【作者】 张长；

【导师】 曾光明； 余健；

【作者基本信息】 湖南大学 ， 环境工程， 2007， 博士

【摘要】 双酚A（BPA）是典型的内分泌干扰物，诸多研究表明BPA在试管试验与活体试验中均表现出对动物体急性毒性和对生殖、胚胎、神经系统发育的内分泌干扰影响，由于其在水体中广泛存在，因此可通过多种途径使人类遭受直接或潜在的暴露风险。本文分别研究了BPA在水环境多介质中的3种典型行为：在沉积物上的吸附行为、微生物好氧降解行为、饮用水混凝过程中的行为，以期为客观评价BPA在水体中的转化、归趋与有效控制水体这类有机物的污染提供理论依据。BPA在湘江沉积物上的吸附主要以快速吸附为主，慢速吸附发挥的作用较小。在达到最大吸附量之后，都有一个释放过程发生，使得沉积物上部分BPA解吸下来，溶解在水中，表现为吸附量下降。达到吸附平衡的时间在8h左右。BPA在湘江沉积物上的吸附等温线很好地符合Freundlich模型，呈非线性。吸附平衡常数K_f与沉积物总有机碳f_oc也呈线性正相关，表现为随之沉积物有机碳含量的增加，其单位沉积物上吸附的BPA也增加。沉积物有机质中的碳黑物质和孔隙填充相造成了BPA的非线性吸附和解吸滞后行为，解吸迟滞程度主要取决于沉积物中有机质组分。沉积物对BPA的吸附是一个放热过程，表现为随着温度的升高，单位沉积物上吸附的BPA减少，主要为物理吸附，主要吸附作用力为疏水键力，BPA在沉积物上的吸附是自发的且吸附都是焓推动。在一定溶质浓度下，随着沉积物浓度的增大，BPA单位吸附量减少；离子强度对BPA在沉积物上的吸附影响显著，随着离子强度的增大，单位沉积物上的BPA吸附量也随之增大；在较低pH值的酸性环境下，BPA吸附量随着pH值的降低而增加，而在较高pH值的碱性环境这种趋势不明显。从好氧堆肥反应器的渗滤液中分离到1株BPA降解菌Achromobacter xylosoxidans B-16，此菌株对BPA的好氧降解最适宜环境条件为pH 7.0、温度30℃，而且菌液接种量、初始BPA浓度对BPA的降解影响较大，此菌株的BPA的降解活性在高BPA浓度时会受到抑制。考察了BPA的降解动力过程，结果表明在低浓度（3、5、10mg／L）时符合一级反应动力学特征，而在较高底物浓度（20mg／L、50mg／L）下不能用一级反应动力学描述。鉴定出3种降解中间产物，分别是对羟基苯甲醛、对羟基苯甲酸和对苯二酚，主要有三种主要降解途径：a)对羟基苯乙酮被氧化转变为对羟基苯甲酸，然后再转变为二氧化碳和细胞内物质；b)对羟基苯甲酮直接转变为二氧化碳和细胞内物质；c)对异丙烯酚受到羟基自由基的攻击转变为对苯二酚，然后被细胞代谢消耗。对苯二酚在4.5d内被累积，结果显示对苯二酚比其它中间产物代谢慢且明显会抑制菌株的BPA降解活性，在BPA降解过程中，各种代谢酶的数量或活性不同。在较低有机物浓度和浊度条件下，PAC在pH=5.0～6.0时对BPA有一定的混凝去除效果，此时水体中带正电的羟基铝盐电中和是主要作用机理。随着PAC投加量的增加，可以发现BPA的去除效果呈先上升后下降的趋势，理论上最佳的混凝剂投量BPA／PAC=1：2（质量比）。原水中的腐殖酸类有机物对BPA混凝行为影响较大，较高的腐殖酸浓度削弱了PAC对BPA的混凝效果。原水中的浊度物质对BPA混凝行为影响较大，较高的浊度也会削弱PAC对BPA的混凝效果。更多还原

【Abstract】 It has been reported that BPA has estrogenic activity and acute toxicity toward aquatic organisms and human cultured cells （Nakagawa and Tayama, 2000）. It has also been detected that the pollution of BPA can be created when using BPA to manufacture other compounds and products including releases from many current commodities. In this study,three typical behaviors of BPA in aqueous medium was investigated including adsorption behavior on sediments,biodegradation in aqueous medium and behavior in coagulation.The adsorption behavior of bisphenol A （BPA） on sediments was investigate through batch adsorption experiments. The sediment samples were collected from Xiangjiang River （Changsha, Central-south China）. Data obtained from adsorption experiments show that the rapid adsorption plays the main role rather than slow adsorption in adsorption process of BPA on sediments. Freundlich model can describe the adsorption behavior of BPA on sediments very well. The calculated K_f (mg^1-n lⁿ g^-1 ) ranged from 0.0072 to 0.0178 （n ranged from 0.6944 to 0.8106）. Through analyzing the data of adsorption experiments and properties of sediments, we consider that black carbon （e.g. soot- and charcoal-like material, collectively termed black carbon or BC） and hole-filling domain of the organic matters in sediment are responsible for the observed nonlinear adsorption and desorption hysteresis. The calculated hysteresis coefficient H ranged from 0.6718 to 1.0928. Negative and low molar formation enthalpy (△H⁰ = -5.735 kJ mol^-1) indicates that adsorption process of BPA on sediments is an exothermic reaction, attributed to the physical adsorption which is dominated by dispersive force and driven by enthalpy thoroughly. In this study, the amount of adsorbed BPA on sediment was found to decrease as sediment concentration increased, whereas it increased with an increase of ironic concentration. In acidic surroundings, the amount of adsorbed BPA on the sediment was found to decrease as pH value increased, whereas it varied indistinctively in alkaline surroundings.A novel bacterium designated strain B-16 was isolated from the compost leachate of the municipal solid waste （MSW） in a laboratory reactor. This strain was identified as a gram-negative bacterium, Achromobacter xylosoxidans that could grow on bisphenol A （BPA, a representative endocrine disruptor） as a sole carbon source under aerobic condition. BPA-degrading characteristics of strain B-16 were investigated in liquid cultures. The results show that BPA degradation was influenced by several factors （e.g. inoculum size, substrate concentration, temperature and pH, etc）. The optimum temperature and pH were found to be 35℃and 7.0, respectively. BPA-degrading activity and cell growth were inhibited at high substrate concentration. Metabolic intermediates detected during the degradation process were identified as p-hydroxybenzaldehyde, p-hydroxybenzoic acid and p-hydroquinone, respectively. BPA was firstly metabolized to form three intermediates p-hydroxyacetophenone, p-hydroxybenzaldehyde and p-isopropenylphenol. Subsequently, there are three main pathways: Pathway （I）, in which p-hydroxyacetophenone was oxidized to form p-hydroxybenzoic acid and that converted to carbon dioxide and biomass, Pathway （II）, in which p-hydroxybenzaldehyde was converted to carbon dioxide and biomass directly, Pathway （III）, in which p-isopropenylphenol was converted to p-hydroquinone by·OH radicals attack and mineralized later. The fact that p-hydroquinone accumulated during 4.5 d indicates that it was mineralized more slowly than other metabolites. Apparently, the relevant amounts or activities of the enzymes involved in the degradation pathway were significantly different.When the concentration of organic matter and turbidity was low in the solution, BPA was found to be removed by PAC coagulation to a certain extent at pH 5.0-6.0, attributed to the electronic counteract mechanism which is dominantwd by aluminous salts in the solution. The removal of BPA increased firstly as PAC dose increased, subsequently decreased. The optimal PAC dose was found at BPA/PAC=1:2（M/M）. The humic matters and the turbidity matters in the solution has significant effect on BPA removal by PAC coagulation. The BPA removal will be weaken at high TOC and high turbidity.更多还原