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Many methods for the quantitative concentration of small amounts of viruses from natural water supplies have been considered. One of the most promising of these is the adsorption of viruses onto a 0.45pm cellulose nitrate membrane filter apparatus. A quantity of water is passed through the filter by gravity or pressure filtration. The viruses present in the water are adsorbed onto the membrane and are subsequently eluted by the use of a beef extract eluant. The virus-containing elution is then layered upon tissue culture, preferably the BGM cell line, for isolation by the plaque method. The isolated virus is then identified by serological techniques.The research presented here utilized the cellulose nitrate membrane filter system for the detection of viruses from local waterways and sewage treatment influents and effluents. Examination of the water was done for the Enterovirus group of viruses consisting primarily of the Echovirus, Coxsackievirus, and Poliovirus groups.Although viral cytopathic effect was detectable in a few cell cultures innoculated with collected water samples, no virus was isolated and identified by serological techniques or electron microscopy. The use of continuous cell lines produced numerous problems during this study. Subsequently, any viruses in positive CPE flasks could not be repassaged in BGM cultures. No viruses could be identified by neutralization in tissue culture. Identification of the positive flasks could not be made by electron microscopy.

Thesis (Ph. D.)--University of New South Wales, 1995. / Also available online.

Thesis (MScIng)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Thesis (M.S.)--West Virginia University, 1998. / Title from document title page. "October 1998." Document formatted into pages; contains viii, 80 p. : ill. Includes abstract. Includes bibliographical references (p. 78-80).

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Sulfonated polysulfone has been shown to possess desirable physical properties for use as a reverse osmosis desalination membrane. In this work, an extensive of dense membranes made from sulfonated polysulfone having 0.2, 0.4, 0.5, 0.6, 0.8, and 1.0 degree of sulfonation is described. The degree of sulfonation (D.S.) was maintained during the membrane fabrication process as evidenced by IR analysis. The effect of the degree of sulfonation and the counter ion, namely Na and K, on the properties of the membrane were examined. The hydrophilic nature of the material increased with increasing degrees of sulfonation, as evidenced by water uptake and the contact angle of water on the membrane surface. The amount of water increased from 0.6% for polysulfone to 19.2% for sodium salt of sulfonated polysulfone with D.S. of 1.0, and 12.2% for potassium salt of sulfonated polysulfone with D.S. of 1.0. The contact angle of water on polysulfone membranes was 75.1°. The contact angle of water decreased to 25.5° and 60.3° for sodium and potassium salt of sulfonated D.S. = 1.0) polysulfone, respectively. The decrease in the contact angle of water indicated an increase in the hydrophilicity of the membrane surface. Both the water uptake study and the contact angle measurement indicated greater hydrophilicity for the sodium salts of sulfonated polysulfone when compared to the potassium salts of sulfonated polysulfone for a given degree of sulfonation. The nature of the water within the membrane was found to be less hydrogen-bonded when compared to the bulk water. The surface of the membrane and the polymer powder was found to be different by ESCA analysis, and were also different from the bulk of the material. Neither the membrane surface nor the polytner powder surface had the same stoichiometry as the bulk. Ion exchange occurred not only on the membrane surface, but extended into the bulk with an overall ion exchange of about 80%. Electrical properti.es of the membranes were investigated by measuring the partial ionic conductivity and the selectivity of the membrane. The electrolyte/membrane/ electrolyte system showed ohmic behaviour. The membrane potential difference under applied transient current was greatly dependent on the nature of the cation, whereas the nature of the anion had no effect. The activation energy had minimal dependence on the membrane thickness, but depended on the nature of the electrolyte system. The effective size of the ion-conducting channels seemed to increase with higher degrees of sulfonation, probably due to a swelling process. SEM photomicrographs were taken to study membrane morphology and, in some cases, performance as a reverse osmosis membrane could be predicted from the SEM photomicrographs . / Ph. D.

Maintenance of membrane performance requires inevitable cleaning or defouling of fouled membranes. Membrane cleaning using enzymes such as proteases, lipases, α-glucosidases from a sulphidogenic bioreactor was investigated. At first, dilute and concentrated enzyme extract were prepared form the sulphidogenic pellet. Enzyme assays on 0.5 % azocaisen, 1 % triacetin and 1 mg/ml ρ-nitrophenyl-α-D-glucopyranoside were performed using the concentrated enzyme extract (0 – 200 mg/ml). For membrane fouling, an abattoir effluent was obtained from Ostritech Pty (Ltd), Grahamstown, South Africa. The effluent was characterised for presence of potential foulants such as lipids, proteins, amino acids and carbohydrates. Static fouling of polysulphone membranes (0.22 μm, 47 mm) was then performed using the abattoir effluent. Cleaning of the fouled membranes was also performed using at first the dilute and then the concentrated form (200 mg/ml) of enzyme extracts. Qualitative and quantitative biochemical analysis for proteins, lipids and carbohydrates was performed to ascertain the presence of foulants on polysulphone membranes and their removal by dilute or concentrated enzyme extracts. The ability of dilute enzyme extracts to remove proteins lipids, and carbohydrates fouling capillary UF membrane module; their ability to restore permeate fluxes and transmembrane pressure after cleaning/defouling was also investigated. Permeate volumes from this UF membrane module were analysed for protein, amino acids, lipids, and carbohydrates concentrations after fouling and defouling. Fouling was further characterized by standard blocking, cake filtration and pore blocking models using stirred UF cell and polyethersulphone membranes with MWCO of 30 000, 100 000 and 300 000. After characterization of fouling, polyethersulphone membranes with MWCO of 30 000 and 300 000 were defouled using the concentrated enzyme extract (100 mg ml). Enzyme activities at 200 mg/ml of enzyme concentration were 8.071 IU, 86.71 IU and 789.02 IU for proteases, lipases and α-glucosidases. The abattoir effluent contained 553 μg/ml of lipid, 301 μg/ml of protein, 141 μg/ml of total carbohydrate, and 0.63 μg/ml of total reducing sugars. Proteins, lipids and carbohydrates fouling polysulphone membranes after a day were removed by 23.4 %, when a dilute enzyme was used. A concentrated enzyme extract of 200 mg/ml was able to remove proteins, lipids and carbohydrates up to 5 days of fouling by 100 %, 82 %, 71 %, 68 % and 76 % respectively. Defouling of dynamically fouled capillary ultrafiltration membranes using sulphidogenic proteases was successful at pH 10, 37°C, within 1 hour. Sulphidogenic proteases activity was 2.1 U/ml and flux Recovery (FR %) was 64. Characterization of fouling revealed that proteins and lipids were major foulants while low concentration of carbohydrates fouled polyethersulphone membranes. Fouling followed standard blocking for 10 minutes in all the membranes; afterwards fouling adopted cake filtration model for membranes with 30 000 MWCO and pore blocking model for membranes with 300 000 MWCO. A concentration of 100 mg/ml of enzyme extract was able to remove fouling from membranes with MWCO of 30 000. Defouling membranes that followed pore blocking model i.e. 300 000 MWCO was not successful due to a mass transfer problem. From the results of defouling of 30 000 and 300 000 MWCO it was concluded that defouling of cake layer fouling (30 000 MWCO) was successful while defouling of pore blocking fouling was unsuccessful due to a mass transfer problem. The ratio of enzymes present in the enzyme extract when calculated based on enzymatic activity for proteases, lipases and α-glucosidases was 1.1 %, 11 % and 87.9 %. It was hypothesized that apart from proteases, lipases, α and β-glucosidases; phosphatases, sulphatases, amonipeptidases etc. from a sulphidogenic bioreactor clean or defoul cake layer fouling by organic foulants and pore blocking fouling provided the mass transfer problem is solved. However, concentration of enzymes from a sulphidogenic bioreactor has not been optimized yet. Other methods of concentrating the enzyme extract can be investigated for example use of organic solvents.

The optimization of a reverse osmosis (RO) system includes optimization of the design of the individual membrane modules, the system structure and the operating conditions of the system. Most previous studies considered either the optimal design of individual modules only or optimization of system structure and operating conditions for fixed module dimensions. This thesis developed a method to simultaneously optimize the module dimensions, system structure and operating conditions. The method comprised rules for generating a general superstructure for an RO system given the number of modules along with rules for generating technically and mathematically feasible sub-structures. The superstructure was based on maximum connectivity between unit operations. A connectivity matrix was used to represent the superstructure. The matrix was useful for checking sub-structure's feasibility and deriving a model for the sub-structure's optimization, comprising the minimum number of variables and constraints which minimized computational time and increased accuracy. For optimization, a nonlinear objective function of the annualized profit of the RO system was formulated, consisting of the revenue obtained from permeate sales, capital costs of the unit operations and operating costs for the system. It was found that RO system optimization is a nonconvex optimization problem. The most effective optimization procedure involved a combination of evolutionary computation, which was good for locating the global optimum, and a gradient-based method, which was superior in finding the exact optimum. Small population size, adaptive mutation rate and steady state replacement were the most efficient parameter settings for the evolutionary computation. Optimal design of two-stage RO systems with and without energy recovery, bypass and recycle streams was studied. Dimensions of predicted optimal modules approached those of current commercial modules but with much shorter feed channels. The mathematical optimum also had higher operating pressures. The optimum system structure was a series arrangement with different module dimensions in each stage. A sensitivity analysis showed that trends in the optimal design were similar when unit costs changed. An investigation of the scalability of the method for a three-stage RO system revealed several weaknesses. These are probably surmountable with the addition of more RO system specific knowledge.

Macromolecular components, including protein and polysaccharides, are viewed as one type of major foulants in the complex feed membrane filtration systems such as membrane bioreactor (MBR). In this thesis, the mechanisms of macromolecular fouling including protein and polysaccharide in the complex feed solution are explored by using Bovine serum albumin (BSA) and alginate as model solution. During the filtration of BSA and washed yeast with 0.22 ????m PVDF membrane, it was found that the critical flux of mixture solution was controlled by washed yeast concentration while the existence of BSA significantly changed the cake reversibility of much larger particles. The fouling mechanisms of alginate, as a model polysaccharide solution, were investigated both in dead end and crossflow membrane filtration. In the dead end experiments, it was found that the cake model appears to fit the entire range of the ultrafiltration data while the consecutive standard pore blocking model and cake model are more applicable to microfiltration membranes. The alginate was featured with high specific cake resistance and low compressibility despite some variations between different membranes. The specific cake resistance ( c ) is similar to c of BSA and actual extracellular polymer substance (EPS) in MBR systems reported in the literature, and higher than that of many colloidal particles. In a system contained alginate-particles mixture, it was found that the existence of alginate dramatically increased the cake specific resistance and decreased the cake compressibility. The fouling mechanism of alginate was also studied using long term cross flow filtration under subcritical flux. A two-stage TMP profile similar to that typically observed in MBR was obtained, confirming the important role of EPS during membrane fouling in MBR. In addition to adsorption, trace deposition of alginate also contributed to the initial slow TMP increase during the subcritical filtration. TMP increase during the long-term filtration was found not only due to the increase of the amount of deposition, but also the increase of specific cake resistance. A combined standard pore blocking and cake filtration model, using a critical pore size for the transition time determination, was developed and fit the experimental results well.