A Simple Method to Identify the Dominant Fouling Mechanisms during Membrane Filtration Based on Piecewise Multiple Linear Regression

Abstract

Membrane fouling is a complicated issue in microfiltration and ultrafiltration. Clearly identifying the dominant fouling mechanisms during the filtration process is of great significance for the phased and targeted control of fouling. To this end, we propose a semi-empirical multiple linear regression model to describe flux decline, incorporating the five fouling mechanisms (the first and second kinds of standard blocking, complete blocking, intermediate blocking, and cake filtration) based on the additivity of the permeate volume contributed by different coexisting mechanisms. A piecewise fitting protocol was established to distinguish the fouling stages and find the significant mechanisms in each stage. This approach was applied to a case study of a microfiltration membrane filtering a model foulant solution composed of polysaccharide, protein, and humic substances, and the model fitting unequivocally revealed that the dominant fouling mechanism evolved in the sequence of initial adaptation, fast adsorption followed by slow adsorption inside the membrane pores, and the gradual growth of a cake/gel layer on the membrane surface. The results were in good agreement with the permeate properties (total organic carbon, ultraviolet absorbance, and fluorescence) during the filtration process. This modeling approach proves to be simple and reliable for identifying the main fouling mechanisms during membrane filtration with statistical confidence.

Pressure‐dependent fouling behavior during sterile filtration of mRNA‐containing lipid nanoparticles

“…Additional insights into the underlying fouling behavior were obtained by replotting the flux data in the form suggested by Hermans and Bredee (1936): $$$\frac{{d}^{2}t}{d{v}^{2}}\unicode{x0200A}=\unicode{x0200A}k{\left(\frac{{dt}}{{dv}}\right)}^{n},$$$where t is the filtration time, v is the throughput (filtrate volume per unit membrane area), and k is a proportionality constant with units dependent on the value of n . All four of the classical blocking models can be described by Equation (2) with the power‐law exponent defining the fouling mechanism: n = 2 corresponds to complete pore blockage (in which foulants block pore entrances), n = 3/2 corresponds to pore constriction (in which the pore radius decreases as foulants deposit along the pore walls), n = 1 corresponds to intermediate pore blockage (in which foulants either block pore entrances or deposit on previously blocked pores), and n = 0 corresponds to cake filtration (in which foulants accumulate on the membrane surface in a permeable cake) (Ho & Zydney, 2000; Iritani & Katagiri, 2016; Iritani et al, 2015; Peles et al, 2022; H. Xu, Xiao, et al, 2020). Results are shown in Figure 2, with all derivatives evaluated numerically using a finite difference analysis accounting for the nonconstant intervals for the volumetric throughput (accurate to second order in ∆ v ), with the derivative averaged over approximately 20 s intervals to minimize numerical noise.…”

“…) with the power-law exponent defining the fouling mechanism: n = 2 corresponds to complete pore blockage (in which foulants block pore entrances), n = 3/2 corresponds to pore constriction (in which the pore radius decreases as foulants deposit along the pore walls), n = 1 corresponds to intermediate pore blockage (in which foulants either block pore entrances or deposit on previously blocked pores), and n = 0 corresponds to cake filtration (in which foulants accumulate on the membrane surface in a permeable cake)(Ho & Zydney, 2000;Iritani & Katagiri, 2016;Iritani et al, 2015;Peles et al, 2022;H. Xu, Xiao, et al, 2020).…”

Ultra-thin membrane filter with a uniformly arrayed nanopore structure for nanoscale separation of extracellular vesicles without cake formation

“…15,16 Various pore blocking parameters were calculated using simple linear models and utilized into a single linearly combined model. 34 Using the methodological way, we could nd the proportional weight of each pore blocking mechanism to the total degradation of lter performance. To examine the complex effect of the pore blocking mechanism, the ltration was carried out using the mixture solution of 100 nm and 200 nm beads for 60 min.…”

Recent Mitigation Strategies on Membrane Fouling for Oily Wastewater Treatment

“…As we are aware, membrane fouling is considered the main issue that decreases the membrane's performance and restricts wider applications of the membrane. In general, fouling is defined as the membrane-solution interaction that causes accumulation of suspension or dissolved solids either on the surface of the outer membrane, on the membrane's pores, or within the membrane's pores [54]. Membrane fouling can be classified into four types: organic precipitation, colloids, inorganic precipitation, and biofoulings [55,56].…”