Effect Of Transmembrane Pressure Research Articles

ZrO2 Nanoparticles Filler-Based Mixed Matrix Polyethersulfone/Cellulose Acetate Microfiltration Membrane for Oily Wastewater Separation

Membrane technology has emerged as a dynamic field of study in academia and industry for treating produced oily wastewater. ZrO2 nanoparticles (ZrO2 NPs) filler-based mixed matrix polyethersulfone/cellulose acetate microfiltration membranes were fabricated and inspected in the oily wastewater remediation. The fabricated bare PES membrane, PES/CA blended polymers membrane, and PES/CA blended polymers incorporating ZrO2 NPs (ZrO2@PES/CA) membranes by phase inversion technique were inspected by field emission scanning electron microscopy, atomic force microscopy, Fourier-transform infrared spectroscopy, and measurement of water contact angle and porosity. The ZrO2@PES/CA membrane which consisted of 0.5 wt.% ZrO2 NPs (0.5%ZrPC) afforded increased hydrophilicity and reduced water contact angle from 70° for P membrane to 30.23°. Also, the 0.5%ZrPC membrane gave pure water flux of 88.89 L/m2.h, high oil rejection of 98.2% and showed remarkable antifouling capacity with a high flux recovery ratio of 89.3% and relative flux reduction of 34.3%. The effect of transmembrane pressure (1, 2, 3, and 4 bar), feed temperature (25, 40, and 50 °C), and an initial oil concentration (250, 500, 750, and 1000 mg/L) on the permeation flux and oil rejection of the 0.5%ZrPC membrane was investigated. The results revealed that ZrO2@PES/CA membranes have a significant potential for effective oil removal with high permeability and antifouling ability. The 0.5%ZrPC membrane confirmed its durability and reusability when kept an acceptable oil removal after 5 cycles.

The Effect of Transmembrane Pressure and Diffusion of Essential Substances on the Transformation of the Structure in Polymer Films of UPM-100 and PP-190 Type

The Effect of Transmembrane Pressure and Diffusion of Essential Substances on the Transformation of the Structure in Polymer Films of UPM-100 and PP-190 Type

Production of high-quality drinking water from chillers and air conditioning units’ condensates using UV/GAC/MF/NF hybrid system

In hot and humid regions, like the Middle East nations, where access to drinking water is minimal, water recycling and purification are essential. In this work, high-quality drinking water was produced by treating the condensates obtained from the air conditioning units. A membrane-based hybrid system consisting of ultraviolet irradiation, granular activated carbon, microfiltration, and nanofiltration membranes (UV/GAC/MF/NF) was applied in series to minimize the NF membrane fouling and enhance the product water quality. The microbial, organic, and ionic species of the feed and the product water were analyzed, and the target was defined to maximize the permeate flux (JV) and minimize the concentration of the organic matter in the product water (CODP). The effects of trans-membrane pressure (TMP, 2–5 bar) and feed flow rate (QF, 340–510 L h−1) on the target parameters were investigated through the Taguchi design of experiments and the ANOVA method. The obtained results showed that at the optimum conditions, almost a complete reduction of TDS (>98.37%), of COD (>97.87%), of BOD5 (>96.04%), of the total and digestive coliforms (100%), and turbidity (91.06%) were achieved. Additionally, it was found that the TMP and the QF were the most influential parameters on JV and CODP, respectively. The product water analysis at different stage cuts showed that the hybrid system is capable of recovering more than 97% of the feed water while the TDS, BOD5, and turbidity of the product water are only 2.58 ppm, 2.62 mg. L−1, and 0.22 NTU, respectively.

Optimization of hemicellulose recovery from black liquor using ZnO/PES ultrafiltration membranes in crossflow mode

Black liquor, one of the by-products of pulp and paper industry, is an underexplored resource with great potential for the recovery of valuable biopolymers such as lignin and hemicelluloses. In this work, the hemicellulose was recovered from this liquor, containing 17 % of total dissolved solids, using ZnO/polyethersulfone ultrafiltration membrane. The hemicellulose was concentrated into the retentate stream while lignin was permeated through these membranes. The effects of transmembrane pressure (1 to 4 bar), time (up to 8 h) and crossflow velocity (0.1 and 0.2 m/s) were studied for ultrafiltration process operating in crossflow mode. The highest rejection of hemicellulose was achieved up to 90.7 ± 1.9 % at 4 bar. At 3 bar, the yield of hemicellulose was ≈ 90 % and 84 % for the volume reduction up to 60 % and 78 %, respectively. Mathematical modeling was applied to analyze the membrane fouling mechanism responsible for the flux reduction during filtration at constant pressure, as well as to predict the changes in hemicellulose and lignin concentration during the filtration process.

The Effect of Temperature and Transmembrane Pressure on the Camel Milk Ultrafiltration Performance: An Optimization Study

In this study, the effects of transmembrane pressure (TMP, 80-160 kPa) and temperature (T, 20-40 oC) were investigated on the ultrafiltration (UF) performance of camel milk, including pseudo-steady state permeate flux (JPSS), intrinsic membrane resistance (Rm), reversible fouling resistance (Rrf), irreversible fouling resistance (Rif), solutes rejection (protein (RP), lactose (RL), ash (RA) and total solids (RTS)) and minerals rejection (aluminum (RAl), iron (RFe), zinc (RZn), manganese (RMn), calcium (RCa), phosphorus (RPh), sodium (RNa), magnesium (RMg), and potassium (RK)). According to the obtained results, increasing TMP led to a significant increase in JPSS, Rrf, and RA while increasing T caused a significant increase in JPSS, Rrf, RL, RA, and the rejection of all minerals. Although the total fouling resistance (Rf) increased by increasing TMP and T, the share of Rrf was higher in high TMP and T compared to Rif. The results also showed that none of the linear, quadratic, and interaction effects of TMP and T on the Rm, RTS, and RP of the samples were significant. In general, camel milk solute rejections, i.e., RTS, RP, RL, RA, RAl, RFe, RZn, RMn, RCa, RPh, RNa, RMg, and RK were, on average, 51.03, 97.51, 4.73, 34.07, 99.05, 95.70, 90.64, 99.99, 46.09, 32.74, 20.44, 19.44, and 7.78%, respectively. Finally, the optimum UF performance conditions in this research with the lowest Rrf, Rif, RL, and RA while the highest JPSS and RP were 135 kPa TMP and 35 oC T.

Mathematical modeling of vibratory shear‐enhanced nanofiltration in the preconcentration of coffee extracts for soluble coffee manufacturing

AbstractA semi‐empirical model was applied to evaluate the performance of a vibratory nanofiltration (NF) system, using 150‐Da TS80 NF membrane, for the preconcentration of coffee extracts in soluble coffee processing. The effects of transmembrane pressure (TMP), feed concentration, and module vibration on flux enhancement were correlated with membrane surface concentrations and fouling resistances under steady state operation. Vibratory shear thinned the boundary layer and increased the mass transfer coefficient of the solvent (water) by a factor of 3.5. Membrane surface concentrations and fouling resistances reduced by 60% compared with crossflow (CF) NF operation. These reductions enhanced permeate fluxes by about 2–3 times that of CF operation, with low flux decline. Feed concentration and TMP promoted polarization more than the negative effect of vibration. Osmotic pressure resistances were dominant under low feed concentrations and TMP. However, concentration polarization resistances exceeded osmotic pressure resistances as TMP and feed concentrations were increased. Real rejections relative to membrane surface chemical oxygen demand (COD) were above 0.99, indicating the potential of the operation to recover permeate that is reusable for ancillary plant operations. Overall, the experimental and theoretical permeate fluxes and CODs were in reasonable agreement, indicating the reliability of the model.Practical ApplicationsVibratory membrane processes alleviate the issues on membrane fouling that is advantageous when integrated into food and beverage processes. Its application as a coffee extract preconcentration alternative to thermal evaporation opens opportunities for sustainable soluble coffee production that can be adapted in other food and beverage industries. However, the unique dynamic nature of the vibratory membrane system challenges conventional approaches for understanding and predicting the mechanisms of the process. This gap limits the overall transferability of the technology to broader industry sectors. The semi‐empirical resistance‐in‐series model developed in this study correlates the important factors with the vibratory NF performance based on fundamental concepts: concentration polarization, osmotic pressure effects, and fouling resistance. The model is not only useful in managing membrane fouling in vibratory systems, but also in optimizing and developing alternative approaches on similar lines and their scale‐up to promote other industrial applications.

Separation of bacteria Kocuria rhizophila BR-1 from its broth during synthesis of gold nanoparticles using ceramic membrane by shear-enhanced filtration process

In the present study, disc type ceramic membranes made from China clay, quartz and calcium carbonate were used for the separation of bacteria Kocuria rhizophila from its broth by shear-enhanced filtration process. Porosity, water permeability and average pore size of the membrane were 42%, 3.24 × 10−4 L m−2 h−1 Pa−1 and 180 nm, respectively. The membrane exhibited good chemical tolerance in acid, alkali and chlorine solutions. The effect of trans-membrane pressure and rotational speed on permeate flux and bacterial rejection was investigated. It was found that the permeate flux increased (40–163.5 L m−2 h−1) and bacterial rejection decreased (99.2–94.5%) with increasing pressure (69–345 kPa). With an increase in rotation (50–250 rpm), the permeate flux increased from 156.5 to 176.8 L m−2 h−1, while bacterial rejection decreased from 94.3 to 83.2%. The pressure of 345 kPa and rotational speed of 250 rpm with flux of 176.8 L m−2 h−1 and rejection of 83% was selected as an optimum process condition. The analysis of fouling models revealed that the cake filtration model provided the highest R2 (0.89) value followed by intermediate pore blocking (0.87) which indicates that cake filtration model has the best fit with the experimental data. Henceforth, the shear enhanced filtration process used in this study can be considered as a pertinent filtration process for efficient recovery of biological products at industrial scale.

Membrane Bioreactor Technology: The Effect of Membrane Filtration on Biogas Potential of the Excess Sludge.

Although the membrane bioreactor technology is gaining increasing interest because of high efficiency of wastewater treatment and reuse, data on the anaerobic transformations of retentate are scarce and divergent. The effects of transmembrane pressure (TMP) in microfiltration (MF) and ultrafiltration (UF) on the pollutant rejection, susceptibility of ceramic membrane to fouling, hydraulic parameters of membrane module, and biogas productivity of retentate were determined. Irrespective of the membrane cut-off and TMP (0.2–0.4 MPa), 97.4 ± 0.7% of COD (chemical oxygen demand), 89.0 ± 4.1% of total nitrogen, and 61.4 ± 0.5% of total phosphorus were removed from municipal wastewater and the permeates can be reused for irrigation. Despite smaller pore diameter, UF membrane was more hydraulically efficient. MF membrane had 1.4–4.6 times higher filtration resistances than UF membrane. In MF and UF, an increase in TMP resulted in an increase in permeate flux. Despite complete retention of suspended solids, strong shearing forces in the membrane installation changed the kinetics of biogas production from retentate in comparison to the kinetics obtained when excess sludge from a secondary clarifier was anaerobically processed. MF retentates had 1.15 to 1.28 times lower cumulative biogas production than the excess sludge. Processing of MF and UF retentates resulted in about 60% elongation of period in which 90% of the cumulative biogas production was achieved.

Treatability of household waste plastic garbage bag recycling industry wastewater with membrane

In this study, household waste plastic garbage bag recycling industry wastewater was treated by a membrane process to recycle water for using in the bags washing process. Two different ultrafiltration (UP150 and UP005) and nanofiltration (NF270 and NF90) membranes were tested. The steady-state permeate flux was obtained 14.9 and 19.2 L/m2.h at 5 bar for UP150 and UP005 membranes, respectively. However, the steady-state permeate flux was 12.9 and 8.9 L/m2.h at 20 bar for NF270 and NF90 membranes, respectively. The chemical oxygen demand (COD) was also tested for all membrane permeates and the highest COD removal efficiency was obtained for NF90 membrane. Thus, optimization was carried out using NF90 membrane and the effect of transmembrane pressure (10, 20, 30 bar) and solution pH (5, 7, 9) on COD removal efficiency was tested. The results showed that the highest steady-state permeate flux (23.5 L/m2.h) and COD removal efficiency (95.1%) were obtained at 30 bar and pH 9. After the optimization of the membrane type and operating conditions, 75% recovery was obtained to re-use in the bags washing process. The concentrate stream was treated by an activated sludge process to manage membrane concentrate and to provide discharge standards. The maximum COD removal efficiency in biological treatment for membrane concentrate stream was 96.2% under steady-state condition using a sequencing batch reactor (SBR) operated at 10 days of sludge retention time and 12 h of hydraulic retention time. The proposed combined process including membrane and activated sludge processes was successfully used to recover wastewater.

Design and optimization of a hybrid process based on hollow-fiber membrane/coagulation for wastewater treatment.

Treatment of textile wastewater using ultrafiltration membranes was carried out in this study. Since membrane fouling is a major operational problem that decreases the membrane separation efficiency, wastewater was treated with polyaluminum chloride (PACl) and alum (aluminum sulfate) as coagulant to decrease the fouling of ultrafiltration membranes. PACl was selected as the best coagulant in the experiments. Also, chitosan was used as coagulant aid upon developing the hybrid process. The obtained optimum dosage of PACl coagulant was 100mg/L, and maximum turbidity and COD removal of 35% and 66% were attained, respectively. The pretreated wastewater by coagulation was sent to ultrafiltration process for further removal of turbidity and COD. Three ultrafiltration hollow-fiber membranes made of polypropylene (PP), polyvinylidene fluoride (PVDF), and polyethersulfone (PES) were applied in this study. In general, the filtration results were evaluated for two types of samples treated under coagulation and without treatment; the results were unfavorable for the second type. The effects of transmembrane pressure (TMP) and cross velocity on membranes performance were also investigated for process optimization. The obtained results showed that PVDF membrane had the highest flux and turbidity removal, whereas the PES membrane had the highest COD removal. Also, the results revealed that turbidity and COD removal by all membranes were decreased by increasing TMP and cross velocity.

Thin film composite membranes: Does the porous support truly have negligible resistance?

The permeation resistance of the porous support in a thin film composite (TFC) membrane is believed to be negligible compared with that of the thin polyamide film. Indeed, the resistance of a porous support, as determined from direct water permeation experiments as a function of transmembrane pressure (TMP), is only a fraction of the total resistance of a typical TFC membrane. However, the true resistance of the porous support in a TFC membrane, especially during high-pressure reverse osmosis (RO), could be significantly different from the value obtained via direct permeation measurement. Although the porous support is subjected to mechanical loading equivalent to the overall TMP, the effective TMP across the porous support that generates deformation can be significantly lower due to the internal pressure of the water within the pores. In this study we utilized a serial configuration, consisting of a TFC membrane on top of a representative porous support, to quantify the true resistance of the porous support under conditions of high mechanical loading but low permeation. Unsurprisingly, the results confirm that the porous support resistance appears negligible as compared with that of the TFC membrane under low TMP. However, after exposure to high TMP in the serial configuration, the porous support evidences up to 15X larger plastic strain and 28X higher resistance as compared to the same support tested separately under low TMP. At TMP = 8.3 MPa, the additional porous support beneath the TFC membrane increases the overall resistance by 31%. Using a resistance in-series model, the data suggest that the true resistance of the porous support could be as high as ~ 45% that of the thin film under the high-TMP but low-permeation condition encountered during high-pressure RO desalination.

Recovery of Aromatics from Orange Juice Evaporator Condensate Streams by Reverse Osmosis.

The aim of this work was to analyze the potential of reverse osmosis (RO) membranes in the recovery and concentration of aroma compounds from orange juice evaporator condensate (EC) streams. Concentration experiments were performed by using three RO spiral-wound aromatic polyamide membranes (SG1812C-34D, SC1812C-34D and SE1812) with different NaCl rejections. The effect of transmembrane pressure, axial feed flowrate and volume concentration ratio (VCR) on permeate flux was studied. Rejections of the investigated membranes towards specific aroma compounds (octanol, α-terpineol, terpinen-4-ol, cis-carveol, karvon, linalool) in selected operating conditions were also evaluated. The concentrations of the aroma compounds were determined by gas chromatography coupled with mass spectrometry (GC-MS) using headspace solid-phase microextraction (HS-SPME) as a sample preparation approach. For all selected membranes, the permeate flux increased linearly by increasing the operating pressure from 5 to 25 bar; on the other hand, the feed flowrate did not have any significant effect on the permeate flux. High retention values towards aroma compounds (>80%) were measured for all selected membranes. However, the SC membrane showed the highest rejection values (>96%) and the best correlation between concentration factor of aroma compounds and VCR.

Photocatalytic membrane reactor performance towards oxytetracycline removal from synthetic and real matrices: Suspended vs immobilized TiO2-P25

Integrated hybrid systems coupling microfiltration (MF) with UVA photolysis (UVA-MF) or TiO2-P25 photocatalysis (UVA/TiO2-MF) were investigated for the removal of oxytetracycline (OTC) from synthetic (ultrapure water-UPW) and real (secondary effluent from an urban wastewater treatment plant-UWW) matrices, both spiked with 5 mg L−1 of OTC. The photocatalytic membrane reactor (PMR) was tested both using the TiO2-P25 nanoparticles in suspension or immobilized on the external surface of the membrane – nano-engineered membrane (NEM). In all cases, reaction occurs only inside the membrane module. The effect of transmembrane pressure (TMP) (1.0–2.0 bar) and of TiO2-P25 loading (0.1–0.4 g L–1) in slurry conditions, on the efficiency of the photocatalytic UVA/TiO2-MF system was investigated. Additionally, OTC oxidation efficiency was evaluated as a function of the amount of TiO2-P25 deposited on the external surface of the ceramic MF membrane. The membrane ensured the retention of TiO2-P25 particles, when using the PMR catalyst slurry system. The higher OTC removal efficiency (>90% of antibiotic removal after 30 min) as well as the higher permeate flux decline (66% after 5 h) were observed when using the highest TiO2-P25 loading. The NEM contributed to the in-situ OTC and by-products oxidation, improving its antifouling properties, and, consequently, leading to a low permeate flux decline (8% after 5 h) when using UPW as solution matrix. However, a permeate flux decline of 66% was observed for UWW-NEM after the same reaction time. Despite the advantages of NEM, the OTC removal efficiency was higher when using TiO2-P25 slurry due to the higher photocatalyst surface area. Nevertheless, the NEM showed a good stability of the catalyst thin film during 3 consecutive reaction cycles.

Effects of operating conditions during hollow fiber ultrafiltration of bitter gourd (Mormordica charantia) extract and analysis of nutritional qualities in subsequent storage study

AbstractBitter gourd extract was clarified by cross flow ultrafiltration using a hollow fiber module under total recycle mode using polysulfone based membrane. The 70 kDa membrane was found to be the most suitable among the 10‐, 44‐, 70‐, and 120 kDa molecular weight cut‐off membranes. Variations of various resistances, viz. membrane hydraulic resistance, pore blocking resistance, and fouling layer resistance with operating conditions were examined. Effect of transmembrane pressure and cross flow rate on flux and quality parameters were examined and based on these results 138 kPa transmembrane pressure and 30 L/hr cross flow rate were found suitable operating conditions for processing of extract. Storage study revealed that the ultrafiltered extract could be successfully stored for 20 weeks without any additive, preservative and flavoring agent, maintaining its natural taste, aroma, nutrition, flavor, color, smell, and other nutritional qualities at par to fresh extract.Practical applicationsAqueous extract of vegetables possesses many ingredients having therapeutic values and medicinal importance. Bitter gourd is one such vegetable containing many health benefits. The present work deals with development of a cold sterilization process for bitter gourd extract using hollow fiber ultrafiltration without any additives, preservatives, and subsequent in‐depth storage analysis. Novelty of the process includes identification of suitable membrane for this purpose, detailed flux decline analysis of the selected membrane, effects of operating conditions on the throughput and physicochemical parameters of the processed extract. The storage study indicates that the extract can be preserved for 20 weeks without any external chemicals maintaining the natural flavor, taste, and nutrient profiles of the original extract. Filtration experiments were conducted in scalable hollow fiber units. Therefore, this study is of paramount significance in scaling up of processing of bitter gourd extract having long shelf life.

Simultaneous clarification and dehydration of crude palm oil using superhydrophobic polypropylene membrane

Clarification and dehydration processes are generally employed to produce high-quality crude palm oil (CPO). In this work, superhydrophobic hollow fiber polypropylene (PP) membrane is used to perform a simultaneous clarification and dehydration. The effect of transmembrane pressure (TMP), temperature, and water content on the membrane performance are investigated. Results indicate that the permeate flux was increased with the increase of TMP and temperature. However, the permeate flux was decreased with the increase of water content. Meanwhile, the water removal was slightly affected by those parameters. The superhydrophobic PP membrane can produce CPO with 59% non-dissolved solid removal, >99% water removal, and 47% clarity improvement (at 40 °C and 2 bar TMP). In addition, it was found that the fouling mechanism was dominated by cake filtration. Air scouring could be effectively used to recover the membrane flux with a flux recovery ratio of 90% (backflush duration = 5 min, filtration cycle = 2).

Analysis of fouling and juice quality in crossflow ultrafiltration of watermelon juice

Abstract Raw watermelon juice was clarified in a laboratory scale flat plate ultrafiltration system incorporating polyethersulphone membranes with a molecular weight cut-off of 50 kDa. The experiments have been carried out over a wide range of trans-membrane pressures (1-3 bar). The effect of ultrafiltration with molecular weight cut-off (MWCO) of 50 kDa PES membrane on permeate properties is reported. The effects of trans-membrane pressure (TMP) on permeate flux and resistances were studied. The flux decay was analyzed through the resistance in series model which showed increase of both reversible and irreversible resistance with trans-membrane pressure, The TSS content of the permeate was found to be almost the same with feed while the ascorbic acid content in the permeate was on the lower side as compared to in feed.

Impact of transmembrane pressure (TMP) on membrane fouling in microalgae harvesting with a uniform shearing vibration membrane system

A uniform shearing vibration membrane system can mitigate membrane fouling during algae filtration. In this paper, the effects of transmembrane pressure (TMP) on the membrane filtration performance at 8 kPa, 9 kPa and 10 kPa were investigated. The results of membrane fouling mechanisms predicted by Hermia's model surmised that membrane fouling is principally caused by the cake layer model, and the application of the Unified Membrane Fouling Index for quantitative evaluation of antifouling properties substantiating membranes in sub-critical condition exhibited superior antifouling properties. The reversible membrane fouling was largely dependent on polysaccharides due to size exclusion. Proteins tended to block the membrane pores and to cause irreversible fouling. It was also observed that high-molecular weight (>100 kDa) extracellular organic matters contributed a significant portion of membrane fouling. For greater insight, the CRiteria Importance Through Intercriteria Correlation (CRITIC) method was administered; it could be concluded that the removal of proteins was more responsible for the total fouling resistance than was the removal of polysaccharides, especially for membranes at the TMP of 9 kPa.

Analysis of Fouling Mechanism in Polysulfone based Ultrafiltration Membrane during Peat Water Filtration

Polysulfone (PSf) has been widely used as ultrafiltration (UF) membrane material due to its thermal and chemical stability. However, membrane fouling becomes a severe problem limiting the potential of PSf membrane. This fouling is mainly formed by deposition of organic onto membrane surface which resulting the decrease of permeate flux. There are four fouling mechanisms proposed by Hermia (1982), namely cake formation, standard blocking, intermediate blocking, and complete blocking. In this work, the types of fouling mechanism that occurred in PSf based UF membrane during peat water filtration were investigated. In addition, the effect of trans-membrane pressure was also studied. The determination of fouling mechanism was conducted by optimization of the fouling parameters, including Kcf (cake formation), Ksb (standard blocking), Kib (intermediate blocking), and Kcb (complete blocking). The results showed that complete blocking became the dominant fouling mechanism in this work. Meanwhile, the trans-membrane pressure did not affect fouling mechanism.

Detoxification of highly acidic hemicellulosic hydrolysate from wheat straw by diananofiltration with a focus on phenolic compounds

Nanofiltration was studied for detoxification of lignocellulose hydrolysates obtained in harsh conditions. A hemicellulosic hydrolysate obtained from sulfuric acid steam explosion of wheat straw and presenting very low pH (= 1) and high osmotic pressure (28 bar) was studied and 8 inhibitory compounds were followed, among which 4 phenolic compounds. Several polymeric nanofiltration membranes were compared for separation performances and permeabilities; DK membrane (GE Osmonics) proved suitable with high rejection of sugars (> 99%) and lower rejections of inhibitors. Acetic acid and furfural were quasi-fully transmitted whereas the rejection of compounds ranked as follow: HMF (5-hydroxymethyl-furfural) < coumaric acid < levulinic acid < vanillin < ferulic acid < syringaldehyde with values of 40%, 50%, 60%, 80%, 90% and 98%, respectively, at a permeate flux of 14 L h−1 m−2. Diafiltration was carried out at a transmembrane pressure of 26 bar until 3 DV (Diafiltration Volume) to complete detoxification, and continuous and sequential-dilution modes were compared. Thanks to the permeability of the membrane to the monovalent form of sulfuric acid HSO4-, effective transmembrane pressure was increased and pH reached 2. At 3 DV, both modes showed removal performances between 92% (acetic acid and furfural) and 25% (syringaldehyde). Irreversible fouling was observed, leading to 30% permeability loss after diafiltration.

Experimental investigation of oil-in-water microfiltration assisted by Dielectrophoresis: Operational condition optimization

Membrane filtration is an efficient method in treating oily waste water containing fine oil droplets. However rapid fouling of membrane and decay in process performance has resulted in limited industrial application of membrane processes for oily waste water treatment. In this paper, electric field is used as an assisting force to improve oil in water microfiltration performance. An electrically safe membrane module is fabricated and used for microfiltration studies in the presence of electric field. A statistical study is developed for conducting necessary experiments to identify optimum processing conditions in the presence of an AC electric field. Two response functions of stable flux and oil rejection are defined and optimized with response surface methodology and central composite design. The effects of trans membrane pressure, cross flow velocity, feed concentration and applied voltage on stable permeate flux and oil rejection are studied for an emulsion of 1.93μm oil droplets in water in a microfiltration system with cellulose acetate membrane of 0.45μm pore size. Results reveal that induction of electric field can considerably improve process performance. Variation in studied factors results in the flux ranging from 64 to 140L/m2hr while rejection varies between 85% and 97%. Quadratic models are suggested for flux and rejection with 0.93 and 0.83 R2 values respectively. Optimum conditions are predicted at 136.2L/m2hr for flux and 94.1% for rejection, observed at 360V, 1.1m/s, 900ppm and 2.5bar. The real values for flux and rejection are 131.8L/m2hr and 88.7% respectively representing −3.4% and −6.0% relative errors for the correlations.