Modeling Sieving Filtration using Multiple Layers of Parallel Pores

Abstract

Experimental retention data with several membrane filters show that the filtration efficiency decreases considerably over time, which appears to be inconsistent with a size exclusion retention mechanism. Several model descriptions of the porous structure are considered to describe this behavior. Simulation results with a sieving mechanism are compared to experimental data and the influence of input parameters are investigated. Fairly simple models may be used to qualitatively describe the retention behavior. More complex models are necessary to allow for a more accurate description of the physical geometry of the structure and a better quantitative representation of the experimental data.

Modeling and Analysis of Particle Deposition Processes on PVDF Membranes Using SEM Images and Image Generation by Auxiliary Classifier Generative Adversarial Networks

“…The density clusters identified on the SEM images of PVDF membranes by density-based spatial clustering of application with noise (DBSCAN) are shown in Figure 10b. The particle deposition patterns, which were reported in previous studies obtained through experimental and mathematical conventional approaches [5,8,12,15,30], were also recognized in these figures. Namely, at a low feed water concentration of 2 mg/L, the exclusion and attachment mechanisms seemed to be prevalent, with particles rejected by the same or smaller sized pores and particles attached on the membrane surfaces forming scattered small aggregates (Figure 10a,b far left).…”

“…Such a phenomenon was reported in stochastic-based modeling studies [15], mainly through the flux variation approach, rather than variations of feed particle concentrations. This observation could be further investigated through image analysis of the membranes deposited with particles at different initial feed water concentrations of 0, 2, 5, and 8 mg/L (Figure 10a,b).…”

“…This process was clearly seen at 5 mg/L-the small pores were blocked faster than at 2 mg/L, thus, enhancing the flux through the larger pores, which resulted in lower particle retention rates. The experimental results by Beuscher [15] for the filtration of a 50 nm beads suspension through membranes of different pore sizes (0.02-0.04 µm) reported an overall decrease in the retention efficiency, which could not be explained if size exclusion was the only phenomenon at play. Thus, it was estimated that the water flux was diverted to large pores, due to the clogging of small pores.…”

“…The assumption of pores and throats as simple geometrical structures is one of the main drawbacks of conventional modeling, as the success of pore-network models depends on the adequate representation of the real pore space [14]. Alternatively, a stochastic approach describes the efficacy of particle removal, based on size exclusion mechanisms [15]. However, both approaches fail to accurately describe the membrane structure and filtration phenomena and were not well validated by experimental results [10].…”

Water Flux Reduction in Microfiltration Membranes: A Pore Network Study

“…Duclos‐Orsello et al modeled a microfiltration membrane by considering both internal and external fouling. Beuscher developed a simplified 2D series of independent layers with a pore‐size distribution in each layer as a structure of the membrane to study the retention behavior. In this study, the probability of a particle being captured in a pore smaller than the particle size itself was only dependent on the fraction of pores that were smaller than the particle.…”