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

This thesis deals with water reclamation and water reuse in the South African water supply context. The overall objective of the study is to assess the potential role and feasibility of reverse osmosis as a water reclamation process. In order to achieve this objective a number of separate desk, laboratory and pilot plant studies were conducted. It was concluded from the first desk study that a significant potential role exists for reverse osmosis in the South African water economy, mainly for the treatment of industrial effluents and, in the longer term, for the reclamation of water from sewage effluents and for the treatment of effluents and recycled water in indirect water reuse situations. A cost analysis showed that reverse osmosis could become economically viable in some water reuse situations in the near future provided that a productive membrane life of about three years can be achieved and that membrane fluxes can be maintained at design rates. These findings indicated the need for a pilot plant study to determine the effects of pretreatment and membrane cleaning on flux levels and rejection. A 50 m³/d pilot plant was designed and operated for a period of about six months from which it was concluded that acceptable flux levels can be maintained in tubular reverse osmosis plants treating well-oxidized activated sludge effluent with and without extensive pretreatment, provided both chemical and physical cleaning methods are employed. The desk study on the rejection of contaminants by reverse osmosis membranes indicated the need for a simple model that can be used to predict the removal of organic compounds of interest in water reclamation applications. It was concluded from a fundamental laboratory study, which included the evaluation of existing membrane models against laboratory data, that the solvophobic theory can be adapted in a simplified form to predict the transport of dissolved organic compounds in relatively non-polar reverse osmosis membranes. Based on reverse osmosis, diffusion, sorption and desorption data a mechanism is, furthermore, proposed for the transport of phenol in different membranes.

The effectiveness of reverse osmosis (RO) membrane systems may be compromised due to fouling, of which biofouling (excessive growth of biomass) is the most troublesome. Effective control of biofouling is essential to improve membrane performance and reduce operating costs. The periodic application of chemical cleaning agents is possibly the most widely practiced method of biofouling control in RO membranes. This research investigated advanced chemical cleaning strategies for biofouling control. The first part of this study concluded that short-term accelerated biofouling studies using lab-scale membrane fouling simulators (MFSs) are a representative and suitable approach for the prediction of long-term biofouling development in membrane systems. Thereon, the superior efficiency of urea as an alternative to conventional chemical cleaning agents was demonstrated (i) at lab-scale using MFSs, (ii) for full-scale industrial spiral-wound membranes and (iii) for multiple cleaning cycles during long-term operation. Periodic chemical cleaning with urea resulted in better restoration of membrane performance, higher biomass inactivation, enhanced biofilm solubilization and removal, disintegration of extracellular polymeric substances (EPS) particularly proteins, and a considerable reduction of key biofilm-forming bacteria. This research presented enhanced chemical cleaning strategies aiming to increase the removal of biofilms, reduce biomass accumulation and its impact on membrane performance, and delay fresh biofilm formation.

No description available.

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