两相分离生物反应器净化非稳态氯苯废气的机理研究

Chlorobenzenes are concerned as hydrophobic organic contaminants with severe environmental pollution, high biological toxicity, and weak biodegradability. Efficient purification of waste gas containing chlorobenzene with fluctuant loading from pharmaceutical and chemical industry has become a difficult issue in the field of waste gas treatment. The conventional biological treatments usually suffer from mass transfer limitations and substrate toxicity, which result in low process elimination capacities and stability..This project adopts silicone oil as non-aqueous phase, and establishes a two-phase partitioning bio-trickling filter (TPBTF) to purify fluctuant chlorobenzene waste gas. The relation between silicone oil and the cellular resistant mechanism from toxicity of substrate, the effect of silicone oil on cellular hydrophobicity and community structure, and the microbial metabolism mechanism in the two liquid phases will be analyzed. The mass transfer behavior between oil, water and microorganism phases in TPBTF will be revealed through the investigation on hydrodynamic characteristics and liquid film resistance. Furthermore, the mass transfer and reaction kinetics in TPBTF will be established according to the instantaneous mass transfer and reaction characteristics of chlorobenzene waste gas with fluctuant loading. On the basis of above investigation, the cooperative effects between absorption, desorption and microbial metabolism with the addition of non-aqueous phase would be determined. Then, the mechanism for purification of waste gas containing chlorobenzene with fluctuant loading by TPBTF is revealed, thus laying sound foundation for the application of biotechnology in the treatment of waste gas containing chlorobenzenes and other hydrophobic VOCs.

氯苯类化合物是一类环境污染严重、生物毒性较高、可生物降解性较差的疏水性有机污染物。如何有效净化化工、医药等行业排放的非稳态氯苯类废气已成为当前废气治理领域的一大难点。由于存在传质阻力和底物毒性，常规的生物处理技术往往难以奏效。.本申请以硅油为非水相体系，建立基于水-油双液相体系的双相分离生物滴滤塔（TPBTF）以净化非稳态氯苯废气，明确硅油与细胞抗底物毒性机制之间的关系，考察硅油对生物疏水性和群落结构的影响，解析双液相体系中的微生物代谢机制；通过对流体力学特性和液膜阻力的研究，揭示TPBTF内氯苯的油-水-生物膜多相传质行为；在此基础上，考察进口负荷阶跃性变化时氯苯的瞬态传质和反应特征，建立氯苯在TPBTF中的传质-反应动力学模型，明晰非水相体系强化下的吸收、解吸和生物代谢之间的协同效应，揭示TPBTF净化非稳态氯苯废气的机理，为生物法高效净化氯苯类及其它疏水性VOCs废气的应用奠定基础

氯苯类化合物是一类生物毒性较高、可生物降解性较差的疏水性有机污染物。由于存在传质阻力和底物毒性，非稳态氯苯废气的高效去除是目前VOCs治理领域的难点之一。本项目采用两相分离生物反应器实现氯苯废气的高效净化。. 分离筛选到1株氯苯降解菌LW26，经鉴定确定该菌株为Delftia tsuruhatensis，其适宜的生长和降解条件为：温度25~30℃、pH 6.0~9.0。菌株LW26降解氯苯的过程符合Haldane动力学模型，最大比生长速率μmax和最大比降解速率γmax分别为0.42 h-1和2.53 h-1。比较正辛醇、十二醇、癸二酸二乙酯、硅油、十六烷、十八烯6种有机溶剂对降解菌LW26的生物相容性和生物可降解性，筛选出硅油作为非水相。利用硅油强化菌株LW26处理氯苯，当硅油比例为20%时，菌株LW26对氯苯去除效果最佳，最高降解浓度约是单相体系的2.5倍。当氯苯浓度为33 mg/瓶时，两相体系中菌体的1,2双加氧酶酶活和电子传递链活性分别维持在0.155U/mg-protein和234.9 mg·g-1·h-1，而单相体系中几乎检测不到。因此，当底物浓度较高时，硅油的存在使微生物得以保持较高的生物活性。实验还发现，当硅油比例为20%时，约有75%的菌体粘附在水-硅油界面上，此时菌体的细胞表面疏水性约是单相的10倍。推测硅油可诱导菌株LW26细胞表面疏水性的提高，使更多的菌体细胞粘附在水-油界面，界面上的LW26可直接摄取溶解在硅油中的氯苯。. 分别考察了两相生物滴滤塔（TPBTF）和两相生物搅拌式反应器（TPSTB）对氯苯废气的去除效果。发现TPSTB无论在稳态及非稳态均较单相有较明显的优势，而TPBTF仅在非稳态时具有优势。对利用TPSTB处理氯苯废气过程中的氧气和氯苯传质行为进行了研究。随着硅油比例的增加，氧传质系数反而减小，但由于加入硅油后氧气的传质推动力大大增加，两相分离反应器中的氧传质速率仍然大于单相反应器。求得两相和单相反应器中氯苯从气相传质到水相（包括通过NAP传质到水相）的最大比例 分别为0.99和0.67，表明两相分离反应器中氯苯的传质明显优于单相反应器。此外，确定了传质-反应动力学模型，该模型可较好地模拟TPSTB处理非稳态氯苯废气的过程。

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