【作者】 孙永利；

【导师】 李鑫钢；

【作者基本信息】 天津大学 ， 化学工程， 2007， 博士

【摘要】 五氯苯酚(PCP)作为一种持久性有机污染物,对人类和环境具有很大的危害,对PCP生态毒性及生物降解的研究一直是国际关注热点。本文提出用固定化-共代谢方法来处理含PCP的废水,对PCP的生态毒性和固定化-共代谢生物降解过程机理进行了系统的研究。以原生动物为靶生物对PCP的生态毒性进行了综合评价,确定了PCP对原生动物群落12h急性中毒的最大无致死和最小全致死浓度范围,并得出半数致死效应浓度(LC50)为2.40mg/L。对活性污泥废水的土著混合菌进行驯化、分离,得到四株降解PCP的优势菌:NERCDT-A、NERCDT-B、NERCDT-C和NERCDT-D,根据16SrDNA测序结果,确定该四株菌分属于Klebsiella terrigena、Uncultured bacterium、Bacterium SV26II和Pseudomonas migulae菌属。通过正交实验及各菌株的生长曲线的研究,以PCP的降解效果为目标,确定了固定化微生物降解PCP的最优操作条件为:选用PVA+海藻酸钠为包埋材料,包埋100mL吸光度在0.85nm～0.90nm范围内的菌液,pH值为8.0。通过间歇实验,系统地研究了游离菌种、固定化单株菌和固定化混合菌对废水中PCP的去除效果。实验结果表明:固定化微生物降解PCP优于游离菌种,固定方法可以使PCP的去除率提高35%。通过固定化-共代谢降解实验研究表明,不同的共代谢基质对PCP的降解速率有着不同影响:葡萄糖和丁二酸对PCP降解起促进作用;苯酚对PCP降解的影响程度与浓度有关,10mg/L浓度的苯酚对PCP的降解起到促进作用,而5mg/L和50mg/L浓度的苯酚却抑制了PC P的降解;丙三醇对PCP降解有明显抑制作用。通过固定化单株菌和固定化-共代谢降解PCP的实验数据拟合与理论研究,提出了单底物、双底物降解动力学模型,并定量化地描述了固定化菌体在单底物和双底物生物降解系统中的降解动力学行为,模型结果与实验数据吻合良好。更多还原

【Abstract】 Pentachlorophenol (PCP) is one of persistent organic pollutants. It is existed broadly in the waters. The research of toxicity and biodegradation of PCP is focused by international chemical field. The immobilization-cometabolism method is used to remove PCP which is existed in the wastewater. The toxicity of PCP and the mechanisms of immobilization- cometabolism have been investigated.The toxicity of pentachlorophenol (PCP) with protozoan community as target organism was studied. In the 12h-cute toxicity testing, the maximal tolerance and minimal all lethal were tigated, the half lethal concentration was 2.40 mg/L. Through mixed culture four strains that could live in the high concentration of PCP have been isolated by enriching, screening and culturing from activated sludge. They are called NERCDT-A, NERCDT-B, NERCDT-C, NERCDT-D. The four strains are identified by 16SrDNA as Klebsiella terrigena, Uncultured bacterium, Bacterium SV26II and Pseudomonas migulae, respectively. The fittest vegetal conditions and optimized biodegradation condition have been determined by orthogonal experiments and the bacteria growth curves. The PVA mixed algin has been chosen as embedding material and 10mL bacteria was embedded which absorbency is varied from 0.85nm to 0.90nm. The value of pH is 8.0.The experiments have been used in detail to compare the effect of PCP removal by bacteria in solution, the immobilized single bacteria and the immobilized mixed bacteria. Results show that the velocity of degradation used by immobile bacteria method is faster than that used by bacteria in solution. The removal rate of PCP is increased by 35%.Four cometabolism substrates have been used to compare the effect of different growth substrates, which include glucose, butyric acid, glycerol and phenol. Results show that the glucose and butyric acid can promote the degradation rate of PCP, and the glycerol will restrain it. The effect of phenol is related by the initial concentration of phenol. When the concentration of phenol is 10mg/L, the existing of phenol can promote the degradation rate of PCP by using immobilization-cometabolism. When the concentration of phenol is 5mg/L and 50mg/L, the restrain effect is obviously observed. Based on the experimental data and theoretical research of immobilization- cometabolism, single substrate and two substrates model are presented to quantificationally describe the process of PCP degradation. The result of simulation is in good agreement with the experiment data.更多还原