本文選題：耐酸反硝化細(xì)菌　切入點：反硝化特性　出處：《東華理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：酸法地浸采鈾過程中,常采用硝酸銨為淋洗劑,致使硝酸鹽進(jìn)入到含礦含水層,造成地浸采礦退役后地下水環(huán)境硝酸鹽的超標(biāo)。微生物反硝化脫氮法因其效率高、成本低常被廣泛應(yīng)用于處理含氮廢水。但反硝化細(xì)菌的作用條件一般為中性或偏堿性,酸性或偏酸性條件下的較為少見。本論文針對酸性礦山地下水中pH低、硝酸鹽含量高等問題,采用選擇性培養(yǎng)基,從新疆某鈾礦山含礦含水層地下水樣品中富集、分離和馴化耐酸性硝酸鹽還原菌(Denitrifying Bacteria,DNB);采用稀釋涂布和平板劃線法純化菌種;采用Biolog生理生化試驗和16S rDNA基因序列分析鑒定所獲得菌株(G16X-D),采用兼性厭氧液體培養(yǎng)法研究不同初始pH值、溫度、碳源、C/N等因素對G16X-D生長和反硝化特性的影響,優(yōu)化其反硝化培養(yǎng)條件;分析不同初始NO_3~--N濃度與G16X-D反硝化速率的動力學(xué)關(guān)系、考察重金屬離子(Zn~(2+)、Cd~(2+)、U~(6+))對其去除NO_3~--N的影響。此外,在優(yōu)化的環(huán)境條件下研究了該G16X-D對微生物浸鈾浸出液中NO_3~--N去除的效果,為今后的應(yīng)用提供理論依據(jù)。本文主要獲得以下研究結(jié)果:通過富集分離與馴化,得到一株耐酸性反硝化細(xì)菌G16X-D,形態(tài)學(xué)觀察、Biolog生理生化試驗以及16S rDNA基因序列分析鑒定結(jié)果表明,菌株G16X-D屬于銅綠假單胞菌(Pseudomonas aeruginosa)。影響因素試驗結(jié)果表明,pH4.50的條件下,菌株G16X-D具有較高的反硝化能力,反硝化作用主要發(fā)生在對數(shù)生長期。菌株G16X-D優(yōu)化的反硝化培養(yǎng)條件為:最適碳源為葡萄糖,C/N=3.0,溫度為35℃,此條件下72 h內(nèi)初始NO_3~--N濃度為160mg·L~(-1)的還原率達(dá)到92.74%,比生長速率μ=0.0472 h~(-1),最短倍增時間t_d=14.68 h。菌株G16X-D的最適pH值為5.77~7.70。動力學(xué)研究表明,NO_3~--N濃度S=350.84 mg·L~(-1)時,其最大反硝化速率V_(max)=2.99mg·L~(-1)·h~(-1),半飽和常數(shù)K_m=162.50 mg·L~(-1),抑制常數(shù)K_i=757.47 mg·L~(-1)。Cd~(2+)對菌株的反硝化作用具有抑制作用,濃度越高抑制性越強(qiáng);U~(6+)濃度在7.50mg·L~(-1)以下時,促進(jìn)反硝化作用的進(jìn)行,大于7.50 mg·L~(-1)時,具有抑制作用;少量的鋅離子有助于反硝化作用的進(jìn)行,50 mg·L~(-1)以上則會有抑制作用;3種重金屬離子對G16X-D的毒性大小順序為Cd~(2+)U~(6+)Zn~(2+)。在優(yōu)化的反硝化培養(yǎng)條件下,以鈾礦石微生物浸出液為試驗原水樣,未稀釋的試驗原水樣對G16X-D的反硝化作用具有強(qiáng)烈的抑制性;G16X-D以1%接種于在初始NO_3~--N濃度分別為86.52 mg·L~(-1)和163.52 mg·L~(-1)的試驗水樣中,培養(yǎng)8 d后,NO_3~--N去除率分別為64.4%和41.4%;試驗廢水中最佳接種量為7.5%時,初始濃度為160mg·L~(-1)的NO_3~--N經(jīng)96 h去除率可達(dá)91.2%。G16X-D對pH4.50的偏酸性礦山廢水中NO_3~--N的去除取得了良好的效果。
[Abstract]:In the process of in-situ leaching of uranium by acid method, ammonium nitrate is often used as leaching agent, which causes nitrate to enter the ore-bearing aquifer, which results in the excess of nitrate in groundwater environment after the decommissioning of in-situ leaching and mining. The microbial denitrification and denitrification process has high efficiency. Low cost is widely used in the treatment of nitrogen-containing wastewater. However, denitrifying bacteria are generally neutral or alkaline, and rare under acidic or acidic conditions. In order to solve the problem of high nitrate content, selective culture medium was used to enrich and domesticate the acid tolerant nitrate reducing bacteria (Denitrifying Bacteriae DNBBN) from the groundwater samples of a uranium ore bearing aquifer in Xinjiang, and the bacteria were purified by dilution coating and plate marking. The strain G16X-DX was identified by Biolog physiological and biochemical test and 16s rDNA gene sequence analysis. The effects of different initial pH, temperature and carbon source C / N on the growth and denitrification of G16X-D were studied by facultative anaerobic liquid culture. The conditions of denitrification culture were optimized, the kinetic relationship between different initial NO_3~--N concentrations and the denitrification rate of G16X-D was analyzed, and the effect of heavy metal ions on NO_3~--N removal was investigated. The effect of G16X-D on the removal of NO_3~--N from microorganism leaching uranium leachate was studied under the optimized environmental conditions, which provided theoretical basis for the future application. The following results are obtained in this paper: enrichment, separation and acclimation. A strain of acid tolerant denitrifying bacteria G16X-Dwas obtained. The physiological and biochemical tests of Biolog and the sequence analysis of 16s rDNA gene showed that the strain G16X-D belonged to Pseudomonas aeruginosa. Strain G16X-D had high denitrification ability, and denitrification mainly occurred in logarithmic growth period. The optimum denitrification conditions of strain G16X-D were as follows: glucose C / N = 3.0 and temperature 35 鈩，

本文編號：1603701