本文關鍵詞：納米銀和二氧化鈰對MBBR脫氮性能及微生物群落的影響研究　出處：《安徽大學》2017年碩士論文　論文類型：學位論文

  更多相關文章： 移動床生物膜反應器 納米銀和二氧化鈰 脫氮性能 微生物群落

【摘要】：銀納米顆粒(AgNPs)和二氧化鈰納米顆粒(CeO_2NPs)因其優(yōu)良特性,被廣泛用于各領域。AgNPs和CeO_2NPs在生產、運輸、使用及廢棄過程中不可避免地會通過各種環(huán)境介質釋放至水體例如污水處理系統(tǒng),對其效能產生潛在的不利影響。本文以移動床生物膜反應器(MBBR)為研究對象,通過構建高效脫氮體系,探究AgNPs和CeO_2 NPs(10 mg/L)單獨及共存時對MBBR脫氮性能的短期影響和長期影響及微生物群落的長期影響。主要結論如下:(1)AgNPs和CeO_2 NPs短期內(12 h)通過抑制氨單加氧酶(AMO)和硝酸還原酶(NR)活性影響總氮(TN)去除。AgNPs、CeO_2 NPs、AgNPs和Ce02 NPs混合物使MBBR TN去除率從79.00%(對照組)分別降至73.13%、76.82%和76.18%。AgNPs和CeO_2NPs長期(100 d)作用于MBBR后,AMO活性恢復、NR活性被抑制和生物量減少導致TN去除率下降。AgNPs、CeO_2NPs、AgNPs和CeO_2 NPs混合物使TN去除率分別為降至75.49%、72.10%和69.98%,與對照組(80.07%)有顯著差異。(2)MBBR暴露于AgNPs和CeO_2 NPs后,大量納米顆粒(NPs)附著在微生物表面,短期內細胞膜完整性受到嚴重損傷,長期適應后細胞膜受損減少。(3)AgNPs和CeO_2NPs改變MBBR胞外聚合物(EPS)產量和性質。短期內AgNPs和CeO_2NPs顯著增加松散型胞外聚合物(LB-EPS)含量;長期暴露后,AgNPs 增加 MBBR EPS 含量,CeO_2 NPs、AgNPs 和 CeO_2 NPs 混合物顯著降低TB-EPS含量。EPS主要通過蛋白(PRO)和多糖(PS)抵御AgNPs和CeO_2NPs 毒性。(4)NPs長期作用于MBBR后,微生物多樣性高低程度順序為:添加CeO_2 NPs添加AgNPs對照組添加AgNPs和CeO_2 NPs混合物。兩種NPs單獨存在增加了微生物多樣性以抵抗外界沖擊,共存時對MBBR系統(tǒng)沖擊性大,微生物難以做出調整。群落差異性分析表明AgNPs和CeO_2NPs使MBBR微生物群落結構產生較大差異。對樣本進行不同水平上群落結構分析,AgNPs和CeO_2NPs改變群落優(yōu)勢菌群占比,增加硝化細菌(Nitrosomonas和Nitrospira)豐度,顯著降低反硝化細菌(Dechloromonas和Thauera)豐度,抑制反硝化活性,影響MBBR脫氮。AgNPs增加Zoogloea(具抗重金屬作用)豐度,而O_2NPs、AgNPs和CeO_2NPs混合物降低其豐度。(5)總體上,CeO_2NPs對MBBR的影響作用大于AgNPs,兩種NPs共存時對MBBR的毒性大于其單獨存在時。
[Abstract]:Silver nanoparticles (AgNPs) and two cerium oxide nanoparticles (CeO_2NPs) are widely used in various fields because of their excellent properties. In the process of production, transportation, utilization and abandonment, AgNPs and CeO_2NPs will inevitably be released to water bodies through various environmental mediums, such as sewage treatment systems, which will have potential adverse effects on their efficiency. In this paper, a moving bed biofilm reactor (MBBR) was used as the research object. By building an efficient nitrogen removal system, we explored the short-term and long-term effects of AgNPs and CeO_2 NPs (10 mg/L) on the MBBR denitrification performance and the long-term effects of microbial community. The main conclusions are as follows: (1) AgNPs and CeO_2 NPs (12 h) affect the removal of total nitrogen (TN) by inhibiting the activity of ammonia monooxygenase (AMO) and nitrate reductase (NR) in the short term. The mixture of AgNPs, CeO_2 NPs, AgNPs and Ce02 NPs reduced the removal rate of MBBR TN from 79% (control group) to 73.13%, 76.82% and 76.18%, respectively. After AgNPs and CeO_2NPs (100 d) acted on MBBR, the recovery of AMO activity, the inhibition of NR activity and the decrease of biomass resulted in the decrease of TN removal rate. The mixture of AgNPs, CeO_2NPs, AgNPs and CeO_2 NPs decreased the removal rate of TN to 75.49%, 72.10% and 69.98% respectively, which were significantly different from those of the control group (80.07%). (2) when MBBR was exposed to AgNPs and CeO_2 NPs, a large number of nanoparticles (NPs) adhered to the surface of microorganisms. In the short term, the integrity of cell membrane was seriously damaged, and the damage of cell membrane decreased after long-term adaptation. (3) AgNPs and CeO_2NPs change the yield and properties of MBBR extracellular polymer (EPS). In the short term, AgNPs and CeO_2NPs significantly increased the content of loose extracellular polymeric substances (LB-EPS). After long-term exposure, AgNPs increased the content of MBBR EPS, and CeO_2 NPs, AgNPs and CeO_2 NPs mixture significantly decreased the content of AgNPs. EPS protects against AgNPs and CeO_2NPs toxicity mainly through protein (PRO) and polysaccharide (PS). (4) after the long-term effect of NPs on MBBR, the order of microbial diversity was as follows: adding CeO_2 NPs to AgNPs control group adding AgNPs and CeO_2 NPs mixture. The two types of NPs alone increase the microbial diversity to resist external shocks, and have a great impact on the MBBR system when they coexist, and the microbes are difficult to adjust. The group fall heterosexual analysis showed that AgNPs and CeO_2NPs made large differences in the microbial community structure of MBBR. The community structure of samples was analyzed at different levels. AgNPs and CeO_2NPs changed the proportion of dominant bacteria in the community, increased the abundance of nitrifying bacteria (Nitrosomonas and Nitrospira), significantly reduced the abundance of denitrifying bacteria (Dechloromonas and Thauera), inhibited the denitrification activity, and affected the MBBR denitrification. AgNPs increases the abundance of Zoogloea (with heavy metal resistance), while the mixture of O_2NPs, AgNPs and CeO_2NPs reduces its abundance. (5) on the whole, the effect of CeO_2NPs on MBBR is greater than that of AgNPs, and the toxicity of the two kinds of NPs is greater than that of the MBBR when it exists alone.
【學位授予單位】：安徽大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：X703;X172

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本文編號：1340405