The deposition and resuspension of sediments are issues of considerable concern in combined sewer systems management. Sediments can produce the loss of hydraulic capacity and odour generation in sewers, and are also considered the main source of pollution due to their occasional uncontrolled discharges into the environment via Combined Sewer Overflows (CSO). Sewer sediments contain granular and cohesive organic fractions that can have a significant influence on bed resistance. In order to address the relationship between sewer sediment composition and its erodibility, accumulation and erosion experiments were performed in a flume test facility fed with wastewater. The flume was placed in a Wastewater Treatment Plant (WWTP), in which different circular pipe geometries were set. Wastewater flow inlet conditions and bed structures were monitored during the experiments. The photogrammetric technique Structure from Motion (SfM) was applied to record the bed deposit structures, providing accurate measurements of the accumulation rates. The SfM was also used to assess sediment transport and the characteristics of the bed forms after the erosion tests. In addition, velocity distributions and shear stress profiles were measured during the erosion tests to characterize flow resistance and sediment erosion. During both accumulation and erosion tests, sediments were sampled in order to analyse their physicochemical properties, thus highlighting the study of the biodegradability of the organic matter. Different deposition periods showed biological transformations in the bed deposit structure, which were seen to affect its cohesion, and in consequence, its erosion threshold. Tests with significant erosion rates agreed in broad terms with dimensionless sediment transport models derived from previous experimental studies performed with partly cohesive and organic materials in sewer pipes.

沉积物的沉积和再悬浮是联合下水道系统管理中相当关注的问题。沉积物会导致下水道的水力损失和气味的产生，并且由于它们偶尔会通过联合下水道溢流（CSO）不受控制地排入环境，因此也被认为是主要的污染源。下水道沉积物中含有颗粒状和粘结性有机物，对床层阻力具有重要影响。为了解决下水道沉积物成分与其易蚀性之间的关系，在装有废水的水槽测试设备中进行了累积和侵蚀实验。将水槽放置在废水处理厂（WWTP）中，在其中设置了不同的圆形管道几何形状。在实验过程中监测废水流入口条件和床结构。摄影测量技术“运动结构”（SfM）被用于记录床沉积物结构，从而提供对累积速率的精确测量。SfM还用于评估侵蚀试验后的沉积物迁移和床层特征。此外，在侵蚀试验过程中测量了速度分布和切应力曲线，以表征流阻和沉积物侵蚀。在堆积和侵蚀测试中，对沉积物进行采样以分析其理化性质，从而突出了对有机物的生物降解性的研究。不同的沉积期表明床沉积物结构发生了生物转化，这会影响其凝聚力，因此，它的侵蚀阈值。具有显着腐蚀速率的测试在广泛意义上与从以前的实验研究得出的无量纲沉积物传输模型相一致，该实验是对下水道中的部分粘结性有机材料进行的。