Dans un contexte de fort développement des biotechnologies, de plus en plus de composés sont extraits, généralement par l'utilisation d'un solvant, à partir de bio-ressources renouvelables. L'éthanol (parfois en mélange avec de l'eau) est un des solvants utilisés car il permet de solubiliser des molécules polaires moyennement hydrophobes et peut être, lui-même, produit par fermentation à partir de bio-ressources renouvelables. Après l'étape d'extraction, les procédés baro-membranaires, et en particulier l'ultrafiltration (UF), peuvent être des solutions pertinentes en vue d'un fractionnement plus fin des constituants de l'extrait. Cependant, à ce jour, si ce procédé est largement développé en milieu aqueux, peu d'études portent sur l'UF en milieu hydro-alcoolique à des teneurs supérieures à 15% en éthanol. Le but de ces travaux est d'étudier l'impact du changement de solvant sur les mécanismes de transfert en UF. Pour cela, une étude systématique de l'UF a été réalisée dans des mélanges eau/éthanol de composition variable allant jusqu'à 30% d'éthanol en volume. L'UF a été conduite en utilisant une protéine modèle, le lysozyme, choisie en raison simultanément de sa bonne stabilité dans les milieux filtrés et de la variation de sa charge en fonction de son environnement physico-chimique (pH, force ionique). L'ajout de sels (NaCl, KH2PO4) aux milieux hydro-alcooliques a permis de montrer l'impact de la modulation des interactions électrostatiques, connues pour jouer un rôle important sur les performances de rétention en UF en milieu aqueux. Les rétentions expérimentales, obtenues au moyen d'une membrane en oxyde de zirconium, ont été interprétés à l'aide du modèle CDE (convection – diffusion – migration électrophorétique) précédemment développé à l'ISCR pour les milieux aqueux et contribuent ainsi à l'extension du domaine d'application de ce modèle. / In the context of the rapid growth of the biotechnological sector, more and more molecules are extracted from renewable resources using solvent extraction. Ethanol (alone or in mixture with water) is one of the most used solvent as it allows solubilizing polar molecules exhibiting moderately hydrophobic nature. Furthermore, it can be itself produced by fermentation using renewable bioresources as a substrate. Following the extraction step, pressure-driven membrane processes, and ultrafiltration (UF) in particular, can be used for further fractionation of the alcoholic extract. However, to date, UF is widely studied in aqueous solution but only few studies deal with its application to the filtration of hydro-alcoholic medium for ethanol concentration above 15%. The objective of this work is thus to study the consequences of the solvent modification on UF transfer mechanisms. To this end, a systematic study of UF in water/ethanol mixture of variable composition up to 30 % (v/v) has been carried out. Lysozyme has been chosen as the model solute due to its high stability in the tested conditions and its surface charge modification according to the physicochemical environment (pH, ionic strength). Thereby, electrostatic interactions known to play a key role in aqueous UF, where modulated by salt addition (NaCl, KH2PO4) to the hydro-alcoholic mixtures. Experimental results obtained using a zirconium oxide membrane were analyzed using the CDE (convection, diffusion and electrophoretic migration) model previously developed in our group for aqueous filtration. The range of application of the CDE model is thus enlarged to the case of water/ethanol mixtures.

To assess polishing of anaerobic secondary effluent and symbiotic bioremediation of primary effluent by microalgae, bench scale bubbling column reactors were operated in batch modes to test nutrients removal capacity and associated factors. Chemical oxygen demand (COD) together with oil and grease in terms of hexane extractable material (HEM) in the reactors were measured after batch cultivation tests of Chlorella Vulgaris, indicating the releasing algal metabolites were oleaginous (dissolved HEM up to 8.470 mg/L) and might hazard effluent quality. Ultrafiltration adopted as solid-liquid separation step was studied via critical flux and liquid chromatography-organic carbon detection (LC-OCD) analysis. Although nutrients removal was dominated by algal assimilation, nitrogen removal (99.6% maximum) was affected by generation time (2.49 days minimum) instead of specific nitrogen removal rate (sN, 20.72% maximum), while phosphorus removal (49.83% maximum) was related to both generation time and specific phosphorus removal rate (sP, 1.50% maximum). COD increase was affected by cell concentration (370.90 mg/L maximum), specific COD change rate (sCOD, 0.87 maximum) and shading effect. sCOD results implied algal metabolic pathway shift under nutrients stress, generally from lipid accumulation to starch accumulation when phosphorus lower than 5 mg/L, while HEM for batches with initial nitrogen of 10 mg/L implied this threshold around 8 mg/L. HEM and COD results implied algal metabolic pathway shift under nutrients stress. Anaerobic membrane bioreactor effluent polishing showed similar results to synthetic anaerobic secondary effluent with slight inhibition while 4 symbiotic bioremediation of raw municipal wastewater with microalgae and activated sludge showed competition for ammonium together with precipitation or microalgal luxury uptake of phosphorus. Critical flux was governed by algal cell concentration for ultrafiltration membrane with pore size of 30 nm, while ultrafiltration membrane rejected most biopolymers (mainly polysaccharides). Further research would focus on balancing cell growth, specific nutrients removal, and specific COD change by utilizing rotating biological contactor.

Low-pressure membrane systems such as Microfiltration (MF) and Ultrafiltration (UF) have been presented as viable option to pre-treatment systems in potable water applications. UF membranes are sporadically backwashed with ultra-filtered water to remove deposited matter from the membrane and restore it. Several factors that may cause permeability and selectivity decrease are involved and numerous procedures are applicable to achieve this objective. Membrane cleaning is the most important step required to maintain the characteristics of the membrane. This research was made with the purpose of investigating the effects of acid cleaning during chemically enhanced backwashing (CEB) on the performance of ultrafiltration (UF) membranes in seawater reverse osmosis (SWRO) pretreatment. To accomplish this, the questions made were: Does the acid addition (before or after the alkali CEB) influence the overall CEB cleaning effectiveness on Dow UF membrane? Does the CEB order of alkali (NaOCl) and acid (H2SO4) affect the overall CEB cleaning effectiveness? If yes, which order is better/worse? What is the optimal acid CEB frequency that will ensure the most reliable performance of the UF?. To answer this queries, a series of sequences were carried out with different types of chemical treatments: Only NaOCl, daily NaOCl plus weekly acid, daily NaOCl plus daily acid, and weekly acid plus daily NaOCl. To investigate the consequence of acid by studying the effect of operational data like the trans-pressure membrane, resistance or permeability and support that by the analytical experiments (organic, inorganic and microbial characterization). Microorganisms were removed almost completely at hydraulic cleaning and showed no difference with addition of acid. As a conclusion of the operational data the organic and inorganic chatacterization resulted in the elimination of the first sequence due to the acummulation of fouling over time, which produces that the cleaning increases downtime, productivity diminishes, Increases water cost, shortens membrane lifespan and the frequency of cleaning in place (CIP). The elimination of the third sequence, NaOCl followed by daily acid, resulted in excessive dosing of acid which affects fibers and increases the water cost. The removal of organic carbon and inorganic fractions for the second and third sequence were investigated. The better removal of Iron was in the last sequence with value of 11.52 mg/l due to acid was dose first which target inorganic foulants. The better removal of bio polymers was obtained at the second sequence with a value of 0.95 mg/l owed to the influence of chorine CEB to acid which oxidized biopolymers with higher molecular weight to smaller, then when the acid CEB removed it in a larger amount. While the last sequence was 0.57 mg/l. It can be concluded that second sequence provided a better removal that the last sequence. To support this conclusion, the operational data was compared to the second sequence is operationally sustainable, therefore in this revision the best sequence was the second.

The diploma thesis deals with the application of membrane processes for the treatment of washing water from sand filters of pool technology to parameters suitable for its reuse, not only on a theoretical level, but also on a real example. The experimental part deals with the monitoring of relevant parameters given by Decree no. 568/2000 Sb. and other technologically significant water quality indicators. All monitored parameters in the reverse osmosis permeate reached satisfactory values and thus it was concluded that the effluent water is suitable for reuse. Instead of being discharged into the sewer, it is possible to recycle 70 to 80 % of the washed water per day thanks to the applied technology, which saves approximately 20 m3 of water per day.

Membrane processes are considered energy-efficient for water desalination and treatment. However most membranes are based on polymers prepared from fossil petrochemical sources. The development of multilayer membranes for nanofiltration and ultrafiltration, with thin selective layers of naturally available cellulose, has been hampered by the availability of non-aggressive solvents. We propose the manufacture of cellulose membranes based on two approaches: (i) silylation, coating from solutions in tetrahydrofuran, followed by solvent evaporation and cellulose regeneration by acid treatment; (ii) casting from solution in 1-ethyl-3-methylimidazolum acetate ([C2mim]OAc), an ionic liquid, followed by phase inversion in water. In the search for less harsh, greener membrane manufacture, the combination of cellulose and ionic liquid is of high interest. Due to the abundance of OH groups and hydrophilicity, cellulose-based membranes have high permeability and low fouling tendency. Membrane fouling is one of the biggest challenges in membrane industry and technology. Accumulation and deposition of foulants onto the surface reduce membrane efficiency and requires harsh chemical cleaning, therefore increasing the cost of maintenance and replacement. In this work the resistance of cellulose 5 membranes towards model organic foulants such as Suwanee River Humic Acid (SRHA) and crude oil have been investigated. Cellulose membrane was tested in this work for oil-water (o/w) separation and exhibited practically 100 % oil rejection with good flux recovery ratio and membrane resistivity. The influence of anionic, cationic and ionic surfactant as well as pH and crude oil concentration on oil separation was investigated, giving a valuable insight in experimental and operational planning.

<p>The clogging of filtration membrane by particles otherwise known as fouling is a major concern in membrane filtration technology due reduction of flux, membrane lifespan and system performance, with an associated increase in process and operating costs in industries that utilize membrane in their production process. Cleaning or replacement of a fouled membrane requires production to be interrupted or the entire system to be shut down. This is because the cleaning or replacement of the fouled membrane requires production to be interrupted for the cleaning process or the entire system to be shut down for the replacement process to take place, leading to great losses to the industries involved. Many approaches have been devised over the years to tackle this problem, of which not only undermine the performance of the filtration membrane but also contribute to great losses to industries that apply them. Cheaper and more efficient means of fouling control remains the key to solving this problem. </p> <p> </p> <p>A water filtration system is proposed that uses piezoelectric crystals attached on a tubular polyvinylidene fluoride (PVDF) membrane to increase flux and delay the clogging of the pores of the filtration membrane (by particles). Filtration tests with mud solution showed that the membrane vibrated with piezoelectrics reduced the clogging of the pores and increased permeate flux of the filtration process as compared to the non-vibrated membrane. To optimize the permeate flux production of the system and fouling reduction, the effects of voltage, concentration and location of piezoelectric crystals<a> were investigated. An equation to best fit the experimental data was developed which can help in the optimization of the variables.</a></p> <p> </p> <p> </p> <p> </p> <p> </p> <p> </p>

Increasing demand for fresh water in arid and semi-arid areas, similar to the Middle East, pushed for the use of seawater desalination techniques to augment freshwater. Seawater Reverse Osmosis (SWRO) is one of the techniques that have been commonly used due to its cost effectiveness. Recently, the use of Ultrafiltration (UF) was recommended as an effective pretreatment for SWRO membranes, as opposed to conventional methods (i.e. sand filtration). During UF operation, intermittent cleaning is required to remove particles and contaminants from the membrane's surface and pores. The different cleaning steps consume chemicals and portion of the product water, resulting in a decrease in the overall effectiveness of the process and hence an increase in the production cost. This research focused on increasing the plant's efficiency through optimizing the cleaning protocol without jeopardizing the effectiveness of the cleaning process. For that purpose, the design of experiment (DOE) focused on testing different combinations of these cleaning steps while all other parameters (such as filtration flux or backwash flux) remained constant. The only chemical used was NaOCI during the end of each experiment to restore the trans-membrane pressure (TMP) to its original state. Two trains of Dow™ Ultrafiltration SFP-2880 were run in parallel for this study. The first train (named UF1) was kept at the manufacturer's recommended cleaning steps and frequencies, while the second train (named UF2) was varied according to the DOE. The normalized final TMP was compared to the normalized initial TMP to measure the fouling rate of the membrane at the end of each experiment. The research was supported by laboratory analysis to investigate the cause of the error in the data by analyzing water samples collected at different locations. Visual inspection on the results from the control unit showed that the data cannot be reproduced with the current feed water quality. Statistical analysis using SAS JMP® was performed on the data obtained from UF2 determined that the error in the data was too significant, accounting for 42%. Laboratory inspection on water samples concluded that the water quality feeding to the UF membranes was worse than that of the raw water. This led to a conclusion that severe contamination occurred within the main feed tank where the water was retained before arriving to the UF modules. The type of contamination present in the feed tank is yet to be investigated. Though, frequent cleaning or flushing of the feed tank is recommended on regular basis.

Transparent exopolymer particles (TEP) have been reported as one of the main factors of membrane fouling in seawater reverse osmosis (SWRO) process. Research has been focused on algal TEP so far, overlooking bacterial TEP. This thesis investigated the effects of coagulation on removal of bacterial TEP/TEP precursors in seawater and subsequent reduction on TEP fouling in ultrafiltration (UF), as a pretreatment of SWRO. Furthermore, the performance of pretreatment (coagulation + UF) has been investigated on a bench-scale SWRO system. TEP/TEP precursors were harvested from a strain of marine bacteria, Pseudoalteromonas atlantica, isolated from the Red Sea. Isolated bacterial organic matter (BOM), containing 1.5 mg xanthan gum eq./L TEP/TEP precursors, were dosed in Red Sea water to mimic a high TEP concentration event. Bacterial TEP/TEP precursors added to seawater were coagulated with ferric chloride and aluminum sulfate at different dosages and pH. Results showed that ferric chloride had a better removal efficiency on TEP/TEP precursors. Afterwards, the non-coagulated/coagulated seawater were tested on a UF system at a constant flux of 130 L/m2h, using two types of commercially available membranes, with pore sizes of 50 kDa and 100 kDa, respectively. The fouling potential of coagulated water was determined by the Modified Fouling Index (MFI-UF). Transmembrane pressure (TMP) was also continuously monitored to investigate the fouling development on UF membranes. TEP concentrations in samples were determined by the alcian blue staining assay. Liquid chromatography-organic carbon detection (LC-OCD) was used to determine the removal of TEP precursors with particular emphasis on biopolymers. Finally, SWRO tests showed that TEP/TEP precursors had a high fouling potential as indicated by MFI-UF, corresponding to the TMP measurements. Coagulation could substantially reduce TEP/TEP precursors fouling in UF when its dosage was equal or higher than 0.2 mg Fe/L. The flux decline experiments showed that coagulation + UF pretreated water had a smaller fouling potential than MF pretreated water. This thesis also provides useful and practical information on controlling bacterial TEP/TEP precursors fouling in UF and RO systems.

Several attempts have been made to combine the unique characteristics of graphene oxide (GO) and commercial polymers for successfully designing and fabricating next-generation membranes in filtration and separation technologies. The first part of the work develops a high flux polyethersulfone ultrafiltration membranes, by embedding GO sheets, starting from the polymer/GO solutions in ionic liquid and N, N dimethylformamide as co-solvents and promoting the pore formation via non-solvent induced phase separation. In the second part of the work, a protic ionic liquid was introduced as a solvent to disperse GO sheets and fabricate GO liquid crystal membranes for nanofiltration. The third part addresses the stability enhancement. GO membranes frequently disintegrate in aqueous environments due to swelling. Ethylenediamine was then used as a crosslinker, and the membranes were tested for organic solvent nanofiltration. Additionally, overcoming the permeation-rejection trade-off is challenging. Hence, the fourth work involved the intercalation of silica nanoparticles to form dual-sized nanochannels. In the final work, GO membranes were fabricated on the surface of hollow fibers to overcome scalability issues, by using a feasible spray coating method for efficient nanofiltration. Hollow fibers were crosslinked with hexamethylene diamine and GO was spray-coated on the crosslinked polymeric fibers for organic solvent nanofiltration. Overall, this study demonstrates the potential of GO in developing high-performance membranes for liquid separations relevant for industrial applications, such as wastewater treatment, food, chemical, petrochemical, and pharmaceutical processing.

Protein quality in freeze-dried skimmilk (SM), regular cottage cheese (RCC), retentate (Ret) and cottage cheese made from ultrafiltrated skimmilk (UFCC) were evaluated by chemical (amino acid score) and biological methods. Biological evaluation was at 5, 8 and 11% protein level in growing rats by measuring biological value (BV), net protein utilization (NPU) and nitrogen efficiency for growth (NEG) over a 14-day period. A 28-day protein efficiency ratio (PER) was determined on the same products at 10% protein level. Effects of added lactose on PER of retentate, regular and UFCC were also evaluated. The most limiting amino acids were cystine + methionine. Amino acid score for Animal Nutrition Research Council (ANRC) reference casein, SM, RCC, Ret and UFCC was 0.72, 0.91, 0.87, 0.91 and 0.98 respectively according to Food and Agricultural Organization/World Health Organization (FAO/WHO) pattern and 0.45, 0.56, 0.54, 0.57 and 0.61 respectively according to whole egg pattern. PER was 2.7, 3.0, 2.7, 3.1 and 2.8 for ANRC reference casein, SM, RCC, Ret and UFCC respectively. PER for retentate and skimmilk were significantly different from the cottage cheese. No significant difference in protein quality was obtained when the products were fed at 5, 8 and 11% levels. Average BV was 93, 91, 91, 95 and 94 for ANRC reference casein, SM, RCC, Ret and UFCC respectively. Average NPU was 87, 84, 83, 85 and 85 for ANRC reference casein, SM. RCC, Ret and UFCC respectively. Average NEG values were 66, 73, 70 77 and 73 for ANRC reference casein, SM, RCC, Ret and UFCC respectively. PER values were 2.7, 3.0, 2.7, 3.1 and 2.8 for ANRC reference casein, SM, RCC, Ret and UFCC respectively. Addition of lactose to a level equal to that in skimmilk reduced the PER value of RCC, Ret and UFCC by about 4%, 6% and 4% respectively. Though no significant difference in protein quality of the products were obtained, there was a tendency of ultrafiltration to increase protein quality.