维管束纤维对微泡污泥多层级孔隙构建及干化行为调控的机制研究

Micro-foam sludge (MFS) is a porous medium with a consistent and steady structural that is built by the leaching of endogenous surfactants in the sludge and mechanical whipping. MFS effectively enlarges the surface area and promotes the moisture transfer, which enhance the drying capacity of sludge. However, it appears that the poor efficiency of foaming process, caused by the multiple sources and changeful properties of sludge, has become a determining step. The earlier experiment indicated that the wood fiber had a positive effect on the formation and stability of MFS. Inspired by this case, the vascular bundles from agricultural and forestry residues will be selected, prepared and characterized. The influence characteristics of vascular bundles made on the foaming efficiency and microstructure of MFS will be found out respectively, which will help to explain the process mechanism of sludge foaming. On that basis, the addition of vascular bundles will rebuild the form and migration of water, influence the heat transfer and the macroscopic morphological characteristics of the sludge, which will be studied and help to clarify the behaviors and mechanism of MFS drying. The drying process of sludge will be simulated based on the theory of heat and mass transfer in the porous medium. It helps to take the advantages of mass transfer in the hierarchical networks constructed by the pores of MFS and vascular bundles simultaneously. Finally, the regulatory strategies of vascular bundles will be created to build an efficient and stable scheme for sludge foaming and drying process, and to enrich the current theories of sludge drying.

微泡污泥是通过污泥内源表面活性物质溶出结合机械搅拌，使其内部分布大量微泡而形成的一类多孔介质。其可以增大物料表面积并改善水分传递过程，是提升污泥干化速率的新方法之一。然而，由于污泥来源复杂且性质多变，影响了污泥微泡扩增效率，制约了其在污泥干化中的应用。通过稳泡剂材料筛选，申请人发现木质纤维对微泡污泥形成及稳定具有促进作用。本项目以此为切入点，将具有立体孔隙网络结构的维管束纤维引入污泥微泡扩增过程，系统考察其对污泥微泡扩增效率及多孔介质结构的影响规律，阐明对污泥微泡扩增过程的作用机理。在此基础上，综合分析维管束纤维对微泡污泥干化速率、水分形式、水分迁移、热量传递及宏观形态的影响规律，依托多孔介质热质传输理论对干化过程进行模拟，以期发挥微泡污泥及维管束纤维所构建的多层级孔隙结构高效的物质输运优势，构建维管束纤维对污泥微泡扩增及微泡污泥干化的调控策略，形成高效稳定的污泥微泡扩增快速干化整体方案。

微泡污泥是通过污泥内源表面活性物质溶出结合机械搅拌，使其内部分布大量微泡而形成的一类多孔介质，其可以增大物料表面积并改善水分传递过程，是提升污泥干化速率的新方法之一。研究以提升污泥微泡扩增效率为主要目标，广泛考察了不同污水厂、不同工艺、不同季节的污泥泥质变化特征，系统筛选了不同的长径比工程木质纤维，软木、硬木纤维，高纤维素含量黄麻纤维及高木质素含量油茶壳纤维等生物质材料对于微泡扩增过程中污泥密度下降速率和泡沫稳定性的影响规律。鉴于油茶壳纤维对于污泥微泡扩增效率提升的显著优势，优化了投加比例、粒径范围、搅拌时间及污泥密度等主要影响因素，通过污泥浸出液理化性质分析、油茶壳纤维组分表征、物料水分类型及流变性能测试、活性成分外源投加验证等方式，解析了油茶壳纤维对于污泥微泡扩增的促进机制，提出了污泥微泡形成过程的表面活性物质浓度、泡沫液膜可用水分及泡沫稳定因子三要素平衡观点。在后继的物料干化过程中，微泡污泥稳定性的提升并未对干化效率产生明显抑制效应。该项研究对于构建高效稳定的污泥微泡扩增快速干化整体技术方案，丰富污泥干化理论体系具有积极作用。