高效处理废水的快速传质生物流化床及动力学研究

The inner loop bio-fluidized bed has been developed as a efficient wastewater treatment technology. The research results on the mass transfer behavior and hydrodynamics were the important theoretical foundations for the structure optimization and industrial application. Because there were obvious differences between up-flow and down-flow areas in inner loop fluidized bed in respects of the fluidized power source and structure, the rules of hydrodynamic model and mass transfer bahaviour, which were studied on external circulating fluidized bed and up-flow area of inner loop fluidized bed, were not suitable for guiding the large-scale design of full bed area in inner loop fluidized bed. In this project, a kind of suitable controlled porous mineral carrier would be prepared learning from RBAO technique. The operation parameters to achieve the fast mass transfer fluidization in the full bed area based on prepared carriers were investigated. The flow field distribution characteristics in up-flow and down-flow areas were measured respectively to evaluate the hydrodynamic properties and the corresponding multi-phases mass transfer behavior and mixing characteristics in full bed area were also studied. The inner relation between carrier physical properties and kinetic parameters of fast mass transfer inner loop fluidized bed was induced and multi-dimensioned dynamic model was also built. The research results would provided the reliable theoretical and strong technological foundations for the construction and industrial application of inner loop bio-fluidized bed with fast mass transfer in full bed for wastewater treatment efficiently.

内循环生物流化床是一种高效的废水处理技术，对该类流化床的传质行为和动力学研究是结构优化、工业化放大应用的重要理论基础。由于内循环流化床中上升区与下降区在动力主体、流化床结构等方面呈现明显的差异，以往较多对外循环流化床和内循环流化床上升区的传质行为研究及建立的动力学模型对内循环流化床全床层区域的设计及放大还有较多的不足和不适用。本课题拟借鉴多孔陶瓷RBAO工艺，制备适宜的可控多孔无机载体，研究基于该多孔载体的全床层区域快速流化生物流化床的外部操作参数，测试分析上升区和下降区快速流化的流场分布特征，研究不同区域的多相快速传质行为和混合特征，深入剖析载体物性与传质行为和流体力学的内在关系，建立快速传质的动力学模型。最终为高效处理废水的全床层区域快速流化传质生物流化床的建立及其工业化应用提供可靠的理论依据和坚实的技术基础。

生物流化床是一种高效的废水处理技术，对该类流化床的传质行为和动力学研究是结构优化、反应器效能提高的重要理论基础。本项目从多孔载体研制、反应器结构优化、流体力学、生物反应动力学及废水降解性能等方面进行了系统性研究，开发出全床层快速流化内循环流化床。自制了适宜密度、高孔隙率、高生物亲和性的多孔磁性载体GM，考察了以此为载体的厌氧生物流化床处理PTA废水，挂膜启动时间缩短至14天，COD去除率在77%至89%之间，TA去除率在70%至83%之间。厌氧区载体颗粒表面及孔内附着了产甲烷杆菌、产甲烷球菌和甲烷八叠球菌。利用Fluent软件对流场特性进行了数值模拟，构建了日处理2吨的生物流化床，与传统生物工艺相比，高效生物流化床工艺HRT缩短了60%，处理成本降低了30%。以聚丙烯为载体，将射流器引入反应器，实现沼气辅助流化。有射流器情况下混合时间比无射流器情况下缩短了43.48%。最佳循环水流量为30 L/min，最佳吸气量为10 L/min，最佳载体装填量为60%。当HRT为20 h，COD浓度为4224 mg/L，TA浓度为2044 mg/L时，COD去除率达到84.6%，TA去除率为83%。解析混合流化动力作用下生物载体局部流化的形成条件，构建微流态型厌氧生物反应器，当载体装填量为50%，循环水量为25 L/min，辅助气量为120 L/h时，反应器内载体流化比例达到83%，此时混合时间为17 s。污泥的添加对系统的COD和TA去除率总体影响较小，去除率分别稳定在77%和75%左右。在HRT为20 h、SRT为20 d的条件下，污泥减量化效果为34.7%。本项目开发的快速流化生物流化床通过吸纳化工快速传质流态化技术来强化微生物降解有机物的作用环境，有效解决当前废水生物处理装置实际效率低、占地面积大等问题，为满足与日俱增的废水处理“节能减排”巨大需求提供关键的技术支撑。