This master thesis project was carried out as a part of the chlorate research conducted at the Process RD&I department for bleaching chemicals at AkzoNobel Pulp and Performance Chemicals AB in Bohus. During the project already implemented filter cloths as well as new types of filters were studied and compared by experimental trials. The results were then examined in an attempt to evaluate existing filtration systems as well as investigate if there are other, better alternatives. The impurities found in a chlorate plant account for an efficiency loss in the process and a reduction of impurities would hence result in an energy reduction and a cleaner product. The trials were conducted at one of AkzoNobel’s chlorate plants. Six filters were studied and evaluated by measuring turbidity of the electrolyte and pressure over the filter during the experiments. Samples of the electrolyte were analyzed to obtain the metal content, and thereby the impurity content, of the electrolyte. The structures of the filters were studied by optical microscopy. The results from the trials show that all filter types except one, a needle felt filter, seem to be suitable for chlorate electrolyte filtration (including the filter types already used in the plants). The other filters all reach turbidity values below 0.1 FNU immediately or within 90 minutes of filtration, which is considered good enough. The results from the metal content analysis show a similar trend where the metal concentrations decrease to levels below the detection limits immediately or within 90 minutes of filtration. Apart from the lab trials performed some measurements were made on the existing filtration equipment in the chlorate plant. The measurements show varying results, partly similar to those achieved during the lab filter trials but also results showing a higher turbidity value and metal content, indicating that full scale operation are more complicated than lab scale operation. The lab trial results obtained with the filter types already used in the plants show that lower impurity content is possible to achieve. However, this would require closer monitoring of the filtration systems in the plants. Apart from the filtration trials, an attempt to determine the sizes of the particles present in the electrolyte using laser diffraction was performed. However, too little was known of the chlorate electrolyte’s optical data for the measurements to be reliable. Further work is needed before a method for size determination of the particles in a chlorate electrolyte can be achieved. Also, an Optical Filtration Test was tried on the electrolyte but was not sensitive enough for utilization on electrolyte with low (below 1 FNU) turbidity values.  The project concluded that a switch to another filtration system is unmotivated, unless a change in the product requirements would occur. Since the impurities have proven to affect the efficiency of the process, it is recommended to make an effort into utilizing the filtration system to its full extent.

An innovative approach for the removal of heavy metal ions such as Pb2+ and Cd2+ from aqueous solution was evaluated. It was established that alkaline filtration, which is in essence the combination of alkaline precipitation and membrane filtration, could drastically increase both the efficiency and completeness of Pb2+ or Cd2+ ions removal, producing water whose metal concentration satisfying drinking water standard from a simulation wastewater containing 5 ppm or more Pb2+ or Cd2+ ions. Filtration with three different membranes, including microfiltration (MF), ultrafiltration (UF), and nanofiltration (NF) membranes, were studied at three different pH levels, i.e., 7.0, 8.5, and 10, in terms of metal ion rejection, flux, and permeate pH and at varied dissolved inorganic carbon (DIC) concentration. Increasing the pH of the feed in the tested range would lead to the decrease of metal ion concentration in permeate while flux was in general unaffected. When the feed pH was 10, the Pb2+ concentration in permeate was below 10 ppb regardless of the DIC concentration and membrane for filtration. The effects of DIC concentration were significant but complex. It was found that MF, UF, NF could all effectively reject Pb2+ ions at pH 8.5 and pH 10 although only NF was charged. A hypothesis was proposed to explain the mechanism of alkaline filtration based on experimental data.

Reduced graphene oxide (rGO) has attracted considerable interest recently as the low cost and chemical stable derivative of pristine graphene with application in many applications such as energy storage, water purification and electronic devices. This dissertation thoroughly investigated stacked rGO membrane fabrication process by vacuum-driven filtration, discovered asymmetry of the two surfaces of the rGO membrane, explored application perspectives of the asymmetric rGO membrane in fog collection and microstructure patterning, and disclosed membrane compaction issue during water filtration and species rejection. In more details, this dissertation revealed that, with suitable pore size, the filtration membrane substrate would leave its physical imprint on the bottom surface of the rGO membrane in the form of surface microstructures, which result in asymmetric dynamic water wettability properties of the two surfaces of the rGO membrane. The asymmetric wettability of the rGO membrane would lead to contrasting fog harvesting behavior of its two surfaces. The physical imprint mechanism was further extended to engineering pre-designed patterns selectively on the bottom surface of the rGO membrane. This dissertation, for the first time, reported the water flux and rejection kinetics, which was related to the compaction of the rGO membrane under pressure in the process of water filtration.

A study of the feasibility of lagoon-intermittent sand filter treatment of dairy wastewaters from the Utah State University dairy was performed from 1978 through 1980. The report also includes an analysis of alternative dairy wastewater treatment systems utilizing a computer model. A simple and inexpensive method of dairy wastewater treatment is needed so that the small (50- 300 cows) dairy farmer can meet the 30 mg/ ~ of BODs federal effluent standard and still earn a profit. The influent to the USU dairy treatment system, the lagoon effluent and the filter effluent were sampled during the summers of 1978 and 1979 for BOD s , suspended solids and volatile suspended solids . The data show t hat removal efficiencies over 90 percent were achieved by the lagoon-intermittent sand filter system, but the effluent BODs and suspended solids concentrations did not meet the federal standards. The high effluent concentrations were a. result of the lagoon being overloaded. The treatment system's construction allowed runoff, groundwater and milking center washwater to enter the lagoon causing greater than expected hydraulic and organic mass loading rates. Despite high influent concentrations the intermittent sand filters consistently removed 80 percent of the suspended solids from the lagoon effluent. If the quality of the lagoon effluent were improved by reducing the organic mass loading rate, the effluent from lagoon intermittent sand filter treatment of dairy wastewaters would meet the federal standards.

Slow rate sand filtration (SSF) amended with a 20 em surface layer of clinoptilolite, a natural zeolite, was compared to SSF with no amendment in a field scale SSF facility treating 85 m3/d of water. Parameters examined included turbidity, coliforms, and ammonium removal. The control filter with sand and the experimental filter amended with the zeolite were also compared with respect to duration of filter cycle, cold weather operation, and economics. Amended and unamended filters were appr oximately equivalent with respect to ammonium and coliform removal at 10° C. The zeolite amended cell was superior to the unamended cell with respect to coliform and turbidity removal at 3° C. The zeolite amended cell had filter cycle durations four times longer and operation and maintenance costs 25% lower than the unamended cell. Laboratory column studies were also conducted to compare a control column of construction sand to a homogeneous sand-zeolite mixture. and to SSF amended with zeolite or coarse sand. Construction sand and clinoptilolite were very similar in metal removal efficiency. Head loss developed most rapidly in the SSF column with construction sand only. Head loss developed more slowly resulting in longer filter cycles when the SSF was amended with a zeolite or coarse sand surface layer. A homogeneous sand-clinoptilolite mixture had filter cycles longer than construction sand, but shorter than SSF amended with a coarse surface medium. Batch reactor tests were utilized to compare adsorption of reovirus to sand and clinoptilolite. Reovirus adsorption was approximately equivalent for the two media.

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Hemicelluloses (HC) are the second most abundant plant polysaccharides after cellulose, constituting 25-30% of plant materials. In spite of their abundance, HC are not effectively utilized. Recently, considerable interest has been directed to HC-based biomaterials because of their high oxygen barrier properties, which has potential in food packaging applications. In this study, HC were extracted from sugarcane bagasse and southern yellow pine using a hydrothermal technique which utilizes hot compressed water without catalyst. The parameters affecting the yield of extracted HC such as temperature, time and pressure, were tested and optimized. Eighty four percent of xylose was extracted from sugarcane bagasse at the optimum condition, 180 °C 30 min and 1 MPa pressure. In the case of southern yellow pine, 79% of the mannose was extracted at 190 °C for 10 min and 2 MPa pressure. Concentration and isolation of HC from bagasse and southern yellow pine HC extract were performed by membrane filtration and freeze drying systems. Isolated HC were characterized by FT-IR and 13C NMR techniques and used as a starting material for film preparation. Films were prepared in 0/100, 50/50, 60/40, 70/30 and 80/20% ratios of HC and sodium carboxymethylcellulose (CMC). Thirty five percent of sorbitol (w/w of HC and CMC weight) was also added as a plasticizer. Films were evaluated by measuring water absorption, water vapor permeability (WVP), tensile property and oxygen barrier capability. At 55% relative humidity (RH) and 25 °C the water absorption of both sugarcane bagasse and southern yellow pine HC-based films tended to increase as HC content increased. The lowest WVP of sugarcane bagasse (3.84e-12 g/Pa h m) and southern yellow pine HC films (2.18e-12 g/Pa h m) were determined in 60/40 HC/CMC films. Tensile test results showed that as HC content increases the Young’s modulus decreases, deflection at maximum load and percentage of strain at break increase. It implies that the film properties are changing from stiff to elastic. The oxygen permeability for 60/40 bagasse HC/CMC film was 0.005265 cc μm / (m2 day kPa) and for 70/30 pine HC/CMC film was 0.007570 cc μm /(m2 day kPa).

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No description available.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.