Université de Toulouse, Mines Albi, CNRS, Centre RAPSODEE, Campus Jarlard, 81013, Albi, France.
Université de Toulouse, Mines Albi, CNRS, Centre RAPSODEE, Campus Jarlard, 81013, Albi, France.
Water Res. 2018 Dec 15;147:413-421. doi: 10.1016/j.watres.2018.10.016. Epub 2018 Oct 8.
The rheological behavior of mechanically dewatered sewage sludges is complex but essential as it affects almost all treatment, utilization and disposal operations, such as storage, pumping, land-spreading, or drying. In this work, a specific methodology coupling experiments and modelling is developed to characterize the rheological and textural properties of highly concentrated sludge. The experimental part based on a uniaxial compression method has been presented in a previous paper (Liang et al., 2017). This article is dedicated to the modelling part, which includes the behavior identification and the parameters optimization. Previous and additional mechanical tests allow the identification of a visco-elasto-plastic behavior. This behavior is then modelled with a Burgers-Ludwik model, with 7 rheological parameters. This model is able to simulate the viscoelastic behavior of sludge under the yield stress, and the visco-elasto-plastic hardening behavior over the yield stress. The optimization of model parameters is carried out in two steps and relies on the calculation of basins of attraction and confidence intervals with initial conditions estimated from the mechanical tests. Finally, the entire characterization methodology, from experimental mechanical tests to model parameter optimization, is applied to sludge samples at different operating conditions and structural states. The determination of the rheological properties of sludge is achieved with excellent matching between simulation and experimental results. Being able to take into account these impact factors, the rheological model can be used to predict the sludge behavior in various operating conditions.
机械脱水污水污泥的流变性复杂，但却至关重要，因为它几乎会影响到所有的处理、利用和处置操作，如储存、泵送、土地铺展或干燥。在这项工作中，开发了一种特定的结合实验和建模的方法来表征高浓度污泥的流变性和结构特性。基于单向压缩方法的实验部分已在上一篇论文（Liang 等人，2017 年）中介绍。本文致力于建模部分，包括行为识别和参数优化。以前和额外的机械测试允许识别粘弹性塑性行为。然后，该行为使用 Burgers-Ludwik 模型进行建模，该模型具有 7 个流变学参数。该模型能够模拟屈服应力下污泥的粘弹性行为，以及屈服应力以上的粘弹塑性硬化行为。模型参数的优化分两步进行，依赖于使用从机械测试中估计的初始条件计算吸引盆地和置信区间。最后，将整个特征描述方法，从实验机械测试到模型参数优化，应用于不同操作条件和结构状态下的污泥样品。通过模拟和实验结果之间的良好匹配，实现了对污泥流变性的确定。考虑到这些影响因素，流变模型可用于预测各种操作条件下的污泥行为。
