scholarly journals Improved Nylon 6,6 Nanofiber Membrane in A Tilted Panel Filtration System for Fouling Control in Microalgae Harvesting

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 252 ◽  
Author(s):  
Normi Izati Mat Nawi ◽  
Nur Syakinah Abd Halim ◽  
Leong Chew Lee ◽  
Mohd Dzul Hakim Wirzal ◽  
Muhammad Roil Bilad ◽  
...  
Keyword(s):  
Steady State ◽  
Mechanical Strength ◽  
Membrane Filtration ◽  
Aeration Rate ◽  
Nanofiber Membrane ◽  
Total Energy Consumption ◽  
Solvent Vapor ◽  
Relaxation Period ◽  
Microalgae Harvesting ◽  
Nylon 6,6

The competitiveness of algae as biofuel feedstock leads to the growth of membrane filtration as one of promising technologies for algae harvesting. Nanofiber membrane (NFM) was found to be efficient for microalgae harvesting via membrane filtration, but it is highly limited by its weak mechanical strength. The main objective of this study is to enhance the applicability of nylon 6,6 NFM for microalgae filtration by optimizing the operational parameters and applying solvent vapor treatment to improve its mechanical strength. The relaxation period and filtration cycle could be optimized to improve the hydraulic performance. For a cycle of 5 min., relaxation period of ≤2 min shows the highest steady-state permeability of 365 ± 14.14 L m−2 h−1 bar−1, while for 10 min cycle, 3 min. of relaxation period was found optimum that yields permeability of 402 ± 34.47 L m−2 h−1 bar−1. The treated nylon 6,6 NFM was also used to study the effect of aeration rate. It is confirmed that the aeration rate enhances the steady-state performance for both intermittent and continuous mode of aeration. Remarkably, intermittent aeration shows 7% better permeability than the full aeration for all tested condition, which is beneficial for reducing the total energy consumption.

scholarly journals Improving Performance of Electrospun Nylon 6,6 Nanofiber Membrane for Produced Water Filtration via Solvent Vapor Treatment

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2117 ◽  
Author(s):  
Nur Syakinah Abd Halim ◽  
Mohd Dzul Hakim Wirzal ◽  
Muhammad Roil Bilad ◽  
Nik Abdul Hadi Md Nordin ◽  
Zulfan Adi Putra ◽  
...  
Keyword(s):  
Produced Water ◽  
Separation Performance ◽  
Electrospun Nanofiber ◽  
Nanofiber Membrane ◽  
Solvent Vapor ◽  
Acid Vapor ◽  
Dispersed Oil ◽  
Nylon 6,6 ◽  
Highly Porous ◽  
Vapor Treatment

Electrospun nanofiber membrane (NFM) has a high potential to be applied as a filter for produced water treatment due to its highly porous structure and great permeability. However, it faces fouling issues and has low mechanical properties, which reduces the performance and lifespan of the membrane. NFM has a low integrity and the fine mat easily detaches from the sheet. In this study, nylon 6,6 was selected as the polymer since it offers great hydrophilicity. In order to increase mechanical strength and separation performance of NFM, solvent vapor treatment was implemented where the vapor induces the fusion of fibers. The fabricated nylon 6,6 NFMs were treated with different exposure times of formic acid vapor. Results show that solvent vapor treatment helps to induce the fusion of overlapping fibers. The optimum exposure time for solvent vapor is 5 h to offer full retention of dispersed oil (100% of oil rejection), has 62% higher in tensile strength (1950 MPa) compared to untreated nylon 6,6 NFM (738 MPa), and has the final permeability closest to the untreated nylon 6,6 NFM (733 L/m2.h.bar). It also took more time to get fouled (220 min) compared to untreated NFM (160 min).

scholarly journals Electrospun Nylon 6,6/ZIF-8 Nanofiber Membrane for Produced Water Filtration

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2111 ◽  
Author(s):  
Nur Syakinah Abd Halim ◽  
Mohd Dzul Hakim Wirzal ◽  
Muhammad Roil Bilad ◽  
Nik Abdul Hadi Md Nordin ◽  
Zulfan Adi Putra ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Steady State ◽  
Water Reuse ◽  
Produced Water ◽  
Pure Water ◽  
Volume Ratio ◽  
High Porosity ◽  
Nanofiber Membrane ◽  
Zeolitic Imidazolate Framework ◽  
Nylon 6,6

This study develops electrospun nylon 6,6 nanofiber membrane (NFM), incorporating zeolitic imidazolate framework-8 (ZIF-8) as the additive for produced water (PW) filtration. Electrospun NFM is suitable to be used as a filter, especially for water treatment, since it has a huge surface area to volume ratio, high porosity, and great permeability compared to the conventional membranes. These properties also enhance its competitiveness to be used as reverse osmosis pre-treatment, as the final stage of PW treatment water reuse purpose. However, the fouling issue and low mechanical strength of NFM reduces hydraulic performance over time. Therefore, this study employs ZIF-8 as an additive to improve nylon 6,6 NFM properties to reduce fouling and increase membrane tensile strength. Results show that the optimum loading of ZIF-8 was at 0.2%. This loading gives the highest oil rejection (89%), highest steady-state pure water permeability (1967 L/(m2·h·bar)), 2× higher than untreated nylon 6,6 NFM with tensile strength 5× greater (3743 MPa), and a steady-state permeability of 1667 L/(m2·h·bar) for filtration of real produced water.

scholarly journals Effect of Solvent Vapor Treatment on Electrospun Nylon 6,6 Nanofiber Membrane

2018 ◽  
Vol 429 ◽  
pp. 012019 ◽  
Author(s):  
N S A Halim ◽  
M D H Wirzal ◽  
M R Bilad ◽  
A R M Yusoff ◽  
N A H M Nordin ◽  
...  
Keyword(s):  
Nanofiber Membrane ◽  
Solvent Vapor ◽  
Effect Of Solvent ◽  
Nylon 6,6 ◽  
Vapor Treatment

scholarly journals Efficient Synthesis of PVDF/PI Side-by-Side Bicomponent Nanofiber Membrane with Enhanced Mechanical Strength and Good Thermal Stability

Nanomaterials ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 39 ◽  
Author(s):  
Ming Cai ◽  
Hongwei He ◽  
Xiao Zhang ◽  
Xu Yan ◽  
Jianxin Li ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Mechanical Strength ◽  
Polyvinylidene Fluoride ◽  
Chemical Structure ◽  
Electrospun Fiber ◽  
Nanofiber Membrane ◽  
Application Range ◽  
Good Thermal Stability ◽  
Filtration Properties

Bicomponent composite fibers, due to their unique versatility, have attracted great attention in many fields, such as filtration, energy, and bioengineering. Herein, we efficiently fabricated polyvinylidene fluoride/polyimide (PVDF/PI) side-by-side bicomponent nanofibers based on electrospinning, which resulted in the synergism between PVDF and PI, and eventually obtained the effect of 1 + 1 > 2. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the morphology and chemical structure of nanofibers, indicating that a large number of side-by-side nanofibers were successfully prepared. Further, the thermal stability, mechanical strength, and filtration properties of PVDF/PI were carefully investigated. The results revealed that the bicomponent nanofibers possessed both good mechanical strength and remarkable thermal stability. Moreover, the mechanical properties of PVDF/ PI were strengthened by more than twice after the heat treatment (7.28 MPa at 25 °C, 15.49 MPa at 230 °C). Simultaneously, after the heat treatment at 230 °C for 30 min, the filtration efficiency of PVDF/PI membrane was maintained at about 95.45 ± 1.09%, and the pressure drop was relatively low. Therefore, the prepared PVDF/PI side-by-side bicomponent nanofibers have a favorable prospect of application in the field of medium- and high-temperature filtration, which further expands the application range of electrospun fiber membranes.

Interpretation of Radiophosphate Dynamics in Lake Waters

1992 ◽  
Vol 49 (2) ◽  
pp. 252-258 ◽  
Author(s):  
T. R. Fisher ◽  
D. R. S. Lean
Keyword(s):  
Steady State ◽  
Membrane Filtration ◽  
Cell Damage ◽  
Gel Filtration ◽  
Turnover Time ◽  
Steady State Distribution ◽  
State Distribution ◽  
Order Of Magnitude ◽  
Lake Waters ◽  
Functional Components

Models of planktonic phosphorus dynamics over the last 30–40 yr depend on the steady-state distribution of isotope for the determination of compartment size. Radiophosphate data for P-deficient lakes in summer have shown a steady-state distribution of 1–15% of 32P in the filtrate within 0.5–5 h. To explain this, a phosphate back-flux term from the particulate fraction has been widely accepted (phosphate is believed to be released from the internal pools of phosphate consumers and by excretion from herbivores and bacterivores). We show that dialysis of lake water at isotopic steady state provides values for the dissolved [32P]PO4 compartment up to an order of magnitude lower than those obtained by membrane filtration and gel filtration chromatography. This apparently occurs as a result of minor cell damage during filtration when most of the [32P]PO4 is in the particulate pool. Consequently, the size of the phosphate pool and the magnitudes of phosphate uptake and back-flux may have been overestimated by up to a factor of 10. Furthermore, the turnover time of the particulate compartment lengthens from ~ 40 min to > 1 d, which is more consistent with models describing P fluxes between functional components of the plankton.

scholarly journals Development and evaluation of flux enhancement and cleaning strategies of woven fibre microfiltration membranes for raw water treatment in drinking water production

2015 ◽  
Author(s):  
◽  
Kumnandi Pikwa
Keyword(s):  
Membrane Filtration ◽  
Pure Water ◽  
Aeration Rate ◽  
Raw Water ◽  
Flux Enhancement ◽  
Average Flux ◽  
Particle Adsorption ◽  
Filtration Unit ◽  
Feed Samples ◽  
Pore Plugging

Woven Fibre Microfiltration (WFMF) membranes have several advantages over its competitors with respect to durability, making it a favourable alternative for the developing world and operation during rough conditions. Wide application of membrane technology has been limited by membrane fouling. The durability of the WFMF membrane allows more options for flux enhancement and cleaning methods that can be used with the membranes even if they are vigorous. Therefore, the purpose of this work was to develop and evaluate flux enhancement and cleaning strategies for WFMF membranes. Feed samples with high contents of organics and turbidity were required for the study. Based on this, two rivers which are Umkomaasi and Duzi River were identified to satisfy these criteria. A synthetic feed with similar fouling characteristics as the two river water was prepared and used for this study. The synthetic feed solution was made up of 2 g/ℓ of river clay in tap water and 0.5% domestic sewerage was added into the solution accounting for 2% of the total volume. A membrane filtration unit was used for this study. The unit consisted of a pack of five membrane modules which were fully immersed into a 100 litres filtration tank. The system was operated under gravity and the level in the filtration tank was kept constant by a level float. The study focused on evaluating the performance of the woven fibre membrane filtration unit with respect to its fouling propensity to different feed samples. It also evaluated and developed flux enhancement and cleaning strategies and flux restoration after fouling. The results were compared to a base case for flux enhancement and pure water fluxes for cleaning. The WFMF membrane was found to be prone to both internal and external fouling when used in the treatment of raw water (synthetic feed). Internal fouling was found to occur quickly in the first few minutes of filtration and it was the major contributor for the loss of flux from the WFMF membrane. The fouling mechanism responsible for internal fouling was found to be largely pore blocking and pore narrowing due to particle adsorption on/in the membrane pores. The structure (pore size, material and surface layout) of the WFMF membrane was found to be the main cause that made it prone to internal fouling. The IV major fouling of the WFMF membrane was due to internal fouling, a high aeration rate of 30 ℓ/min had minimal effect on the fouling reduction. An aeration rate of 30 ℓ/min improved the average flux by only 36%, where a combination of intermittent backwashing with brushing and intermittent backwashing with aeration (aeration during backwashing only) improved average flux by 187% and 135% respectively. Pre-coating the WFMF membrane with lime reduced the effects of pore plugging and particle adsorption on the membrane and improved the average flux by 66%. The cleaning strategies that were most successful in pure water flux (PWF) recovery were high pressure cleaning and a combination of soaking and brushing the membrane in a 0.1% NaOCl (desired) solution. PWF recovery by these two methods was 97% and 95% respectively. Based on these findings, it was concluded that the WFMF membrane is susceptible to pore plugging by colloidal material and adsorption/attachment by microbiological contaminants which took effect in the first hour of filtration. This led to a 50% loss in flux. Also, a single flux enhancement strategy proved insufficient to maintain a high flux successfully. Therefore, combined flux enhancement strategies yielded the best results.

Operational factors of submerged inorganic membrane bioreactor for organic wastewater treatment: sludge concentration and aeration rate

2003 ◽  
Vol 47 (1) ◽  
pp. 121-126 ◽  
Author(s):  
E.J. Hwang ◽  
D.D. Sun ◽  
J.H. Tay
Keyword(s):  
Membrane Filtration ◽  
Ceramic Membrane ◽  
Filtration Efficiency ◽  
Optimal Operation ◽  
Aeration Rate ◽  
Inorganic Membrane ◽  
Operation Condition ◽  
Critical Flux ◽  
Filtration System ◽  
Sludge Concentration

Various sludge concentrations and aeration rates were evaluated to find the optimal operation condition of a submerged ceramic membrane filtration system. 5.6 g/L of sludge was diluted with water to concentrations of 2.8 g/L and 1.4 g/L, and the three sludge concentrations were compared in terms of filtration characteristics such as pressure and filtrate flux. Flux was at the highest value of about 30 L/m2.hr at 50 kPa when sludge concentration was 1.4 g/L. In contrast, when sludge concentrations increased to 2.8 g/L and 5.6 g/L, the flux at 50 kPa decreased significantly to 18 L/m2.hr and 10 L/m2.hr, respectively. It was concluded that the sludge concentration directly affected the filtration efficiency, and low sludge concentration was suitable for improving filtration efficiency. Adjusting the aeration rate from 2 L/min to 4 L/min at 5.6 g/L of sludge and 50 kPa of pressure increased flux from 10 L/m2.hr to 13 L/m2.hr. It was obvious that the vigorous aeration improved the filtration efficiency, but the aeration rate did not seem to be high enough to maintain flux lower than critical flux.

A mechanically durable, sustained corrosion-resistant photothermal nanofiber membrane for highly efficient solar distillation

2019 ◽  
Vol 7 (39) ◽  
pp. 22296-22306 ◽  
Author(s):  
Ying Xu ◽  
Hongbo Xu ◽  
Zhigao Zhu ◽  
Haoqing Hou ◽  
Jinlong Zuo ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Nanofibrous Membrane ◽  
Core Shell ◽  
Nanofiber Membrane ◽  
Corrosion Resistant ◽  
Highly Efficient ◽  
Solar Distillation

A core–shell structured PDA/PEI/PPy@PI nanofibrous membrane with excellent wet mechanical strength, efficient solar evaporation and sustained anti-corrosion capacity.

Comparison of different oxygen transfer testing procedures in full-scale membrane bioreactors

2003 ◽  
Vol 47 (12) ◽  
pp. 169-176 ◽  
Author(s):  
S. Krause ◽  
P. Cornel ◽  
M. Wagner
Keyword(s):  
Wastewater Treatment ◽  
Steady State ◽  
Oxygen Transfer ◽  
Membrane Filtration ◽  
Treatment Plant ◽  
Complete Removal ◽  
Membrane Bioreactors ◽  
Full Scale ◽  
Efficient Operation ◽  
Testing Procedures

Membrane bioreactors (MBRs) for wastewater treatment offer the advantage of a complete removal of solids from the effluent. The secondary clarifier is replaced by a membrane filtration and therefore high biomass concentrations (MLSS) in the reactor are possible. The design of the aeration system is vital for an energy efficient operation of any wastewater treatment plant. Hence the exact measurement of oxygen transfer rates (OTR) and α-values is important. For MBRs these values reported in literature differ considerably. The OTR can be measured using non-steady state methods or using the off-gas method. The non-steady state methods additionally require the determination of the respiration rate (oxygen uptake rate ≡ OUR), which usually is measured in lab scale units. As there are differences of OUR between lab scale and full scale measurements, off-gas tests (which do not require an additional respiration test) were performed in order to compare both methods at high MLSS concentrations. Both methods result in the same average value of OTR. Due to variations in loading and wastewater composition variations of OTR in time can be pointed out using the off-gas method. For the first time a comparison of different oxygen transfer tests in full scale membrane bioreactors is presented.

Influence of CO2 and O2 Feeding Rates on the Continuous Bioleaching of a Chalcopyrite Concentrate Using Sulfolobus Metallicus

2009 ◽  
Vol 71-73 ◽  
pp. 393-396 ◽  
Author(s):  
D. Cautivo ◽  
J.C. Gentina
Keyword(s):  
Steady State ◽  
Aeration Rate ◽  
Volumetric Productivity ◽  
Copper Extraction ◽  
Feeding Rates ◽  
Steady State Condition ◽  
Transfer Rates ◽  
Continuous Bioreactor ◽  
Limiting Nutrient ◽  
Chalcopyrite Concentrate

Bioleaching of secondary sulfides is a technical and economical well established bioprocess. However in the case of bioleaching of primary sulfides, like chalcopyrite and enargite, still is necessary to improve the bioprocess kinetic. One alternative that has been proposed to overcome this situation is to use hyperthermophilic bioleaching microorganisms. Nevertheless, higher process temperatures modifies in a different extent operation parameters like CO2 and O2 transfer rates, both gases being essential to the bioprocess. The aim of this work was to establish quantitatively, using a continuous bioreactor operating at steady state conditions, which gas limits the growth and activity of bioleaching microorganisms when air is used as source of both of them. The experiments were run in a 3.3 L agitated continuous bioreactor operated at 70°C, pH 1.8 and 150 g/L of copper concentrate rich in chalcopyrite. Operating at steady state condition with an aeration rate of 1.2 vvm, a copper solubilization volumetric productivity of 1.7 g(Cu2+)(L•day)-1 and a copper extraction of 55% were obtained. Enriching the inflow air with CO2 up to 5% (v/v) showed the maximum values of these indexes, increasing 34% the volumetric productivity of copper solubilization and reaching 74% of copper extraction. On the opposite way, enriching air with oxygen or increasing the aeration rate did not bring about any change either of the volumetric productivity or the percentage of copper extraction. The results allow concluding that the CO2 is the limiting nutrient for cell growth in the continuous bioleaching of a chalcopyrite concentrate using hyperthermophilic microorganisms.

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