【作者】 方程冉；

【导师】 沈东升；

【作者基本信息】 浙江大学 ， 环境工程， 2010， 博士

【摘要】 邻苯二甲酸酯（Phthalic acid esters,PAEs）,主要用于塑料的增塑剂,被视作内分泌干扰素或环境激素,美国环保总局和我国均将其列为优先控制污染物。废弃塑料通常与其他生活垃圾一起填埋处理,因此,渗滤液的排放是PAEs进入环境的重要途径。随着生活垃圾污染问题日益突出,了解PAEs在垃圾填埋体中的降解条件和迁移转化规律,分析加速PAEs矿化的填埋控制条件,成为减少其通过渗滤液二次污染的关键。以往为数不多的关于填埋场PAEs的降解研究很少涉及生物反应器填埋场,本研究以传统卫生填埋场为对照,将填埋垃圾和渗滤液作为一个整体系统,选用列入我国水体中优先控制污染物的PAEs作为目标物,研究生物反应器填埋场中PAEs迁移转化行为,分析生物反应器填埋场稳定化进程中生态环境的理化、生化和微生物特性对PAEs生物降解的影响,解析PAEs生物降解的生物反应器填埋场作用机制,主要结论如下:（1）实际垃圾填埋的传统卫生填埋场（CL）、回灌型生物反应器填埋场（RL）和两相型生物反应器填埋场（BL）的垃圾及渗滤液均检测到了邻苯二甲酸二甲酯（DMP）、邻苯二甲酸二丁酯（DBP）和邻苯二甲酸二辛酯（DOP）,其中DBP含量最高。各填埋场的稳定化进程顺序为BL＞RL＞CL,填埋场的稳定化进程影响着PAEs在垃圾中的降解行为,相比于填埋场产酸期,填埋场产甲烷期时的环境条件更有利于PAEs的降解。垃圾中DMP及DBP降解较快,其中DMP至实验结束已降解完全,而DOP降解较慢。CL、RL和BL中PAEs残留总量变化符合指数衰减模型,不同运行工艺的填埋场中PAEs残留总量差异显著,渗滤液回流明显加速了PAEs的生物降解,而产甲烷反应器的引入更能促进PAEs在填埋场中的去除。（2）按实际生活垃圾的组分比例自配模拟垃圾,构建了模拟回灌型生物反应器填埋场。分析填埋初始、产酸期和产甲烷期垃圾中普通和耐受DBP三大类微生物数量的动态变化发现,细菌数量最多,真菌次之,放线菌最少。DBP对初始垃圾各微生物的抑制不明显,但产酸期垃圾和产甲烷期垃圾真菌和放线菌均不同程度地受到了抑制,且放线菌受到的抑制率普遍高于真菌,而产酸期垃圾和产甲烷期垃圾细菌受DBP影响不明显,DBP对垃圾微生物的不良影响程度表现为放线菌＞真菌＞细菌。细菌、真菌、放线菌与脱氢酶存在极显著的相关性,而与VSS、BDM等存在显著的负相关性（P＜0.01）。（3）从模拟回灌型生物反应器填埋场产甲烷期垃圾中分离到了两株DBP高效降解菌T1和T5。根据形态学观察、生理生化鉴定及16s rDNA序列测定,菌株T1和T5同归入肠杆菌属,分别命名为Enterobacter sp.T1和Enterobacrersp.T5。Enterobacter sp.T1降解DBP的最佳pH值为7,最佳温度为35℃;Enterobacter sp.T5降解DBP的最佳pH值为7,最佳温度为30-35℃。当DBP初始浓度小于1000mg/L时,Enterobacter sp.T1对DBP的生物降解反应符合一级动力学模型1n C=-0.0359t+A,DBP降解半衰期为19.32h;Enterobacter sp.T5对DBP的生物降解反应符合一级动力学模型1n C=-0.0332t+A,DBP降解半衰期为20.88h。分析Enterobacter sp.T5降解DBP的代谢色谱图,初步判定其主要降解产物为MBP和PA。此外,两菌株均能不同程度利用DMP、DEP或DOP为唯一碳源和能源,说明其对PAEs的代谢具有广谱性。（4）不同时期垃圾中DBP的降解符合一级动力学模型,速率常数在0.0140-0.0187 d^-1之间,半衰期在37.1-49.5d之间。垃圾中DBP的浓度变化对其自身的生物降解影响不明显。产甲烷期垃圾中DBP的降解快于初始垃圾和产酸期垃圾,而产酸期垃圾中DBP的降解相对最慢,pH是影响DBP降解速率的关键因素。回接DBP降解优势菌后,各垃圾中DBP降解速率均有不同程度提高,其中接种后产甲烷期垃圾DBP降解速率常数显著高于未接种垃圾（p＜0.05）。混合菌对DBP的降解能力明显高于单株菌,其协同作用可有效促进垃圾中DBP的降解。至50d时,接种T1、T5和混合菌的产甲烷期垃圾中DBP的去除率从未接种时的60.3%分别上升为74.5%、72.4%和87.3%。更多还原

【Abstract】 Phthalic acid diesters （PAEs）, used primarily in polyvinylchloride （PVC） as plasticicers and known as endocrine-disrupting chemicals or environmental hormones, has been listed as priority pollutants by US EPA and China. Generally, discarded plastic are co-landfilled with other municipal solid waste （MSW）. Therefore, landfill leachate is an important way of PAEs entering the environment. With respect to the increasingly pollution arisen by MSW, investigating the PAEs transformation and degradation in landfill and analyzing the landfill condition for accelerating their mineralization are important for controlling PAEs secondary pollution by leachate. There are few studies conducted to evaluate the behavior of PAEs in bioreactor landfills. In this study, PAEs listed as priority pollutants in water by Environmental Monitoring of China were chosen as target pollutants. Considering the refuse and leachate as one whole system, the behavior of PAEs in two simulated landfill bioreactors were investigated. A conventional landfill was set as a control. In addition, effect of general physicochemical, biochemical and microbial characterization of the landfill on PAEs biodegradation were evaluated. Finally, mechanism of bioreactor landfill on the PAEs biodegradation was also analyzed. The main conclusions of this study are list below.（1） Dimethyl phthalate （DMP）, dibutyl phthalate （DBP） and dioctyl phthalate （DOP） were all detected in both leachate and refuse from conventional landfill （CL）, recirculated landfill （RL） and bioreactor landfill （BL）. Among the three PAEs, the DBP concentration was observed with the highest level. The stabilization process of landfill, with sequences of BL>RL>CL, play an important role on the biodegradation of PAEs in refuse. Compared to the acidic environment, the methanogenic environment is beneficial for PAEs degradation. DMP and DBP degraded rapidly, and DMP was completely degraded in landfill conditions, while the concentration of DOP decreased slowly. The residual amounts of PAEs with significant differences are well fit exponential decay models in CL, RL and BL. The operation of leachate recirculation can obviously accelerate PAEs biodegradation than conventional operation, and the introduction of methanogenic reactor can further promote the removal of PAEs in landfill.（2） Based on the real proportional characteristics of MSW, simulated MSW were loaded into the simulated leachate recirculation bioreactor landfill. The abundance of the common and the tolerant microbe of the three kinds of anaerobic microorganisms in refuse were investigated at initial phase, acidic phase and methanogenic phase, respectively. It showed that the number of bacteria was the largest while the number of actinomycetes was the smallest. The growth of microorganisms was not significantly inhibited by DBP at initial phases. However, the growth of actinomycetes and fungi was inhibited both at acidic phase and methanogenic phase, and the inhibition of actinomycetes was stronger than that of fungi. The toxicity effect of DBP on microorganisms in refuse has the ranking of actinomycetes>fungi>bacteria. In addition, the numbers of bacteria, fungi and actinomycetes significant positivly corrected with dehydrogenase activity, but negative corrected with VSS, BDM of refuse （P<0.01）.（3） Two bacterial strains including T1 and T5 capable of utilizing DBP as their sole source of carbon and energy were isolated from refuse of simulated recirculated landfill. Based on their morphology, physio-biochemical characteristics, and 16S rDNA sequence, the strains were identified as Enterobacter sp. and named as Enterobacter sp. T1 and Enterobacter sp. T5, respectively. The optimal pH and temperature for their biodegradation activities were 7.0, 35℃and 7.0, 30-35℃,respectively. The degradation kinetics of DBP by Enterobacter sp. T1 fit a first-order kinetic model of ln C= -0.0359t+A with the degradation half-life of 19.32h. when the DBP concentration was lower than 1000mg/L. Similarly, degradation of DBP by Enterobacter sp. T5 fit a first-order kinetic model of ln C= -0.0332t+A with the degradation half-life of 20.88h. The degradation productions of two major metabolites were identified as phthalic acid and monobutyl phthalate. In addition, those two strains also grew in conditions of DMP, diethyl phthalate （DEP） or DOP solution as the sole source of carbon and energy, respectively. It suggested that the range of their metabolism objects was wide.（4） The degradation of DBP fit first-order kinetic models in refuse of different phases, the rate constants were 0.0140-0.0187 d^-1 and the degradation half-lives were of 37.1-49.5d. The effect of DBP concentration on its degradation in refuse was not obvious. DBP was degraded fastest in the refuse of methanogenic phase, while slowest in the refuse of acidic phase. pH is the key factor of DBP biodegradation. In addition, the degradation rate of DBP obviously increased after inoculating the dominant DBP degradation bacteria in the refuse. The rate constant of inoculation was significant higher than the nonvaccinated in the refuse of methanogenic phase （p<0.05）. The degradation ability of mixed bacteria was obviously higher than single strain, it suggested that the synergistic effect can promote the DBP degradation effectively in the refuse. Till day 50, the removal rate of DBP in the refuse of methanogenic phase increased from 60.3% to 74.5%, 72.4% and 87.3% when T1, T5 and mixed bacterial were inoculated, respectively.更多还原