【摘要】：再生水地下回灌是解決水資源短缺的一種有效途徑。然而,經(jīng)過處理的再生水中仍含有痕量的重金屬,其穿過土壤和滲濾帶引起地下水污染是一個(gè)受到關(guān)注的敏感問題。再生水地下回灌過程中重金屬的遷移與截留受重金屬的性質(zhì)和濃度、滲濾層的水文條件、生物等多種因素影響。特別是當(dāng)生物膜存在時(shí),重金屬在滲濾層中的遷移更加復(fù)雜。研究再生水地下回灌過程中重金屬運(yùn)移與生物膜胞外聚合物相互作用有助于揭示實(shí)際再生水地下回灌過程中銅的遷移和沉積規(guī)律,預(yù)測(cè)重金屬對(duì)地下水的污染狀況。為地下水重金屬治理提供科學(xué)的理論依據(jù),具有一定的理論指導(dǎo)意義。本文中以重金屬銅抗性細(xì)菌Citrobacter freundii JPG1(Genbank accession KU513787)為對(duì)象,研究其對(duì)多種重金屬的抗性。發(fā)現(xiàn)菌株JPG1對(duì)Cu~(2+)、Cd~(2+)、Ni~(2+)、Co~(2+)、Ag~+、Cr_2O_7~(2-)離子的MIC(Minimal Inhibitory Concentration,最小抑菌濃度)值分別為3、4、3、2、0.06、2 mM。重點(diǎn)研究了地下水中常見重金屬Cu~(2+)離子對(duì)菌株JPG1生長(zhǎng)的抑制作用。菌株JPG1具有較好的Cu~(2+)抗性,Cu~(2+)離子濃度小于0.25 mM基本不抑制其生長(zhǎng);Cu~(2+)離子濃度為1 mM時(shí),對(duì)JPG1的抑制率約50%。在靜態(tài)實(shí)驗(yàn)中,分別研究了菌株JPG1自身EPS(Extracellular Polymeric Substance,胞外聚合物)形成能力以及0.1mM銅對(duì)菌株JPG1-石英砂復(fù)合體EPS的影響。結(jié)果發(fā)現(xiàn)菌株JPG1的EPS形成能力較強(qiáng),其EPS產(chǎn)量為118.82mg/g·VSS(mg/g·干重)。其中,蛋白和多糖含量分別為90.67、28.14 mg/g·VSS。0.1mM的Cu~(2+)離子作用影響了菌株JPG1-石英砂復(fù)合體EPS含量,使蛋白含量從491.67μg/g增加到700μg/g,而多糖含量維持在127-130μg/g。推測(cè)菌株JPG1可能是通過產(chǎn)生更多的胞外蛋白來抵抗Cu~(2+)離子的毒性作用。采用動(dòng)態(tài)砂柱實(shí)驗(yàn)研究Cu~(2+)離子的運(yùn)移和截留與菌株JPG1-石英砂復(fù)合體EPS形成間的相互作用。結(jié)果發(fā)現(xiàn)生物膜的形成導(dǎo)致了菌株JPG1-石英砂復(fù)合體孔隙的堵塞,使?jié)B透系數(shù)低于初始時(shí)的10%。對(duì)于0.1 mM Cu~(2+)而言,菌株JPG1-石英砂復(fù)合體EPS的形成能將絕大部分的Cu~(2+)離子截留在砂柱中,出水中最大Cu~(2+)離子濃度僅為進(jìn)水的3.05%。Cu~(2+)離子自下而上的穿透過有生物膜附著的石英砂柱后,首先抑制底層生物膜EPS的含量,使其EPS產(chǎn)量減少了原來的36.86%。Cu~(2+)離子滲透進(jìn)砂層內(nèi)部,使第二層到第五層中EPS分泌受到刺激,增加了原來的63%-141%。總之,菌株JPG1-石英砂復(fù)合體的EPS對(duì)回灌中的Cu~(2+)離子起到良好的截留作用。同時(shí),Cu~(2+)離子的運(yùn)移在一定程度上也刺激菌株JPG1-石英砂復(fù)合體EPS的分泌,二者表現(xiàn)為相互促進(jìn)的作用。
[Abstract]:Reclaimed groundwater recharge is an effective way to solve the shortage of water resources. However, the treated recycled water still contains trace heavy metals, and the contamination of groundwater through soil and leachate is a sensitive problem. The migration and interception of heavy metals in reclaimed water are affected by the properties and concentrations of heavy metals, the hydrological conditions of leachate, biology and other factors. Especially when biofilm exists, the migration of heavy metals in percolation is more complicated. The study of the interaction between heavy metal migration and biofilm extracellular polymer during underground recharge of reclaimed water is helpful to reveal the migration and deposition of copper in the process of underground recharge of reclaimed water and to predict the pollution of groundwater caused by heavy metals. To provide a scientific theoretical basis for the treatment of heavy metals in groundwater, which has a certain theoretical significance. The resistance of copper-resistant bacteria (Citrobacter freundii JPG1 (Genbank accession KU513787) to various heavy metals was studied in this paper. It was found that the MIC (Minimal Inhibitory Concentration, minimum inhibitory concentration (MEC) of JPG1 to Cu~ (2), Cd~ (2), Ni~ (2), Co~ (2), Ag~, Cr_2O_7~ (2-) ions were 3 ~ 4 ~ (3), 3 ~ (3) ~ 0. 06 ~ (2) mM., respectively. The inhibitory effects of Cu~ (2) ions on the growth of strain JPG1 in groundwater were studied. The strain JPG1 had good Cu~ (2) resistance, Cu~ (2) ion concentration less than 0.25 mM did not inhibit its growth, and when Cu~ (2) ion concentration was 1 mM, the inhibition rate of JPG1 was about 50%. In the static experiment, the formation ability of EPS (Extracellular Polymeric Substance, extracellular polymer (EPS (Extracellular Polymeric Substance,) of strain JPG1 and the effect of 0.1mM copper on the EPS of JPG1- quartz sand complex were studied. The results showed that the EPS formation ability of strain JPG1 was strong, and its EPS yield was 118.82mg/g VSS (mg/g dry weight). The effect of Cu~ (2) on the content of protein and polysaccharide in the quartzite complex of the strain JPG1- was influenced by the action of Cu~ (2) with the content of 90.67c28.14 mg/g VSS.0.1mM, which increased the content of protein from 491.67 渭 g / g to 700 渭 g / g, while the content of polysaccharide was maintained at 127-130 渭 g / g. It is speculated that the strain JPG1 may resist the toxicity of Cu~ (2) ion by producing more extracellular proteins. The interaction between the migration and retention of Cu~ (2) ions and the formation of EPS of strain JPG1- quartz sand complex was studied by dynamic sand column experiment. The results showed that the formation of biofilm resulted in the pore blockage of the quartz sand complex of strain JPG1-, and the permeability coefficient was lower than that at the beginning. For 0. 1 mM Cu~ (2), the formation of strain JPG1- quartz sand complex EPS can intercept most of Cu~ (2) ions in the sand column. The maximum concentration of Cu~ (2) ion in the effluent was only 3.05. Cu2 ions from the bottom to the top of the quartz sand column with biofilm attached, and the content of EPS in the bottom biofilm was inhibited firstly. The EPS production decreased the original 36.86. Cu2 ion penetration into the sand layer, stimulated the secretion of EPS from the second layer to the fifth layer, increased the original 63-141. In conclusion, the EPS of the JPG1- quartz sand complex had a good retention effect on the Cu~ (2) ion in the recharge. At the same time, the migration of Cu~ (2) ions also stimulated the secretion of EPS from JPG1- quartz sand complex to a certain extent.
【學(xué)位授予單位】：東北師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：X703;X523

【引證文獻(xiàn)】

相關(guān)博士學(xué)位論文 前1條

1 郎琪;城市再生水回用河湖河床滲濾介質(zhì)堵塞發(fā)生機(jī)理研究[D];中國(guó)農(nóng)業(yè)大學(xué);2017年

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本文編號(hào)：2291173