Hollow Fiber Membrane Contactor Research Articles

Improving the measurement of total dissolved sulfide in natural waters: A new on-site flow injection analysis method

Total dissolved sulfide (TDS) plays multiple important roles in the aquatic environments. However, the determination of trace levels of TDS in natural waters is challenging because TDS is vulnerable to oxidation and volatilization. In this study, a fully automated flow injection analysis spectrophotometric system, incorporating a hollow fiber membrane contactor (HFMC) and a long path length liquid waveguide capillary cell, was fabricated to facilitate the on-site measurement of trace TDS in natural waters. The HFMC was used for matrix separation and analyte preconcentration. The measurement was based on the reaction of sulfide and N,N-dimethyl-p-phenylenediamine in the presence of FeCl3 under acidic conditions to yield methylene blue (MB). The proposed method was highly sensitive, with detection and quantification limits of 0.57 and 1.90 nmol L−1, respectively. The linear working range was from 1.90 to 150 nmol L−1, with a correlation coefficient of 0.9995. The repeatability, expressed as the relative standard deviation, was less than 0.86% (n = 15) and the recoveries varied from 76.2 ± 0.1% to 103.9 ± 0.6% (n = 3) for spiked samples. This method was applied to conduct a field analysis of TDS in a reservoir, giving results aligned with those obtained using a standard MB method. This work demonstrates that the new method for determining TDS was effective for both laboratory analysis and on-site measurement.

CO2 absorption into aqueous ammonia using membrane contactors: Role of solvent chemistry and pore size on solids formation for low energy solvent regeneration

Solids formation can substanitally reduce the energy penalty for ammonia solvent regeneration in carbon capture and storage (CCS), but has been demonstrated in the literature to be difficult to control. This study examines the use of hollow fibre membrane contactors, as this indirect contact mediated between liquid and gas phases in this geometry could improve the regulation of solids formation. Under conditions comparable to existing literature, NH4HCO3 was evidenced to primarily crystallise in the gas-phase (lumen-side of the membrane) due to the high vapour pressure of ammonia, which promotes gaseous transmission from the solvent. Investigation of solvent reactivity demonstrated how equilibria dependent reactions controlled the onset of NH4HCO3 nucleation in the solvent, and limited ‘slip’ through transfomation of ammonia into its protonated form which occurs prior to the phase change. Crystallisation in the solvent was also dependent upon ammonia concentration, where sufficient supersaturation must develop to overcome the activation energy for nucleation. However, this has to be complemented with a reduction in solvent temperature to offset vapour pressure and limit the risk of gas-phase crystallisation. While changes to the solvent chemistry were sufficient to shift from gas-phase to liquid phase crystallisation, wetting was observed immediately after nucleation in the solvent. This was explained by a local region of supersaturation within the coarse membrane pores that promoted a high nucleation rate, altering the material contact angle of the membrane sufficient for solvent to breakthrough into the gas phase. Adoption of a narrower pore size membrane was shown to dissipate wetting after crystallisation in the solvent, illustrating membrane contactors as a stable platform for the sustained separation of CO2 coupled with its simultaneous transformation into a solid. Through resolving previous challenges experienced with solids formation in multiple reactor configurations, the cost benefit of using ammonia as a solvent can be realised, which is critical to enabling economically viable CCS for the transition to net zero, and can be exploited within hollow fibre membrane contactors, eliciting considerable process intensification over existing reactor designs for CCS.

A Numerical Study on Removal of CO2 by 2-(tert-Butylamino) Ethanol in a Hollow Fiber Membrane Contactor

A Numerical Study on Removal of CO₂ by 2-(tert-Butylamino) Ethanol in a Hollow Fiber Membrane Contactor

Hollow-Fiber Membrane Contactor for Biogas Recovery from Real Anaerobic Membrane Bioreactor Permeate.

This study demonstrates the application of hollow-fiber membrane contactors (HFMCs) for the recovery of biogas from the ultrafiltration permeate of an anaerobic membrane bioreactor (AnMBR) and synthetic effluents of pure and mixed CH4 and CO2. The developed membrane degassing setup was coupled with a pilot-scale AnMBR fed with synthetic domestic effluent working at 25 °C. The membrane degassing unit was able to recover 93% of the total dissolved CH4 and 83% of the dissolved CO2 in the first two hours of permeate recirculation. The initial recovery rates were very high (0.21 mg CH4 L−1 min−1 and 8.43 mg CO2 L−1 min−1) and the membrane was able to achieve a degassing efficiency of 95.7% for CH4 and 76.2% for CO2, at a gas to liquid ratio of 1. A higher mass transfer coefficient of CH4 was found in all experimental and theoretical evaluations compared to CO2. This could also be confirmed from the higher transmembrane mass transport resistance to CO2 rather than CH4 found in this work. A strong dependency of the selective gas transport on the gas and liquid side hydrodynamics was observed. An increase in the liquid flow rate and gas flow rate favored CH4 transport and CO2 transport, respectively, over each component. The results confirmed the effectiveness of the collective AnMBR and membrane degassing setup for biogas recovery. Still, additional work is required to improve the membrane contactor’s performance for biogas recovery during long-term operation.

Numerical modeling of wastewater treatment using HOLLOW fiber membrane contactors based on the stiff spring method

In this study the efficiency of a porous HOLLOW fiber membrane module (PHFMM) was studied using a simple and generic method. Stiff spring method (SSM) was applied in order to solve two-dimensional transient model equations of transport of diluted species through an extractive HOLLOW fiber membrane contactor (HFMC). The influence of equilibrium partition coefficient on membrane efficiency and exit concentration has also been investigated. The predictions made by the present model matched the experimental data obtained for Cu2+removal in a kerosene solution of di 2-Ethylhexyl phosphoric acid (D2EHPA) from wastewater. The results of the model showed that the predictions are in good agreement with the experimental data obtained for different values of species concentration. Furthermore, it was demonstrated that the membrane efficiency and exit concentration could not be predicted well for many ranges of equilibrium partition coefficients by applying non-stiff method. The efficiency of membrane which predicted 56%, can be calculated by non-stiff method only if the partition coefficient considered 800 or more. In contrast, the membrane efficiency was completely fixed and in quite good agreement with the experimental data over a wide range of equilibrium partition coefficients from very low values of 0.02 to a very high values of more than 800 upon application of stiff spring-based method. Similarly, the exit concentration of Cu2+ predicted very well to about 0.4 mol/m3 when the inlet concentration was 1 mol/m3 for a very wide range of partition coefficient by stiff-spring method. However, the outlet concentration of Cu2+ could not be predicted well by non-stiff method unless the partition coefficient supposed to be more than 800. Ultimately, simulation results verify that the stiff spring method is more reliable and accurate in comparison with non-stiff spring method.

Modeling of hollow fiber membrane contactors (HFMCs) for the recovery of dissolved methane from anaerobic effluents

Anaerobic treatment of wastewater from various sources is becoming increasingly popular as it can convert 73% of the chemical oxygen demand present in the wastewater to biogas. Methane in the biogas is the major contributor to produce energy in subsequent downstream processes. However, a significant amount of methane usually escapes to the environment through the treated effluent. This study proposes a model that can predict the recovery of dissolved methane and other performance parameters from the effluent of an anaerobic reactor using porous and dense hollow fiber membrane contactors (HFMCs) for the pilot- or large-scale application. The model introduced a distribution factor, m, to the liquid mass transfer coefficient to fit the experimental removal of dissolved methane and the methane desorption flux, JCH4, through the HFMCs. The factor m was found to have a linear relationship with the average JCH4. Further, it was found that a net energy gain of 0.34 MJ·m-3 (0.024 MJ·kg-1CH4 for 16 mg·L-1 dissolved methane in the feed) is achieved for an effluent flow rate of 11 m3·d-1, with a methane content of 35% recovered from the HFMC. A break-even payback period will be attained when multiple modules of HFMC are used. The model provides simplified investigation of the potential and effectiveness of the HFMCs for dissolved methane recovery from anaerobic effluent, with further verification using data from pilot- and large-scale systems.

Experimental and modeling investigation of ultrafine polyvinylidene fluoride hollow fiber membrane module for recovery of lactic acid from aqueous solutions

AbstractThis study investigated the aqueous lactic acid extraction process using indigenous ultrafine polyvinylidene fluoride (PVDF) hollow fiber membrane contactor. Ultrafine PVDF hollow fibers with tighter pore structure were produced by wet spinning technique and fabricated in‐house with an epoxy resin. A kinetic study was performed by varying acid concentrations ranging from 60 to 1320 mol/m3 in an aqueous phase and 210–620 mol/m3 tri‐n‐octylamine (TOA) concentration in 1‐octanol diluent. The solutions were allowed to flow countercurrently using peristaltic pumps at constant aqueous and organic flow velocity of 0.006 and 0.005 m/s, respectively. A PRO/II simulation of the membrane contactor system was carried out to validate experimental results. The study showed a maximum acid extraction of 88 ± 0.1% for initial acid and amine concentrations of 250 and 620 mol/m3, respectively, which corresponds to a high KD value of 11.5 which is larger than the value found from PRO/II simulation for direct mixing of the aqueous and organic phases which demonstrates the merit of the membrane contactor. The exploratory study on kinetics has helped in understanding the mass transfer phenomena of the solute across the membrane. In addition, membrane characterization was done to investigate the surface and cross‐sectional morphologies and mechanical strength properties.

Enhancement of CO2 removal by promoted MDEA solution in a hollow fiber membrane contactor: A numerical and experimental study

In this work, carbon dioxide (CO2) loading capacity of methyldiethanolamine (MDEA) solution promoted by potassium lysinate (KLys) was experimentally measured by using a gas absorption setup at different concentrations and temperatures. The CO2 removal efficiency of the MDEA + KLys solution was investigated for a CO2/N2 gas mixture by using computational fluid dynamic (CFD) simulations in a hollow fiber membrane contactor (HFMC). The effects of operating conditions including solvent concentration, solvent flow rate, gas flow rate, inlet CO2 concentration and module length on the CO2 removal efficiency were also studied. The experimental results revealed that CO2 loading capacity increases with increasing KLys concentration in the solution, while decreases as temperature increases. The simulation results indicated that MDEA + KLys solution has higher CO2 removal efficiency compared to pristine MDEA and MEA solutions. The CO2 removal efficiency increases with increasing solvent concentration, solvent flow rate and module length, whereas decreases as gas flow rate increases. The zeolitic imidazolate framework-8 (ZIF-8), as sorbent, was then incorporated into the MDEA + KLys solution and its effect on the CO2 removal efficiency was also examined. The MDEA + KLys + ZIF-8 nano-absorbent showed higher CO2 removal efficiency than that of MDEA + KLys absorbent, where introducing 0.4 wt.% ZIF-8 enhanced CO2 removal from ⁓96% to ⁓99%. The results of this work suggest that both MDEA + KLys absorbent and MDEA + KLys + ZIF-8 nano-absorbent are promising candidates for CO2 absorption processes. However, for practical use as well as a complete investigation, their behavior should be assessed by using other parameters of solvent such as reactivity with CO2, corrosion rate, and regeneration performance.

Synergistic interplay between Aliquat 336 and organophosphorus extractants towards non-dispersive extraction of arsenic from petroleum produced water via hollow fiber membrane contactor

This work presents the elimination of arsenic from petroleum produced water via hollow fiber membrane contactor (HFMC). Results demonstrate that the extractability of arsenic is successfully achieved through the blended extractants of Aliquat 336 + Cyanex 921 suggesting the occurrence of synergism. Under optimum conditions, the extraction and stripping of arsenic achieved 94.42% and 78.90%, respectively. Slope analysis is applied to determine the stoichiometric coefficients of synergistic interplay. Both kinetics and mathematical modelling are employed to describe the behaviors arising in the HFMC system. It is seen that chemical reactions proved to govern the transportation of arsenic across HFMC. Besides, a novel approach as regards reaction mechanisms in a binary system is adopted.

Ozone Diffusion Through a Hollow Fiber Membrane Contactor for Pharmaceuticals Removal and Bromate Minimization

Ozone Diffusion Through a Hollow Fiber Membrane Contactor for Pharmaceuticals Removal and Bromate Minimization

An Integrated Hollow Fiber Membrane Contactor and Chemical Precipitation to Recover N, P and K from Human Urine Wastewater

An Integrated Hollow Fiber Membrane Contactor and Chemical Precipitation to Recover N, P and K from Human Urine Wastewater

Ammonia Removal Using Thermally Induced Phase Separation Pvdf Hollow Fibre Membrane Contactors

Ammonia Removal Using Thermally Induced Phase Separation Pvdf Hollow Fibre Membrane Contactors

A Multicomponent Counter-Current Flow Model for Simulating Water and Oxygen Effects on Membrane Contactor Co2 Removal and Case Study of Hollow Fiber Membrane Contactor

A Multicomponent Counter-Current Flow Model for Simulating Water and Oxygen Effects on Membrane Contactor Co2 Removal and Case Study of Hollow Fiber Membrane Contactor

Solutions of the mass continuity equation in hollow fibers for fully developed flow with some notes on the Lévêque correlation

In this study a historical perspective of the mass continuity equation for fully developed laminar flow in the lumen side of a hollow-fiber membrane contactor is presented with respect to the lumen-wall boundary condition (BC). It is shown that the constant wall concentration case (Dirichlet boundary condition) imposed by the Graetz-Lévêque postulations is a sub-case of the mixed Neumann-Dirichlet linear BC largely overestimating the performance of such contactors. For the linear BC the analytical solution derived by the separation of variables method is revisited proving that it is very accurate and practical even in the region very close to the entrance of the computational domain. The analysis is extended by incorporating and solving nonlinear lumen-wall BCs with the method-of-lines approach by discretizing the radial domain using the Gauss-Jacobi orthogonal collocation and integrating the resulting initial-value differential-algebraic system. The analytical solution, the derivation of the collocation matrices and the numerical solution are presented with the aid of the open-source SageMath and the commercial package Maple.

Optimizing SO2 Adsorption from Flue Gas Using Microporous Polypropylene Hollow Fiber Membrane Contactor

This study optimized the operational parameters of removing SO2 from flue gas via a polymeric hollow fiber membrane contactor (HFMC) using the response surface methodology (RSM). The distilled water and polypropylene hollow fibers were applied as the adsorbent and membrane material, respectively. Three experimental parameters were chosen as independent variables: liquid flow rate, gas flow rate, and initial SO2 concentration. The SO2 removal efficiency was significantly affected by the initial SO2 concentration. The optimal ratio of liquid-to-gas flow rate was found to be 0.25 to reach maximum separation efficiency (98.81%). The optimal value of the liquid flow rate was 33 l/h, and the optimal gas flow rate was 131 l/h. The effect of CO2 presence, module length, fibers number, temperature, and the adsorbent nature were also investigated under optimal values obtained for the ratio of liquid-to-gas flow rate. Results indicated that CO2 presence in the flue gas slightly affects SO2 removal using water as an absorbent in HFCM. Furthermore, it was indicated that the SO2 removal efficiency was a function of the flue gas temperature and number of fibers: it decreased as the temperature rose from 20 to 50°C and the fiber numbers increased from 300 to 1000. This study offers a model to predict the efficiency of SO2 removal using HFMC under different conditions and provides the ground to further explore the industrial applications of this technology.

Computational fluid dynamics analysis of CO 2 absorption intensification in an hollow fiber membrane contactor using SiO 2 and carbon nanotubes nanofluids

A numerical parametric analysis of CO2 removal from the air using silica (SiO2) and carbon nanotube (CNT) nanofluids (NFs) in a gas–liquid hollow fiber membrane contactor in the non-wetted condition is investigated in this work. Diffusion in radial and axial directions is considered in the tube, the shell compartments, and the membrane regarding the convection mechanism. Different significant factors, including liquid and gas flow rates, membrane porosity, inlet concentration of CO2, liquid temperature, number of fibers, and nanoparticle diameters, are investigated in viable ranges. The finite element method is implemented to solve governing equations. The model output is validated against the experimental data of CO2 absorption with NFs, and an acceptable agreement is obtained. The results of the simulation indicate the CNT NFs outperform SiO2 NFs in CO2 absorption. Also, the performance of CO2 removal improves with the nanoparticle diameter reduction in the base fluid, inlet CO2 concentration, gas flow rate, and temperature. In the tube, by adding 0.5 wt % CNT and silica nanoparticles, the absorption rate improves by 47.6% and 39.6%, respectively. Finally, three correlations among significant parameters to predict CO2 removal is presented due to the lack of specific correlations for this model in the literature.

Evaluation of an ozone diffusion process using a hollow fiber membrane contactor

Conventional ozonation processes efficiently remove micropollutants in water treatment, but uncontrolled ozone dosing can produce problematic by-products. Bubbleless operation could help overcome this hurdle. To evaluate this alternative, ozonation was carried out using a polytetrafluoroethylene (PTFE) hollow fiber membrane contactor. The objective was to conduct an extensive characterization of the ozone transfer in an in/out configuration. The overall mass transfer coefficient KLa was determined and was higher than in bubble columns. The transfer resistance due to the membrane was estimated to be lower than 1%. The impact of several variables (liquid flowrate, gas flowrate, and ozone concentration) on the ozone transfer was studied. Ozone concentration was the variable that most increased ozone transfer, followed by the liquid flowrate and then to a lesser extent the gas flowrate. The impact of the presence of a reaction in the water was also evaluated using an organic dye (Acid Orange 7). The Hatta number and the acceleration factor were calculated, corresponding to a reaction that took place partially in the liquid film and in the liquid bulk. Finally, the impact of ozone on membrane material over time was evaluated.

Economic analysis of the scale-up and implantation of a hollow fibre membrane contactor plant for nitrogen recovery in a full-scale wastewater treatment plant

Nitrogen recovery technologies such as the hollow fibre membrane contactor are now being developed. However, an economic analysis is needed prior to their full-scale application in wastewater treatment plants. The aim of this study was to analyse the economic and environmental aspects of scaling-up this method. To achieve it, a full-scale 40,000 m3·day−1-wastewater treatment plant influent flow rate was simulated jointly with a membrane contactor plant to evaluate the minimum costs of optimum operating conditions of membrane contactors (pH, feed flow rate and membrane surface). The optimum conditions for treating 600 m3·day−1 of reject water was found to be 10 pH, 0.08 m3·s−1 feed flow rate and 10,580 m2 of membrane surface, obtaining a 4% nitrogen ammonia sulphate solution. The results indicated capital (membrane modules and pumps) and operating costs (reagents and energy) of 0.0095 €·m−3 and a profit of 0.0090 €·m−3, including energy savings in terms of aeration and sales of the recovered ammonia sulphate, with the added benefit of reducing CO2-eq by 10.3 tons per day.

Integration of a calcium carbonate crystallization process and membrane contactor–based CO2 capture

This research work presents the integration of polypropylene hollow fiber membrane contactor–based CO2 absorption unit using aqueous sodium hydroxide (NaOH) as the absorbent solution, and precipitation of high-quality calcium carbonate by addition of calcium chloride. The integrated crystallization process bypasses the need for cost-intensive energy regeneration of the absorbent solution. Given the lifetime of high added value precipitated calcium carbonate, the proposed approach for integrating solid particle formation and a carbon dioxide mitigation technique can be considered as a potential post-combustion technology for carbon capture, utilization and sequestration (CCUS). The overall CO2 mass transfer coefficient in the membrane contactor and subsequent crystallization process was investigated by conducting the experiments at different operating conditions. For a maximum hydroxide concentration of 5.01molL-1, an overall mass transfer coefficient of 2.25·10-4ms-1 and CO2 flux of 2.45·10-4molm-2s-1 were obtained for a 0.5Lmin-1 of gas flow rate. The proposed liquid–liquid crystallization process produces a narrow size distribution of micron-sized calcium carbonate with a mean diameter of 3–8 µm that can be used in the paper, coatings, food and biomedical industries.

The design of multi-stage open-loop hollow fiber membrane contactor and its application in ammonia capture from hydrolyzed human urine

Hollow fiber membrane contactor (HFMC) is a promising technology for removing or recovering wastewaters' volatile components. Developing a rational design method is very important for guiding its further application. In this study, we proposed a method to design the multi-stage open-loop hollow fiber membrane contactor (HFMC) employing shell-side influent. In addition, a three-stage HFMC was designed to capture ammonia from real hydrolyzed human urine. A continuous 1344 h performance was conducted. The results showed that the experimental effluent total ammonium nitrogen (TAN) concentration and ammonia mass transfer coefficient matched the predicted results well, which indicated that the design method was feasible and accurate. The three-stage HFMC showed excellent ammonia capture capacity with a TAN recovery efficiency of 93.29%, and the final effluent TAN concentration was 30.98±14.70 mg/L which met our design requirement (lower than 50 mg/L). More than 98.92% of the inorganic ions and 96.85% of the organic matter were retained in the effluent. The stripping solution after ammonia capture was the high-purity ammonium sulfate solution with low concentration of small molecular weight hydrophilic organic substances. The inorganic and organic membrane fouling was mild and randomly distributed. The inorganic membrane fouling was attributed to the deposition of calcium-, magnesium-, phosphate-related inorganic compounds, while the organic membrane fouling was mainly protein and carbohydrate. After the ammonia capture process, the surface hydrophobicity and pore properties of the membranes had no significant changes. These results demonstrated that the multi-stage open-loop HFMC could be a potential alternative for ammonia recovery from the high concentration of ammonium nitrogen wastewater.