Chemical and Environmental Engineering, School of Engineering, RMIT University, Melbourne, VIC 3001, Australia; Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia.
Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia.
Water Res. 2022 Aug 15;222:118903. doi: 10.1016/j.watres.2022.118903. Epub 2022 Jul 25.
Due to the non-homogeneous and multiphase nature of anaerobic lagoon constituents, CFD modelling for process optimisation requires continuous functions for shear and solid-liquid separation properties across a large range of solids concentrations. Unfortunately, measurement of existing material properties of anaerobic sludges is limited to only shear or solid-liquid separation, or to a limited solids concentration. In this work, the shear properties of an anaerobic sludge were measured from 0.4 to 12.5 vol%, which corresponds to the solids concentrations seen in lagoons. The sludge showed Newtonian behaviour at 0.4 vol% and Herschel-Bulkley yield stress fluid behaviour for higher concentrations ranging from 0.5 to 12 vol%. We compared multiple approaches to determine relationships between the model fitting parameters of consistency, k, flow index, n, and shear yield stress, τ with solids volume fraction ϕ.The solid-liquid separation properties were measured from sedimentation and filtration experiments to obtain compressibility and permeability properties across all the above-mentioned concentrations, enabling development of hindered velocity sedimentation curves. Comparison to full-scale anaerobic digestate identified that the pilot lagoon sludge had faster sedimentation at a given solids concentration in comparison to the digestate. This is the first study on simultaneous rheological characterisation and solid-liquid separation behaviour of an anaerobic sludge across a wide range of concentrations, thus enabling CFD modelling of the hydrodynamics and performance of anaerobic lagoons.
由于厌氧塘成分的非均相和多相性质，用于过程优化的 CFD 建模需要在很大的固体浓度范围内具有连续的剪切和固液分离性能函数。不幸的是，对厌氧污泥现有材料特性的测量仅限于剪切或固液分离，或者仅限于有限的固体浓度。在这项工作中，测量了厌氧污泥的剪切性能，范围从 0.4 到 12.5 体积%，这对应于塘中看到的固体浓度。在 0.4 体积%时，污泥表现出牛顿行为，而在 0.5 到 12 体积%的较高浓度范围内则表现出赫歇尔-布尔克利屈服应力流体行为。我们比较了多种方法来确定一致性、k、流动指数、n 和剪切屈服应力、τ与固体体积分数ϕ之间的模型拟合参数之间的关系。通过沉降和过滤实验测量固液分离性能，以获得所有上述浓度的可压缩性和渗透性特性，从而开发出受阻速度沉降曲线。与全规模厌氧消化物的比较表明，在给定的固体浓度下，中试塘污泥的沉降速度比消化物快。这是首次对宽浓度范围内的厌氧污泥进行流变特性和固液分离行为的同步研究，从而能够对厌氧塘的水动力和性能进行 CFD 建模。
