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Simulation of boron rejection by seawater reverse osmosis desalinationPatroklou, G., Sassi, Kamal M., Mujtaba, Iqbal M. January 2013 (has links)
yes / Boron is a vital element for growth of creations, but excessive exposure can cause detrimental effects to plants,
animals, and possibly humans. Reverse Osmosis (RO) technique is widely used for seawater desalination as well
as for waste water treatment. The aim of this study is to identify how different operating parameters such as pH,
temperature and pressure can affect boron concentrations at the end of RO processes. For this purpose, a
mathematical model for boron rejection is developed based on solution-diffusion model which can describe
solvent and solute transport mechanism through the membranes. After a wide and thorough research, empirical
correlations developed in the past are filtered, adopted and calibrated in order to faction with reliability as part of
the solution-diffusion model of this work. The model is validated against a number of experimental results from the
literature and is used in further simulations to get a deeper insight of the RO process. The general findings of the
boron rejection model are supporting the case that with increasing pH and operating pressure of the feed water,
the boron rejection increases and with increasing feed water temperature the boron rejection decreases.
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Evaluation and minimisation of energy consumption in a medium-scale reverse osmosis brackish water desalination plantAlsarayreh, Alanood A., Al-Obaidi, Mudhar A.A.R., Al-Hroub, A.M., Patel, Rajnikant, Mujtaba, Iqbal M. 25 March 2022 (has links)
Yes / The Reverse Osmosis (RO) process has been expansively used in water treatment as a result of its low energy consumption compared to thermal distillation processes, leading to reduced overall water production cost. Evaluation and minimisation of energy consumption (expressed in kWh/m3 of fresh water production) in a medium-scale spiral wound brackish water RO (BWRO) desalination plant of the Arab Potash Company (APC) are the main aims of this research. The model developed earlier by the authors has been integrated to simulate the process and achieve the main aims. Energy consumption calculations of low salinity BWRO desalination plant, with and without an energy recovery device, have been carried out using the gPROMS software suite. In other words, this research evaluated the impact of adding an energy recovery device on the RO process energy consumption of the APC, which is introduced for the first time. Also, the effects of several operating conditions of BWRO process include the feed flow rate, pressure and temperature on the performance indicators, which include the energy consumption and total plant recovery at different energy recovery device efficiencies, were studied. The simulation results showed that the total energy consumption could be reduced at low values of feed flow rates and pressures and high values of temperatures. More importantly, there is an opportunity to reduce the total energy consumption between 47% and 53.8% compared to the one calculated for the original design without an energy recovery device.
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Recovery of Xylitol from Fermentation of Model Hemicellulose Hydrolysates Using Membrane TechnologyAffleck, Richard Peter 12 January 2001 (has links)
Xylitol can be produced from xylose or hemicellulose hydrolysates by either chemical reduction or microbial fermentation. Current technology for commercial production is based on chemical reduction of xylose or hemicellulose, and xylitol is separated and purified by chromatographic methods. The resultant product is very expensive because of the extensive purification procedures.
Microbial production of xylitol is being researched as an alternative method for xylitol production. Apart from the chromatographic separation method and activated carbon treatment, no other separation method has been proposed for the separation of xylitol from the fermentation broth.
Membrane separation was proposed as an alternative method for the recovery of xylitol from the fermentation broth because it has the potential for energy savings and higher purity. A membrane separation unit was designed, constructed, tested, and successfully used to separate xylitol from the fermentation broth. Eleven membranes were investigated for xylitol separation from the fermentation broth. A 10,000 nominal molecular weight cutoff (MWCO) polysulfone membrane was found to be the most effective for the separation and recovery of xylitol. The membrane allowed 82.2 to 90.3% of xylitol in the fermentation broth to pass through while retaining 49.2 to 53.6% of the Lowry's method positive material (such as oligopeptides and peptides). Permeate from the 10,000 MWCO membrane was collected and crystallized. Crystals were analyzed by HPLC for xylitol and impurities and determined to have purity up to 90.3%. / Master of Science
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Fresh water by reverse osmosis based desalination: simulation and optimisation.Mujtaba, Iqbal M., Villafafila, A. 05 1900 (has links)
No / The reverse osmosis (RO) desalination process to make fresh water from seawater has been studied here. First, a model for the process is developed. Sensitivity of different operating parameters (feed flow rate, feed pressure) and design parameters (internal diameter, total number of tubes) on the recovery ratio are studied via repetitive simulation. Finally, an optimisation framework for the process is developed so as to maximize the recovery ratio or a profit function using different energy recovery devices, subjectto general constraints. The optimal operating parameters (feed flow rate, feed pressure) and design parameters (internal diameter, total number of tubes) are determined by solving the optimisation problem using an efficient successive quadratic programming (SQP) based method. The optimal values for the decision variables depend on the constraints introduced, and are also sensitive to variations in water and energy prices, as well as feed concentration. The use ofthe emerging energy recovery devices is widely justified, reporting much higher reductions in operating costs than the traditional technology used for this purpose. Using a pressure exchanger device, it is possible to reduce energy consumption by up to 50%.
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Optimisation of design and operating parameters of reverse osmosis process for the removal of phenol from wastewaterKhan, Shamraze, Al-Obaidi, Mudhar A.A.R., Kara-Zaitri, Chakib, Mujtaba, Iqbal M. 18 October 2022 (has links)
Yes / Reverse Osmosis (RO) is widely used for separating organic and inorganic pollutants in wastewater. In this research, the one-dimensional steady state model of a spiral wound RO for the removal of phenol from wastewater, was simulated using gPROMS software to identify optimal design and operating parameters. The design parameters included the membrane length, width and feed spacer channel and operating conditions included temperature and pressure of the RO process. The optimal design parameters were able to maximise the removal of phenol from wastewater. The simulation results showed that the removal of phenol from wastewater was significantly influenced by the combination of membrane width, operating pressure, and feed temperature. The four main parameters (permeate concentration, solute flow, solute rejection, and water flux) that govern the performance of a reverse osmosis membrane were found to be influenced by the design and operating conditions.
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Ultrasonic-time-domain-reflectometry as a real time non-destructive visualisation technique of concentration polarisation and fouling on reverse osmosis membranesKoen, Louis Johannes 12 1900 (has links)
Thesis (MEng)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: Fouling is readily acknowledged as one of the most critical problems limiting the
wider application of membranes in liquid separation processes. A better
understanding of fouling layer formation and its monitoring is needed in order to
improve on existing cleaning techniques. Plant operation can be optimised if fouling
can be monitored by noninvasion means either on the plant itself or on an attached
monitoring device.
The overall scope of this research was to develop a non-destructive, real-time, in situ
visualisation technique or device for concentration polarisation and fouling layer
monitoring. Ultrasonic-time-domain-reflectometry (UTDR) was employed as a
visualisation technique to provide real-time characterisation of the fouling layer.
A 24 cm-long rectangular flat sheet aluminium cell was designed and used as
separation device for a desalination system. The experimental results obtained using
this module confirmed that there are an excellent correspondence between the flux
decline behaviour and the UTDR response from the membrane. The ultrasonic
technique could effectively detect fouling layer initiation and growth on the
membrane in real-time. In addition to the measurement of fouling, the ultrasonic
technique was also successfully employed for monitoring membrane cleaning. Since
no real-time permeation data is available during cleaning operations in industrial
applications, a UTDR monitoring device may prove to be a very valuable technique
in optimising cleaning strategies.
The technique was further tested on an 8-inch diameter spiral wrap industrial
module and good results were obtained. Stagnant zones, as well as flux flow
behaviour inside the module could be determined. However, more research IS
needed to fully understand the complex phenomena inside a spiral wrap module.
Overall, the UTDR technique and its use in monitoring devices have a major impact
in the membrane industry due to its extremely powerful capabilities. / AFRIKAANSE OPSOMMING: Membraan-bevuiling of -verstopping is die grootste struikelblok wat die algemene
aanwending van membrane vir verskillende watersuiweringsprosesse negatief
beinvloed. 'n Beter begrip van membraan-bevuiling, asook beter metingsmetodes
daarvan is nodig om op bestaande skoonmaaktegnieke te verbeter.
Die hoofdoel van hierdie studie was die ontwikkeling van 'n nie-destruktiewe-in-lyn
visuele tegniek vir die meting van konsentrasie polarisasie en membraan-bevuiling.
Deur gebruik te maak van ultrasoniese klank golwe, is 'n tegniek ontwikkel wat 'n
direkte visuele aanduiding kon gee van die toestand van membraan-bevuiling binnein
die module.
'n Reghoekige aluminium-module, 24 cm lank, is ontwerp en gebou waarbinne die
membraan geplaas is vir die skeidingsproses. Resultate dui daarop dat daar 'n
uitstekende verband bestaan tussen die afname in permeaatvloei en die ultrasoniese
eggo vanaf die membraan. Die ultrasoniese tegniek kon die vorming van en toename
in membraan-bevuiling doeltreffend karakteriseer. In teenstelling hiermee, is die
tegniek ook suksesvol aangewend om die skoonmaak-proses van membrane te
ondersoek. Met min of geen data beskikbaar vir die skoonmaak-proses van
membrane in die industriële sektor, het die tegniek enorme potensiaal in die
optimisering van bestaande skoonmaak-tegnieke.
Die tegniek is verder aangewend op 'n industriële 8-duim deursnee spiraal-module
en goeie resultate is verkry. Stagnante sones asook vloed-vloei-patrone binne-in die
module kon suksesvol bepaal word. Baie navorsing is egter nog nodig om die
ingewikkelde data wat gegenereer word tydens die ondersoek van 'n spiraal-module
ten volle te verstaan.
Die enorme potensiaal en moontlikhede van die ultrasoniese tegniek kan die begin
wees van 'n revolusie in die membraan-industrie.
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Efficiency improvements for small-scale reverse-osmosis systemsSusanto-Lee, Robertus January 2006 (has links)
The water supplies of some small inland communities may come in the form of river systems that offer brackish water. Not fit for immediate human consumption, the water can be further processed using reverse osmosis to be converted into drinking water.In very remote areas there are limited energy resources, and for those areas that lie beyond a municipal distribution grid, renewable energy sources may be used. A reverse osmosis system that operates from the limited power generated by a renewable energy system must do so with the utmost of efficiency. Three methods in improving the efficiency of small-scale reverse-osmosis system are investigated, namely high-pressure pump speed control, feed water heating and vacuum pump based energy recovery.
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Removal of N-nitrosamine by Nanofiltration and Reverse Osmosis MembranesMiyashita, Yu 09 April 2007 (has links)
The rejections of selected N-nitrosamines by commonly used high-pressure nanofiltration (NF) and reverse osmosis (RO) membranes were quantitatively evaluated using a bench-scale cross-flow filtration apparatus. The selected nitrosamines included N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), N-nitrosopyrrolidine (NPYR), N-nitrosodiethylamine (NDEA), N-nitrosodi-n-propylamine (NDPA), N-nitrosodi-n-butylamine (NDBA) and N-nitrosodiphenylamine (NDPHA). Nitrosamine rejections were evaluated under steady state at elevated feed concentrations, since NDMA rejections were found to be consistent with feed concentrations over three orders of magnitude. The steady-state nitrosamine rejections by NF membranes varied significantly, from 9 to 75%, depending on nitrosamine compounds and tested membranes. For hydrophilic compounds, rejections increased with increasing molecular weight. The nitrosamine rejections by brackish RO membranes reached as high as 97% for higher molecular weight nitrosamines. However, for low molecular weight nitrosamines such as NDMA, rejections as low as 54% were observed. This low level of rejections was attributed to diffusive solute transport being more effective than convective transport. Physicochemical properties such as molecular weight and aqueous diffusivity showed reasonable correlations with nitrosamine permeability constants.
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Optimal reverse osmosis network configuration for the rejection of dimethylphenol from wastewaterAl-Obaidi, Mudhar A.A.R., Kara-Zaitri, Chakib, Mujtaba, Iqbal M. 25 October 2017 (has links)
Yes / Reverse osmosis (RO) has long been recognised as an efficient separation method for treating and removing harmful pollutants, such as dimethylphenol in wastewater treatment. This research aims to study the effects of RO network configuration of three modules of a wastewater treatment system using a spiral-wound RO membrane for the removal of dimethylphenol from its aqueous solution at different feed concentrations. The methodologies used for this research are based on simulation and optimisation studies carried out using a new simplified model. This takes into account the solution-diffusion model and film theory to express the transport phenomena of both solvent and solute through the membrane and estimate the concentration polarization impact respectively. This model is validated by direct comparison with experimental data derived from the literature and which includes dimethylphenol rejection method performed on a small-scale commercial single spiral-wound RO membrane system at different operating conditions. The new model is finally implemented to identify the optimal module configuration and operating conditions that achieve higher rejection after testing the impact of RO configuration.
The optimisation model has been formulated to maximize the rejection parameters under optimal operating conditions of inlet feed flow rate, pressure and temperature for a given set of inlet feed concentration. Also, the optimisation model has been subjected to a number of upper and lower limits of decision variables, which include the inlet pressure, flow rate and temperature. In addition, the model takes into account the pressure loss constraint along the membrane length commensurate with the manufacturer’s specifications. The research clearly shows that the parallel configuration yields optimal dimethylphenol rejection with lower pressure loss.
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The removal of pesticides and heavy metals by reverse osmosisChong, Brian S. H. 18 April 2009 (has links)
In the past few years, the contamination by pesticides and heavy metals in surface water and groundwater has increased. Reverse osmosis is a unit process that has demonstrated capacity to remove dissolved pesticides and heavy metals from aqueous solution, and it is therefore worthwhile to consider this treatment process as a potential removal technique for hazardous constituents.
The purpose of this investigation was to determine the effectiveness of a field scale reverse osmosis unit, with a spiral wound poly(ether/urea) membrane, in removing pesticides and heavy metals from a contaminated source. The removal efficiency for a single contaminant alone and a part of a mixture was examined. The performance of new and used membranes over time was also investigated.
The average removal of pesticides was better than 99 percent. Reverse osmosis separation of pesticides was found to be dependent on the characteristics of the membrane and the physical/chemical properties of the pesticides. Pesticides in the mixed solution were found to behave independently. Sorption of the pesticides onto the reverse osmosis membrane was found to play a major role in the overall removal efficiency.
Better than 99 percent average removal was achieved for all the metals except arsenic. The importance of the physical/chemical properties of the metal ions such as solubility, ionic radius, and electronegativity were determined. In tests to compare removal efficiency between new membrane and membrane which had been used, virtually no differences occurred. / Master of Science
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