Increase In Transmembrane Pressure Research Articles

Experimental evaluation of graphene oxide/TiO2-alumina nanocomposite membranes performance for hydrogen separation

In recent years, graphene oxide membranes showed interesting performances in terms of high permeating flux and perm-selectivity in several applications of gas separation because of their inherent properties combined to a low energy consumption. In this paper, a graphene oxide layer is coated on modified TiO2-alumina tubular substrate in order to prepare graphene oxide nanocomposite membranes useful for hydrogen separation. Nanocomposite graphene oxide membrane samples were obtained by using vacuum deep coating method, depositing the graphene oxide solution as single layers on TiO2-alumina substrate. Temperature and pressure variations were evaluated to achieve high H2 permeance, high H2/CO2 selectivity and membrane performance stability during the experimental tests. Furthermore, it was found that the temperature increase causes a perm-selectivity (H2/N2 and H2/CO2) decrease, while the transmembrane pressure increase involves a general improvement of the perm-selectivity.

Control of indigenous quorum quenching bacteria on membrane biofouling in a short-period MBR

In this paper, the immobilized quorum quenching (QQ) bacteria – microbial bag was added to a short-period membrane bioreactor (MBR) and its antifouling ability and mechanism were studied by monitoring the changes in transmembrane pressure (TMP), along with the production of N-acyl-homoserine lactones (AHLs), extracellular polymeric substance (EPS) and soluble microbial products (SMP). The QQ bacteria showed efficient mitigation of TMP increase in different membrane fouling stages. In the control MBR group, the TMP reached 43 kPa on the 4th day, while in the experimental group, TMP of QQ-MBR was only 18 kPa at the same time. The detection result of EPS and SMP content of protein and polysaccharide in MBRs showed that QQ bacteria had significant inhibitory effects on EPS and SMP. Also, the QQ bacterial exhibited excellent AHLs degradation rate in MBR reaction tank.

Modeling of NF/RO membrane fouling and flux decline using real-time observations

Many numerical models for membrane filtration have been developed to explain and predict fouling mechanisms. The models can simulate flux decline, transmembrane pressure increase, and fouling thickness based on theoretical equations. However, the simulated fouling layer thicknesses have not been validated by in-situ observations on membrane surfaces because the membrane system is operated under a sealed and pressurized condition. In this study, humic acid fouling layers on nanofiltration and reverse osmosis membranes were monitored in-situ and in real-time using optical coherence tomography (OCT). The OCT system detected fouling layer growth over time, and showed that the compact and thick fouling layer had an estimated thickness of 80 µm. When comparing the thickness of the fouling layer between OCT and scanning electron microscopy (SEM) images, the OCT images showed values that were approximately 8 times higher than those of the SEM images. By comparing the obtained fouling thickness values with the estimated results, two existing models (Faridirad model and pore blockage-cake filtration model) were validated in terms of root mean square error (RMSE), Akaike Information Criteria (AIC), and coefficient of determination (R2). Both models showed similar high R2 (≥0.97) and low RMSE (<10-5) values, but the pore blockage-cake filtration model had lower AIC values than the Faridirad model. This study highlighted that the in-situ and real-time monitoring of fouling thickness can provide significant information for developing an accurate and precise membrane model.

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).

The Impact of Mechanically-Imposed Shear on Clogging, Fouling and Energy Demand for an Immersed Membrane Bioreactor.

The impact of the application of mechanically-imposed shear on the propensity for fouling and clogging (or “sludging”—the agglomeration of sludge solids in the membrane channel) of an immersed flat sheet (iFS) membrane bioreactor (MBR) was studied. The bench-scale test cell used contained a single flat sheet fitted with a crank and motor to allow the membrane to be oscillated (or reciprocated) vertically at a low rate (20 RPM). The membrane was challenged with sludge samples from a local MBR installation treating petroleum industry effluent, the sludge having previously been demonstrated as having a high sludging propensity. Sludging was measured by direct visual observation of membrane surface occlusion by the agglomerated solids, with fouling being notionally represented by the rate of transmembrane pressure increase. Results demonstrated membrane reciprocation to have a more beneficial impact on sludging amelioration than on suppressing fouling. Compared with the stationary membrane, sludging was reduced by an average of 45% compared with only 13% for fouling suppression at the reference flux of 15 L·m−2·h−1 applied. The specific energy demand of the mechanical shear application was calculated as being around 0.0081 kWh·m−3, significantly lower than values reported from a recent pilot scale study on a reciprocated immersed hollow fibre MBR. Whilst results appear promising in terms of energy efficiency, it is likely that the mechanical complexity of applying membrane movement would limit the practical application to low flows, and a correspondingly small number of membrane modules.

Effect of chemical dose on phosphorus removal and membrane fouling control in a UCT-MBR

To enhance phosphorus removal and make the effluent meet the strict discharge level of total phosphorus (TP, 0.5 mg/L), flocculant dosing is frequently applied. In this study, the performance of aluminum sulfate dosing in a University of Cape Town Membrane Bioreactor (UCT-MBR) was investigated, in terms of the nutrients removal performance, sludge characteristics and membrane fouling. The results indicated that the addition of aluminum sulfate into the aerobic reactor continuously had significantly enhanced phosphorus removal. Moreover, COD, NH4+-N and TN removal were not affected and effluent all met the first level A criteria of GB18918-2002. In addition, the addition of aluminum sulfate had improved the sludge activity slightly and reduced transmembrane pressure (TMP) increase rate from 1.13 KPa/d to 0.57 KPa/d effectively. The alleviation of membrane fouling was attributed to the increased average particle sizes and the decreased accumulation of the small sludge particles on membrane surface. Furthermore, the decline of extracellular polymeric substance (EPS) concentration in mixed sludge liquid decreased its accumulation on membrane surface, resulting in the mitigation of membrane fouling directly.

Coupling continuous sand filtration to ultrafiltration for drinking water treatment: Improved performance and membrane fouling control

In order to alleviate the membrane fouling, a short flow drinking water process coupled the continuous sand filtration (CSF) to ultrafiltration (UF) was developed to treat the micro-polluted surface water and the membrane fouling mechanism was further discussed. The results indicated that the CSF process significantly enhanced the removal of ammonia (NH4+-N), accounting to an average removal of more than 70%. Furthermore, the natural organic matters (NOM) were also efficiently removed, with CODMn, UV254 and DOC reduced by approximately 30%, 17% and 18%, respectively. After 2 months of operation, the biological activity developed gradually within the CSF, which sparked an efficient removal performance of Fe and Mn. Besides, three dimensional fluorescence parallel factor analysis (PARAFAC) was employed to trace and characterize membrane fouling and a significantly positive correlation between the fluorescent foulants and irreversible fouling was observed. In addition, further simulations indicated that cake layer formation should be responsible for the trans-membrane pressure (TMP) increase. In order to gain a deep insight to the membrane fouling, the composition of foulants in the chemical backwash water was characterized, and humic substances and metal ions (i.e. Fe, Mn, Ca and Mg) were the main components, which demonstrated that the irreversible membrane fouling should be related to the synergistic effects of inorganic ion precipitates and humic substances. Overall, coupling CSF to UF filtration can significantly enhance its removal performance and control the membrane fouling, which is expected to be a promising alternative based on the principle of aquatic ecosystems for the micro-polluted raw water.

Temperature susceptibility of a mesophilic anaerobic membrane bioreactor treating saline phenol-containing wastewater

This study examined the temperature susceptibility of a continuous-flow lab-scale anaerobic membrane bioreactor (AnMBR) to temperature shifts from 35 °C to 55 °C and its bioconversion robustness treating synthetic phenolic wastewater at 16 gNa+.L−1. During the experiment, the mesophilic reactor was subjected to stepwise temperature increases by 5 °C. The phenol conversion rates of the AnMBR decreased from 3.16 at 35 °C to 2.10 mgPh.gVSS−1.d−1 at 45 °C, and further decreased to 1.63 mgPh.gVSS−1.d−1 at 50 °C. At 55 °C, phenol conversion rate stabilized at 1.53 mgPh.gVSS−1.d−1 whereas COD removal efficiency was 38% compared to 95.5% at 45 °C and 99.8% at 35 °C. Interestingly, it was found that the phenol degradation process was less susceptible for the upward temperature shifts than the methanogenic process. The temperature increase implied twenty-one operational taxonomic units from the reactor's microbial community with significant differential abundance between mesophilic and thermophilic operation, and eleven of them are known to be involved in aromatic compounds degradation. Reaching the upper-temperature limits for mesophilic operation was associated with the decrease in microbial abundance of the phyla Firmicutes and Proteobacteria, which are linked to syntrophic phenol degradation. It was also found that the particle size decreased from 89.4 μm at 35 °C to 21.0 μm at 55 °C. The accumulation of small particles and higher content of soluble microbial protein-like substances led to increased transmembrane pressure which negatively affected the filtration performance. Our findings indicated that at high salinity a mesophilic AnMBR can tolerate a temperature up to 45 °C without being limited in the phenol conversion capacity.

Fouling characteristics of humic substances on tight polysulfone-based ultrafiltration membrane

Fouling characteristics of humic substances on tight ultrafiltration (UF) membrane have been investigated. The tight UF membrane was prepared by blending polysulfone (PSf) in N.N-dimethylacetamide (DMAc) with 25%wt of Polyethylene glycol (PEG400) and 4%wt of acetone. Fouling characteristic of the modified PSf membrane was observed during peat water filtration in different trans-membrane pressure (TMP). It was found that the acetone modified membrane provided 13% increase in TMP during five hours of peat water filtration, where a stable flux was reached within 150 minutes. Meanwhile, the increase of TMP from 10 psig to 30 psig resulted in a fouling resistance enhancement of 60%. Furthermore, based on the fouling analysis, fouling mechanism at the first phase of filtration was attributed to intermediate blocking while the second phase was cake formation.

Performance of a full-scale ceramic MBR system to treat domestic sewage

Abstract Application of membrane technology for water reclamation has grown significantly in recent years due to reduced footprint size and more consistent product water quality. For a membrane bioreactor (MBR) system, it is critical for it to be robust to allow membrane systems to operate at higher flux without significant increase of trans-membrane pressure (TMP). A full-scale ceramic MBR system was installed at Changi Water Reclamation Plant (CWRP) as part of an MBR retrofit project to increase treatment capacity without expanding the plant's footprint. The nominal capacity of the ceramic MBR system is 15,000 m3/d. The system has been successfully operating since January 2017 with a net flux of 30–60 L/m2-hr (LMH). Stable operation was observed at nominal production capacity for more than 3 months. During that period, the TMP was stable in the range of 9–14 kPa for Tank A and 10–17 kPa for Tank B. Permeate turbidity was recorded in the range of 0.04–0.06 NTU for both Tank A and Tank B.

Application of silica and germanium dioxide nanoparticles/ polyethersulfone blend membranes for removal of emerging micropollutants from water

One of the current global issues of increasing environmental-health concern is the ubiquitous occurrence of emerging micropollutants (EMPs) in aquatic environments. Among these EMPs, bisphenol A (BPA), technical 4-nonylphenol (NP), tonalide (AHTN), carbamazepine (CBZ), caffeine (CAF) and galaxolide (HHCB) find their way into aquatic environments as a result of their ever increasing production and consumption coupled with their incomplete removal in conventional water and wastewater treatment plants. This study fabricated silicon dioxide (silica) (SiO2) and germanium dioxide (GeO2) embedded polyethersulfone (PES) blend membranes using phase inversion method for the removal of EMPs from water samples collected from North West Province, South Africa. The EMPs were extracted and enriched by auto-trace solid-phase extraction and analyzed using comprehensive two dimensional gas chromatography coupled to time of flight mass spectrometry (GCxGC-TOFMS). The fabricated membranes' permeation properties were determined by computing the pure water flux and EMPs' rejection. The water flux was observed to increase with increase in transmembrane pressure as well as increase in SiO2 and GeO2 nanoparticle loadings in the polymer matrices. Compared to the pristine PES, the contact angles for the SiO2/PES and GeO2/PES membranes were much lower, showing increased hydrophilicity of the membranes with increase in SiO2 and GeO2 nanoparticle loadings in the matrices. The mean EMPs' concentrations (ng/L) ranges in the feed were found to be: BPA (5.19 ± 0.8 to 53.60 ± 4.25), CAF (6.09 ± 0.00 to 49.96 ± 3.45), CBZ (0.68 ± 0.00 to 3.06 ± 0.74), HHCB (21.31 ± 4.24 to 13.31 ± 14.8), AHTN (8.31 ± 2.23 to 141.82 ± 21.70), and NP (0–174.99 ± 14.5). Even though SiO2/PES membranes showed slightly higher EMPs' removal efficiencies than their GeO2/PES counterparts, both membranes showed the highest and lowest removal efficiencies range of 97.85–99.00% (for HHCB) and 87.42–93.00% (for CAF), respectively. The results showed superiority in capability of the fabricated nanocomposite membranes in removing EMPs from water.

Effect of Hybrid Process of Pre-ozonation and CNT Modification on Hollow Fiber Membrane Fouling Control

Polyvinylidene fluoride (PVDF) hollow fiber ultrafiltration membranes were modified with carbon nanotube (CNT). Combined with the ozonation process, the effect of the hybrid pre-ozonation and CNT modification on fouling alleviation was investigated. The impacts of CNT loading mass and ozone dosage on the variation of flux and antifouling ability of the membrane modules were evaluated. Under a critical flux of 144 L·(m2·h)-1, CNT loading mass of 3 g·m-2, and ozone dosage(O3/DOC) of 0.22 mg·mg-1, the results revealed that the filtration volume of the hybrid process was promoted to 850 L·m-2, which was about 4.5 times higher than that of the original unmodified membrane. With a flux of 18 L·(m2·h)-1 and 15 day operation, the filtration volume was promoted to 3000 L·m-2, which was 10 times that of the unmodified membrane. The fouling membrane surface was observed using confocal laser scanning electron microscopy (CLSM). The results demonstrated that more living bacteria were present on the membrane surface of the unmodified membrane, which showed a rapid transmembrane pressure (TMP) increase. Both pre-ozonation and CNT modification decreased the total amount of microorganisms and the amount of the living bacteria as well, which mitigated the increase in TMP. After pre-ozonation, the presence of a CNT layer on the membrane surface further decreased the number of living bacteria. Although the CNT layer captured some dead bacteria, it had no obvious relationship with the increase in TMP.

Reactive Photo-Fenton ceramic membranes: Synthesis, characterization and antifouling performance

To develop reactive and antifouling membrane filtration systems, a photo-Fenton ceramic membrane was prepared by coating goethite (α-FeOOH) catalysts on a zirconia/titania alumina membrane via a cross-linking method. Scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to characterize α-FeOOH catalysts and the surface coating quality. The cross linker yielded stable covalent binding between catalyst and membrane under room temperature and produced a homogeneous and smooth coating of catalyst on ceramic membranes. Photo-Fenton reactions were initiated with addition of H2O2 under UV irradiation to improve the foulant degradation on membrane surface while filtration. Membrane fouling was simulated by bovine serum albumin (BSA) and humic acid (HA). Our results show that the photo-Fenton reactions on the coated membranes slowed down the fouling kinetics and even reversed the fouling, leading to a stable transmembrane pressure (TMP) over time of filtration, as opposed to a monotonous increase of TMP due to surface fouling. The batch experiments verified that the photo-Fenton reactions achieved the degradation rates of 76% and 86% for HA and BSA respectively within 60 min, with the mineralization rates of over 80% as indicated by the total organic carbon measurement. This study embarks on a novel antifouling membrane filtration process via incorporation of photo-Fenton reactions. The findings are also important for diverse applications of surface fouling mitigation and rationale design of fouling resistant surfaces or materials through photo-Fenton or other catalytic reactions.

Bacteriophage Infectivity Against Pseudomonas aeruginosa in Saline Conditions.

Pseudomonas aeruginosa is a ubiquitous member of marine biofilm, and reduces thiosulfate to produce toxic hydrogen sulfide gas. In this study, lytic bacteriophages were isolated and applied to inhibit the growth of P. aeruginosa in planktonic mode at different temperature, pH, and salinity. Bacteriophages showed optimal infectivity at a multiplicity of infection of 10 in saline conditions, and demonstrated lytic abilities over all tested temperature (25, 30, 37, and 45°C) and pH 6–9. Planktonic P. aeruginosa exhibited significantly longer lag phase and lower specific growth rates upon exposure to bacteriophages. Bacteriophages were subsequently applied to P. aeruginosa-enriched biofilm and were determined to lower the relative abundance of Pseudomonas-related taxa from 0.17 to 5.58% in controls to 0.01–0.61% in treated microbial communities. The relative abundance of Alphaproteobacteria, Pseudoalteromonas, and Planococcaceae decreased, possibly due to the phage-induced disruption of the biofilm matrix. Lastly, when applied to mitigate biofouling of ultrafiltration membranes, bacteriophages were determined to reduce the transmembrane pressure increase by 18% when utilized alone, and by 49% when used in combination with citric acid. The combined treatment was more effective compared with the citric acid treatment alone, which reported ca. 30% transmembrane pressure reduction. Collectively, the findings demonstrated that bacteriophages can be used as a biocidal agent to mitigate undesirable P. aeruginosa-associated problems in seawater applications.

Characterization of dissolved organic matter and membrane fouling in coagulation-ultrafiltration process treating micro-polluted surface water

Coagulation–ultrafiltration (C–UF) is widely used for surface water treatment. With the removal of pollutants, the characteristics of organic matter change and affect the final treatment efficiency and the development of membrane fouling. In this study, we built a dynamic C–UF set-up to carry out the treatment of micro-polluted surface water, to investigate the characteristics of dissolved organic matter from different units. The influences of poly aluminum chloride and poly dimethyldiallylammonium chloride (PDMDAAC) on removal efficiency and membrane fouling were also investigated. Results showed that the dosage of PDMDAAC evidently increased the UV254 and dissolved organic carbon removal efficiencies, and thereby alleviated membrane fouling in the C–UF process. Most hydrophobic bases (HoB) and hydrophobic neutral fractions could be removed by coagulation. Similarly, UF was good at removing HoB compared to hydrophilic substances (HiS) and hydrophobic acid (HoA) fractions. HiS and HoA fractions with low molecule weight accumulated on the surface of the membrane, causing the increase of transmembrane pressure (TMP). Membrane fouling was mainly caused by a removable cake layer, and mechanical cleaning was an efficient way to decrease the TMP.

Ultra-stable and cost-efficient protic ionic liquid based facilitated transport membranes for highly selective olefin/paraffin separation

Facilitated transport membranes (FTMs) for olefin/paraffin separations have failed to achieve commercial success due to the instability of carriers although great efforts have been made. In this work, ultra-stable and cost-efficient protic ionic liquid based FTMs (PIL-FTMs) were firstly prepared by utilizing the Brönsted acidic property of PILs to stabilize the carrier. The gas solubility in the carrier/PILs was measured and the separation performances of PIL-FTMs were evaluated systemically. The results indicated that the structure of PILs affected the C2H4 permeability and the presence of ether group and hydroxyl group in PILs significantly enhanced the C2H4/C2H6 selectivity. The carrier concentration led to structural variation of PIL-FTMs, thus manipulating the gas separation performances of PIL-FTMs. The increase of transmembrane pressure decreased C2H4 permeability and C2H4/C2H6 selectivity, indicating a typical feature of FTMs. The increase of temperature increased the C2H4 permeability but decreased C2H4/C2H6 selectivity. The separation performances of PIL-FTMs were much higher than other results in the literature. Furthermore, the PIL-FTMs exhibited excellent stability during the long-term experiments carried out for six months. Finally, the investigation of separation mechanism revealed that the hydrogen-bonding and coordinative interactions between PILs and carrier accounted for the high separation efficiency of PIL-FTMs. In all, the excellent long-term stability, outstanding separation performances and economic feasibility of PIL-FTMs could play an important role in moving these membranes toward industrial application.

Water Reclamation Using a Ceramic Nanofiltration Membrane and Surface Flushing with Ozonated Water.

A new membrane fouling control technique using ozonated water flushing was evaluated for direct nanofiltration (NF) of secondary wastewater effluent using a ceramic NF membrane. Experiments were conducted at a permeate flux of 44 L/m2h to evaluate the ozonated water flushing technique for fouling mitigation. Surface flushing with clean water did not effectively remove foulants from the NF membrane. In contrast, surface flushing with ozonated water (4 mg/L dissolved ozone) could effectively remove most foulants to restore the membrane permeability. This surface flushing technique using ozonated water was able to limit the progression of fouling to 35% in transmembrane pressure increase over five filtration cycles. Results from this study also heighten the need for further development of ceramic NF membrane to ensure adequate removal of pharmaceuticals and personal care products (PPCPs) for water recycling applications. The ceramic NF membrane used in this study showed approximately 40% TOC rejection, and the rejection of PPCPs was generally low and highly variable. It is expected that the fouling mitigation technique developed here is even more important for ceramic NF membranes with smaller pore size and thus better PPCP rejection.

Application of low-dosage UV/chlorine pre-oxidation for mitigating ultrafiltration (UF) membrane fouling in natural surface water treatment

This study describes some results concerning the hybrid process of ultraviolet/chlorine (UV/chlorine) as a pre-oxidation strategy prior to ultrafiltration for the treatment of natural organic matter (NOM)-contaminated surface water. Chlorine has been extensively used in water treatment since it can act as disinfectant or coagulant aid. In addition, the combination of UV and chlorine, compared to the other oxidants generally used in water treatment, offers a potentially effective and cheaper alternative for pre-oxidation process. Parallel tests with or without the application of chlorine were conducted to evaluate the effect of chlorine dosage on the increase of trans-membrane pressure under low dosage of UV irradiation. The results showed that UV/chlorine pre-oxidation achieved remarkable reduction of both total membrane fouling (49%) and reversible membrane fouling (59%) at 4 mg/L dose of chlorine as a result of the removal of both high molecular weight (MW) (1–20 kDa) humic substances and lower MW compounds. Hybrid process of UV/chlorine and UF membrane achieved significant removal of DOC (34%) and UV254 (49%) at chlorine dosage of 4 mg/L and a UV dosage of 180 mJ/cm2. Modeling fit results indicated that the NOM-related membrane fouling mitigation was probably attributed to the alleviation of intermediate pore blocking and standard pore blocking with intermediate pore blocking playing a more important role. Additionally, the UV/chlorine unit could have a bright prospect for engineering application as it performed better in cost control as pretreatment prior to UF membrane compared to other pre-oxidation processes.

Biocatalytic membrane with acylase stabilized on intact carbon nanotubes for effective antifouling via quorum quenching

This study developed biocatalytic membranes that can effectively control the surface biofouling based on the enzymatic quenching of bacterial quorum sensing. Acylase (AC) was immobilized and stabilized on intact carbon nanotubes (CNTs) via enzyme adsorption, precipitation, and crosslinking (EAPC) method, maintaining 66% of its initial enzyme activity for 200 days under rigorous shaking (200 rpm). This highly stable EAPC was anchored on the polyvinylidene fluoride (PVDF) microfilter using polydopamine coatings (EAPC membrane). The antifouling performance and mechanism of EAPC membrane was intensively evaluated under static incubation with a model bacterium of Pseudomonas aeruginosa. When compared with the PVDF membranes with and without free AC, the EAPC membrane enhanced the water permeability by 5-folds at an optimum loading of 0.40 g-CNTs/m2 by effectively inhibiting the biofilm formation. The EAPC membrane with this optimal CNT loading did not increase the hydraulic resistance of membrane itself. In the lab-scale continuous filtrations, the EAPC membrane with its loading of 0.40 g-CNTs/m2 demonstrated 1.6-fold delay of trans-membrane pressure increase compared to the PVDF membrane. It is anticipated that biocatalytic membrane based on quorum quenching nanobiocatalysis has a great potential in antifouling applications without changing the process configuration or additional treatments.

Fouling mechanism in ultrafiltration of vegetable oil

Energy efficient and cost-effective separation of impurities from vegetable oil is a great challenge for vegetable oil processing. Several technologies have been developed, including pressurized membrane, chemical treatment, and chemical free separation methods. Among those technologies, ultrafiltration membrane is one of the most attractive processes with low operating pressure and temperature. In this work, hydrophobic polypropylene ultrafiltration membrane was used to remove impurities such as non-dissolved solids from palm kernel oil. Unfortunately, the hydrophobicity of polypropylene membrane leads to significant impact on the reduction of permeate flux due to membrane fouling. This fouling is associated with the accumulation of substances on the membrane surface or within the membrane pores. For better understanding, fouling mechanism that occurred during palm kernel oil ultrafiltration using hydrophobic polypropylene membrane was investigated. The effect of trans-membrane pressure and feed temperature on fouling mechanism was also studied. The result showed that cake formation became the dominant fouling mechanism up to 50 min operation of palm kernel oil ultrafiltration. Furthermore, the fouling mechanism was not affected by the increase of trans-membrane pressure and feed temperature.