L'objectif de ce travail a été d'évaluer la NF en tant qu'étape de purification au sein d'un procédé de production d'acide lactique. Une étude bibliographique a tout d'abord permis d'identifier différents niveaux potentiels d'intégration. Ceux-ci ont été évalués à partir d'une étude expérimentale réalisée pour une membrane donnée (Desal DK, Ge Water) avec des solutions de complexité croissante contenant en proportions variables l'espèce cible (acide lactique / lactate de sodium) et une impureté (glucose). Les rétentions intrinsèques de chaque soluté ont dans tous les cas été déterminées. Il est montré en particulier que la rétention du sucre diminue en présence d'une espèce dissociée (sel). Cet effet, dépendant à la fois de la nature et de la concentration du sel, provient vraisemblablement d'une diminution du rayon apparent du glucose dû au phénomène de "salting-out". L'ampleur de cette diminution a pu être quantifiée à partir de modèles de transport spécifiques.

Antioxidants are molecules capable of stabilizing and preventing oxidation. Certain peptides, protein hydrolysates, have shown antioxidant capacities, which are obtained once liberated from the native protein structure. Soy protein isolates (SPI) were enzymatically hydrolyzed by pepsin and pancreatin mixtures. The soy protein hydrolysates (SPH) were fractionated with sequential ultrafiltration (UF) and nanofiltration (NF) membrane steps. Heat pre-treatment of SPI at 95 degrees celsius (C) for 5 min prior to enzymatic hydrolysis was investigated for its effect on peptide distribution and antioxidant capacity. SPH were subjected to UF with a 10 kDa molecular weight cut off (MWCO) polysulfone membrane. UF permeate fractions (lower molecular weight than 10 kDa) were fractionated by NF with a thin film composite membrane (2.5 kDa MWCO) at pH 4 and 8. Similar peptide content and antioxidant capacity (α=0.05) were obtained in control and pre-heated SPH when comparing the respective UF and NF permeate and retentate fractions produced. FCR antioxidant capacities of the SPH fractions were significantly lower than their ORAC antioxidant capacities, and the distribution among the UF and NF fractions was generally different. Most UF and NF fractions displayed higher antioxidant capacities when compared to the crude SPI hydrolysates, showing the importance of molecular weight on antioxidant capacity of peptides. The permeate fractions produced by NF at pH 8 displayed the highest antioxidant capacity, expressed in terms of Trolox equivalents (TE) per total solids (TS): 5562 μmol TE/g TS for control SPH, and 5187 μmol TE/g TS for pre-heated SPH. Due to the improvement in antioxidant capacity of peptides by NF at pH 8, the potential for NF as a viable industrial fractionation process was demonstrated. Principal component analysis (PCA) of fluorescence excitation-emission matrix (EEM) data for UF and NF peptide fractions, followed by multi-linear regression analysis, was assessed for its potential to monitor and identify the contributions to ORAC and FCR, two in vitro antioxidant capacity assays, of SPH during membrane fractionation. Two statistically significant principal components (PCs) were obtained for UF and NF peptide fractions. Multi-linear regression models (MLRM) were developed to estimate their fluorescence and PCA-captured ORAC (ORAC-FPCA) and FCR (FCR-FPCA) antioxidant capacities. The ORAC-FPCA and FCR-FPCA antioxidant capacities for NF samples displayed strong, linear relationships at different pH conditions (R-squared>0.99). Such relationships are believed to reflect the individual and relative combined contributions of tryptophan and tyrosine residues present in the SPH fractions to ORAC and FCR antioxidant capacities. Therefore, the proposed method provides a tool for the assessment of fundamental parameters of antioxidant capacities captured by ORAC and FCR assays.

Nowadays, organic pollutants occurring in surface waters have raised substantial concern in public. Triclosan (TCS) is one of the antimicrobial agents which are utilized in both domestic and industrial application. In this study nanofiltration (NF) of TCS in surface water was investigated. Laboratory scale cross-flow device is operated in total recycle mode and DK-NF and DL-NF membranes were used. Kesikk&ouml / pr&uuml / Reservoir (Ankara) water was used as raw water. Effect of natural organic matter (NOM) content of raw water on TCS removal is searched through addition of humic acid (HA) into the raw water as to represent for NOM. Steady state permeate fluxes are monitored throughout the experiments to explore the flux behavior of the membranes. During the experiments, performance of the membranes is assessed by monitoring TCS, as well as other water quality parameters, such as UVA254 and total organic carbon (TOC) in the feed and permeates waters. Results obtained put forward that TCS removal by NF membrane is not as same as reported in the literature. In the literature, membrane removal efficiency is reported as above 90%. However, this study proved that this would be true if and only if one does not considers the adsorption of TCS by the system itself, in the absence of membrane. It is now clear that, because of adsorption of the TCS onto the experimental set up (feed tank, pipings etc.) / the real TCS removal efficiency of the nanofiltration is around 60-70%.

Arsenic is a known carcinogen, causing cancers of the skin, lungs, bladder and kidney. Current research suggests that drinking water is the most common pathway for long-term low dose exposure. Arsenic contaminated drinking water has caused serious health problems in many countries including: India, Bangladesh, Argentina, Chile, Taiwan, the United States and Canada. Nanofiltration (NF) is a promising technology for arsenic removal since it requires less energy than traditional reverse osmosis membranes. Several studies have shown that nanofiltration is capable of removing the oxidized form of arsenic [As(V)] while the reduced form of arsenic [As(III)] is poorly removed. To exploit this difference it has been suggested that a pretreatment step which oxidizes the As(III) to As(V) would improve the performance of membrane filtration, but this has never been demonstrated. The research had three objectives: The first was to investigate the ability of NF membranes to treat arsenic contaminated groundwater and evaluate the influence of the membrane type and operating conditions. Secondly, the effectiveness of a solid phase oxidizing media (MnO2) to oxidize arsenite to arsenate was investigated. Lastly, the MnO2 was combined with NF membrane filtration to determine the benefit, if any, of oxidizing the arsenic prior to membrane filtration. A pilot membrane system was installed to treat a naturally contaminated groundwater in Virden, Manitoba, Canada. The groundwater in Virden contains between 38 and 44 µg/L of arsenic, primarily made up of As(III), with little particulate arsenic. In the first experiment three Filmtec® membranes were investigated: NF270, NF90 and XLE. Under all conditions tested the NF90 and NF270 membranes provided insufficient treatment of Virden's groundwater to meet Canada's recommended Interim Maximum Acceptable Concentration (IMAC) of 25 µg/L. The XLE membrane provided better arsenic removal and under the conditions of 25 Lmh flux and 70% recovery produced treated water with a total arsenic concentration of 21 µg/L. The XLE membrane is therefore able to sufficiently treat Virden's ground water. However treatment with the XLE membrane alone is insufficient to meet the USEPA's regulation of 10 µg/L or Canada's proposed Maximum Allowable Concentration (MAC) of 5 µg/L. The effects of recovery and flux on total arsenic passage are consistent with accepted membrane theory. Increasing the flux increases the flow of pure water through the membrane; decreasing the overall passage of arsenic. Increasing the recovery increases the bulk concentration of arsenic, which leads to higher arsenic passage. The second experiment investigated the arsenic oxidation capabilities of manganese dioxide (MnO2) and the rate at which the oxidation occurs. The feed water contained primarily As(III), however, when filtered by MnO2 at an Empty Bed Contact Time (EBCT) of only 1 minute, the dominant form of arsenic was the oxidized form [As(V)]. At an EBCT of 2 minutes the oxidation was nearly complete with the majority of the arsenic in the As(V) form. Little arsenic was removed by the MnO2 filter. The third and final experiment investigated the benefit, if any, to combining the membrane filtration and MnO2 treatment investigated in the first and second experiments. The effect of MnO2 pretreatment was dramatic. In Experiment I, the NF270 and NF90 membranes were unable to remove any arsenic while the XLE removed, at best, approximately 50% of the arsenic. Once pretreated with MnO2 the passage of arsenic through all of the membranes dropped to less than 4 µg/L, corresponding to approximately 91% to 98% removal. The dramatic improvement in arsenic removal can be attributed to charge. All three membranes are negatively charged. Through a charge exclusion effect the rejection of negatively charged ions is enhanced. During the first experiment, As(III) (which is neutrally charged) was the dominant form of arsenic, and was uninfluenced by the negative charge of the membrane. Once oxidized to As(V), the arsenic had a charge of -2, and was electrostatically repelled by the membrane. This greatly improved the arsenic rejection characteristics of the membrane. Nanofiltration alone is not a suitable technology to remove arsenic contaminated waters where As(III) is the dominant species. When combined with MnO2 pre-oxidation, the arsenic rejection performance of nanofiltration is dramatically improved.

Arsenic is a known carcinogen, causing cancers of the skin, lungs, bladder and kidney. Current research suggests that drinking water is the most common pathway for long-term low dose exposure. Arsenic contaminated drinking water has caused serious health problems in many countries including: India, Bangladesh, Argentina, Chile, Taiwan, the United States and Canada. Nanofiltration (NF) is a promising technology for arsenic removal since it requires less energy than traditional reverse osmosis membranes. Several studies have shown that nanofiltration is capable of removing the oxidized form of arsenic [As(V)] while the reduced form of arsenic [As(III)] is poorly removed. To exploit this difference it has been suggested that a pretreatment step which oxidizes the As(III) to As(V) would improve the performance of membrane filtration, but this has never been demonstrated. The research had three objectives: The first was to investigate the ability of NF membranes to treat arsenic contaminated groundwater and evaluate the influence of the membrane type and operating conditions. Secondly, the effectiveness of a solid phase oxidizing media (MnO2) to oxidize arsenite to arsenate was investigated. Lastly, the MnO2 was combined with NF membrane filtration to determine the benefit, if any, of oxidizing the arsenic prior to membrane filtration. A pilot membrane system was installed to treat a naturally contaminated groundwater in Virden, Manitoba, Canada. The groundwater in Virden contains between 38 and 44 µg/L of arsenic, primarily made up of As(III), with little particulate arsenic. In the first experiment three Filmtec® membranes were investigated: NF270, NF90 and XLE. Under all conditions tested the NF90 and NF270 membranes provided insufficient treatment of Virden's groundwater to meet Canada's recommended Interim Maximum Acceptable Concentration (IMAC) of 25 µg/L. The XLE membrane provided better arsenic removal and under the conditions of 25 Lmh flux and 70% recovery produced treated water with a total arsenic concentration of 21 µg/L. The XLE membrane is therefore able to sufficiently treat Virden's ground water. However treatment with the XLE membrane alone is insufficient to meet the USEPA's regulation of 10 µg/L or Canada's proposed Maximum Allowable Concentration (MAC) of 5 µg/L. The effects of recovery and flux on total arsenic passage are consistent with accepted membrane theory. Increasing the flux increases the flow of pure water through the membrane; decreasing the overall passage of arsenic. Increasing the recovery increases the bulk concentration of arsenic, which leads to higher arsenic passage. The second experiment investigated the arsenic oxidation capabilities of manganese dioxide (MnO2) and the rate at which the oxidation occurs. The feed water contained primarily As(III), however, when filtered by MnO2 at an Empty Bed Contact Time (EBCT) of only 1 minute, the dominant form of arsenic was the oxidized form [As(V)]. At an EBCT of 2 minutes the oxidation was nearly complete with the majority of the arsenic in the As(V) form. Little arsenic was removed by the MnO2 filter. The third and final experiment investigated the benefit, if any, to combining the membrane filtration and MnO2 treatment investigated in the first and second experiments. The effect of MnO2 pretreatment was dramatic. In Experiment I, the NF270 and NF90 membranes were unable to remove any arsenic while the XLE removed, at best, approximately 50% of the arsenic. Once pretreated with MnO2 the passage of arsenic through all of the membranes dropped to less than 4 µg/L, corresponding to approximately 91% to 98% removal. The dramatic improvement in arsenic removal can be attributed to charge. All three membranes are negatively charged. Through a charge exclusion effect the rejection of negatively charged ions is enhanced. During the first experiment, As(III) (which is neutrally charged) was the dominant form of arsenic, and was uninfluenced by the negative charge of the membrane. Once oxidized to As(V), the arsenic had a charge of -2, and was electrostatically repelled by the membrane. This greatly improved the arsenic rejection characteristics of the membrane. Nanofiltration alone is not a suitable technology to remove arsenic contaminated waters where As(III) is the dominant species. When combined with MnO2 pre-oxidation, the arsenic rejection performance of nanofiltration is dramatically improved.

Cocoon cooking wastewaters (CW) and silk degumming wastewaters (SDW) of silk processing industry were treated by membrane processes for sericin recovery. CW contains only sericin while SDW contains both sericin and soap. Sericin in CW had four molecular weight (MW) fractions / 175-200 kDa (Sericin-1), 70-90 kDa (Sericin-2), 30-40 kDa (Sericin-3) and 10-25 kDa (Sericin-4). Two alternative process trains were developed for CW / 1. centrifugation + microfiltration + nanofiltration + precipitation, 2. centrifugation + microfiltration + nanofiltration + dialysis + precipitation. In the first process, a sericin/silkworm protein mixture was obtained with a sericin content of 39-46%. In the second one, however, a pure sericin product was obtained. The sericin recovery efficiency of the developed process train was found as 76%. Severe flux declines of 70-75% were observed in NF stage in both process trains. However, cleaning with 0.5 M NaOH and 190-200 mg/L free chlorine restored the fluxes by 83-127%. The MW of sericin in SDW was 110-120 kDa. The soap and sericin were separated in the pre-treatment stage consisting of centrifugation (pH 3.5, 10 min) and gravity settling (4 oC, 24 h). The ultrafiltration membrane with molecular weight cut-off of 5 kDa achieved 59% sericin recovery at pH 3.5, accompanied by severe flux decline of 88%. Furthermore, clean water flux was restored by only 31% via chemical cleaning.

ABSTRACT SULPHATE REMOVAL BY NANOFILTRATION FROM WATER Karabacak, Asli M.Sc., Department of Environmental Engineering Supervisor: Prof. Dr. &Uuml / lk&uuml / Yetis Co-advisor: Prof. Dr. Mehmet Kitis December 2010, 152 pages Excess sulphate in drinking water poses a problem due to adverse effects on human health and also due to aesthetic reasons. This study examines the nanofiltration (NF) of sulphate in surface water using a laboratory cross-flow device in total recycle mode. In the study, three NF membranes, namely DK-NF, DL-NF and NF-270, are used. The influence of the main operating conditions (transmembrane pressure, tangential velocity and membrane type) on the steady-state permeates fluxes and the retention of sulphate are evaluated. Kizilirmak River water is used as the raw water sample. During the experimental studies, the performance of NF is assessed in terms of the parameters of UVA254, sulphate, TOC and conductivity of the feed and permeates waters. Results indicated that NF could reduce sulphate levels in the surface water to a level below the guideline values, with a removal efficiency of around 98% with all three membranes. DK-NF and NF-270 membranes showed fouling when the surface water was fed directly to the system without any pre-treatment. MF was found to be an effective pretreatment option for the prevention of the membrane fouling, but no further removal of sulphate was achieved. Parametric study was also conducted. No change in flux values and in the removal of sulphate was observed when the crossflow velocity was lowered. The flux values were decreased as the transmembrane pressure was lowered / however there were not any decrease in the sulphate removal efficiency.

Synthetic single-walled metal oxide (aluminosilicate) nanotubes (SWNTs) are emerging materials for a number of applications involving molecular transport and adsorption due to their unique pore structure, high surface reactivity, and controllable dimensions. In this thesis, I discuss the potential for employing SWNTs in next generation separation platforms based upon recent progress on synthesis, interior modification, molecular diffusion properties, transport modeling and composite membrane preparation of metal oxide SWNTs. First, I describe the structure, synthesis, and characterization of the SWNTs. Thereafter, chemical modification of the nanotube interior is described as a means for tuning the nanotube properties for molecular separations. Interior functionalization of SWNTs (e.g. carbon nanotubes and metal oxide nanotubes) is a long-standing challenge in nanomaterials science. After controlled dehydration and dehydroxylation of the SWNTs, I then demonstrate that the SWNT inner surface can be functionalized with various organic groups of practical interest via solid-liquid heterogeneous reactions. Finally, I describe a mass transport modeling and measurements for composite membranes composed of SWNTs as fillers. This work demonstrates the use of SWNTs for novel scalable separation units from both a nanoscale and a macroscale point of view.

Ziel dieser Arbeit ist die Abtrennung von monovalenten Anionen wie Chlorid, Fluorid, Bromid und Nitrat aus hochkonzentrierten alkalischen wässrigen Lösungen, die als Matrix zweiwertigen Anionen (Carbonat und Sulfat) besitzen. Nach Auswertung der Literatur eignen sich vor allem die Verfahren Ionenaustausch und Nanofiltration für diesen Zweck. Die untersuchten Ionenaustauscher weisen eine geringe Selektivität für die einwertigen Anionen auf, so dass die für einwertige Anionen nutzbare Kapazität mit steigendem Gehalt an zweiwertigen Anionen sinkt. Dabei steigt die Kapazität in der Reihenfolge Fluorid→Chlorid→Bromid→Nitrat. Die beobachteten Selektivitäten bei der Nanofiltration steigen in der gleichen Reihenfolge, wobei die Trennrate zwischen ein- und zweiwertigen Anionen vom Membrantyp abhängt. Es konnte ein Zusammenhang zwischen den Kapazitäten der untersuchten stark basischen Anionenaustauscher für monovalente Anionen und den Rückhalten für diese Anionen bei den Nanofiltrationsmembranen mit den Ionenhydratationsparametern festgestellt werden.

D. Tech. Chemical Engineering / Concerns for the limitations of conventional technology for acid mine water treatment and the potential use of waste water have led to increased interest in membrane technologies. Studying the physical properties of nanofiltration membranes is a very important development in nanofiltration separation process. For optimum separation performance, the nanofiltration membranes have to possess certain physical properties, given the appropriate interactions with solutes in the process stream. This study investigated the performance evaluation of Nano-Pro-3012 and NF90 membranes in the treatment of synthetic wastewater effluents and acid mine water and the influence of membrane characteristics on retention in nanofiltration. The research was aimed to evaluate the performance of a new acid stable nanofiltration material (Nano-Pro-3012) produced by Bio Pure Technology for the removal of heavy metals from shaft 8 at Rand Uranium wastewater treatment plant and compare with a commercially available nanofiltration membrane.