【作者】 梁峙；

【导师】 韩宝平；

【作者基本信息】 中国矿业大学 ， 环境工程， 2009， 博士

【摘要】 我国北方某城市水源地受到了四氯化碳的污染,本文依托国家自然科学基金资助,系统研究了白腐真菌对四氯化碳的降解特征。从污染区土壤中分离出131个菌株,通过筛选,并以四氯化碳为唯一碳源培养,最终发现白腐真菌是降解四氯化碳的首选菌种。取得研究成果如下:1.本文研究了多因素综合条件对白腐真菌生长的影响,试验表明,当摇瓶机转速为160r/min,温度为30℃,稻壳浸出液为90mL/L,葡萄糖浓度为35g/L,pH值为4.5时,菌体生物质量浓度最大,达到4.563g/L。2.研究了环境条件对白腐真菌降解四氯化碳的影响。结果表明,四氯化碳质量浓度为48μg/L,稻壳浸出液体积浓度为50mL/L,葡萄糖质量浓度为15g/L,温度为30℃,摇瓶机转速为140r/min,是白腐真菌降解四氯化碳的最佳因素组合。3.通过白腐真菌发酵进程试验及各模型参数的计算,建立了菌体生长动力学模型: Cx(t)=0.091exp(0.0718t)/[0.976+0.0241exp(0.0718t)]胞外多糖生成动力学模型: P_x (t)= 0.0477+0.8318C_x(t)+0.105ln[0.976+0.024exp(0.0718t)]底物消耗动力学模型: C_s (t)= 14.107-3.023C_x(t)-0.856ln[0.976+0.024exp(0.0718t)]。同时通过降解试验和模型参数的计算,建立了白腐真菌对四氯化碳降解动力学模型: Y (t)= -0.1054t+3.129。4.通过土柱模拟污染区土壤层砂壤土静态降解试验,研究了污染区土壤四氯化碳的降解规律。结果表明,一定量的四氯化碳对白腐真菌的生长具有刺激作用,使其在污染物的诱导下成为优势菌。翻耕能有效地提高溶氧,提高电导率,在同等条件下,翻耕的降解率是不翻耕的1.45倍。同时表明,添加分散剂也能显著地提高生物降解率,其中以稻壳作为分散剂降解效率最高,其最终降解率可以达到93.9%。在土柱降解体系中,含水量也是影响降解的主要因素,当水分含量在25%时,降解率最高可达到94.6%,过高的含水量会降低对四氯化碳的降解。同样,过高的接种量也会使降解率不断降低。5.在土柱模拟污染区土壤层砂壤土的动态降解中,通过四氯化碳淋溶过程的垂向迁移,研究了各因素对降解四氯化碳的影响。试验表明,各取样孔的降解率随时间均表现出由低到高的变化,其中,底部(D5)取样孔降解效果较好,它的最终降解率达到60.1%。试验显示,温度是影响降解率的重要因素之一,通过计算在一定范围内,温度每增加4℃其降解率则提高14-23%。研究发现,降解菌株对高浓度四氯化碳有一定忍耐能力,当浓度为88.7μg/L时,其最终降解率最大达到64.2%。通过动态分析发现,低流量对土壤的通透性影响较小,有助于提高降解率,而过高的流量(90mL/min),会使填充层整体浸泡在水中,降解过程几乎停止。在土柱动态降解体系中,五种分散剂在填充层中的降解率均高于对照(砂壤土),其中稻壳的降解能力最为优秀,降解率达到81.2%。试验同时显示,定期翻耕能有效地提高微生物与四氯化碳的接触,通过翻耕处理会使降解率提高两倍。从动态的观点分析,适宜的葡萄糖浓度(25g/L)有利于菌体的降解,过高浓度,会使细胞渗透压增高,同时也增加了土壤对四氯化碳的吸附和滞留,因而也影响到菌体对其的降解,使降解率下降。更多还原

【Abstract】 The article studies the carbon tetrachloride of difficult degradation for object and 131 strains is separated from the pollution soil sample. They are screened and cultured on the carbon tetrachloride as the only carbon source. The results showed finally that survival ability of the white-rot fungus is strongest in includes in selective medium which contains the carbon tetrachloride.This paper study that the effect of multi-factor comprehensive conditions on the white-rot fungus growth. Simultaneously the article study that the environmental condition influences the white-rot fungus to biodegrade the carbon tetrachloride. The test finally obtained optimum scheme for mycelium growth and to degrade the carbon tetrachloride.Through the white-rot fungus ferment experiment and calculate various model parameters the mycelium growth kinetics model was established: C_x(t)=0.091exp(0.0718t)/[0.976+0.0241exp(0.0718t)] Extracellular polysaccharide formation kinetics model: P_x(t)= 0.0477+0.8318C_x(t)+0.105ln[0.976+0.024exp(0.0718t)] Base consumption kinetics model: C_s(t)= 14.107-3.023C_x(t)-0.856ln[0.976+0.024exp(0.0718t)] The degeneration kinetics model which the white-rot fungus degrades the carbon tetrachloride: Y (t )= -0.1054t+3.129Through the packing column simulates static biodegeneration experiment in shallow layer sandy loam, the research discovered that a certain amount carbon tetrachloride can stimulate the white-rot fungus’s growth. It can become dominant fungi under the pollutant induction. The plowing can enhance effectively the dissolving oxygen and raises the conductivity. Under the same condition, plowing degeneration rate is 1.45 times of not plowing. The increase dispersant can also enhance obviously the biodegradation rate. Rice husk as dispersant, its degradation rate is highest, the final degeneration rate is 93.9%. Similarly, the overhigh inoculation amount will also reduce the degeneration rate unceasingly.In the packing column simulation shallow layer sandy loam’s dynamic degeneration, through carbon tetrachloride vertically migrates in leaching process, we study the effect of each factor on carbon tetrachloride degradation. Experiment shows that the degradation rate of sampling holes change with time. The change is shown from low to high. Simultaneously experiments showed that temperature is one of the important factors to influence degradation rate. Through the calculation, the degradation rate will increase 14-23% when the temperature increases 4 degrees Celsius in a certain range.In the dynamic experiment, the degeneration rate of five kind of dispersant is higher than the sandy loam (control) in packing layer. The rice husk’s degeneration ability is most excellence and the degeneration rate is 81.2%. The regular ploughing can also enhance the contact opportunity with microorganism and the carbon tetrachloride, increases porosity, maintains the temperature, promote degeneration. The experiment shows that the degeneration rate can enhance two times through ploughing processing.Analyzes from the dynamic viewpoint, the suitable glucose concentration (25g/L) can promote mycelium’s degeneration, the overhigh concentration will increases the osmotic pressure of cell, the cell of dehydration will be inhibited. Simultaneously, the soil viscosity is increased, the carbon tetrachloride isl increased adsorption and detention, reduces contact opportunity with microorganism’s, thus will affect its degeneration rate.更多还原