scholarly journals Feed Spacer Geometries and Permeability Coefficients. Effect on the Performance in BWRO Spriral-Wound Membrane Modules

Water ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 152 ◽  
Author(s):  
Alejandro Ruiz-García ◽  
Ignacio de la Nuez Pestana
Keyword(s):  
Reverse Osmosis ◽  
Brackish Water ◽  
Specific Energy Consumption ◽  
Operating Conditions ◽  
Single Element ◽  
Permeability Coefficients ◽  
Membrane Performance ◽  
Geometry Design ◽  
Water Permeability Coefficient ◽  
The Impact

Reverse osmosis (RO) is the most widely used technology to desalinate brackish water and seawater. Significant efforts have been made in recent decades to improve RO efficiency. Feed spacer geometry design is a very important factor in RO membrane performance. In this work, correlations based on computational fluid dynamics and experimental work were applied in an algorithm to simulate the effect of different feed spacer geometries in full-scale brackish water reverse osmosis (BWRO) membranes with different permeability coefficients. The aim of this work was to evaluate the impact of feed spacers in conjunction with the permeability coefficients on membrane performance. The results showed a greater impact of feed spacer geometries in the membrane with the highest water permeability coefficient (A). Studying only one single element in a series, variations due to feed spacer geometries were observed in specific energy consumption ( S E C ) and permeate concentration ( C p ) of about 6.83% and 10.42%, respectively. Allowing the rolling of commercial membranes with different feed spacer geometries depending on the operating conditions could optimize the RO process.

scholarly journals Performance Assessment of SWRO Spiral-Wound Membrane Modules with Different Feed Spacer Dimensions

Processes ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 692 ◽  
Author(s):  
A. Ruiz-García ◽  
I. Nuez
Keyword(s):  
Reverse Osmosis ◽  
Pressure Vessels ◽  
Operating Conditions ◽  
Solute Permeability ◽  
Permeability Coefficients ◽  
Water Permeability Coefficient ◽  
Seawater Reverse Osmosis ◽  
Membrane Modules ◽  
The Impact ◽  
Spiral Wound

Reverse osmosis is the leading process in seawater desalination. However, it is still an energy intensive technology. Feed spacer geometry design is a key factor in reverse osmosis spiral wound membrane module performance. Correlations obtained from experimental work and computational fluid dynamics modeling were used in a computational tool to simulate the impact of different feed spacer geometries in seawater reverse osmosis spiral wound membrane modules with different permeability coefficients in pressure vessels with 6, 7 and 8 elements. The aim of this work was to carry out a comparative analysis of the effect of different feed spacer geometries in combination with the water and solute permeability coefficients on seawater reverse osmosis spiral wound membrane modules performance. The results showed a higher impact of feed spacer geometries in the membrane with the highest production (highest water permeability coefficient). It was also found that the impact of feed spacer geometry increased with the number of spiral wound membrane modules in series in the pressure vessel. Installation of different feed spacer geometries in reverse osmosis membranes depending on the operating conditions could improve the performance of seawater reverse osmosis systems in terms of energy consumption and permeate quality.

scholarly journals Bench-scale study of ultrafiltration membranes for evaluating membrane performance in surface water treatment

2016 ◽  
Vol 51 (2) ◽  
pp. 128-140 ◽  
Author(s):  
Dillon A. Waterman ◽  
Steven Walker ◽  
Bingjie Xu ◽  
Roberto M. Narbaitz
Keyword(s):  
Hollow Fiber ◽  
Membrane Fouling ◽  
Organic Matter Content ◽  
Operating Conditions ◽  
Cycle Duration ◽  
Operational Parameters ◽  
Constant Flux ◽  
Bench Scale ◽  
Membrane Performance ◽  
The Impact

Currently, there is no standard bench-scale dead-end ultrafiltration (UF) testing system. The aim of the present study was to design and build a bench-scale hollow fiber UF system to assess the impact of operational parameters on membrane performance and fouling. A bench-scale hollow fiber UF system was built to operate at a constant flux (±2% of the set-point flux) and included automated backwash cycles. The development of the bench-scale system showed that it is very difficult to maintain a constant flux during the first minute of the filtration cycles, that digital flow meters are problematic, and that the volume of the backwash waste lines should be minimized. The system was evaluated with Ottawa River water, which has a relatively high hydrophobic natural organic matter content and is typical of Northern Canadian waters. The testing using different permeate fluxes, filtration cycle duration and backwash cycle duration showed that this system mimics the performance of larger systems and may be used to assess the impact of operating conditions on membrane fouling and alternative pretreatment options. Modeling the first, middle, and last filtration cycles of the six runs using single and dual blocking mechanisms yielded inconsistent results regarding the controlling fouling mechanisms.

Assessment of ultrafiltration as a pretreatment of reverse osmosis membranes for surface seawater desalination

2003 ◽  
Vol 3 (5-6) ◽  
pp. 437-445 ◽  
Author(s):  
A. Brehant ◽  
V. Bonnelye ◽  
M. Perez
Keyword(s):  
Reverse Osmosis ◽  
Low Dose ◽  
Operating Conditions ◽  
Surface Seawater ◽  
Seawater Desalination ◽  
Dead End ◽  
Pre Treatment ◽  
Desalination Plants ◽  
The Impact ◽  
Variable Quality

Pre-treatment of seawater feeding reverse osmosis (RO) membranes is a key step in designing desalination plants, especially when treating surface seawater with highly variable quality. The objective of the study was to assess the potential of ultrafiltration (UF) pre-treatment prior to RO for desalting seawater with high-fouling tendency. A UF pilot plant equipped with an Aquasource membrane was directly operated on Gibraltar surface seawater in dead-end mode. The competitiveness of UF pre-treatment towards conventional pre-treatment was assessed by looking at the impact on RO hydraulic performances. The study showed that UF provided permeate water with higher quality than with a conventional pre-treatment. The main seawater compounds responsible for UF fouling were organic matter released by phytoplanktonic organisms. The combination of UF with a pre-coagulation at low dose helped in controlling this fouling and providing water in steady state conditions. The performance of RO membranes downstream of UF exceeded the usual operating conditions encountered in seawater desalination. The combined effect of higher recovery and higher flux rate promises to significantly reduce the RO plant costs.

scholarly journals Removal of Naturally Occurring Strontium by Nanofiltration/Reverse Osmosis from Groundwater

Membranes ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 321
Author(s):  
Yang-Hui Cai ◽  
Xiao Jin Yang ◽  
Andrea Iris Schäfer
Keyword(s):  
Reverse Osmosis ◽  
Membrane Fouling ◽  
Bone Growth ◽  
Water Flux ◽  
Applied Pressure ◽  
Permeate Flux ◽  
Membrane Performance ◽  
Toc Removal ◽  
Naturally Occurring ◽  
The Impact

Removal of naturally occurring strontium (Sr) from groundwater is vital as excessive exposure may lead to bone growth problems in children. Nanofiltration/reverse osmosis (NF/RO) is commonly used in groundwater treatment due to the high effectiveness and simple maintenance of these pressure driven membrane processes. In this research, a pilot-scale NF/RO system was used to desalinate a natural groundwater sample containing high Sr concentration (10.3 mg/L) and “old” groundwater organic matter (70.9 mg/L) from Esilalei in northern Tanzania to understand the removal of strontium by NF/RO. The impact of applied pressure (10–15 bar) and groundwater pH (3–12) on the membrane performance including permeate flux, strontium and total organic carbon (TOC) flux and removal was investigated. Increasing applied pressure was found to enhance the flux by increasing the driving force and enhance Sr and TOC removal by dilution effect (water flux higher than Sr passage). The alkaline pH caused severe flux decline likely due to membrane fouling and scaling, while it slightly enhanced Sr removal of RO membranes, but weakened the TOC removal. In contrast, acidic and neutral pH of groundwater enhanced TOC removal. These findings suggest that appropriately high applied pressure and acidic pH condition of groundwater are recommended to apply to the NF/RO membrane system in groundwater desalination to achieve better membrane performance.

Understanding how operating conditions affect biofouling structure in spacer filled membrane filtration channels using optical coherence tomography

2020 ◽  
Author(s):  
Kees Theo Huisman ◽  
Bastiaan Blankert ◽  
Szilard Bucs ◽  
Johannes S. Vrouwenvelder
Keyword(s):  
Optical Coherence Tomography ◽  
Reverse Osmosis ◽  
System Performance ◽  
Operating Conditions ◽  
Process Conditions ◽  
Feed Water ◽  
Optical Coherence ◽  
Biofilm Development ◽  
Biofilm Structure ◽  
The Impact

<p><strong>Abstract</strong></p> <p>The growth of biofilms, causing biofouling on the membrane and feed spacer surface, is an unavoidable phenomenon in reverse osmosis. Biofouling can lead to unacceptable losses in product quality and quantity, and membrane lifetime. Process conditions such as crossflow velocity and nutrient concentration in the feed water strongly affect the development of biofilms. To improve system performance, understanding the relation between process conditions, biofilm development, and system performance is key. Optical coherence tomography (OCT), is increasingly applied to characterize biofilm structure in-situ and non-destructively. In OCT, near-infrared light is used to capture 2D and 3D images from within optical scattering media. In spacer filled channels with representative biodegradable nutrient conditions in the feed, biofilms often develop heterogeneously and dispersed. In such systems, commonly used structural parameters such as average thickness, average roughness, and average porosity may not be reflected in the system performance.</p> <p>In this study, biofilm structural and spatial parameters are explored with the objective to link biofouling in spacer filled channels to system performance indicators. For this purpose, biofilms are grown in membrane fouling simulators at different nutrient concentrations and flow rates. Biofilm development on the feed spacer and on the membrane and system performance (pressure drop, transmembrane pressure, rejection) are monitored. Understanding the impact of (i) feed water quality and flow rate on biofilm growth and of (ii) biofilm structure and spatial distribution on system performance will lead to the development of more effective strategies for biofouling control.</p> <p><strong>Keywords</strong></p> <p>Biofouling; desalination; drinking water production; reverse osmosis; optical coherence tomography; feed spacer; biofilm structure</p>

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