多环芳烃是一类广泛分布于环境中的有机污染物,具有致毒、致突变、致癌等作用。美国 EPA 将 13 种多环芳烃的化合物列为优先控制污染物。本论文以水溶性最强的多环芳烃——萘为研究对象,得出了萘的挥发模型和好氧微生物对萘的吸附模型。并对取自北京某污水处理厂的污泥进行好氧培养和驯化,研究驯化后的好氧微生物对萘的降解动力学。进一步对驯化后的好氧微生物进行分离,得到能够高效降解萘的菌株,并对得到的纯菌体进行细胞固定化的研究。 在本研究中,首先研究了萘在水中的挥发模型(无 VSS 存在),结合试验数据和理论公式(Fick 第一定律)得出水溶液中萘的传质系数 k 值为 2.49×10-7m/s,而完全由经验公式计算出的 k 值为 2.538×10-6m/s,通过比较得出所使用模型的有效性;进一步研究得出,当萘溶液中 VSS 浓度为 500mg/L 时,水溶液中萘的传质系数 k 值为 2.18×10-7m/s。

Polycyclic aromatic hydrocarbons are a type of organic pollutants widely distributed in the environment, which have toxic, mutagenic, carcinogenic and other effects. The US EPA prioritizes the control of 13 polycyclic aromatic hydrocarbon compounds as pollutants. This paper takes naphthalene, the most water-soluble polycyclic aromatic hydrocarbon, as the research object, and obtains the volatilization model of naphthalene and the adsorption model of aerobic microorganisms on naphthalene. And aerobic cultivation and domestication of sludge from a sewage treatment plant in Beijing were carried out to study the degradation kinetics of naphthalene by domesticated aerobic microorganisms. Further isolate the domesticated aerobic microorganisms to obtain strains that can efficiently degrade naphthalene, and study the cell immobilization of the obtained pure bacterial cells. In this study, the volatilization model of naphthalene in water (without the presence of VSS) was first studied. Based on experimental data and theoretical formula (Fick's first law), the mass transfer coefficient k value of naphthalene in aqueous solution was determined to be 2.49 × 10-7m/s, while the k value calculated entirely from empirical formula was 2.538 × 10-6m/s. The effectiveness of the model used was compared and concluded; Further research has shown that when the concentration of VSS in naphthalene solution is 500mg/L, the mass transfer coefficient k value of naphthalene in aqueous solution is 2.18 × 10-7m/s.

通过吸附试验可知,驯化后的好氧活性污泥对水溶性萘的吸附在10分钟即达到最大吸附量,在60分钟时达到吸附-解吸平衡。驯化后的微生物对萘的吸附等温曲线符合langmuir吸附等温式,同时也符合Frendlich吸附等温式。进一步研究可知,在酸性条件下,活性污泥对萘的吸附量较大,且pH值的变化对吸附量的影响不大;当pH大于7时,活性污泥对萘的平衡吸附量随着pH值的升高迅速降低。 驯化后的好氧微生物对萘的降解符合一级反应动力学。在VSS=100mg/L和VSS=200mg/L两种情况下,反应速率常数分别为:0.0824h-1和0.1302 h-1。 对驯化后的活性污泥中的微生物进行分离,得到两株细菌,革兰氏染色均呈阳性。 最后分别使用 PVA-硼酸凝胶小球和 PVA-硼酸-纱布复合载体两种方法对微生物细胞进行固定化的研究,按照它们对萘的降解速率由大到小的顺序排列:自由菌纱布固定化细胞凝胶小球固定化细胞。

According to the adsorption test, the domesticated aerobic activated sludge reaches its maximum adsorption capacity for water-soluble naphthalene in 10 minutes and reaches adsorption desorption equilibrium at 60 minutes. The adsorption isotherm curve of domesticated microorganisms for naphthalene follows both the Langmuir adsorption isotherm and the Frendlich adsorption isotherm. Further research shows that under acidic conditions, activated sludge has a greater adsorption capacity for naphthalene, and the change in pH value has little effect on the adsorption capacity; When the pH is greater than 7, the equilibrium adsorption capacity of naphthalene by activated sludge rapidly decreases with the increase of pH value. The degradation of naphthalene by domesticated aerobic microorganisms follows a first-order reaction kinetics. The reaction rate constants for VSS=100mg/L and VSS=200mg/L are 0.0824h-1 and 0.1302 h-1, respectively. Two bacterial strains were isolated from the domesticated activated sludge, and Gram staining was positive for both strains. Finally, two methods, PVA boric acid gel beads and PVA boric acid gauze composite carrier, were used to immobilize microbial cells. According to their degradation rate of naphthalene, they were arranged in order from high to low: free bacteria gauze immobilized cells gel beads immobilized cells.

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