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•Ion exchange chromatography improved filterability of aggregate-spiked proteins.•Mixed-mode AEX most effectively reduced aggregate in mAb under test conditions.•Modified CEX best ...improved filterability of plasma IgG under test conditions.•Very small amount of high molecular weight aggregates affects the filterability significantly.•A best fit clogging model was identified by analysis of virus filter performance.
Virus filtration is a critical process in the production of biotherapeutics and drug products derived by plasma fractionation. The processing steps upstream of virus removal filtration impact the filterability (throughput and flux) of process solutions. We processed mAb and plasma IgG spiked with aggregate and plasma IgG spiked with IgM by chromatography resins and examined the filterability of the output on a virus filter (Planova BioEX). The greatly reduced filterability for protein solutions with aggregate was improved by processing with specific chromatography resins, but residual amounts of high molecular weight aggregates had a marked impact on filterability. For mAb, mixed-mode AEX effectively reduced aggregate content and significantly improved filterability. Mixed-mode AEX was also effective for reducing aggregates in plasma IgG but modified CEX showed even greater improvement in filterability. The results clearly show that virus filter performance can be optimized by careful choice of column chromatography. Finally, applying the throughput and flux from the virus filter to four classical clogging models showed that mAb with aggregate and plasma IgG with IgM were best fit to the standard blocking model and plasma IgG with aggregate was best fit to the complete blocking model, suggesting that differences in solution properties result in different clogging mechanisms.
•Experiment to identify influence factors of nozzle clogging.•Identification of reasons causing clogging of sphere-filled polycarbonate.•Dimensionless number to describe intermittent clogging.•Model ...for the occurrence of nozzle clogging.•Mathematical viscosity model to approximate printability of materials.
Fused filament fabrication with reinforced or filled polymers provides improved material properties compared to ordinary feedstock. A current limitation of these materials is the occurrence of nozzle clogging at higher filler contents. In this work, an experiment is designed to identify the factors causing nozzle clogging. Glass sphere-filled polycarbonate is investigated by varying nozzle and filler diameters, the resin viscosity, the filler content, and the extrusion pressure. Equations identifying nozzle clogging and intermittent clogging conditions are provided. Based on these results, a model for the clogging of sphere-filled polymers is proposed. Last, a mathematical model is derived, which approximates the printability of filled polymers without the preparation of composites. This model is based on the nozzle geometry, the filler type and content, the resin viscosity, and the printer’s maximum extrusion force.
•We have suggested A pore-scale approach for modeling of salt aggregates formation.•The nucleation process is incorporated via a new probabilistic model.•The existing clogging model cannot capture ...the behavior of salt aggregates.•The model can replicate “self-enhancing of salt growth”.
The optimal CO2 storage operation requires high permeability in the near-well region in order to keep it safe and cost-efficient. Nucleation and growth of salt crystals driven by the evaporation of formation water into under-saturated (dry) super-critical CO2 streams result in the changes in porosity and permeability of the near well-bore area. Permeability reduction is one of the main reasons for injectivity losses in the context of CO2 storage in saline aquifers. According to recent studies, during CO2 storage, salt crystals grow in two different forms: 1) single, large crystals in the aqueous phase, and 2) aggregates of micro-meter size salt crystals in the CO2-rich vapor phase. All previous numerical studies at pore-scale have addressed the formation of single, large crystals in the aqueous phase. In this work we have developed a 3D pore-scale reactive transport solver based on a D3Q19 advection-diffusion Lattice-Boltzmann model. The model takes for the first time salt nucleation into consideration via a new probabilistic approach to simulate the formation of micro-meter size salt crystal aggregates in the CO2-rich phase and their effect on changes in pore morphology and permeability. Comparing the results of porosity-permeability relations with some of the well-known clogging models, confirms the need for a new clogging model to capture the permeability reduction caused by salt aggregates.
Purpose
Water from different sources generally contains different kinds of suspended particles, which introduces the challenge of how to control physical clogging during managed aquifer recharge ...(MAR). Suspended solid concentration (SS) and turbidity (NTU) are widely recognized as indicators of physical clogging potential. The aims of this study were to examine the degree of physical clogging caused by organic and inorganic suspended particles and elaborate the different mechanisms that controlled clogging under specific SS and NTU conditions.
Materials and methods
Column experiments were performed by continuous suspended particle injection through a saturated porous medium under stable physicochemical and hydrodynamic conditions. Three sets of transport tests were carried out. One test was conducted with chlorinated-secondary wastewater (CSW), which SS was 17.59 ± 0.44 mg L
−1
corresponding to 3.09 ± 0.05 NTU. The other two tests were silica-particle wastewater (SPW) with the same SS (1.73 ± 0.03 NTU) and the same NTU (29.21 ± 0.57 mg L
−1
SS) as the CSW, abbreviated to SPW-SS and SPW-NTU, respectively. The particle breakthrough curves (BTCs), spatial deposition profiles, and variations in hydraulic conductivity were measured. The transport model, DLVO theory, and O’Melia and Ali clogging model were applied to explain the mechanisms of physical clogging in different systems.
Results and discussion
The retention of inorganic particles was greater than that of organic particles; 56.02% of organic particles were retained in CSW, while 87.62 and 86.36% of inorganic particles were retained in SPW-SS and SPW-NTU, respectively. The distribution of organic particles was less uniform than that of inorganic particles. However, the variation of the relative hydraulic conductivity (
K
/
K
0
) was more significant for organic particles than for inorganic particles, with decreased by just 1.80 ± 0.64% in SPW-SS and 4.03 ± 1.64% in SPW-NTU, but decreased by 85.86 ± 1.22% in CSW. This study explained the results with the support of classical models and the DLVO theory. The physicochemical characteristics of suspended particles determined whether and how physical clogging occurred.
Conclusions
Suspended particles with different properties follow different transport-deposition processes and have different tendencies to cause physical clogging. Especially for organic particles, clogging degree is quite noticeable. Our results imply that the same SS and NTU threshold values cannot be applied to different types of source water during recharge to prevent physical clogging, even in the same controlled environmental conditions. Physicochemical characteristics of suspended particles need to be considered when developing physical clogging indicators.
Open graded friction course (OGFC), as a highly permeable mixture, has the characteristics of good friction and splash-and-spray reduction during rainstorms. The limitations of the use of such ...mixtures include the fact that they are affected by poor durability, including strength and permeability durability issues. In a previous study, oil shale waste, as a fine aggregate in the mixture (with a particle size less than 4.75 mm), could effectively improve the overall properties of OGFC, but the permeability durability was not clear. Thus, a comprehensive investigation of the permeability durability of oil shale waste as a fine aggregate is essential to achieving a better understanding in order to promote its engineering application. In this paper, the long-term permeability when using oil shale waste as a fine aggregate in OGFC was systematically investigated based on a self-developed laboratory physical clogging procedure. The test results illustrated the effectiveness of the utilization of oil shale waste as a fine aggregate in terms of permeability durability. A comprehensive index of the clogging coefficient containing mass, porosity and permeability coefficient was proposed based on gray relation entropy theory, the physical clogging model of COF-OGFC (OGFC containing oil shale waste filler) was established and the clogging speed of COF-OGFC was quantified based on the Mistcherlich growth model. The analysis showed that there is an essential difference in the clogging behavior of permeable pavement in the spring and summer. The maximum clogging degree of the permeable pavement in summer is about 40% higher than that in spring, while the clogging rate is much lower than in the spring, at only about 14%, which indicates that the clogging behavior of permeable asphalt pavement in spring is mostly in the rapid clogging mode, and that in summer is mostly in a slow deposition clogging mode. Moreover, the test results showed that the most important influences on the spring clogging behavior of COF-OGFC were the sandy clogging materials and particle sizes ranging from 150 μm to 1180 μm, which can be used to provide a reference for the design of anti-slip sand.
This chapter describes version 2 of the HYDRUS Wetland module and discusses experience using wetland models and the HYDRUS Wetland module. It also describes remaining challenges in using these tools ...and summarizes needs for further development and research. When developing a wetland model, a number of different processes have to be considered: the flow model, the transport model, the biokinetic model, the plant model and the clogging model. Constructed Wetland Model 1 (CWM1) has been developed with the main goal of providing a widely accepted model formulation for biochemical transformation and degradation processes in subsurface flow (SSF) constructed wetlands (CWs). Both CW2D and CWM1 biokinetic models have been developed to describe processes in constructed wetlands treating domestic wastewater. The chapter shows simulation results for vertical flow (VF) CWs. Horizontal flow (HF) systems can be simulated when only saturated water flow conditions are considered.
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