scholarly journals Theoretical Analysis of a Mathematical Relation between Driving Pressures in Membrane-Based Desalting Processes

Membranes ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 220
Author(s):  
Sung Ho Chae ◽  
Joon Ha Kim
Keyword(s):  
Theoretical Analysis ◽  
Forward Osmosis ◽  
Operational Parameters ◽  
Similarity Coefficients ◽  
Pressure Retarded Osmosis ◽  
Mathematical Relation ◽  
Transport Direction ◽  
Clear Relation ◽  
Conservation Rule ◽  
Do So

Osmotic and hydraulic pressures are both indispensable for operating membrane-based desalting processes, such as forward osmosis (FO), pressure-retarded osmosis (PRO), and reverse osmosis (RO). However, a clear relation between these driving pressures has not thus far been identified; hence, the effect of change in driving pressures on systems has not yet been sufficiently analyzed. In this context, this study formulates an actual mathematical relation between the driving pressures of membrane-based desalting processes by taking into consideration the presence of energy loss in each driving pressure. To do so, this study defines the pseudo-driving pressures representing the water transport direction of a system and the similarity coefficients that quantify the energy conservation rule. Consequently, this study finds three other theoretical constraints that are required to operate membrane-based desalting processes. Furthermore, along with the features of the similarity coefficients, this study diagnoses the commercial advantage of RO over FO/PRO and suggests desirable optimization sequences applicable to each process. Since this study provides researchers with guidelines regarding optimization sequences between membrane parameters and operational parameters for membrane-based desalting processes, it is expected that detailed optimization strategies for the processes could be established.

Effects of a PFI refiner’s operational parameters on the swellability of recycled fiber

TAPPI Journal ◽  
2020 ◽  
Vol 19 (5) ◽  
pp. 239-246
Author(s):  
XIAONING SHEN ◽  
BO LI ◽  
WENXUAN MO ◽  
XIN-SHENG CHAI
Keyword(s):  
Water Retention ◽  
Fiber Quality ◽  
Operational Parameters ◽  
Fiber Morphology ◽  
Water Retention Value ◽  
Electron Microscopic ◽  
Mathematical Relation ◽  
Scanning Electron Microscopic ◽  
Recycled Fiber ◽  
Scanning Electron

This paper presents data on the effects of operational parameters (number of revolutions, linear pressure, and gap) of the PFI refiner on the swellability of recycled fiber, which was characterized by water retention value (WRV). The results showed that the increase of recycled fiber’s WRV was proportional to the number of revolutions and the linear pressure, but inversely proportional to the gap. The mathematical relation between these parameters and the fiber WRV could be described by an empirical model for gaps greater than 0.1 mm. Scanning electron microscopic images of fiber morphology showed that the basic framework of fibers could be maintained with the gap greater than 0.1 mm, but was destroyed with smaller gaps. This model provides a technical reference for quantitative control of refining treatment and an effective method for improving recycled fiber quality.

scholarly journals Effect of fouling on performance of pressure retarded osmosis (PRO) and forward osmosis (FO)

2018 ◽  
Vol 565 ◽  
pp. 450-462 ◽  
Author(s):  
Endre Nagy ◽  
Imre Hegedüs ◽  
Emily W. Tow ◽  
John H. Lienhard V
Keyword(s):  
Forward Osmosis ◽  
Pressure Retarded Osmosis

scholarly journals The Question of Religion in T. S. Eliot’s Poetry: “Ash-Wednesday” as a Case Study

2019 ◽  
Vol 7 (11) ◽  
pp. 12
Author(s):  
Mohammed Bassou
Keyword(s):  
Theoretical Analysis ◽  
Religion And Literature ◽  
Devotional Poetry ◽  
Do So

This article puts under scrutiny the religious manifestations in Eliot’s devotional poetry and the meditative questions that he raises. To do so, it limits the scope of my analytical reading to one of his well-known meditative poems, “Ash-Wednesday.”  I shall start with a theoretical analysis of his famous article, “Religion and Literature” and argue for the presence of its milestone ideas in Eliot’s poetry taking “Ash-Wednesday as a case study.” The study also discerns Eliot’s renunciation of the main tenets of Romanticism which he made use of before his conversion.

scholarly journals Module-Scale Simulation of Forward Osmosis Module-Part A: Plate-and-Frame

2016 ◽  
Vol 1 (2) ◽  
pp. 249 ◽  
Author(s):  
Muhammad Roil Bilad
Keyword(s):  
Forward Osmosis ◽  
Mass Conservation ◽  
Feed Solution ◽  
Transfer Model ◽  
Operational Parameters ◽  
Permeable Membrane ◽  
Promising Alternative ◽  
A Value ◽  
Scale Optimization ◽  
Module Performance

In forward osmosis (FO), a semi-permeable membrane separates a concentrated draw and a diluted feed solution. FO has emerges as a promising alternative for various applications. To support further development of FO process, a larger scale optimization is required to accurately envisage the most critical factors to be explored. In this study, we applied a mass-transfer model coupled with the mass conservation and area discretization to simulate the performance of plate-and-frame FO modules (10 sheets of 1x1m). Effects of numerous parameters were simulated: modes, flow orientations (co-, counter- and cross-currents), spacers and spacer properties, membrane parameters and operational parameters. Results show that counter-current flow orientation offers the highest flux with minimum spatial distribution. Module performance can be improved by developing FO membrane through reducing membrane structural (S) parameter and increasing water permeability (A): increasing A-value only significant at low S-value, and vice versa (i.e., for A-value of 1 LMH/atm, S-value must be below 50 µm). Furthermore, inclusion of spacer in the flow channel slightly increases the flux (merely up to 2%). Module performance can also be enhanced by increasing feed flow rate, lowering solute in the feed and increasing solute in the draw solution.

scholarly journals A Review of CFD Modelling and Performance Metrics for Osmotic Membrane Processes

Membranes ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 285
Author(s):  
Kang Yang Toh ◽  
Yong Yeow Liang ◽  
Woei Jye Lau ◽  
Gustavo A. Fimbres Weihs
Keyword(s):  
Performance Metrics ◽  
Forward Osmosis ◽  
Cfd Modelling ◽  
Membrane Processes ◽  
Pressure Retarded Osmosis ◽  
Multi Scale ◽  
Scale Modelling ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance ◽  
Module Performance

Simulation via Computational Fluid Dynamics (CFD) offers a convenient way for visualising hydrodynamics and mass transport in spacer-filled membrane channels, facilitating further developments in spiral wound membrane (SWM) modules for desalination processes. This paper provides a review on the use of CFD modelling for the development of novel spacers used in the SWM modules for three types of osmotic membrane processes: reverse osmosis (RO), forward osmosis (FO) and pressure retarded osmosis (PRO). Currently, the modelling of mass transfer and fouling for complex spacer geometries is still limited. Compared with RO, CFD modelling for PRO is very rare owing to the relative infancy of this osmotically driven membrane process. Despite the rising popularity of multi-scale modelling of osmotic membrane processes, CFD can only be used for predicting process performance in the absence of fouling. This paper also reviews the most common metrics used for evaluating membrane module performance at the small and large scales.

scholarly journals Biofouling Mitigation Approaches during Water Recovery from Fermented Broth via Forward Osmosis

Membranes ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 307
Author(s):  
Stavros Kalafatakis ◽  
Agata Zarebska ◽  
Lene Lange ◽  
Claus Hélix-Nielsen ◽  
Ioannis V. Skiadas ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Forward Osmosis ◽  
Cross Flow ◽  
Feed Solution ◽  
Mitigation Strategies ◽  
Water Recovery ◽  
Operational Parameters ◽  
Solution Ph ◽  
Sustainable Solutions ◽  
Cross Flow Velocity

Forward Osmosis (FO) is a promising technology that can offer sustainable solutions in the biorefinery wastewater and desalination fields, via low energy water recovery. However, microbial biomass and organic matter accumulation on membrane surfaces can hinder the water recovery and potentially lead to total membrane blockage. Biofouling development is a rather complex process and can be affected by several factors such as nutrient availability, chemical composition of the solutions, and hydrodynamic conditions. Therefore, operational parameters like cross-flow velocity and pH of the filtration solution have been proposed as effective biofouling mitigation strategies. Nevertheless, most of the studies have been conducted with the use of rather simple solutions. As a result, biofouling mitigation practices based on such studies might not be as effective when applying complex industrial mixtures. In the present study, the effect of cross-flow velocity, pH, and cell concentration of the feed solution was investigated, with the use of complex solutions during FO separation. Specifically, fermentation effluent and crude glycerol were used as a feed and draw solution, respectively, with the purpose of recirculating water by using FO alone. The effect of the abovementioned parameters on (i) ATP accumulation, (ii) organic foulant deposition, (iii) total water recovery, (iv) reverse glycerol flux, and (v) process butanol rejection has been studied. The main findings of the present study suggest that significant reduction of biofouling can be achieved as a combined effect of high-cross flow velocity and low feed solution pH. Furthermore, cell removal from the feed solution prior filtration may further assist the reduction of membrane blockage. These results may shed light on the challenging, but promising field of FO process dealing with complex industrial solutions.

scholarly journals On the understanding and feasibility of “Breakthrough” Osmosis

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jun Jie Wu ◽  
Robert W. Field
Keyword(s):  
High Power ◽  
Forward Osmosis ◽  
Solute Concentration ◽  
Pressure Retarded Osmosis ◽  
Permselective Membrane ◽  
Order Of Magnitude ◽  
Theoretical Paper ◽  
Salt Diffusion ◽  
Power Densities ◽  
Very High

Abstract Osmosis is the movement of solvent across a permselective membrane induced by a solute-concentration gradient. Now in ‘Forward Osmosis’ it is empirically observed that the diffusion of the solute is counter to that of the solvent i.e. there is so-called “reverse salt diffusion”. However it has been recently suggested, in a theoretical paper, that if allowance is made for minor deviations from ideal semi-permeability then operation in an overlooked mode of “breakthrough” osmosis would be possible and importantly it would yield relatively large rates of osmosis. A consequential prediction was that in “breakthrough mode”, Pressure-Retarded Osmosis (PRO) would generate very high power densities exceeding those in the conventional mode by one order of magnitude. The practicality of this suggestion was explored and necessarily questions were then raised regarding the foundation of the Spiegler-Kedem-Katchalsky model. Arising from: Yaroshchuk, A., Sci. Rep. 7, 45168 (2017); 10.1038/srep45168

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