曝气充氧对黑臭河道沉积物-水界面扩散边界层影响机理及生态效应研究

Aeration is a common ecological restoration technique in the management of urban malodorous river. But, in practice, it often encounter the problem of instability and unsustainability of the restoration effect. The fundamental reason is that the mechanism of aeration ecological restoration failed to fully understand.This project intend to study the characteristic of the diffusive boundary layer(DBL) and its influencing factors in the sediment-water interface of urban malodorous river. Explain the mechanism of aeration on the diffusion boundary layer. Reveal the blocking mechanism of DBL on material exchange in sediment-water interface.The gas-liquid-solid three-phase mass transfer at sediment-water interface during aeration was studied. In the aspect of pollutant degradation and transformation, the mechanism of aeration and oxygenation on the microbial community (structure) and sediment / water physicochemical properties in the sediments of urban malodorous river was analyzed emphatically, the comprehensive toxicity of pollutants in the sediments/water of the urban malodorous river course during aeration was evaluated. Finally, the coupling relationship between aeration process and heterogeneous mass transfer process, microbial community and pollutant degradation process is established. The internal mechanism of aeration to improve the urban malodorous river is revealed. This provides a theoretical basis and technical support for designing a more effective and stable urban malodorous river aeration ecological restoration technology.

曝气充氧是黑臭河道治理中常用的生态修复方式，但在实践过程中，时常会遇到曝气修复效果不稳定和难以持续的问题，其根本原因在于对曝气生态修复的机理未能全面认识。本项目拟通过研究黑臭河道沉积物-水界面扩散边界层（DBL）特征及其影响因素，阐明曝气充氧对扩散边界层的影响机理，揭示扩散边界层对沉积物-水界面物质交换的阻滞机制；从多相传质角度，研究曝气充氧条件下沉积物-水界面处气液固三相传质规律；从沉积物中污染物降解转化路径角度，着重解析曝气充氧对黑臭河道沉积物中微生物群落(结构)和沉积物/水体理化性质的影响机理，评价曝气修复过程中黑臭河道沉积物/水中污染物的综合毒性变化。最终建立曝气充氧与多相传质、微生物活动和污染物降解之间的耦合关系，全面揭示曝气充氧改善黑臭河道的内在机理，补充完善曝气修复理论，为开发设计更有效，更稳定的黑臭河道曝气充氧生态修复技术提供理论依据和技术支持。

项目对曝气条件下沉积物-水界面扩散边界层影响和污染物降解规律开展研究，并对不同曝气工况下污染物在沉积物-水界面的输移过程和生态环境效应进行分析。开展了曝气充氧过程中的相间传质规律及影响因素研究；曝气充氧过程中沉积物-水体中污染物降解规律和水质净化机理研究；黑臭沉积物-水界面特性及曝气条件下界面结构的变化过程研究。.主要完成了以下研究目标：从多相传质角度研究曝气充氧过程中流场特性和多相传质规律，探究了影响曝气传质效率的关键因素，证明了曝气量是影响气泡羽流运动形态和氧转移系数的最显著因素。分析了曝气过程沉积物和水体中污染物降解过程和规律和水体净化效果，以及在此过程中微生物群落变化。证明了在曝气条件下，沉积物-水体中微生物群落结构会发生改变，进而影响到水体中各类污染物质的去除。通过采用微电极系统监测了沉积物-水界面微尺度精细化结构特征，研究了曝气条件下沉积物中氧侵蚀深度的变化过程。解析了沉积物-水界面结构，分析了在不同曝气条件下，微界面的尺度变化和下界迁移过程。.最终从传质角度揭示曝气充氧改善黑臭河道的内在机理，为开发设计更有效、更稳定的水体曝气充氧修复技术，提升水环境治理效果，改善水生态质量提供了技术支撑。