基于多组分反应传质模型的潜流人工湿地堵塞过程模拟研究

Constructed wetland(CW) was considered as a satisfied method for wastewater treatment with the advantages of simpleness of equipment, low cost of construction, operation and maintance, especially when conventional systems could not be applied. However, the clogging in CW was one of the main factors which restricted its application. Aims to the clogging process of subsurface flow constructed wetland, a simulation software name Fluent simulated clogging factors with computational fluid dynamics (CFD) way. In the case of the study on mechanistic model of SSF(Subsurfaced Flow) CW, a simple biological model learned from CW-2D model for the process organic matters is proposed based on the two-dimensional dynamic hydraulic model, which can describe the multi-component reactive transport. By comparing with the measuured data, the model is available to simulater the effect of COD, TSS, and removal and dynamic changes of dissloved accumulated clogging matters in CW. Special evaluation inedx system of the development of the whole clogging process will be put forward, the measuremnts of modified residence time distribution(RTD), hydraulic conductivity of substrate, effective porosity rate of clogging medium. The simulation of dynamic multi-component reactive transport model helps a better understanding and insight to the clogging mechanisms of SSFCW systems, predicting the clogging time exactly and accurately. In order to supply the physical and chemical environment where accumulated organic matter can be degraded and removed, the optimal hydraulic conductivity, practical sewage dosing cycles, stratges, feasible OM load in spatial and temporal distribution and microbial activity of the substrate should be explored. Self-situ recovery strategy will be very reliable. All the research results can be used to guide wetland system design, operation, maintenance and management, and provide theoretical support for the long-term safe operation of the CW ecosystem.

作为一项高效低耗的污水生态处理技术，人工湿地适用性广、管理简便，但堵塞问题制约其推广应用，本研究以潜流人工湿地堵塞过程为切入点，通过计算流体力学(CFD)模拟软件Fluent 模拟湿地堵塞试验前后水力学状态与净化效能变化间相互关系，以二维动态水力学模型为基础，提出描述堵塞发生、发展全过程中的物理、化学、生物特征变化指标；建立基于有机物积累与基质水力停留时间、基质有效孔隙率等水力传导性能的多组分传质过程的数学模型，反应人工湿地系统健康发育的指标评价体系，量化律定堵塞的突变点，为人工湿地堵塞现象的预测、预警提供科学量化指标；以提高基质的水力传导、增强微生物活性、加快有机物降解的理化环境为目标，优化人工湿地污水投配周期及方式、污染负荷时空分布，提出对已堵塞的基质层进行自我原位恢复的策略。上述研究成果可用于指导人工湿地系统的设计、运行维护与管理，为人工湿地生态系统长期安全运行提供理论保障。

作为一项高效低耗的污水生态处理技术，人工湿地适用性广、管理简便，但堵塞问题制约其推广应用，本项目按照国家自然科学青年基金项目计划书中的研究计划，以潜流人工湿地堵塞过程为切入点，基于对中国人工湿地近25年间（1990-2015）的工程案例调查和总结，通过研究团队的野外中试及工程湿地处理系统模拟与监测，对潜流湿地堵塞现象的发生和过程进行了细致深入的分析：分别从湿地进出水有机物分量变化确定堵塞物质来源、人工湿地表层基质有机物积累速率监测、基于多组份反应传质模型潜流湿地堵塞模型优化、湿地基质级配抗堵塞性能评价、湿地基质再生性能评估、人工湿地长效运行管理评价研究共六个方面开展工作。.研究工作的主要进展和成果：通过超滤对湿地进出水中有机物分子量变化进行了跟踪，过高的有机负荷是导致湿地堵塞的最主要原因，通过对活性污泥ASM3模型理论推广，运用多组份反应模型分析得出堵塞物质主要来源于进水难降解有机物质的残留，堵塞物质主要积累在潜流湿地基质表层；单一粒径基质、正级配基质和组合基质对预防湿地堵塞存在效果差异，湿地基质再生可能成为进一步拓展湿地净化空间的有效手段；在人工湿地抗堵塞策略研究方面，发明了一种人工湿地堵塞监测装置、一种延长复合垂直流人工湿地服务年限的装置、通过向人工湿地投加某种生物制剂或通过抗堵塞布水和反冲洗可进行堵塞物溶脱，建立了一种人工湿地长效安全运行的多参数评价系统。