A combined network model for membrane fouling

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:432

Article

Griffiths, I. M.¹  Kumar, A.²  Stewart, P. S.³ 

[1] Math Inst, Oxford OX2 6GG, England

[2] Pall Life Sci, Westborough, MA 01581 USA

[3] Univ Glasgow, Sch Math & Stat, Glasgow G12 8QW, Lanark, Scotland

关键词: Filtration;    Membrane fouling;    Pore clogging;    Caking;    Network model;    Mathematical modelling;   

DOI  :  10.1016/j.jcis.2014.06.021

来源: Elsevier

【 摘 要 】

Membrane fouling during particle filtration occurs through a variety of mechanisms, including internal pore clogging by contaminants, coverage of pore entrances, and deposition on the membrane surface. Each of these fouling mechanisms results in a decline in the observed flow rate over time, and the decrease in filtration efficiency can be characterized by a unique signature formed by plotting the volumetric flux, (Q) over cap, as a function of the total volume of fluid processed, (V) over cap. When membrane fouling takes place via any one of these mechanisms independently the (Q) over cap(V) over cap signature is always convex downwards for filtration under a constant transmembrane pressure. However, in many such filtration scenarios, the fouling mechanisms are inherently coupled and the resulting signature is more difficult to interpret. For instance, blocking of a pore entrance will be exacerbated by the internal clogging of a pore, while the deposition of a layer of contaminants is more likely once the pores have been covered by particulates. As a result, the experimentally observed (Q) over cap(V) over cap signature can vary dramatically from the canonical convex-downwards graph, revealing features that are not captured by existing continuum models. In a range of industrially relevant cases we observe a concave-downwards (Q) over cap(V) over cap signature, indicative of a fouling rate that becomes more severe with time. We derive a network model for membrane fouling that accounts for the inter-relation between fouling mechanisms and demonstrate the impact on the (Q) over cap(V) over cap signature. Our formulation recovers the behaviour of existing models when the mechanisms are treated independently, but also elucidates the concave-downward (Q) over cap(V) over cap signature for multiple interactive fouling mechanisms. The resulting model enables post-experiment analysis to identify the dominant fouling modality at each stage, and is able to provide insight into selecting appropriate operating regimes. (C) 2014 Elsevier Inc. All rights reserved.

【 授权许可】

Free