近年我国排水管网建设发展迅速，但是污水管网运行效能不高，管网运行过程中有机物的沉积降解问题严重制约系统效能提升。重力污水管网低流速导致的颗粒性有机物沉降衰减，已成为污水厂进水碳源不足的重要原因之一。然而目前关于颗粒性有机物管网运行过程沉积衰减特征的相关研究还较少，污水管网颗粒性有机物损失难以量化评估，缺少相应的预测评估方法。因此，加强对污水管网颗粒性有机物沉积衰减特征的研究对排水管网提质增效和污水处理系统综合效能提升具有重要意义。本研究首先以实际污水管网为研究对象，选取管网沿程各代表性管段，探究颗粒性有机物在重力污水管网中的沉积特征。研究发现，在化粪池以及管网上游低流速区存在严重的颗粒性有机物沉积衰减现象，其中大颗粒物的沉降速率最大，而下游市政污水主干管高流速区颗粒物的沉降并不明显。从居民楼出水到污水处理厂进水，颗粒性有机物累计沉积量最高可达70%以上。在此基础上，通过搭建实验室试验测试装置，建立不同类型污水颗粒物沉降发生过程的速率特征评估方法，考察了污水初始悬浮固体浓度、颗粒物粒径以及污水流速等因素对颗粒性有机物沉降的影响。结果表明，污水颗粒物的沉降速率几乎不受初始浓度的影响，而颗粒性有机物粒径越大，污水流速越慢，颗粒物沉降速度越快。论文进一步通过搭建实验室模拟反应器，探究沉积颗粒性有机物再悬浮及衰减特征。研究发现，沉积物上层容易发生颗粒性有机物的衰减，而中层和下层可衰减特性弱。在0.40 m/s的流速下，不同粒级的颗粒物通过再悬浮重新进入污水当中的有机物占沉积的总有机物的比例为0.8%-3.8%左右，衰减的有机物占沉积的总有机物的比例为3.6%-21.1%左右。基于如上工作，论文最终提出颗粒性有机物沉积衰减过程模拟模型，模拟评估重力污水管道中颗粒性有机物的沉积衰减速率。结果表明，提出模型仅需根据颗粒性有机物初始浓度、流速以及水力停留时间等参数即能够较好地预测化粪池、污水管网上游低流速区颗粒性有机物沉积衰减情况。

In recent years, the construction of China‘s drainage network has developed rapidly, but the operational effectiveness of the sewage network is not high, and the problem of organic matter deposition and degradation during the operation of the network seriously restricts the effectiveness of the system. The sedimentation attenuation of particulate organic matter caused by the low flow rate of gravity sewerage network has become one of the important reasons for the insufficient carbon source in the influent water of sewage plants. However, there are still relatively few studies related to the sedimentation attenuation characteristics of granular organic matter pipe network operation, and it is difficult to quantitatively assess the loss of granular organic matter from sewage pipe networks, and there is a lack of corresponding predictive assessment methods. Therefore, it is important to strengthen the research on the deposition attenuation characteristics of particulate organic matter in the sewage network to improve the quality and efficiency of the drainage network and the overall effectiveness of the sewage treatment system.In this study, the deposition characteristics of particulate organic matter in the gravity sewer network were investigated by selecting representative pipe sections along the network. It was found that there was severe attenuation of particulate organic matter deposition in the septic tank as well as in the low-flow velocity zone upstream of the pipe network, where the settling rate of large particulate matter was the largest, while the settling of particulate matter in the high-flow velocity zone of the main municipal sewage pipe downstream was not obvious. The cumulative deposition of particulate organic matter can reach up to 70% or more from the residential building effluent to the sewage treatment plant influent.On this basis, the rate characteristics of the settling process of different types of wastewater particulate matter were assessed by building a laboratory experimental test set-up, and the effects of the initial suspended solids concentration, particulate matter particle size and effluent flow rate on the settling of particulate organic matter were investigated. The results show that the settling rate of particulate matter in sewage is almost independent of the initial concentration, while the larger the particle size of particulate organic matter and the slower the sewage flow rate, the faster the settling rate of particulate matter.The paper further investigates the resuspension and attenuation characteristics of sedimentary particulate organic matter by building a laboratory simulator. It was found that the upper layers of the sediment were susceptible to attenuation of particulate organic matter, while the middle and lower layers were weakly attenuated. At a flow rate of 0.40 m/s, the proportion of particulate matter re-suspended into the effluent by different particle sizes ranged from 0.8% to 3.8% of the total organic matter deposited, and the proportion of attenuated organic matter to the total organic matter deposited ranged from 3.6% to 21.1%.Based on the above work, the thesis finally presents a simulation model for the deposition and decay of particulate organic matter in gravity sewer pipes to evaluate the deposition and decay rate of particulate organic matter. The results show that the proposed model is able to predict the attenuation of particulate organic matter deposition in septic tanks and low-flow areas upstream of the sewer network based only on parameters such as initial particulate organic matter concentration, flow rate and hydraulic retention time.