發(fā)布時間：2018-07-18 14:28

【摘要】：抗生素（antibiotics）在臨床和畜牧飼養(yǎng)業(yè)中應(yīng)用廣泛，其中，四環(huán)素（tetracycline）是使用量較大的抗生素之一。大部分的四環(huán)素未經(jīng)人體或動物充分吸收，直接排出體外，由于其在自然水體中難以降解，持續(xù)的四環(huán)素壓力使得四環(huán)素耐藥細(xì)菌和四環(huán)素耐藥基因不斷增殖，給人體健康帶來嚴(yán)重威脅。厭氧-缺氧-好氧（Anaerobic-Anoxic-Oxic，AAO）水處理工藝是一種傳統(tǒng)的污水處理方法，在城市污水處理廠的應(yīng)用范圍廣泛，運(yùn)行技術(shù)成熟，目前對四環(huán)素類抗生素在污水處理廠的去除影響因素及對微生物群落的影響機(jī)制尚不明確。本研究以四環(huán)素作為研究對象，研究了不同工況下四環(huán)素在AAO系統(tǒng)中的去除情況，采用響應(yīng)面法對實(shí)驗(yàn)進(jìn)行模擬和優(yōu)化，考察系統(tǒng)操作參數(shù)對四環(huán)素去除的影響以及四環(huán)素在活性污泥中的吸附特性；然后研究了四環(huán)素對AAO系統(tǒng)微生物種群的影響，采用宏基因組高通量測序?qū)悠愤M(jìn)行測序，考察微生物群落多樣性及四環(huán)素耐藥基因的變化，同時，通過硝化細(xì)菌的演變情況來探究四環(huán)素對AAO系統(tǒng)硝化作用的影響。 結(jié)果表明：AAO系統(tǒng)的水力停留時間（hydraulic retention time，HRT）和污泥齡（sludge retention time，SRT）分別對四環(huán)素的去除有顯著的影響，然后由響應(yīng)面法分析得出，污泥齡和四環(huán)素初始濃度及其交互作用對四環(huán)素去除率的影響極為明顯，污泥齡、水力停留時間及四環(huán)素初始濃度的二次項(xiàng)對四環(huán)素去除率有一定影響。隨著污泥齡的增大，四環(huán)素去除率逐漸提高。在最佳實(shí)驗(yàn)條件SRT：15.5d，HRT：9.9h，CTC, in：283.3μg/L下對建立的四環(huán)素去除率數(shù)學(xué)模型進(jìn)行驗(yàn)證實(shí)驗(yàn)，發(fā)現(xiàn)實(shí)驗(yàn)值與預(yù)測值具有較高的一致性，說明所建立的四環(huán)素去除率模型具有可靠性和準(zhǔn)確性。不同初始濃度的四環(huán)素在活性污泥上的吸附動力學(xué)符合偽二級模型，化學(xué)吸附是控制整個吸附速率的最重要的因素。不同溫度下，四環(huán)素在活性污泥上的吸附呈現(xiàn)不同的特點(diǎn)：10℃和25℃條件下，吸附較符合Langmuir模型；40℃條件下，吸附較符合Henry模型，活性污泥對四環(huán)素的吸附是吸熱反應(yīng)，在高溫條件下的吸附性能好于低溫條件。 在此基礎(chǔ)上，對優(yōu)化條件下的AAO系統(tǒng)中的微生物種群結(jié)構(gòu)進(jìn)行對照試驗(yàn)，結(jié)果表明加入痕量四環(huán)素會改變系統(tǒng)微生物的群落結(jié)構(gòu)，并在缺氧、厭氧及好氧環(huán)境下都能增大微生物群落多樣性；tet(A)，tet(B)，tet(C)，tet(E)，tet(M)，tet(S)和tet(O)的濃度隨著四環(huán)素的加入都是增大的。所測試的八種四環(huán)素耐藥基因之間具有較強(qiáng)的相關(guān)關(guān)系，其中tet(A)，tet(B)，tet(C)，tet(E)，tet(M)，tet(S)和tet(O)之間的相關(guān)性顯著（P 0.05），而tet(X)與其他檢測到的四環(huán)素耐藥基因的相關(guān)性最弱（P 0.05）。另外，活性污泥中的外排泵基因tet(A, B, C, E)的濃度最高，遠(yuǎn)遠(yuǎn)超過核糖體保護(hù)類和降解四環(huán)素酶類兩類基因。四環(huán)素對AAO反應(yīng)體系TN的去除以及硝化細(xì)菌活性并未產(chǎn)生抑制作用，反而起到一定的促進(jìn)作用。
[Abstract]:The antibiotic (antibiotics) has been widely used in clinical and animal husbandry, among which tetracycline (tetracycline) is one of the most widely used antibiotics. Most of the tetracycline is not fully absorbed by humans or animals and is discharged directly from the body. Because it is difficult to degrade in natural water, the constant pressure of tetracycline causes the proliferation of tetracycline resistant bacteria and tetracycline resistant genes. It poses a serious threat to human health. Anaerobic-Anoxic-Oxicic-AAO (Anaerobic-Anoxic-Oxicic-AAO) water treatment process is a traditional wastewater treatment method. At present, the factors affecting the removal of tetracycline antibiotics in wastewater treatment plants and the mechanism of affecting microbial communities are not clear. In this study, the removal of tetracycline in AAO system under different operating conditions was studied, and the response surface method was used to simulate and optimize the experiment. The effects of system operating parameters on the removal of tetracycline and the adsorption characteristics of tetracycline in activated sludge were investigated, and then the effects of tetracycline on the microbial population of AAO system were studied, and the samples were sequenced by macrogenome high-throughput sequencing. To investigate the diversity of microbial community and the changes of tetracycline resistance genes, and to explore the effect of tetracycline on nitrification of AAO system through the evolution of nitrifying bacteria. The results showed that the HRT (HRT) and (sludge retention time (SRT) of the two systems had significant effects on the removal of tetracycline, respectively, and the response surface method was used to determine the effect of HRT on the removal of tetracycline. The effects of sludge age, initial tetracycline concentration and their interaction on the removal rate of tetracycline were very obvious, and the secondary terms of sludge age, hydraulic retention time and initial concentration of tetracycline had a certain effect on the removal rate of tetracycline. With the increase of sludge age, the removal rate of tetracycline increased gradually. The mathematical model of tetracycline removal rate was verified under the optimal experimental conditions, SRT: 15.5dh HRT: 9.9hCTC, in:283.3 渭 g / L, and the experimental value was found to be in good agreement with the predicted value. The model of tetracycline removal rate is reliable and accurate. The adsorption kinetics of tetracycline on activated sludge with different initial concentrations was in accordance with the pseudo-secondary model, and the chemical adsorption was the most important factor to control the adsorption rate. At different temperatures, the adsorption of tetracycline on activated sludge showed different characteristics. At 10 鈩，

本文編號：2132193