国内外城市污水处理厂的升级改造,并取得了一定的效果。然而有关生物膜和活性污泥中硝化菌的份额以及对硝化的贡献鲜为报道。本研究针对西安市第四污水处理厂二期在好氧段投加悬浮填料的A2/O工艺(简称填料-A2/O工艺),分夏季和冬季两个阶段监测好氧区不同形态的氮的沿程变化和生物膜与活性污泥的最大比硝化速率,计算硝化菌所占份额及投加填料后系统增加的生物量,探讨活性污泥与生物膜中硝化菌对硝化的贡献,最后探讨不同SCOD/NH4+-N下生物膜的生长情况以确定填料的投加位置。论文获得的主要研究结果如下:(1)夏季平均水温23.0℃,氨氮在好氧区第三个廊道末即减小为3.7mg/L,达到了一级A排放标准,可见好氧区夏季约有2/5容积富余。活性污泥AUR和NUR分别为4.43mg NH4+-N/g VSS·h和4.73mg NO2--N/g VSS·h,生物膜AUR和NUR为2.95 mg NH4+-N/g VSS·h和3.77mg NO2--N/g VSS·h,活性污泥中硝化菌的份额约为生物膜的2倍;且活性污泥生物量3859mg/L,生物膜为1530mg/L(填料),折算至整个好氧区生物膜生物量为67 mg/L。温度较高时,活性污泥中硝化菌发挥主要作用,生物膜对系统硝化无强化作用。(2)冬季低温平均水温14℃,活性污泥AUR和NUR分别为3.16mg NH4+-N/g VSS·h和3.39mg NO2--N/g VSS·h,生物膜AUR和NUR为3.63mg NH4+-N/g VSS·h和4.17mg NO2--N/g VSS·h,生物膜上硝化菌所占的份额稍高于活性污泥。冬季生物膜生物量为3690mg/L(填料),活性污泥的生物量为3187mg/L,生物膜膜厚平均为130μm。折算至整个好氧区生物膜生物量为162 mg/L。当投加的填料占硝化总容积的4.4%时,生物膜对系统硝化的贡献约占5.5%,而活性污泥为94.5%。生物膜对系统硝化有一定的强化作用,但与国外同类工程相比生物膜贡献量相对较小,原因为系统的负荷较小,填料区氨氮浓度较低,随着污水处理厂负荷的提高,生物膜的贡献将逐渐提高。(3)A2/O好氧区沿程SCOD/NH4+-N值分别为4.8、3.9、3.0、3.0,在好氧区第三个廊道SCOD/NH4+-N为3.0,生物膜AUR为3.87mg NH4+-N/g VSS·h,NUR为4.88mg NO2--N/g VSS·h,生物量为2854mg/L(填料),此时生物膜对系统硝化的贡献最大,故可考虑将填料区设置在A2/O好氧区第三个廊道。
[Abstract]:At present, most of the biological nitrogen and phosphorus removal processes in the municipal wastewater treatment plant use A2/O and its modified activated sludge process. The malpractice of this process lies in the deviation between the requirements of functional bacteria and the actual operation of the sludge. This situation is more serious under low temperature conditions, because the nitrifying bacteria are more sensitive to the temperature and lower the growth rate, therefore, the two ones are biased. In order to maintain the effect of nitrogen removal (nitrification) at low temperature, the sewage treatment plant generally adopts measures to reduce the sludge load, prolong the sludge age and increase the reflux of the sludge, but this will undoubtedly reduce the treatment capacity and the efficiency of phosphorus removal and increase the efficiency of phosphorus removal. Operation cost. By adding suspended packing in the activated sludge system to form a coexistence system of attached and suspended microorganisms, the nitrifying bacteria concentration in the system can be increased without prolonging the age of sludge, and the effect of phosphorus removal is improved. In recent years, this method has been gradually applied to the cities and cities at home and abroad. The upgrading and transformation of the sewage treatment plant has achieved some effect. However, the share of nitrifying bacteria in the biofilm and activated sludge and the contribution of nitrification are rarely reported. This study is aimed at the A2/O process of adding suspended filler in the aerobic stage of the fourth sewage treatment plant of Xi'an (simply named packing -A2/O process), which is divided into two in summer and in winter. The phase change of different forms of nitrogen in aerobic zone and the maximum specific nitrification rate of biofilm and activated sludge are monitored. The share of nitrifying bacteria and the increase of biomass after adding packing are calculated. The contribution of nitrifying bacteria in activated sludge and biofilm to nitrification is discussed. Finally, the growth of biofilm under different SCOD/NH4+-N is determined. The main results obtained in this paper are as follows: (1) the average water temperature in summer is 23 degrees centigrade, and ammonia nitrogen is reduced to 3.7mg/L at the end of third corridors at the aerobic zone, and the first order A emission standard is reached. It can be seen that the aerobic zone is about 2/5 volume in summer. The active sludge AUR and NUR are 4.43mg NH4+-N/g VSS. H and 4.73mg NO2--N/g VSS. The biofilm AUR and NUR are 2.95 mg NH4+-N/g VSS / h and 3.77mg NO2--N/g VSS H. The proportion of nitrifying bacteria in activated sludge is about 2 times that of biofilm, and the biomass of activated sludge is 3859mg/L, the biofilm is 1530mg/L (packing), and the nitrifying bacteria in the activated sludge play the main role when the biomass of the biofilm is 67 The biological membrane has no strengthening effect on nitrification. (2) the average water temperature of the low temperature in winter is 14 degrees C, the activated sludge AUR and NUR are 3.16mg NH4+-N/g VSS / h and 3.39mg NO2--N/g VSS h respectively, the biofilm AUR and NUR are slightly higher than the activated sludge. The biomass is 3690mg/L (packing), the biomass of activated sludge is 3187mg/L, the membrane thickness of biofilm is 130 u M. to 162 mg/L. in the whole aerobic zone, and the contribution of biofilm to system nitrification is about 5.5% when the added filler is 4.4% of the total nitrification volume, while the activated sludge is 94.5%. biofilm for system nitrification. The contribution of the biofilm is relatively small compared with the foreign similar projects. The reason is that the load of the system is small and the concentration of ammonia nitrogen in the packing area is low. With the increase of the load of the sewage treatment plant, the contribution of the biofilm will gradually increase. (3) the SCOD/NH4+-N value of the A2/O aerobic zone is 4.8,3.9,3.0,3.0, and the third corridor SCOD in the aerobic zone. The /NH4+-N is 3, the biofilm AUR is 3.87mg NH4+-N/g VSS. H, NUR is 4.88mg NO2--N/g VSS. H, and the biomass is 2854mg/L (packing). At this time, the biofilm contributes most to the nitrification of the system. Therefore, the packing area can be set in the third corridors of the aerobic zone.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703

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