表面活性剂控制生物滴滤器内生物膜过度蓄积的机理研究

Gas biofiltration is considered to be stable, cost-effective and environmentally friendly technology, and which is researched and applied widely in this field. Among these technologies, biotrickling filter (BTF) has become an established technology for VOC emission control, but it still exist some deficiencies of the poor performance for hydrophobic VOC removal, the control difficulties for excessive accumulation of biomass and the performance deteriorate during the long-running operation. Based on study on the traditional biological filtration process mechanism, mass transfer theory, microbiology and kinetic model, the applicant of this project research and design a BTF device packed polyurethane sponges with independent intellectual property. A nutrient solution was periodically quantitative supplied to the BTF, and was sprayed onto the media. The effect of surfactant on the long-term removal performance of hydrophobic VOC was investigated under various organic loading and empty bed contact time. From the perspective of mass transfer theory and microbiology reveals the degradation characteristics of mass transfer of hydrophobic VOC and biological filtration process mechanism. And also clarifies the control mechanism of surfactant for excessive biomass accumulation and the dominant species degraded target contaminants in BTF through the dynamic tracking analysis of biomass variation regularity in various stages during continuous operation. This project will extend its application area of the gas biofiltraiton technology and effectively control the biomass excessive accumulation in media, and has important theoretical significance and practical value for maintain long-term stable running performance.

气相生物过滤技术因性能稳定、成本低廉和环境友好的特点而在有机废气处理领域得到广泛研究和应用。其中最为成熟的是生物滴滤器，但是其仍然存在疏水性有机物降解性能差及过程机理认识不足、生物膜过度蓄积控制困难和长期运行时性能下降的难题。本项目申请者等基于传统生物过滤过程机理、传质理论、微生物学和动力学模型研究等，研发了具有自主知识产权的聚氨酯海绵填料生物滴滤装置，采用自动定时定量间歇喷淋营养液，研究表面活性剂对疏水性有机物在不同有机负荷、气体停留时间下长期运行性能的影响，从传质和微生物学的角度揭示疏水性有机物的传质降解特征和生物过滤过程机理；并通过动态跟踪分析连续运行时各个阶段中的生物膜相变化规律，阐明反应器内降解目标污染物的优势菌属以及表面活性剂对生物膜过度蓄积的控制机理，对于拓宽气相生物过滤技术的应用范围和有效控制生物膜过度蓄积，维持长期稳定运行性能具有重要的理论意义和实践价值。

本研究采用具有自主知识产权的聚氨酯海绵填料生物滴滤装置，采用自动定时定量间歇喷淋营养液，针对填料内生物膜、有机负荷、营养物、水份等分布不均，以及填料中生物膜的过量蓄积而导致的堵塞和沟流等问题开展了相关研究。主要考察了两种不同的氮源（NH4Cl和NaNO3）对甲苯去除性能的影响研究；营养液中无表面活性剂时，不同的EBCT和有机负荷以及冲击负荷对BTF去除正己烷性能的影响；表面活性剂（Triton X-100）浓度、高负荷下表面活性剂对BTF性能的影响，以及连续运行时填料中生物膜中的优势菌属及活性研究。结果表明：在两种氮源条件下，BTF的压降都随着气体EBCT的减少而升高，但以NaNO3为氮源时，BTF在长时间的运行后仍表现出更好的性能；当气体EBCT为30 s保持不变时，BTF对正己烷的去除效率随着进口有机负荷的增加而下降。当正己烷浓度为260 mg/m3保持不变时，BTF对正己烷的去除效率随着气体EBCT的减少而降低。此外，在BTF网状聚氨酯海绵填料内形成的生物膜在经历冲击负荷（饥饿、升高或降低负荷）时，性能相当稳定，具有相当强的抗冲击负荷的能力。从本研究中得出的营养液中添加Triton X-100最佳的浓度为0.1 mL/L，并且当负荷为60 g/m3•h时，BTF对正己烷的去除效率达到了83.7%；当营养液中取消Triton X-100，BTF的去除效率下降并稳定在72.8%。本研究的整个周期，营养液中引入的Triton X-100能很好的控制填料中生物膜的过度蓄积，BTF的压降一直维持在100 Pa左右。此外，表面活性剂条件下网状填料骨架表面形成了一层薄而密集的生物膜，并且分布比较均匀，大大提高了传质效率和BTF降解正己烷的性能。通过在营养液中引入表面活性剂能提升疏水性有机物的去除性能和有效控制生物膜过度蓄积，使气相生物过滤技术更加实用、高效和可靠，推动了其快速发展和广泛应用，对气相生物过滤具有重要的理论意义和实践价值。