本文選題：納米銀 + 苯酚��； 參考：《哈爾濱工業(yè)大學(xué)》2015年碩士論文

【摘要】：納米銀廣泛用于日常生活中,隨著納米銀的廣泛應(yīng)用,其潛在的環(huán)境生物效應(yīng)也不容忽視。從消費品中釋放出的納米銀很可能隨生活污水進入到下水道系統(tǒng)中,進而進入污水處理廠中,而納米銀的存在對于污水生物處理系統(tǒng)中的微生物具有一定的毒害作用。此外,苯酚也普遍存在于各個行業(yè)的廢水中,其也具有較高的生物毒性。部分研究已經(jīng)證明納米銀和苯酚分別對微生物有一定的抑制作用,而有關(guān)對反硝化細菌影響的研究較少。因此本文以反硝化菌為模式菌株,分別通過構(gòu)建納米銀與苯酚暴露實驗系統(tǒng),研究兩者對細菌反硝化活性影響以及機制研究,且通過納米銀與苯酚復(fù)合污染,探究兩者對細菌復(fù)合毒害效應(yīng)。本文將細菌分別暴露于含有不同濃度的納米銀(0.1~30mg/L)和苯酚(0.05~6mg/L)培養(yǎng)基中,檢測細菌反硝化能力。當(dāng)投加納米銀濃度為1mg/L時,細菌的NO3--N還原速率k為0.15mg/(L·h),細菌反硝化能力受到一定程度影響。通過透射電鏡(TEM)觀察發(fā)現(xiàn)細菌細胞膜表面比較粗糙,且乳酸脫氫酶(LDH)釋放率為149%,細菌胞內(nèi)產(chǎn)生活性氧(ROS)含量是空白組的6.97倍,隨著投加納米銀濃度的增加細菌反硝化能力明顯降低。苯酚對細菌毒性較高,當(dāng)苯酚投加濃度為0.1mg/L時,NO3--N還原速率僅為0.17mg/(L·h);細菌細胞膜完整性受到影響,LDH釋放率為132%,NR比活性為0.14;而當(dāng)苯酚投加濃度?5mg/L時,細菌幾乎完全喪失活性。改變細菌培養(yǎng)溫度和p H,細菌的增值和酶活受到嚴(yán)重的影響,對有機物代謝主要途徑也有影響。當(dāng)p H6或者p H?8時,細菌NO3--N還原速率明顯降低,培養(yǎng)基中細菌數(shù)量驟減。但是培養(yǎng)環(huán)境的改變并不能降低納米銀和苯酚的生物毒性,較差的培養(yǎng)環(huán)境使細菌生長狀態(tài)較差,此時較低濃度的納米銀和苯酚則會明顯降低細菌反硝化活性,使LDH釋放率較最佳環(huán)境培養(yǎng)時高。納米銀與苯酚之間會發(fā)生一定的吸附效應(yīng),不同接觸溫度下,納米銀對苯酚的吸附平衡點會有所改變,且到達平衡時苯酚吸附量也不同。較低的接觸溫度,使得納米銀與苯酚之間的吸附作用時間較長,達到平衡時苯酚吸附量較高。細菌經(jīng)不同復(fù)合比例的納米銀與苯酚復(fù)合污染時,反硝化能力受到更加強烈的抑制。通過聯(lián)合毒性效應(yīng)評價納米銀與苯酚的復(fù)合效應(yīng),不同復(fù)合比例的AI值均大于零,兩者之間是協(xié)同作用,說明苯酚與納米銀兩者組成的混合物具有更高毒性,對自然界水處理系統(tǒng)中的微生物群落造成更大威脅,為復(fù)合毒性研究結(jié)論提供了理論依據(jù)。
[Abstract]:Nano-silver is widely used in daily life, and its potential environmental biological effects can not be ignored with the wide application of nano-silver. The silver nanoparticles released from consumer products are likely to enter the sewage system with the domestic sewage and then into the sewage treatment plant. The presence of nano-silver has a certain toxic effect on the microorganisms in the sewage biological treatment system. In addition, phenol also exists in wastewater of various industries and has high biotoxicity. Some studies have shown that nano-silver and phenol can inhibit microbes respectively, but few studies have been done on denitrifying bacteria. In this paper, denitrifying bacteria were used as model strains to study the effects of nano-silver and phenol exposure system on denitrification activity and the mechanism of denitrification. To explore the compound toxic effect of the two to bacteria. In this paper, bacteria were exposed to different concentrations of silver nanocrystalline (0.1 mg / L) and phenol (0.05 mg / L) to determine the denitrification ability of bacteria. When the concentration of nano-silver was 1 mg / L, the reduction rate of NO3-N was 0.15 mg / L, and the denitrification ability of bacteria was affected to some extent. The surface of bacterial cell membrane was rough and the release rate of lactate dehydrogenase (LDH) was 149%. The content of reactive oxygen species (Ros) produced by bacteria was 6.97 times of that in the blank group. The denitrification ability of bacteria decreased with the increase of the concentration of silver nanoparticles. The toxicity of phenol to bacteria was higher, when the concentration of phenol was 0.1 mg / L, the reduction rate of NO3-N was only 0.17 mg / L, the release rate of LDH was 0.14 when the cell membrane integrity was affected and the specific activity of NR was 0.14 when the concentration of phenol was 0.1 mg / L, and the bacteria almost completely lost its activity when the concentration of phenol was 5 mg / L. By changing the culture temperature and pH of bacteria, the increment and enzyme activity of bacteria were seriously affected, and the main pathway of organic matter metabolism was also affected. When pH 6 or pH? 8, the reduction rate of NO3-N decreased significantly, and the number of bacteria in culture medium decreased sharply. However, the change of culture environment could not reduce the biological toxicity of silver nanoparticles and phenol, and the lower concentration of silver nanoparticles and phenol could significantly reduce the denitrification activity of bacteria. The release rate of LDH was higher than that in the optimal environment. The adsorption equilibrium point of phenol was changed at different contact temperature, and the adsorption amount of phenol was also different when the equilibrium was reached. With the lower contact temperature, the adsorption time between silver nanoparticles and phenol is longer, and the adsorption amount of phenol is higher when the equilibrium is reached. The denitrification ability of bacteria was inhibited more strongly when the bacteria were polluted by nano-silver and phenol. The composite effect of nano-silver and phenol was evaluated by the combined toxicity effect. The AI values of different composite ratios were all greater than zero, which indicated that the mixture composed of phenol and nano-silver was more toxic. It poses a greater threat to the microbial community in the natural water treatment system and provides a theoretical basis for the conclusion of the compound toxicity study.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X703;X172

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