【作者】 杨帅；

【导师】 杨凤林；

【作者基本信息】 大连理工大学 ， 环境工程， 2010， 博士

【摘要】 氮、磷是导致水体富营养化的优势污染物。随着生物脱氮除磷技术研究的深入,工艺简单、处理效率高、能耗低的新工艺将成为脱氮除磷工艺的发展趋势。本论文用悬浮填料生物膜代替传统膜生物反应器(CMBR)的活性污泥,提出一种新型的移动床膜生物反应器(MBMBR),通过对其运行方式及操作参数的优化调整,强化其脱氮除磷能力,同时对不同工艺方式下MBMBR对有机物、氮磷的去除性能,微生物特性及膜污染情况等进行了考察。首先进行了好氧MBMBR与CMBR对比实验,比较在不同进水条件下,两者对营养物的去除能力和膜污染情况。结果表明：与CMBR相比,MBMBR对TN表现出良好的去除能力。进水COD／TN为8.9,进水TN负荷为7.58 mg TN／L.h时,TN的去除率仍可达到70%以上。通过同步硝化反硝化作用去除的TN占TN去除的89.1%。MBMBR中由于丝状菌的大量存在,形成了厚实致密的滤饼层,造成了更加严重的膜污染。采用间歇曝气方式运行好氧MBMBR实现了短程硝化反应。结果显示：间歇曝气方式下,曝气时间／间歇时间是实现短程硝化的关键因素,COD/TN是影响TN去除效果的主要因素。间歇曝气方式主要是通过抑制亚硝酸盐氧化菌(NOBs)的活性来实现短程硝化。序批式移动床膜生物反应器(SBMBMBR)具有良好的脱氮除磷能力。其中TP的去除效果和厌氧阶段和好氧阶段时间的长短密切相关。当厌氧阶段和好氧阶段均为2 h时,TP的平均去除率达到84.1%。好氧阶段的DO是影响氮磷去除效果的重要参数,在SBMBMBR中,好氧阶段最佳的DO为3 mg/L左右。荧光原位杂交(FISH)结果表明由于生物膜内层的DO较低,亚硝酸盐氧化菌和聚磷菌的含量较少。而生物膜外层和悬浮污泥中,氨氧化菌和亚硝酸盐氧化菌的比例基本相同,并且存在大量的聚磷菌。通过外加硝酸盐或亚硝酸盐引入缺氧段的研究方法证实,厌氧／缺氧／好氧运行的SBMBMBR中,以亚硝酸盐为电子受体的反硝化除磷性能优于以硝酸盐为电子受体的反硝化除磷性能。批实验结果也证实以亚硝酸盐为电子受体的缺氧吸磷速率大于以硝酸盐为电子受体的缺氧吸磷速率。当硝酸盐大量存在时,反硝化菌与聚磷菌竞争有限的有机碳源,占竞争优势。因此,当进水碳源不足时,硝酸盐的存在将严重影响释磷反应的发生,最终影响系统氮磷的去除效果。硝化反应与吸磷反应的竞争实验发现,溶解氧不足的条件下,硝化菌和聚磷菌对溶解氧均未表现出明显的利用优势。在SBMBMBR中,NO2--N的抑制浓度为50 mg/L。实验发现,序批式的运行方式有利于减缓移动床膜生物反应器的膜污染速率。更多还原

【Abstract】 Nitrogen and phosphorus are key nutrients that result in water eutrophication. As the development of biological nutrients removal technology, a new technology with advantages of simple process, high efficiency and less energy consumption will be prevalent in domain of nutrients removal technology. In this sudy, a membrane bioreactor filled with carriers instead of activated sludge named a moving bed membrane bioreactor (MBMBR) was operated to improve the nitrogen and phosphorus removal abilities by optimizing the operational modes and adjusting the operational parameters. The performances of MBMBR on nitrogen and phosphorous removal, the sludge characteristics and membrane fouling were examined in different operational modes.Firstly, the performances of MBMBR and a conventional membrane bioreactor (CMBR) on nutrients removal and membrane fouling were compared at different influent COD/TN ratios. Compared with CMBR, MBMBR demonstrated a good performance on TN removal via simultaneous nitrification and denitrification (SND) at different influent COD/TN ratios. Even running at low COD/TN ratio (COD/TN= 8.9) with 7.58 mg TN/L-h, TN removal efficiencies were maintained above 70.0%, and the TN removal efficiency via SND was 89.1%. Membrane fouling was more serious in MBMBR than in CMBR. Since the overgrowth of filamentous bacteria in MBMBR resulted in severe cake layer, which would do great harm to membrane filtration. An intermittently-aerated mode was conducted to achieve SND via nitrite in the aerobic MBMBR. Results demonstrated that intermittently-aerated mode was an effective approach to achieve nitrition. Intermittently-aerated time is an important factor for achieving short-cut nitrification and the COD/TN ratio is another key factor for achieving TN removal. Batch tests indicated that under the intermittently-aerated mode, short-cut nitrification was achieved because the activities of NOBs were inhibited.Sequencing batch moving bed membrane bioreactor (SBMBMBR) performed well on nitrogen and phosphorus removal at different COD/TN ratios. The TP removal was closely correlated with the length of anaerobic phase and aerobic phase. When anaerobic time and aerobic time were both 2 h, the average TP removal efficiency reached to 84.1%. DO in aerobic phase was an important factor affecting nutrients removal, and the optimal DO was about 3 mg/L in SBMBMBR. Fluorescence in situ hybridization (FISH) results of microbes showed that in the inner layer of the biofilm, there existed only a small amount of NOBs and PAOs because of the low DO concentration. While for the outer layer of the biofilm and the suspended biomass, a large quantity of AOBs, NOBs and PAOs were observed. An anoxic phase was introduced with external nitrate or nitrite addition between anaerobic phase and aerobic phase to study the capability of denitrifying phosphorus removal. Results indicated that better capability of denitrifying phosphorus removal was observed with nitrite addition than that with nitrate addition. A series of batch tests using different type of election acceptors also indicated that compared with nitrate, nitrite is the more capable type of electron acceptor for denitrification phosphorus removal technology. The denitrifying bacteria were suggested to outcompete PAOs for competing limited carbon source. When influent carbon source was deficient, the exist of nitrate would indeed effect biological phosphorus release and finally result in a reduction of the TP removal efficiency. Batch tests indicated that neither nitrifying bacteria nor PAOs showed evident predominance for competing limited DO. In SBMBMBR, the ceiling inhibition concentration of nitrite was 50 mg/L. Furthermore, results indicated that the sequencing batch operation mode can reduce membrane fouling.更多还原