Ultrafiltration Membrane Filtration Research Articles

Novel sulfonated rGOHfO2/PVDF hybrid nanocomposite ultrafiltration membrane towards direct potable reuse water production

Using wastewater to produce safe and reliable reclamation water is a sustainable means of reducing water scarcity. Membrane technology can be a viable path for producing advanced treated water from wastewater. Numerous three-dimensional metal oxide nanoparticles with graphene oxide (GO) have been evaluated in membrane fabrication. On the other hand, there are no reports on the use of GO combined with hafnium oxide (HfO2) for the fabrication of ultrafiltration (UF) membranes to produce direct potable reuse (DPR) water. In this study, rGOHfO2 (reduced GOHfO2) was synthesized using a microwave method. A novel sulfonated rGOHfO2 (SrGOHfO2) nanocomposite was fabricated and added to the polyvinylidene fluoride (PVDF) to develop advanced nanohybrid UF membranes toward the production of DPR water and improve dispersibility and hydrophilicity. The incorporation of SrGOHfO2 into PVDF membranes had very positive effects on hydrophilicity, MWCO, and morphology. The P-SGOHf-2 membrane (0.2 wt % SrGOHfO2) exhibited excellent pure water flux of approximately 301 ± 3% and 133.3 ± 2% than PVDF and P-GOHf membrane, respectively. The P-SGOHf-2 membrane showed high separation efficiency up to 94 ± 1% and 98 ± 04% towards humic acid (HA) and bovine serum albumin (BSA), respectively. The superior antifouling properties were observed in the SrGOHfO2 incorporated membranes compared to the P-GOHf and PVDF membranes, with a 2.9% irreversible fouling ratio (Rir) and a 97.1% flux recovery ratio (FRR) for the P-SGOHf-2 membrane. The excellent performance of the P-SGOHf-2 membrane was attributed to the larger number of sulfonic acid groups (-SO3H) in the SrGOHfO2 nanocomposite. In the tertiary UF membrane filtration mode operation using the secondary effluent of the field-scale wastewater treatment plant, the P-SGOHf-2 membrane performed high flux with reliable effluent quality (154 ± 5L m−2 h−1, 0.26 ± 0.03 NTU, no pathogens), while it exhibited lower membrane resistances during filtration. These advanced nanohybrid membranes can be a sustainable, viable alternative technology compared to the traditional tertiary treatment processes that utilize expensive and complex multi-step processes to produce DPR water.

Impact of membrane configuration on the performance and cost of a pilot-scale UF process treating surface water

The performance of ultrafiltration (UF) is heavily influenced by the specifications of membrane modules and operational modes. Pore size, configuration, and material of the UF membrane influence both treatment and filtration performances. The study compares the performance of outside-in and inside-out UF membrane configuration in a pilot-scale system treating surface water. One of the tested UF modules has multi-bore inside-out type membranes (M1), and the other has reinforced hollow fiber outside-in type membranes (M2). Although the treatment performances were quite similar, the filtration performances of the M1 and M2 were different. In long-term pilot-scale operation, the permeability of the M2 module measured 50 L/m2.h.bar, while the M1 module measured 34 L/m2.h.bar. At the same time, it was observed that the transmembrane pressure (TMP) of M1 was higher than that of M2. A cost analysis was made based on the pilot plant data; estimated capital expenses of 0.019 $/m3 and operation and maintenance (O&M) cost of 0.045 $/m3 were found for the M2 module. This study comparatively presented the long-term operating performance, capital and operational costs for multi-bore inside-out and reinforced outside-in UF membrane configuration.

Simulation analysis of UF membrane filtration process based on magnetic field characteristics

Abstract Membrane fouling will affect the performance of the membrane, resulting in the increase of filtration cost and reduced membrane life. Magnetization technology has the advantages of being green, pollution-free and energy saving, and it has broad potential applications in water treatment. In this study, COMSOL Multiphysics realizes the coupling of magnetic field and flow field by adding the magnetic field force formula in the fluid module. The influence of magnetic field on fluid flow and inorganic pollutant distribution in an ultrafiltration (UF) membrane device were investigated. The simulation results show that the magnetic field improves the water flow velocity in the device to a certain extent, reduces the volume fraction of pollutant particles on the membrane surface, and then reduces the possibility of forming a thicker filter cake layer, which is beneficial to slow down membrane fouling and thus slow down the reduction rate of membrane flux. In addition, the simulation results were verified by the membrane specific flux experiment, and consistent conclusions were obtained.

Techno-economic analysis of single disinfection units and integrated disinfection systems for sewage effluent reclamation

This study aimed to evaluate several potential candidates of single disinfection/disinfectant units and integrated disinfection systems in treating sewage effluent to obtain non-potable water, within a techno-economic analysis framework. Eight candidates of commercially available disinfection units and integrated disinfection systems were selected to be examined under the techno-economic analysis by comparison amongst the sewerage effluent. There were 4 types of treatment processes represented amongst the single disinfection units (Single): ultraviolet (UV), chlorination, microfiltration (MF), and ultrafiltration (UF). Within these processes, MF and UF both were represented twice by HVLP00010 and PVDF021 M (MF membranes); and by PVDF1001 M and PES20kDa (UF membranes). Whereas, for integrated disinfection systems (Integrated), UV disinfection and chlorination act as the primary disinfection unit, with MF/UF, Enviromulti-media (EMM) adsorption, or granular activated carbon (GAC) adsorption integrated as the pre-treatment unit. Two design capacities for water recovery - 100 m³/day (to represent a pilot-scale reproduction) and 5000 m3/day (to represent an industrial-scale reproduction) were defined to analyze and compare the cost effectiveness between single disinfection units and integrated disinfection systems chosen in this study. Amongst the studied setups, single chlorination unit and EMM-UV integrated disinfection system were the two most economical configurations to regenerate treated water for restricted applications. Whereas, the single PVDF1001 M UF membrane filtration unit was ultimately suggested as the most economic and viable technology for unrestricted water reuse purpose at both design capacities, considering the estimated cost at Malaysia currency, RM 0.50/m³ and RM 0.10/m³ for 100 m³/day and 5000 m³/day design capacity, respectively.

Removal of natural organic matter at the Gunbower water treatment plant in northern Victoria, Australia

Advanced treatment processes are vital if organic matter is to be removed from water as efficiently as possible. To produce high quality water that has low concentrations of natural organic matter (NOM), the Gunbower water treatment plant (WTP) in northern Victoria, Australia has implemented a number of processes including magnetic ion exchange (MIEX), coagulation, clarifier, ultrafiltration (UF), and granular activated carbon (GAC) filtration. This research evaluated the efficiencies of these processes in removing NOM employing various analytical methods, namely liquid chromatography–organic carbon detector (LC–OCD) and three-dimensional fluorescence excitation emission matrix (3D-FEEM). In addition, the fouling potential of source water and treated water was assessed using a modified fouling index with ultrafiltration (MFI-UF). Biological stability was also tested using a modified assimilable organic carbon (AOC) detection method. The combination of MIEX, clarifier, coagulation, UF membrane, and GAC filtration resulted in dissolved organic carbon (DOC) being removed (from 6.01 to 0.47 mg/L). Furthermore 3D-FEEM analysis revealed that these treatment processes reduced humic and fulvic-like organics. AOC and MFI-UF decreased from 79.94 μg-C glucose equivalents/L and 46,350 s/L2 in the source water to 4.06 μg-C glucose equivalents/L and 2,057 s/L2 in the treated water, respectively.

Assessing the interaction effects of coagulation pretreatment and membrane material on UF fouling control using HPSEC combined with peak-fitting

In this paper, the effects of alum coagulation pretreatment on the removal of natural organic matter (NOM) from surface water, and on fouling control of the subsequent ultrafiltration (UF) membrane filtration, were studied. Two kinds of UF membrane, made from polyvinyl chloride (PVC) and cellulose acetate (CA), respectively, were tested. The dissolved organics were characterized by high performance size exclusion chromatography (HPSEC) with ultraviolet/visible (UV/vis) and dissolved organic carbon (DOC) detectors, in addition to the conventional organic parameters, such as nonpurgeable dissolved organic carbon (NPDOC) and UV254. The results show that coagulation pretreatment could reduce the flux decline of UF membrane filtration by removing some of the NOM. Alum coagulation was found to have higher removal for large molecular weight organics, such as biopolymers and humic substances, than for low molecular weight acids. The results from HPSEC revealed that the PVC membrane removed mainly the biopolymer fraction, while the CA membrane, in addition to biopolymers, also removed some of the more hydrophilic low molecular weight acids. As alum coagulation preferably removed biopolymers over low molecular weight acids, pre-coagulation had less effect on CA membrane flux decline control than on PVC membrane flux decline control.

Practical performance analysis of an industrial-scale ultrafiltration membrane water treatment plant

Common design and operational issues to evaluate the performance of an ultrafiltration (UF) membrane water treatment plant are highlighted with a case study on an industrial-scale drinking water treatment plant located in Malaysia. This treatment plant has been in operation since February 2013 using dead-end polyethersulfone UF membrane filtration system to produce up to 14 million litres a day of drinking water to a small township. Literature solutions are compared with the practised solutions and elucidated with the case study. Gaps between literature solutions which are mainly based on lab-scale research and industry practices are identified. Reducing this gap will have vast implication to improve the design and operation of industrial-scale UF treatment system.

Effect of slow sand filtration of treated wastewater as pre-treatment to UF

Ultrafiltration (UF) of treated municipal wastewater has been used to produce high-quality reuse water for different applications. However, without pre-treatment, secondary treated wastewater effluent shows high fouling potential and reduces the performance of UF membrane filtration significantly. To remove foulants prior to UF, slow sand filtration (SSF) was investigated in the present work. Two pilot-scale slow sand filters were operated in tandem with UF. The performance of the UF plant was improved to a large extent by delivering slow sand filtrate compared to direct secondary effluent filtration. Removal of common organic fouling indicators (i.e., proteins, carbohydrates, and biopolymers) by SSF was significantly higher at 0.25 m/h versus 0.5 m/h filter loading rate. Results of a comparative analysis of SSF effluent characteristics and UF performance showed that the biopolymer content detected by size exclusion chromatography displayed a good correlation with the filterability of corresponding water sample by UF, while photo-metrically detected proteins and polysaccharides did not present any relationship with UF performance.

Treatment of household grey water with a UF membrane filtration system

As water is becoming a rare resource, the onsite reuse and recycling of grey water are practiced in many countries as a sustainable solution to reduce the overall urban water demand. In this paper, a decentralized grey water treatment system, which used a submerged spiral-wound ultrafiltration (UF) membrane module, was studied. This grey water treatment system aimed to treat and recover the resources present in the grey water. The study revealed that the UF membrane filtration system was able to maintain a permeate flux between 6 and 10 L/m2/h. TOC can be reduced from the influent value of 161 to 28.6 mg/L in the permeate, meaning an average elimination rate of 83.4%. In addition, soluble nutrients such as ammonia and phosphorus can pass through the UF membrane and remain in the permeate. The total nitrogen and total phosphorus in the permeate were 16.7 and 6.7 mg/L respectively. The permeate was low in turbidity (below 1 NTU) and free of suspended solids and had an excellent physical appearance. Around 4...

Treatment of Chemical Mechanical Polishing Wastewater for Water Reuse by Ultrafiltration and Reverse Osmosis Separation

This paper describes the treatment of chemical mechanical polishing (CMP) wastewater from a semiconductor plant through membrane-based ultrafiltration (UF) and reverse osmosis (RO) processes to improve the removal efficiency under different water recovery and to determine the possible mechanisms of membrane blocking and rejection. UF pretreatment led to 42.1–46.9% conductivity, 98.1–99.4% turbidity, and 4.5–24.5% total organic carbon (TOC) removal. These contaminants were almost completely rejected after performing subsequent RO processing: the values of the conductivity, turbidity, and TOC were reduced to 6 μS/cm, 0.01 NTU, and 1.6 mg/L, respectively. The water quality of the permeates after UF or RO membrane filtration could meet the water reuse standards for tap water, cooling water, boiler water, and the feed for a water purification machine. The variation with time of the permeate flux for the UF process was fitted to the Hermia model to examine the possible blocking mechanisms during the filtration ...

The effect of coagulation with MF/UF membrane filtration for the removal of virus in drinking water

Removal of phage MS2 in drinking water by pre-coagulation and filtration through ultrafiltration (UF) and microfiltration (MF) membranes was investigated in a laboratory test unit. Two commercial aluminium-based coagulants (ALG and PAX) were used. The low (≤1–30 pfu/mL) numbers of infective virus detected in permeates show that pre-coagulation/flocculation in combination with both loose UF and MF membrane filtration was an effective hygienic barrier against MS2 virus. Without pre-coagulation/flocculation, no (MF) or only a minor (UF) virus removal was observed. The two coagulants provided high virus removal efficiencies (>7.4 logs) after UF and MF membrane filtration using doses of 5 mg Al/L. Reducing the dose of coagulants to 3 mg Al/L had only a small effect on the removal efficiency, which remained high after UF membrane filtration, and ALG/MF membrane filtration (>7.1 logs). The virus removal obtained with PAX (3 mg Al/L) and MF membrane filtration was slightly less (6.7 logs) than for the other conditions. Combined removal of virus and colour by pre-coagulation/flocculation and MF membrane filtration was also investigated. The low concentrations of both virus and colour in the permeate indicate that low-pressure MF filtration in combination with pre-coagulation/flocculation is a potential efficient technology for removal of virus and colour in drinking water.

Membrane filtration as a pre-treatment method

Pre-treatment of raw water before reverse osmosis (RO) is of great importance for the economy and life of an RO plant. The extent of pre-treatment depends on the raw water quality. Conventional raw water treatment methods are normally used for pre-treatment in RO plants. The aim of this paper is to investigate the possibilities to use membrane methods, primarily ultrafiltration (UF), as alternatives for conventional pre-treatment stages. These methods are discussed from the point of view of both technical and economical competition with conventional methods including operation and maintenance. The cost calculations for RO plants with a capacity of 10,000 m 3/d are based on available cost data from RO plants in operation in the Middle East. Different types of raw water are included in the cost comparison, viz. surface brackish water and seawater with worse quality than normal groundwater. The conventional pre-treatment stages, usually required before reverse osmosis, are discussed as well as the possibilities to replace some of these treatment stages with UF membrane filtration methods, and associated costs. This investigation shows the additional (differential) costs for the UF-RO plant as well as the prerequisites for UF-RO to be competitive with already established, conventional pre-treatment methods.