人工湿地污水生态处理技术具有基建投资省、运行费用低、美化景观和维持生态平衡等优点，在村镇生活废水处理、流域水环境修复等领域具有突出的应用优势。然而，由于设计与运营管理经验的不足，当前人工湿地技术在大型工程应用中普遍存在基质堵塞现象，引起水流场分布不均，有效体积降低，严重时还会出现表面漫流现象，造成蚊蝇滋生，最终会导致系统瘫痪。因此，解决人工湿地基质堵塞问题是实现湿地可持续运行的重要保障。 针对人工湿地基质堵塞问题，本论文对比研究不同类型固体累积对湿地水力学特征和污染物去除效率的影响，解析基质堵塞影响湿地运行效果的作用机理；分析碳源驱动下基质堵塞形成过程中累积固体的物化特征，揭示有机-无机固体间的协同作用机制；基于湿地填料和堵塞物质持水性能差异，开发基质堵塞电法探测技术，建立堵塞程度与视电阻率间的反演模型；最后，提出超声处理堵塞防治技术，并阐明超声处理不同类型固体堵塞的作用机理。取得主要结论如下： (1)明确了基质堵塞的水力学特征影响。有机固体可直接阻断水流通道，此外有机-无机固体协同累积可形成低密度的堵塞物质，相比于单纯的无机固体累积，单位质量有机-无机固体水力学阻力显著增加。随着系统运行，有机固体截留速率和生物降解速率逐渐达到平衡，导致有机固体累积造成的基质渗透性能下降速率逐渐变缓；与之不同，无机颗粒物累积具有叠加作用，导致无机固体累积造成的基质渗透性能下降速率逐渐增加。基质堵塞对水平潜流湿地水流场分布影响显著，适量固体累积切断了系统固有的优先流路径，将平均水力停留时间提升近10％，固体的不断累积最终造成水流方向垂面上基质渗透性能的差异性分布，导致平均水力停留时间缩短约40％。从水流场角度考虑，水平潜流湿地较垂直流湿地更易发生堵塞问题，潜流湿地水流场分布与基质渗透性能无直接关系，水流方向垂面上累积固体的差异性分布是导致系统水流场失稳的直接原因。 (2)明确了基质堵塞的污染物去除影响。固体累积可为污染物和微生物提供大量的吸附点位，强化污染物的吸附和降解作用；固体累积可造成基质有效体积降低，对污染物去除带来不利影响，固体累积正面和负面影响间的平衡决定系统的运行效果。水平潜流湿地内固体累积将总磷去除效率提升了33％-70％，而有机物和氮的去除效率无显著变化；垂直潜流湿地内固体累积并未显著影响系统的水流场分布，因此固体累积对污染物去除主要产生积极影响，有机-无机固体协同累积表现最佳，总磷、氨氮和总氮效率分别提升了32.85％、36.88％和16.79％。无机固体累积导致系统总菌丰度提升6.68倍，且显著丰富了微生物群落多样性。固体累积造成的水力学故障最终发展为表面漫流，水平潜流湿地表面漫流出现后污染物去除效率呈下降趋势，垂直潜流湿地表面漫流伴随着系统进水负荷和污染物去除负荷的大幅度降低，因此表面漫流现象可指示基质的严重堵塞。 (3)解析了有机-无机固体累积协同作用机制。系统内无机累积固体间存在絮凝现象，主要絮凝机制为无机颗粒物间的离子架桥作用；相比于无机累积固体，有机-无机协同累积固体间的絮凝作用更显著，主要絮凝机制为通过胞外聚合物的离子架桥作用和网捕作用。相比无机固体累积，有机-无机固体协同作用显著增加了固体在系统进水端的集中累积，并导致固体分布趋向于在系统上层基质沿水流方向延伸。有机-无机固体结合易形成低密度的凝胶状物质，含少量有机物质(重量比<3％)导致累积固体比体积为无机固体的两倍以上。 (4)开发了电法堵塞探测技术。排空状态基质视电阻率随堵塞程度的增加而逐渐降低，基于此现象建立了视电阻率-堵塞物质体积分数间的ARSF反演模型，模型模拟结果与实际堵塞程度相吻合(斜率=0.986，R²=0.98)。通过电极法对基质视电阻率进行原位探测，结合ARSF反演模型，实现了基质堵塞的原位定量化探测，两极法测量结果(相对误差为8.8％)优于四极法(相对误差为29.4％)，采用两极法探测规模化湿地基质堵塞状况，发现距离进水端5 m范围内基质堵塞最严重。高密度电阻率法有效实现了潜流湿地基质堵塞的三维探测，施伦贝尔法跑极方式测深分辨率高于温纳法，采用高密度电阻率法探测规模化湿地基质垂向堵塞特征，距离进水端1 m断面主要为上层基质堵塞，距离进水端5 m断面的中层基质堵塞较其它位置更为严重。提供了一种精确度高、操作简便、无损基质的湿地基质堵塞探测方法，为区域性堵塞防治提供科技支撑。 (5)提出了超声处理堵塞防治技术。超声处理基质堵塞过程的最佳参数为40 kHz，60 kW／m³；堵塞基质超声处理最佳参数为28 kHz，60 kW／m³。超声对较小粒径固体导致的堵塞连续处理效果更佳，超声更适用于处理有机固体导致的基质堵塞。超声可对累积固体产生多方面的影响，首先，超声可降低累积固体的粒径，处理粒径大于1 μm的颗粒物效果更显著；其次，超声处理可打破累积固体的疏松结构，充分发挥小粒径颗粒物的迁移能力，减少固体的集中累积；再次，超声可增加累积固体的有机物溶出，化学效应产生的羟基自由基可氧化难降解有机固体，弱化有机.无机固体间的协同作用。提供了一种成本极低、耗时较短、无二次污染的湿地基质堵塞防治技术，为人工湿地长期稳定运行提供技术支持。 关键词：人工湿地；基质堵塞；形成机制；电法探测；堵塞防治

 Constructed wetlands (CWs) have the advantages of low construction and operation costs, landscape and ecological benefits, etc. CWs have the prominent superiority in the treatment of decentralized rural wastewater and watershed wastewater. However, due to the lack of experience in design and operation management, most engineered CWs are threatened by substrate clogging, which can cause uneven water flow field, low effective volume, overland flow, mosquito breeding and even system paralysis. Solving the problem of the substrate clogging is the guarantee of realizing the sustainable operation of CWs. According to the problem of substrate clogging, first of all, the effects of different types of solids accumulation on the hydraulic characteristics and pollutants removal efficiency of wetland systems were researched. The influence mechanisms of solids accumulation on the operation of wetland systems were comprehensively analyzed. Then, the physical and chemical characteristics of carbon source-derived accumulated solids were explored, and the interaction mechanisms between organic and inorganic solids, in the process of substrate clogging, were analyzed. Next, based on the principle that clogged substrate usually has low apparent resistivity, the inversion model between clogging degree and apparent resistivity was established. The electrode method and high density resistivity method were adopted to realize three-dimensional quantitative detection of clogged substrate. Based on the above research, the ultrasonic treatment technique was proposed to prevent and control substrate clogging. The ultrasonic parameters were optimized and the mechanisms of ultrasonic treatment of different types of substrate clogging were analyzed. The main research conclusions are as follows: (1)The influences of substrate clogging on hydraulic characteristics are clarified. Organic solids can directly interdict the water flow channel, resulting in the decrease of substrate permeability. Moreover, the synergistic accumulation of organic and inorganic solids can form low density clog matter. Compared with the inorganic solids, the hydraulic influence of per unit organic and inorganic solids is largely increased. With the operation of the system, the interception rate and biodegradation rate of organic solids gradually reach a balance, resulting in the gradual decrease of the permeability decline rate. In contrast, the accumulation of inorganic solids has duplicate effect, resulting in the gradual increase of the permeability decline rate. In horizontal subsurface flow constructed wetlands (HSSF CWs), solids accumulation process can make a difference in the distribution of water flow field. Appropriate amount of solids accumulation can interdict the inherent preferential water flow pathways, which increased the hydraulic retention time (HRT) by nearly 10%. The development of solids accumulation eventually led to the heterogeneity of substrate permeability on the vertical plane of water flow direction, which decreased the HRT by nearly 40%. From the perspective of water flow field, clogging phenomenon is more prone to happen in HSSF CWs than that of in vertical flow constructed wetlands (VF CWs). There is no direct relationship between water flow field distribution and substrate permeability. The immediate cause of the uneven water flow field is the heterogeneity of solids accumulation on the vertical plane of water flow direction. (2)The influences of substrate clogging on pollutants removal are identified. Accumulated solids provided large amount of adsorption sites for pollutants and microorganisms, which can strengthen pollutants removal by medium adsorption and microbial degradation. Besides, accumulated solids reduced the effective volume of wetland system, which can create adverse effects on pollutants removal. The balance between these positive and negative effects can decide the operational performance of CWs. In HSSF CWs, with the development of solids accumulation, the removal efficiency of total phosphate (TP) was enhanced by 33%-70%. Whereas, the performance of organic and nitrogen removal showed no significant changes. In VF CWs, solids accumulation showed little influence on the water flow field. As a consequence, solids accumulation mainly plays a positive role on the wastewater treatment performance. Comparatively, the system with synergistic organic and inorganic solids accumulation showed the best performance. The removal efficiency of TP, ammonia nitrogen (NH₄-N) and total nitrogen (TN) increased by 32.85%, 36.88% and 16.79% respectively. The inorganic solids accumulation increased the abundance of total bacterial by 6.68 times. The inorganic solids accumulation also increased microbial diversity. The hydraulic malfunction caused by solids accumulation eventually developed into overland flow. The appearance of overland flow in HSSF CWs was accompanied by the decrease of pollutants removal performance. In VF CWs, overland flow was accompanied by the significant reduction of inlet load and pollutants removal load. Therefore, the overland flow can be regarded as the appearance of serious substrate clogging. (3)The interaction mechanisms between organic and inorganic solids are analyzed. There exist particle flocculation between accumulated inorganic solids, and the main flocculation mechanism is the ion bridging between inorganic particles. Compared with the accumulated inorganic solids, the particle flocculation is more obvious in organic and inorganic solids, and the main flocculation mechanisms are ion bridging through extracellular polymeric substances (EPS) and sweep flocculation. The synergistic effect of organic and inorganic solids significantly increased the solids accumulation at the inlet end of the system. Compared with the inorganic solids, the distribution of organic and inorganic solids tends to extend in the direction of water flow in the upper substrate of the system. The combination of small amount of organic solids (weight ratio < 3%) and inorganic solids is prone to form gelatinous substance with low density. The specific volume of organic and inorganic solids is more than twice that of inorganic solids. (4)The electrical method to detect substrate clogging is developed. Substrate with heavier clogging showed lower apparent resistivity in the draining phase. Based on this phenomenon, ARSF inversion model between apparent resistivity and solids volume fraction was established. The simulation results are consistent with the actual clogging degree (Slope = 0.986, R² = 0.98). The apparent resistivity of wetland substrate was detected in situ by electrode method, and the in situ quantitative detection of substrate clogging was realized by combining with the ARSF model. The detection results of two probe method (relative error is 8.8%) were more accurate than that of four probe method (relative error is 29.4%). Two probe method was applied to detect the substrate clogging in a large-scale HSSF CWs. Serious substrate clogging was found within 5 m of the inlet end. High density resistivity method effectively realized the three-dimensional detection of substrate clogging. Schlumberger method has higher resolution than wenner method. High density resistivity method was applied to detect the vertical substrate clogging of a large-scale HSSF CWs. In the section 1 m away from the inlet, solid accumulation mainly occurred in the upper substrate. However, in the section 5 m away from the inlet, more solids were accumulated in the middle layer than that of in other layers. The study provides a detection method for substrate clogging with the advantages of high accuracy, simple operation, non-destructive, etc. The method can provide scientific guidance for the regional prevention and control of substrate clogging. (5)The ultrasonic treatment to prevent and control substrate clogging was developed. The optimal parameter for ultrasonic treatment in the process of substrate clogging is 40 kHz, 60 kW/m³, and the optimal parameter for ultrasonic treatment of clogged substrate is 28 kHz, 60 kW/m³. The continuous ultrasonic treatment is more effective to treat substrate clogging caused by solids with small particle size as well as organic solids. Ultrasonic treatment can affect the solids accumulation in multiple ways. Firstly, ultrasonic treatment can reduce the particle size of accumulated solids, especially for the particles larger than 1 μm. Secondly, ultrasound can break the loose structure of accumulated solids, which contribute to the migration of particles and avoid the centralized solids accumulation. Thirdly, ultrasound can increase the organic matter leaching from accumulated solids. Moreover, the hydroxyl radicals produced by chemical effects can oxidize refractory organic solids, which can weaken the synergistic effect between organic and inorganic solids. The research provides a prevention and control technique for substrate clogging with the advantages of low cost, time-saving and no secondary pollution. The method can provide technical support for the long-term stable operation of CWs. Keywords: Constructed wetlands; Substrate clogging; Formation mechanism; Electrical detection; Prevention and control technique.