Microfiltration Membrane System Research Articles

Contribution of proteins to ceramic membrane fouling at the early stage of membrane filtration

Membrane-based filtration is widely applied for water and wastewater treatment, while membrane fouling caused by contaminants such as proteins is an inevitable problem. Protein-containing mixtures or intact model proteins (e.g., bovine serum albumin, BSA) have been conventionally adopted and recognized as important membrane foulants. However, due to the complex composition of the protein-containing mixture or the inappropriate concentrations of model substances adopted, the real contribution of protein-like fractions toward ceramic membrane fouling remains unknown yet. In this work, the fouling behaviors of BSA and tryptones, representing the intact protein and the mixture of peptides, respectively, in a ceramic membrane microfiltration system were investigated. Both of them exhibited a negligible flux decrease and membrane fouling. For comparison, the fouling behaviors of the environmental protein-like substances (EP) extracted from different sludge sources were also examined. In addition, the experimental and simulation results demonstrate that all the EP samples were easier to aggregate and be adsorbed on the membrane surface than the two model proteins because the environmental protein-like substances had more unsaturated groups. However, those properties were insufficient to cause rapid membrane pore blockage or biocake formation compared with the previous studies. Both the model and actual protein fractions led to light membrane fouling, implying that proteins were not mainly responsible for membrane fouling at the early stage of ceramic membrane microfiltration.

Wastewater Management Using Coagulation and Surface Adsorption through Different Polyferrics in the Presence of TiO2-g-PMAA Particles

For the surface adsorption process, a wide range of studies have been carried out to describe the adsorption process. However, no extensive study has been carried out to investigate the pre-treatment method effect on the separation process. The purpose of the present study is to improve the performance of the membrane process in the treatment of oily wastewater. For this purpose, the effects of pre-treatment, membrane modification, and operational parameters were investigated on the microfiltration membrane system. Two methods of coagulation and surface adsorption were used as pre-treatment, and then a modified polysulfone (PSf) membrane containing TiO2 nanoparticles was applied in the microfiltration process. In order to reduce the membrane fouling and increase the permeate flux, the surface of the nanoparticle was modified. In order to check the performance of coagulation, pretreatments of polyferric sulfate (PFS) and polyferric chloride (PFC) were applied. The results showed that the Chemical Oxygen Demand (COD) reduction of 98% can be obtained using 1 g/L of PFS coagulant at pH = 6, while only 81% of COD was removed using 1 g/L PFC. It was also found that the best pH for the performance of this type of coagulant was measured as pH = 10 and the removal efficiency for 1 and 2 g/L of PFC coagulant was obtained as 96.1% and 91.7%, respectively. The results show that in the case of using a coagulant of less than 1 g/L, using PFS is more efficient than PFC; meanwhile, in more than 1 g/L of coagulant, this effect is reversed and the use of PFS will be less efficient than PFC. The performance of the PSf-TiO2 membrane fabricated by the Nonsolvent-induced phase separation (NIPS) method was investigated using modified nanoparticles with an initial size of 10 nm at different operating conditions. The results show that the permeate flux and the rejection can be increased to 563 L/h m2 and 99%, respectively, using the modified PSf membrane. The results of this paper showed that the performance of the adsorption process can be improved by using the coagulation process as a pre-treatment method.

Experimental studies on the effects of coagulation and adsorption as a pretreatment process on the microfiltration of oily wastewater

Abstract To improve the performance of the membrane process in the treatment of oily wastewater, the combined effects of pretreatment, membrane modification, and optimization of operating parameters on the microfiltration membrane system were investigated. First, coagulation and adsorption were used as pretreatment steps. Polyaluminium chloride and ferric chloride were employed as coagulants, and granular activated carbon was used as an adsorbent. In the optimal coagulation condition (1 g/L polyaluminium chloride, pH 7.5), chemical oxygen demand (COD) was reduced by 96%, while in the optimal adsorption condition, in which large amounts of activated carbon were utilized, 48% of COD was eliminated. A membrane of polyethersulfone containing SiO2-g-polymethacrylic acid (PMAA) nanoparticles was then prepared by the non-solvent-induced phase separation method. To reduce fouling and increase the flux of the membrane, the SiO2 nanoparticles were first activated with amine groups and then PMAA was grafted onto the surface of the particles. Subsequently, the operating parameters were studied to optimize the performance of the polyethersulfone (PES)/SiO2-g-PMAA membrane using the response surface methodology (RSM) method. The results indicated that the flux of the modified membrane for pretreated wastewater was 72.2% higher than that of the PES membrane and non-pretreated wastewater at an optimum pressure of 2 bar and a flow rate of 3.5 L/min.

Removal of glycerol from biodiesel using multi-stage microfiltration membrane system: industrial scale process simulation

Abstract Biodiesel purification is one of the most important downstream processes in biodiesel industries. The removal of glycerol from crude biodiesel is commonly conducted by an extraction method using water, however this method results in a vast amount of wastewater and needs a lot of energy. In this study, microfiltration membrane was used to remove glycerol from biodiesel, and a process simulation was carried out for an industrial scale biodiesel purification plant using a microfiltration membrane system. The microfiltration experiment using a simulated feed solution of biodiesel containing glycerol and water showed that the membrane process produced purified biodiesel that met the international standards. The result of the process simulation of a multi-stage membrane system showed that the membrane area could be minimized by optimizing the concentration factor of every stage with the aid of a computer program that was written in Phyton programming language with Visual Studio Code. The overall productivity of a single stage membrane system was the same with that of the multi-stage system, however the single stage system required a larger membrane area. To produce 750 m3 day−1 of purified biodiesel, a multi-stage membrane system consisting of 10 membrane modules required a total membrane area of 1515 m2 that was 57% smaller compared to the single stage system consisting of one membrane module. This membrane area reduction was equivalent to a reduction of the total capital cost of 30%. Based on the analysis of the total capital cost, it was found that the optimum number of stages was 4 since it showed a minimum value of the total capital cost with a membrane area of 1620 m2 that was equivalent to the reduction of the total capital cost of 34%. The result of this simulation showed that the multi-stage microfiltration membrane has great potential to replace the conventional method in biodiesel industries.

Ceramic membrane filtration of skim milk for the production of a casein-enriched permeate

The protein composition of skim milk was adjusted using a pilot-scale membrane microfiltration system to produce a casein-enriched permeate with a ratio of casein to serum protein close to 1:1. Microfiltration was performed at 50 °C to a volume concentration factor of 3 followed by 2 diafiltration steps. Three different membrane pore sizes (0.10, 0.14 and 0.20 μm) were used to compare the separation effect, then the effect of three different transmembrane pressures (100, 120 and 150 kPa) on protein composition in the permeate was studied. Membranes of 0.10 and 0.14 μm retained most of the casein. The 0.20 μm membrane allowed casein to pass through and made the ratio of casein to serum protein in the permeate close to 50:50 with a mean flux of 128.3 kg m−2 h−1 at 120 kPa, demonstrating the potential application of a 0.20 μm membrane to produce a new dairy ingredient.

Mitigation of membrane fouling of alginate with combined actions of aeration and powdered activated carbon: Fouling behaviors and mechanisms.

A laboratory-scale flat-sheet ceramic microfiltration membrane system was developed to investigate the membrane fouling behaviors and mechanisms of sodium alginate (SA) in the presence of aeration and powdered activated carbon (PAC). When the SA concentration increased from 20 to 500 mg/L, the permeate flux decreased by 81.7%, and the transmembrane pressure (TMP) and resistance increased 1.7 and 24.5 times, respectively. At an SA concentration of 500 mg/L, it was found that the membrane fouling tended to decrease with the increase in the aeration rate, indicating high control of the fouling by air scouring, while PAC-aeration scouring produced a significant improvement in the permeate flux with substantially reduced fouling. In the microfiltration of 500 mg/L SA at an air flow rate of 2.2 L/min and PAC concentrations of 40, 100, and 250 mg/L, the flux increased by 179.3%, 238.0%, and 302.7%, the TMP decreased by 32.6%, 34.8%, and 45.7%, and the cake and pore blocking resistance decreased by 78.0%, 85.1%, and 87.9%, respectively, compared to the corresponding values without PAC-aeration scouring. Intermediate blocking and complete blocking models were confirmed to elucidate the effect of aeration scouring and PAC-aeration scouring on the mitigation of membrane fouling by SA. PRACTITIONER POINTS: Air scouring was effective at mitigating membrane fouling of sodium alginate. The addition of PAC could alleviate membrane fouling of SA. Synergistic scouring by aeration and PAC offers a promising means for more-efficient and cost-effective control of membrane fouling. The fouling mechanisms in various scenarios were elucidated.

Process design and simulation of industrial-scale biodiesel purification using membrane technology

Biodiesel is commonly produced through a transesterification reaction of vegetable oil with alcohol in the presence of a catalyst to produce fatty acid methyl ester (FAME). The reaction also produces glycerol as a by-product that must be separated from the FAME to obtain a biodiesel product that meets international standards. The common method to remove glycerol from FAME is washing with water. However, it produces a vast amount of wastewater and consumes much energy. Membrane technology is a promising separation technique for removing glycerol from biodiesel on an industrial scale since the separation using membrane does not produce wastewater and the energy consumption is low. In this work, the application of membrane technology to separate biodiesel and glycerol was studied through a process design and simulation of an industrial scale biodiesel purification process with a production capacity of 723 kL/day. A multistage feed-and-bleed microfiltration membrane system was designed to purify biodiesel from glycerol, and the process simulation was carried out using computer programming. The result of the process simulation showed that purified biodiesel could be produced by using the multistage microfiltration membrane system. The minimum membrane area required for the separation process in each stage could be calculated using the computer program. It was found that the total membrane area decreased with the increasing number of stages. A reduction of the total membrane area of 37% was achieved using ten stages microfiltration system. The optimum number of the stages could be determined through a tradeoff analysis of the cost to minimize the capital cost of the multistage membrane system. For the case study in this work, a stage number of 4 was found as the optimum stage number of the microfiltration system. This result showed that the membrane technology has great potential to be applied for the industrial-scale biodiesel purification process.

Anti-fouling effect by internal air injection in plate-type ceramic membrane fabricated for the treatment of agro-industrial wastewater

The ceramic microfiltration membrane which composed of membrane body having macro pore and active layer having micro pore was fabricated successfully by the process including the sintering of tape-casted and laminated mixture of zirconia and polyvinyl butyral binder, and re-sintering after screen coating of zirconia. The average pore size and porosity of the fabricated membrane were 0.1855 μm and 40 %, respectively. A novel membrane microfiltration system adopting the fabricated ceramic membrane was also devised for the treatment of agro-industrial wastewater, and the effects of external air sparging and internal air injection were investigated. A significant improvement of permeability by external air sparging was not observed, and the permeate flux was about 20 L/m2/h. Despite the abnormal biomass status resulted from low water temperature and poor maintenance of facility, however, the system operated at the initial TMP of 0.4 bar and internal air injection intervals of 5 min showed excellent permeability of 100 L/m2/h. In addition, although several periodic internal air injections with inverse pressure was carried out, structural defects of fabricated ceramic membrane were not observed. Thus, it confirmed that the anti-fouling effect by optimum back-flushing strategy in fabricated ceramic membrane was effective for stability enhancement of agro-industrial complex wastewater treatment process suffering from maintenance.

High purity prebiotic isomalto-oligosaccharides production by cell associated transglucosidase of isolated strain Debaryomyces hansenii SCY204 and selective fermentation by Saccharomyces cerevisiae SYI065

An efficient recycling method was used to develop the continuous production of high purity isomalto-oligosaccharides (IMOs) by cell associated transglucosidase of a novel strain, D. hansenii from maltose and selective fermentation by S. cerevisiae. The most potent transglucosidase producer was screened, isolated and identified as Debaryomyces hansenii using LSU region sequencing. Parameters optimization studies were investigated using whole cells of D. hansenii (∼4023 units L−1 α-glucosidase activity) from 10 L fermenter to increase the transglucosidase activity through biotransformation. IMOs was continuously synthesized by reusing the cell biomass (6 %) in a 3 L bioreactor using microfiltration membrane system with 30 % maltose concentration under controlled temperature of 34 °C in an average of 12 h for 5 cycles. The obtained low purity IMOs (67 %) was further incubated with cell pellet of isolated strain Saccharomyces cerevisiae (4 %, w/v) in 3 L bioreactor for 1 h to utilize glucose completely without affecting the product to obtain high purity IMOs by recycling method. This novel study using these yeasts, was found to utilize more than 98 % maltose with higher conversion efficiency for production of IMOs with >91 % purity, 79 % yield and highest productivity of 198.79 g L-1.h which was confirmed by HPLC.

Enhancing fouling mitigation of submerged flat-sheet membranes by vibrating 3D-spacers

Unsteady-state shear is acknowledged to be more energy-efficient in the mitigation of membrane fouling. In this study, we aimed to understand the effects of three dimensional (3D)-spacer configuration and their vibrating orientation on the extent of fouling mitigation in a submerged flat-sheet membrane microfiltration (MF) system. Several types of 3D-spacers were designed and computational fluid dynamics (CFD) was used to simulate the shear and turbulence along the membrane surface induced by vibrating 3D-spacers. The designed 3D-spacers were produced by 3D printing technique and their fouling control efficiencies were experimentally examined in a submerged flat-sheet membrane MF system with bentonite and sodium alginate as model foulants. Both simulation and experimental results revealed that the wave-like spacer (groove direction vertical to spacer movement direction) could alleviate more membrane fouling than the other designed spacers (e.g., hill-like spacer, wave-like spacer with groove direction parallel to spacer movement direction), regardless of tested permeate fluxes. Furthermore, two types of wave-like spacers were designed based on CFD simulation, in which perforation were placed on the spacer in order to enhance shear rate and provide a path for the back transport of foulants into the bulk feed. The MF membrane tests showed that the presence of either big holes (2 mm diameter) or small holes (1 mm diameter) could not benefit to reduce membrane fouling at a lower permeate flux (20 L/m2h), but the presence of small holes significantly improved membrane performance at a higher permeate flux (40 and 60 L/m2h).

Degradation of p-chloroaniline using an electrochemical ceramic microfiltration membrane with built-in electrodes

An electrochemical ceramic microfiltration membrane with built-in cathode (Ti mesh) and Ti/RuO2 anode, which had dual functions of separation and electrochemical oxidation, was developed for p-chloroaniline (PCA) removal from contaminated waters. Results showed that the degradation of PCA followed the pseudo-first-order kinetics in all conditions. PCA degradation efficiency increased with the increase of applied voltages in the range of 0–3.0 V. The optimum solution pH for PCA decay was 7.0. An initial PCA concentration higher than 30 μM had no significant influence (p > 0.05) on the degradation efficiency of PCA. At an applied voltage of 2.0 V and an electrolysis time/hydraulic retention time of 2 h, the removal efficiency of PCA under flow-through mode was found to be 3.6 times that of flow-by mode, due to the better contact and reaction of contaminants with the oxidants generated in the vicinity of membrane surface. It also showed that OH arisen from anodic water oxidation reaction played a key role in PCA degradation. Benzoquinone, aniline, p-aminophenol, hydroquinone, malonic acid, succinic acid, oxamic acid, maleic acid, oxalic acid, α-ketoglutaric acid and formic acid were identified as the main PCA decay products, leading to a lower biological toxicity of the effluent. The system also demonstrated a favorable performance for contaminant elimination after a long-term operation. These results highlight the potential of this electrochemical microfiltration membrane system for efficient PCA degradation.

Treatment of highly-colored surface water by a hybrid microfiltration membrane system incorporating ion-exchange

Abstract This study investigated the performance of a hybrid membrane filtration system to produce industrial water from highly-colored surface water. The system consists of a membrane filtration process with appropriate pretreatments, including coagulation, pre-chlorination, and anion exchange (IE) process. The results of the pilot-scale experiments revealed that the hybrid system can produce treated water with color of around 5 Pt-Co, dissolved manganese concentration of no more than 0.05 mg/L, and a silt density index (SDI) of no more than 5 when sufficient coagulant and sodium hypochlorite were dosed. Although the IE process effectively reduced the color of the water, a moderate increase in the color of the IE effluent was observed when there was a significant increase in the color of the raw water. This resulted in a severe membrane fouling, which was likely to be attributed to the excess production of inorganic sludge associated with the increased coagulant dosage required to achieve sufficient reduction of color. Such severe membrane fouling can be controlled by optimising the backwashing and relaxation frequencies during the membrane filtration. These results indicate that the hybrid system proposed is a suitable technology for treating highly-colored surface water.

A novel process for the production of high-purity galactooligosaccharides (GOS) using consortium of microbes

ABSTRACTGalactooligosaccharides (GOS) are nondigestible dietary fibers which have a beneficial effect on human health by promoting the growth of probiotic bacteria in the gut. In addition, other health benefits have been reported from oligosaccharides consumption such as stimulation of intestinal mobility, colon cancer prevention, mineral absorption as well as protection against certain pathogenic bacterial infections. The goal of this research was to develop an efficient biotransformation system using a consortium of microbes for the production of ≥85% pure GOS and reusing the cell biomass in repeated cycles of biotransformation. Production of GOS by lactose transgalactosylation using whole cells of Sporobolomyces singularis MTCC 5491 as a source of β-galactosidase and monosaccharides utilization by yeast isolate (NUTIDY007) were studied. For increasing the purity of GOS, growth and bioconversion parameters on the transgalactosylation by the whole cells were investigated. Further, continuous production of GOS was studied in a reactor with microfiltration membrane system. A maximum GOS purity of 42% was achieved using single culture of S. singularis. Under optimized conditions, single culture of S. singularis produced a maximum of 56% pure GOS. Addition of second culture to the reaction mixture for utilization of glucose significantly increased the GOS purity from 56% to ≥85%. The product consisted of tri- to penta-galactooligosaccharides. Trisaccharides were the main component of the reaction mixture. A maximum productivity of 10.9 g/L/hr was obtained under the optimum conditions.

Understanding Alginate Fouling in Submerged Microfiltration Membrane System for Seawater Pretreatment

Understanding Alginate Fouling in Submerged Microfiltration Membrane System for Seawater Pretreatment

Effect of COD/TP ratio on biological nutrient removal in A2O and SBR processes coupled with microfiltration and effluent reuse potential

ABSTRACTTwo bench-scale hybrid processes, anaerobic/anoxic/oxic (A2O) reactor and sequencing batch reactor (SBR), each followed by the microfiltration (MF) system, were simultaneously operated to compare their performances on the removal of organics and phosphorus from both synthetic and real wastewater to further explore the potential for effluent reuse. The effects of different influent chemical oxygen demand (COD) to total phosphorus (TP) ratios (27, 50, 80, and 200) were investigated. For both processes, when the influent COD/TP ratio was 200, the effluent quality was satisfactory for some reuse potential. The MF membrane system showed an evident further removal of COD (20–89%) and color (18–60%), especially the removal of suspended solids (SS) and turbidity with the final effluent SS <1 mg/L and turbidity <0.1 NTU. When real wastewater was tested, the effluent quality was adequate and met the standard goals for regional reuse purposes.

Fabrication of BPPO Isoporous Membranes for Water Treatment

A isoporous brominated poly (phenylene oxide) (BPPO) microfiltration membrane system, fabricated by figure breath method, was demonstrated for the effective removal of impurity from contaminated water. The water permeation flux of BPPO membrane is higher. Such ordered isoporous membranes can also be applied in other size-based separation systems, enabling new opportunities in bioseparation and biosensors.

Treatment of Dairy Wastewater Effluent Using Submerged Membrane Microfiltration System

Treatment of Dairy Wastewater Effluent Using Submerged Membrane Microfiltration System

Treatment of Dairy Processing Wastewater using Integrated Submerged Membrane Microfiltration System

Dairy wastewater effluent has become one of the major concerns for the dairy processing industries. Because of large of wastewater effluent generation, the dairy processing industries may become potential candidates for wastewater reuse. Treated wastewater can be utilized in cooling systems and washing plant floor, as well its potential use for greenery irrigation purposes. In addition, treating dairy effluent will also benefit the environment. The purpose of this study is to characterize wastewater from a selected dairy industry in Kuwait (KD Cow Company) and a study of applying microfiltration treatment process for treating the dairy wastewater. A complete treatment system including biological treatment, powdered activated carbon (PAC) and submerged membrane microfiltration system (CMF-S) was installed at Kuwait Institute for Scientific Research (KISR) research plant. The overall results of this study indicate that the complete system is capable of treating the dairy effluent. The average removal efficiencies of the system for biological oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solid (TDS) were 98.8%, 92.5%, 96.7% respectively

Treatment of oil sands process-affected water by submerged ceramic membrane microfiltration system

With the rapid expansion of the oil sands in Northern Alberta over past decade, oil sands process-affected water (OSPW) management has become a significant issue. Currently, there is an urgent need for the OSPW reuse and/or safe discharge. In this study, coagulation followed by submerged microfiltration (MF) with a range of ceramic membranes was investigated as a potential process for pretreating OSPW. The ceramic MF membranes with the average pore size of 100nm were made of Al2O3 and their selective layer was further modified with SiO2 or TiO2 nanoparticles. Our results showed that membrane surface charge played an important role in controlling membrane fouling. The maximum fouling reduction was achieved when OSPW was treated by SiO2-modified membrane. Surface roughness studies also demonstrated its significant effect on membranes’ filtration performance and fouling. More foulants were deposited on the surface of rough TiO2-modified membrane as compared to smoother SiO2-modified membrane. It was found that removal of organic and inorganic fractions in OSPW was not affected neither by the type/concentration of coagulant nor by membrane’s surface modification. Thus, more than 93% removal of the total suspended solids and less than 17% and 10% removals of the total organic carbon (TOC) and chemical oxygen demand (COD), respectively, were achieved regardless of the membrane type and applied treatment. When MF permeate was used as an influent to the reverse osmosis (RO), this resulted in 98% and 100% reductions in TOC and COD concentrations, respectively. Moreover, RO filtration achieved more than 95% removal of magnesium, calcium, iron, fluoride, chloride, sulfate, nitrate, sodium and potassium and silica. The results of this study showed that combination of RO and MF could be considered as an effective and feasible option for OSPW treatment.

Characterization of membrane foulants in a pilot-scale tunnel construction wastewater treatment process

A pilot-scale combination of a microfiltration (MF) and a reverse osmosis (RO) membrane system was applied on-site to treat tunnel construction wastewater. The MF membrane system initially removed contaminants (turbidity of less than 0.3 NTU) in the form of particulate materials in the feed water, thereby allowing the combined MF–RO system to efficiently remove more than 99% of known organic and inorganic contaminants and qualify the reclaimed water for reuse. The MF membrane autopsy analysis using X-ray fluorescence (XRF) and inductively coupled plasma-mass spectrometry (ICP-MS) revealed that the dominant foulants were inorganic deposits involving Si, Al and Fe, comprising the main components of cement materials, as well as deposits involving heavy metals such as Mn, Cu and Zn in the form of particles. Thus, thick cake contaminants shown by field emission scanning electron microscope (FE-SEM) images might be induced via suspended solids consisting of cement and clay materials and metals.