Membrane technologies are considered a promising solution for water scarcity in arid regions. However, fouling is a major challenge facing the application of membrane technologies. Fouling limits the economic viability and reduces the overall efficiency of membrane processes. Therefore, fouling mitigation is a crucial factor in spreading the use of membrane technologies for new applications. The first step in fouling mitigation is to predict the propensity of fouling. Unfortunately, there are immense limitations in current industrial practises for fouling propensity prediction. These limitations come from using outdated and inapplicable approaches, in which crucial assumptions are made. For example, in the case of crystallisation fouling or “scaling” one of the major simplifications is the use of pure scaling salt data to predict the propensity of scaling when, in reality, co-precipitation is present. This research work aims to introduce a new approach to systematic assessment of the fouling problem under real and complex conditions and to enhance understanding of the importance of including interactive effects and co-precipitation in the prediction of scaling propensity. In this research work a novel procedure accounting for the local variation of thermodynamic properties along a long membrane channel is proposed. A new approach considering ion interaction and process hydrodynamics for the prediction of the scaling propensity is then introduced. This new approach provides for the first time a completely theoretical assessment for pure salt scaling propensity along a full scale filtration channel without the use of any empirical constants. A new procedure for including the effect of co-precipitation on scaling propensity prediction is developed. The effect of process pressure on solubility products is included theoretically for the first time to enhance the accuracy of scaling propensity prediction during the full scale RO process. This research work helps to produce more reliable and accurate prediction of the onset of scaling which will help strategies to mitigate scaling and increase the overall efficiency of RO/NF processes. The new approach can be applied in practical situations and could be developed to a user-friendly programme able to give an accurate prediction of the fouling propensity in full scale processes allowing the optimisation of membrane processes accordingly. Moreover, comprehensive experimental work has been carried out during this PhD research work to enhance understanding of crystallisation fouling and coprecipitation. The effect of salinity and dissolved organics (DO) in CaSO4 and SrSO4 precipitation and co-precipitation are studied and discussed. Quantitative and qualitative thermodynamic and kinetic analyses combined with structural analyses of deposits are carried out to investigate the effect of salinity, DO presence and coprecipitation on SrSO4 and CaSO4 precipitation. The observations in this experimental study are very important for a deeper understanding of the effect of scaling salts’ coexistence, salinity and DO presence on the behaviour of the scaling salts. This is crucial to reaching a reliable prediction of the scaling propensity within RO/NF processes. Finally, the new developed approaches in this thesis have been validated using set of hydrodynamic tests. This set of tests has been carried out using a newly installed laboratory membrane rig. Moreover, a new technique to simulate full scale membrane processes is proposed using a laboratory membrane rig combined with the programs previously developed in this thesis. This new technique can be used to study the effect of process hydrodynamics on scaling and process performance of full scale membrane processes using a laboratory membrane rig. The outcomes of this research work can be used to investigate the optimal operating conditions and to guide design criteria for different RO/NF practical scenarios.

There are two basic needs globally and that is the control and supply of reliable electricity and clean water. However, one of the biggest challenges the world is facing today is the lack of fresh water resources. Lower rainfall, together with population and industry growth, are only a few factors contributing to the fast increasing strain on existing water supplies around the world. This fast increasing need therefore necessitates the investigation into finding alternative sources. One such option is that of desalination. In the last 50 years desalination technologies have been applied to produce high quality fresh water from brackish and seawater resources. In the 1980's a breakthrough was made with the introduction of the membrane desalination technology, known as the reverse osmosis (RO) process. Today newly developed technologies are improving the competitiveness of the reverse osmosis process against the traditional distillation processes. There are a number of options to increase the efficiency of a reverse osmosis plant and one option is to use warm industrial waste water as the feed water to the desalination plant. It is known that the viscosity of water is inversely proportional to its temperature. Therefore, if the feed water temperature of a reverse osmosis plant is increased the membranes will become more permeable. This will result in a higher production volume or in a lower energy demand. South Africa is on the edge of building the first fourth generation nuclear power plant, called the Pebble Bed Modular Reactor (PBMR) at Koeberg. The PBMR will produce a cooling water outlet temperature of 40°C which can be used as feed water to a reverse osmosis plant. In this study design guidelines of a reverse osmosis plant are given in nine steps. These steps were then used during a basic component design of a reverse osmosis plant coupled to the waste water stream of a PBMR nuclear power plant. Furthermore design software programs were used to simulate the coupling scheme in order to validate the outcome of the design guidelines. The results of the two design approaches compared well to one another. It furthermore showed that by using the waste water from the PBMR nuclear power plant the efficiency of the RO plant is increased and the operating cost is decreased. Fresh water can be produced at a cost of R 5.64/m3 with a specific electricity consumption of 2.53 kWh/m3. / Thesis (M.Ing. (Nuclear Engineering)--North-West University, Potchefstroom Campus, 2009.

There are two basic needs globally and that is the control and supply of reliable electricity and clean water. However, one of the biggest challenges the world is facing today is the lack of fresh water resources. Lower rainfall, together with population and industry growth, are only a few factors contributing to the fast increasing strain on existing water supplies around the world. This fast increasing need therefore necessitates the investigation into finding alternative sources. One such option is that of desalination. In the last 50 years desalination technologies have been applied to produce high quality fresh water from brackish and seawater resources. In the 1980's a breakthrough was made with the introduction of the membrane desalination technology, known as the reverse osmosis (RO) process. Today newly developed technologies are improving the competitiveness of the reverse osmosis process against the traditional distillation processes. There are a number of options to increase the efficiency of a reverse osmosis plant and one option is to use warm industrial waste water as the feed water to the desalination plant. It is known that the viscosity of water is inversely proportional to its temperature. Therefore, if the feed water temperature of a reverse osmosis plant is increased the membranes will become more permeable. This will result in a higher production volume or in a lower energy demand. South Africa is on the edge of building the first fourth generation nuclear power plant, called the Pebble Bed Modular Reactor (PBMR) at Koeberg. The PBMR will produce a cooling water outlet temperature of 40°C which can be used as feed water to a reverse osmosis plant. In this study design guidelines of a reverse osmosis plant are given in nine steps. These steps were then used during a basic component design of a reverse osmosis plant coupled to the waste water stream of a PBMR nuclear power plant. Furthermore design software programs were used to simulate the coupling scheme in order to validate the outcome of the design guidelines. The results of the two design approaches compared well to one another. It furthermore showed that by using the waste water from the PBMR nuclear power plant the efficiency of the RO plant is increased and the operating cost is decreased. Fresh water can be produced at a cost of R 5.64/m3 with a specific electricity consumption of 2.53 kWh/m3. / Thesis (M.Ing. (Nuclear Engineering)--North-West University, Potchefstroom Campus, 2009.

No description available.

Thesis (Ph.D.) -- McMaster University, 2001. / Includes bibliographical references. Also available via World Wide Web.

Thesis (M.S.)--California Polytechnic State University, 2009. / Title from PDF title page; viewed on Sept. 16, 2009. "June 2009." "In partial fulfillment of the requirements for the degree [of] Master of Science in Civil and Environmental Engineering." "Presented to the faculty of California Polytechnic State University, San Luis Obispo." Major professor: Yarrow Nelson, Ph.D. Includes bibliographical references (p. 96-100).

A new method of sea water desalination, Centrifugal Reverse-Osmosis (CRO), is developed from concept to patented design and functional prototype of capacity 11,355 litres of fresh water per day. CRO is shown to have significant benefits relative to the leading existing desalination technology, conventional reverse-osmosis. These benefits include: lower energy consumption, reduced initial and replacement membrane costs, lower noise levels and improved reliability. CRO is projected to show increasing cost efficiency as plant capacity increases. For a relatively large CRO plant, 65lm³ fresh water per day, the total cost of desalinated water is projected to be 25.9% lower than the total cost of water produced by a conventional RO plant of equivalent capacity. The current patented design requires further development in order to realize this potential. Toward this end, a computational and experimental study of rotor windage losses and an experimental study of fluid flow losses through the rotor are conducted. In addition a new method for the analysis of stresses in a filament wound rotor shell under combined centrifugal and pressure loading is developed. / Graduate

Thesis (Masters Diploma (Technology)--Cape Technikon, Cape Town,1993 / Various experimental and established membranes were tested on industrial effluents. Ultrafiltration, reverse osmosis and nanofiltration membranes were used in various applications. Research was done on aspects such as the cleaning of fouled membranes, production quality control and process development. Polyvinyl alcohol ultra-thin-film reverse osmosis membranes were manufactured for the desalination of brackish water to a potable standard. The membranes were manufactured in the tubular configuration. Experimental ultrafiltration, reverse osmosis and nanofiltration membranes were tested on cooling water blowdown on a laboratory-scale. On-site testing was done directly on the effluent at a later stage. A s!udy was also conducted to determine the effect of gel-polarization on membrane performance. The gel-layer model was used to predict the limiting flux of specific membranes. Membrane processes were also applied in the fractionation of wine-lees to provide usable by-products such as yeast cells and potassium bitartrate. Ultrafiltration membranes operated in diafiltration mode were used to "wash" the slurry at different solid concentrations. The bitartrate-rich permeate collected from ultrafiltration was then concentrated using reverse osmosis and nanofiltration to allow subsequent precipitation of the product.

No description available.

abstract: Managing water resources has become one of the most pressing concerns of scientists both in academia and industry. The reverse osmosis (RO) water treatment process is a well-researched technology among the pressure driven processes to produce potable water. RO is an energy intensive process and often RO membranes are susceptible to fouling and scaling that drives up operational cost and hinder the efficiency. To increase the performance of RO membranes the feed water is pretreated to remove pollutants before desalination. This work aims to fabricate pretreatment membranes to prevent the effects of fouling and scaling by introducing hydrophilic character to membrane. This work explores electrospinning, a cost-effective and scalable technique, to blend two polymers into a nonwoven membrane comprised of fibers ~100 nm - 10 µm in diameter. A rotary drum collector holding the mat was used to simultaneously collect the electrospun hydrophobic poly(vinyl chloride) (PVC) and hydrophilic poly(vinyl alcohol) (PVA) fibers from two separate solutions. The hydrophilicity of the resulting membrane was tuned by controlling the relative deposition rate of PVA onto the co-spun mat. Fiber diameter and morphologies were characterized by scanning electron microscopy, and Fourier-transform infrared spectroscopy and Confocal fluorescence microscopy further confirmed the presence of both polymers. Moreover, a rigorous analysis to map the PVA/PVC concentration was established to accurately report the relative concentrations of the two polymers on the co-spun mat. After electrospinning, the PVA in the co-spun mats were cross-linked with poly(ethylene glycol) diacid to impart mechanical strength and tune the porosity. EDS analysis revealed inconsistencies in the mass deposition of both polymers suggesting an improvement in the current experimental design to establish a meaningful relationship between PVA concentration and hydrophilicity. However, tensile test revealed that co-spun mats with high mass flow ratios of PVA possessed high mechanical strength showing a significant improvement in the Young’s Modulus. Furthermore, the co-spun mats were challenged with filtration experiments expecting a positive correlation of flux with PVA concentration. But it was found that with increased concentration, crosslinked PVA constricted PVC fibers minimizing the pores causing a lower flux and a dense membrane structure suitable for filtration. / Dissertation/Thesis / Masters Thesis Chemical Engineering 2020