Direct Contact Membrane Distillation System Research Articles

Enhancing the Permeate Flux Improvement of Direct Contact Membrane Distillation Modules with Inserted S-Ribs Carbon-Fiber Filaments.

Three widths of manufacturing S-ribs carbon-fiber filaments acting as turbulence promoters were implemented into the flow channel of direct contact membrane distillation (DCMD) modules to augment the permeate flux improvement in the present study. Attempts to reduce the disadvantageous temperature polarization effect were made by inserting S-ribs turbulence promoters in improving pure water productivity, in which both heat- and mass-transfer boundary layers were diminished due to creating vortices in the flow pattern and increasing turbulence intensity. The temperature polarization coefficient ttemp was studied and found to enhance device performance (less thermal resistance) under inserting various S-ribs carbon-fiber thicknesses and operating both cocurrent- and countercurrent-flow patterns. The permeate fluxes in the DCMD modules with inserted S-ribs carbon-fiber turbulence promoters were investigated theoretically by developing the mathematical modeling equations and were conducted experimentally with various design and operating parameters. The theoretical predictions and experimental results exhibited a great potential to considerably achieve permeate flux enhancement in the new design of the DCMD system. The DCMD module with inserted S-ribs carbon-fiber turbulence promoters in the flow channel could provide a relative permeate flux enhancement up to 37.77% under countercurrent-flow operations in comparisons with the module of using the empty channel. An economic consideration on both permeate flux enhancement and power consumption increment for the module with inserted S-ribs carbon-fiber filaments was also delineated.

Novel integration of thermoelectric distiller with direct contact membrane distillation

A thermoelectric distiller (TED) integrated with a direct contact membrane distillation (DCMD) unit was proposed and numerically investigated. The mathematical models of the hybrid TED--–DCMD system were developed and validated. In the proposed hybrid system, the TED provides the heating demand of the DCMD desalination unit in four novel configurations of TED-DCMD integration. The first configuration integrates the TED-DCMD by adding a DCMD heat exchanger coil inside the condensation tank of a TED, while the second configuration involves two TED condensation tanks with each tank containing a DCMD heat exchanger coil. The third configuration also consists of two TED tanks with an external heat exchanger where thermal energy from the TED produced water is transferred to the DCMD feed stream. The fourth configuration is a modification of the second configuration with a thermal recovery from TED produced water for inlet feed water preheating. To investigate the performance (distillate productivity, specific energy consumption, coefficient of performance, and ratio of TED productivity) of each integrated TED-DCMD configuration, the effects of different operating parameters such as DCMD feed flow rate, TEM current, number of TEMs, and TED produced water temperature were examined. Findings indicated that the third configuration is the most energy efficient, with specific energy consumption (SEC) reaching a minimum value of 217 kWh/m3 at low current operation of 2.1 A, and feed flow rate of 4.0 L/min for 8.0 TEMs in the TED. A maximum freshwater productivity and COPh of 2.74 kg/s and 3.24, are attained by the 4th and 3rd configurations, respectively. Results also indicated that elevating the current input encourages higher water productivity. Meanwhile, higher values of SEC and water productivity are attained when operating TED at saturation temperature.

Experimental investigation of varying design parameters on the production rate and temperature polarisation of a DCMD system

Much of the research in the analysis of Temperature polarisation (TP) and the productivity of a membrane distillation (MD) system tends to concentrate on operational conditions. However, substantial enhancements in permeate flux can be realised through the incorporation of fundamental design modifications. This research showed that TP can be successfully mitigated almost to a level of non-existence, by manipulating the module orientation and flow channel height of an in-house designed direct contact membrane distillation (DCMD) system. Notably, at higher flow channel heights, changing the module orientation from the default horizontal position with the feed side on top (FST) to a sideway orientation led to a remarkable 90% increase in the permeate flux of the DCMD module. Permeate side on top (PST) and sideways orientations performed significantly better than FST for larger channel heights, while at low channel heights, the improvement was slight. Temperature measurements proved that thermal convective currents and secondary flows played a vital role in assisting or opposing TP and cannot be disregarded when investigating the hydrodynamics of a DCMD system. The impact of flow directions was insignificant with different channel heights, while the proximity of the flow inlets played a pivotal role in shaping the temperature profiles along the membrane.

Engineered eco-friendly composite membranes with superhydrophobic/hydrophilic dual-layer for DCMD system

Considerable advancements have been made in the development of hydrophobic membranes for membrane distillation (MD). Nonetheless, the environmentally responsible disposal of these membranes poses a critical concern due to their synthetic composition. Herein, an eco-friendly dual-layered biopolymer-based membrane was fabricated for water desalination. The membrane was electrospun from two bio-polymeric layers. The top hydrophobic layer comprises polycaprolactone (PCL) and the bottom hydrophilic layer from cellulose acetate (CA). Additionally, silica nanoparticles (SiO2 NPs) were electrosprayed onto the top layer of the dual-layered PCL/CA membrane to enhance the hydrophobicity. The desalination performance of the modified PCL-SiO2/CA membrane was compared with the unmodified PCL/CA membrane using a direct contact membrane distillation (DCMD) unit. Results revealed that silica remarkably improves membrane hydrophobicity. The modified PCL-SiO2/CA membrane demonstrated a significant increase in water contact angle of 152.4° compared to 119° for the unmodified membrane. In addition, PCL-SiO2/CA membrane has a smaller average pore size of 0.23 ± 0.16 μm and an exceptional liquid entry pressure of water (LEPw), which is 3.8 times higher than that of PCL/CA membrane. Moreover, PCL-SiO2/CA membrane achieved a durable permeate flux of 15.6 kg/m2.h, while PCL/CA membrane showed unstable permeate flux decreasing approximately from 25 to 12 kg/m2.h over the DCMD test time. Furthermore, the modified PCL-SiO2/CA membrane achieved a high salt rejection value of 99.97% compared to a low value of 86.2% for the PCL/CA membrane after 24 h continuous DCMD operation. In conclusion, the proposed modified PCL-SiO2/CA dual-layer biopolymeric-based membrane has considerable potential to be used as an environmentally friendly membrane for the MD process.

Modeling and simulation of direct contact membrane distillation system integrated with a photovoltaic thermal for electricity and freshwater production

Energy drives the growth, transformation, and economic development of every nation. The vitality of human existence and progress hinges on the accessibility of both energy and water resources. As freshwater resources are diminishing, therefore, desalination needs have increased. In solar membrane distillation systems, the key challenge is maintaining the intake water temperature in the membrane distillation system with fluctuating solar radiation intensity which affects the distillate water quantity and quality. The objective of this study is to enhance and optimize a mathematical model for analyzing a cutting-edge solar-integrated PV/T-DCMD system. In this innovative integration, the direct contact membrane distillation intake water temperature is derived from the photovoltaic thermal output. The integration of direct contact membrane distillation with photovoltaic thermal systems represents a cost-effective and technologically advantageous concept. As the water temperature increases, there is a notable improvement in the evaporation efficiency of PV/T-DCMD systems, with an increase from 35.08% to 42.01%. Additionally, there is a reduction in specific thermal energy consumption, decreasing from 1,192 to 1,386 kWh/m3 as a consequence of the elevated feed water temperature.

An innovative ocean thermal energy conversion system with zeotropic Rankine cycle and direct contact membrane distillation for enhanced efficiency and sustainability

This research introduces an integrated ocean thermal energy conversion water and power cogeneration system (OTEC-WPCS), combining a Zeotropic Rankine Cycle (ZRC) with Direct Contact Membrane Distillation (DCMD) for efficient power and water production. The hydrofluoroolefins (HFOs), chosen for their zero ozone depletion potential (ODP) and extremely low global warming potential (GWP), are used as working fluid components in the ZRC. Additionally, DCMD is implemented for freshwater generation. A mathematical model is established, incorporating both thermodynamic and CFD simulations. The goal is to identify optimal operating conditions that maximize the output of the system. By coupling DCMD and ZRC in series, the system's efficiency reaches 8.92 %, an improvement of 5.71 % compared to a standalone ZRC system. This configuration allows for more efficient use of surface seawater heat compared to an ammonia-based Organic Rankine Cycle (ORC)-DCMD system. The enhancements include an increase in power and water production per unit mass flow of surface seawater by 0.55 kW/(kg·s) and 30 %, respectively. Over 60 % of the system's exergy destruction occurs in the DCMD modules and evaporator, while nearly 80 % of the capital cost is associated with the evaporator, condenser, and DCMD heat exchanger. Enhancing the DCMD module structure and heat exchanger can improve both energy and exergy efficiency, and economic feasibility.

Assessment of direct contact membrane distillation system driven by parabolic trough collector plant technology for electricity and freshwater production: Feasibility and benchmark under different Moroccan climates

Morocco has experienced several years of drought, conventional water resources were insufficient to meet the needs of the population, which prompted the kingdom to seek other resources to ensure the supply of drinking water to this population. The most suitable solution was the desalination of seawater. In this context, the design and investigation of concentrated solar power (CSP) plant integrated with a desalination unit in Morocco are presented in this paper. The CSP part consists of a parabolic trough technology with a two-tank storage system, integrated with a power block of 111 MWe gross consisting of a conventional Rankine cycle. As for the desalination part, it consists of a Direct Contact Membrane Distillation System (DCMD) based on heat and mass transfer equations, and is solved numerically by MATLAB environment; the model was validated by means of the experimental data. The results show that the large-scale Parabolic Trough Collector (PTC) plants are more competitive in Dakhla -southern Morocco- where the annual energy generation and the capacity factor were estimated to be 493.8 GWh, and 47.6%, respectively. Whereas, the Levelized Cost of Electricity (LCOE) is 10.63 ȼ/kWh. Furthermore, it has been found that in the DCMD system, an increase in the feed water temperature leads to an increase in permeate flux. Besides, freshwater production is highest in winters for Dakhla and Agadir (Atlantic Ocean) and it is highest in summers for Saidia and Al Hoceima (Mediterranean Sea). The lowest freshwater production cost is 0.84$/m3 in Dakhla, followed by 0.98$/m3 in Saidia, with the highest production cost at 1.20$/m3 in Agadir.

Performance enhancement of a solar-driven DCMD system using an air-cooled condenser and oil: Experimental and machine learning investigations

Solar-driven direct contact membrane distillation systems (DCMD) are disadvantaged by low freshwater productivity and low gain-output-ratio (GOR). Consequently, this study aims to achieve two primary objectives: i) improving the solar DCMD performance, and ii) harnessing machine learning models for precise and straightforward modeling of the solar DCMD system. To achieve these goals, a novel solar DCMD system powered with oil-filled heat pipe evacuated tube collectors (HP-ETCs) and equipped with an air-cooled condenser was used for the first time. The system was evaluated under eight different scenarios covering both its energy and economic performances. The performance prediction of three different machine learning models including ANN, SVR and RF was assessed for the proposed system. The results showed that integrating an air-cooled condenser and oil-filled HP-ETCs into the solar DCMD system significantly improved the performance and reduced freshwater cost, resulting in: a 35.39–37 % increase in freshwater productivity; a 30.64–31.57 % enhancement in GOR; a 35–38 % rise in daily efficiency; and a 20 % decrease in freshwater cost. The results demonstrate that ANN and SVR have excellent performance for modeling the solar-driven DCMD system, achieving MAPEtest values of approximately 1 % and 4 % for predicting permeate flux and GOR, respectively.

Seasonal dynamic modeling and simulation of solar thermal membrane desalination system for sustainable freshwater production: a case study of Tanta, Egypt

AbstractMembrane distillation (MD) is an effective process for desalinating seawater, combining the merits of both thermal and membrane distillation. In this context, the sizing methodologies and optimization strategies are developed from the balance of the system’s energy demand. Therefore, accurate numerical modeling of the heat transfer and thermodynamic behavior of the MD systems is crucial for the optimal design of solar-based MD systems. The interest in utilizing solar thermal heating techniques for feed water heating in MD systems is increasing worldwide for sustainable freshwater production and lowering energy consumption. Hence, in this research, a coupled analytical modeling based on heat transfer, mass transport, and thermodynamic analysis is created to dynamically simulate a solar direct contact membrane distillation system (SDCMDS) driven by vacuumed tubes solar collectors (VTSCs) to analyze its performance, under real weather of Tanta, Egypt. The influences of the solar collecting area on the performances of the proposed SDCMDS for augmenting the freshwater production of the SDCMDS are studied. Four cases of the proposed SDCMDS are investigated: two identical VTSCs of 1.80 m2 each unit in summer (Case I), two identical VTSCs in winter (Case II), four identical VTSCs in summer (Case III), and four identical VTSCs in winter (Case IV). The results show that the utilization of four VTSCs connected in series significantly improved the feed seawater temperature range from 30.0 to 70.5 °C compared to a feed temperature range of 30.0–49.5 was achievable by utilizing only two VTSCs. Moreover, the daily averaged permeate flux were 2.21, 1.29, 3.41, and 2.07 L/day per m2 of solar harvesting area with daily cumulative distilled water yield of 7.48, 4.60, 23.04, and 14.78 L/day for Cases I, II, III, and IV, respectively, at a saline flowrate of 0.20 kg/s. The daily average total efficiency of the SDCMDS was obtained to be 14.70%, 12.50%, 24.95%, and 22.50% for Cases I, II, III, and IV, respectively.

Thermodynamic analysis of a hybrid novel solar powered humidification-dehumidification coupled with direct contact membrane distillation system

Water scarcity is a well-known global issue, and obtaining potable water in many regions is challenging. Some technologies exist but require high-grade energy for freshwater production, which is not universally accessible. This work emphasizes desalinating saline water using low-grade energy, such as solar energy. The study introduced a novel design of hybrid solar-powered humidification-dehumidification coupled with direct contact membrane distillation (HDH-DCMD), including modeling heat transfer, mass transfer, and fluid flow. The obtained results are further validated against previously published findings. Additionally, a thermodynamic analysis of the hybrid system was conducted to examine the effects of several parameters, including variation in membrane area, top brine temperature (TBT), feed temperature, mass flow rate ratio (MR), and dimensions of the membrane module. The objective was to assess the influence of these factors on the overall distillate production, gain output ratio (GOR), and recovery ratio (RR). The hybrid system offers a significantly improved solution, yielding nearly double the distillate production and GOR compared to standalone HDH and DCMD systems. The performance of HDH and DCMD is interconnected, meaning that if one outperforms the other, the overall output remains constant. The overall distillate production remains unaffected by MR, while GOR is influenced by it, resulting in varying optimal points depending on the specific operating parameters. It has been observed that increasing the TBT results in an increase in distillate production, RR, and GOR. However, when the feed temperature increases, the distillate production and RR remain almost constant while the GOR continues to increase.

Selective recovery of europium from real acid mine drainage by using novel amine based modified SBA15 adsorbent and membrane distillation system

Recovery of rare earth elements (REE) from secondary waste streams promises numerous advantages. Europium (Eu) is an essential component in various high-tech applications, including clean energy technologies. Ensuring a stable supply of europium through recycling reduces the vulnerability to supply disruptions and price fluctuations in the global market. To achieve this, there is a need for development of highly selective and commercially viable adsorbents for Eu recovery. This research presents a novel material, SBA15-NH-PMIDA, synthesized through a two-step surface modification process for selective retrieval of Eu from real acid mine drainage (AMD). Initially, comprehensive physical and chemical characterizations of the material were conducted to confirm its successful synthesis. Subsequent single-solute Eu adsorption experiments demonstrated that SBA15-NH-PMIDA achieved equilibrium within 2 h and exhibited a maximum Langmuir adsorption capacity of 86.21 mg/g at optimal pH of 4.8. It exhibited remarkable selectivity in recovering over 80 % of Eu from pH-adjusted real AMD, with an optimal dosage of 0.8 g/L. Next, a hybrid system amalgamating Direct Contact Membrane Distillation (DCMD) and adsorption was devised. This hybrid system involved the suspension of granulated SBA15-NH-PMIDA within the feed tank to treat pH-adjusted AMD. The DCMD system achieved an 80 % recovery of purified water while concentrating Eu ions by more than threefold, facilitating efficient and selective Eu recovery surpassing 90 %. Importantly, the uptake of other competing metals remained below 10 %. This is attributed to the formation of Eu complexes with phosphonic and carboxyl acid functional groups. SBA15-NH-PMIDA demonstrated its sustainability and viability by consistently retaining over 90 % of its adsorption capacity throughout ten regeneration cycles.

Environmentally friendly electrospun polycaprolactone bio-membrane fabrication for water distillation

Eco-friendly biodegradable polycaprolactone (PCL) membranes were fabricated at different polymer concentrations: 10, 12, and 14 wt% via the electrospinning technique. The membrane's fiber and average pore diameters of various fabricated nanofiber membranes were measured using SEM associated with ImageJ software. The polymer concentration of 10 wt% showed beaded nanofibers compared with 12, and 14 wt% showed bead-free nanofiber structures. Accordingly, the morphological structure, hydrophilicity, chemical structure, and mechanical properties of the two uniform nanofiber membranes of 12 and 14 wt% were compared. The analyses demonstrated that the prepared 12 wt% PCL membrane recorded the most uniform average nanofiber diameter and pore diameter of 328 nm and 0.45 μm, respectively. The contact angle of this fabricated nanofiber was recorded as 118.8°, suggesting its suitability as a hydrophobic membrane for membrane distillation. The PCL membrane's performance in a direct contact membrane distillation (DCMD) system was examined. The membrane showed increased flux that reached about 41.9 kg·m−2·h−1and salt rejection (>94%) at 50 °C feed inlet temperature, 10 °C permeate temperature, 6 L/h feed flow rate, and 10,000 ppm NaCl feed inlet concentration.

Techno-economic-environmental analysis of direct-contact membrane distillation systems integrated with low-grade heat sources: A multi-objective optimization approach

Membrane distillation (MD) is an emerging desalination technology powered by low-grade thermal energy. This paper presents the multi-objective optimal design of the membrane distillation desalination plant. The heat sources are supercritical CO2 (sCO2) Brayton cycle waste heat and geothermal energy. Multi-objective mixed-integer nonlinear programming models are developed to optimize the integrated systems' design and operating conditions based on economic and environmental metrics. The models consider the simultaneous optimization of water production costs (wpc) and environmental impacts (wpei). The environmental performance is quantified through a life cycle assessment using the widely used ReCiPe 2016 method, enabling the identification of the main environmental hotspots throughout the plant's life cycle. Our methodology demonstrates the sustainability of MD desalination plants through various case studies. The results indicate that an appropriate MD system design can significantly reduce the environmental burden with a slight increase in cost. For the sCO2-MD scenario, a cost-effective design can achieve a minimum wpc of 0.758 $/m3 and a minimum wpei of 0.172 Pt/m3 in an environmentally friendly design. A balanced design can reduce the environmental impact by 31.30% with a slight cost increase of 4.48% compared to a cost-effective design. The minimum wpc and minimum wpei for the geothermal MD (GTMD) scenario are 412.27% and 215.94% higher, respectively, compared to the sCO2-MD scenario. Moreover, reducing the wpei of the GTMD system is also more expensive, requiring a 10.67% increase in cost to reduce the environmental impact by 21.65%.

Development of Bench-Scale Direct Contact Membrane Distillation System for Treatment of Palm Oil Mill Effluent

The oil palm industries generate large amounts of effluent that can cause pollution and, as a result, pose serious threats to the environment. Recently, membrane distillation (MD) has been identified as a potential candidate for treatment of palm oil mill effluents (POME). This is because the release of POME at high temperature may reduce the need to preheat the effluent prior to operation. The objective of this article is to manufacture a bench-scale MD system and assess the performance of the system in POME treatment. This project started with the design of a process and instrumentation diagram (P&ID) and continued with the fabrication part. Subsequently, the performance of the direct contact membrane distillation (DCMD) system was tested using POME as a feed solution. Three different feed temperatures (55 °C, 65 °C and 75 °C) were analyzed during the testing. The results obtained show that the permeate flux increased with the increase of feed temperature with the highest flux is 10.76 kg/m2.hr. More than 85% of pollutants including ammonia nitrogen, color, chemical oxygen demand (COD) and turbidity were rejected. This shows that the system is capable of treating POME and producing high quality permeate water.

Behavior and removal of microplastics during desalination in a lab-scale direct contact membrane distillation system

The behavior of microplastic particles (MPPs) is explored in a lab-scale direct contact membrane distillation (DCMD) system used to produce drinking water from seawater, while also analyzing the impact of their presence on the process performance. Commercial MPPs (LDPE, PET and uPVC) were first studied by temperature stress (TS) tests (using amber bottles) to mimic the exposure to the high temperatures commonly used in DCMD (ca. 80 °C), which led to uPVC being selected to be tested under different loads and aging degrees in the DCMD system. By analyzing uPVC MPPs samples before and after the TS and DCMD experiments by ATR-FTIR, UV–Visible spectroscopy and SEM, it was concluded that minor aging is expected to occur. High loads (>0.1 g L−1) of uPVC MPPs decreased the DCMD performance in terms of permeate flux (from 32.8 ± 0.3 with filtered seawater to 28.7 ± 0.3 kg m−2 h−1 with a load of 0.2 g L−1), although no signs of inferior treated water quality were found based on the conductivity and salinity results. The removal of MPPs (size > 1.2 μm) in DCMD applications with seawater was analyzed by μRaman, with all the results suggesting very high removal efficiencies (≥99 %).

Magnetic recyclable Fe3O4@Ti3C2TX nanoparticles for high-efficiency solar membrane distillation

Over the last few years, solar energy has emerged as a sustainable energy which can replace traditional fossil energy sources. Solar evaporation systems are very dependent on the concentration of light-absorbing particles. However, solar evaporation systems have low water production rates and the used nanofluids usually causes secondary pollution. These problems seriously limit the wide application of solar evaporation techniques. In this work, we established a novel solar direct contact membrane distillation system combining Fe3O4@MXene light absorbing particles (Fe3O4 nanoparticles modified with Ti3C2Tx MXene) and membrane distillation, which could improve the water production rates and the used light-absorbing nanoparticles were easily separated by magnetic field for reuse. In this system, Fe3O4@MXene acts as an efficient photothermal conversion particle that heats the feedwater for membrane distillation by absorbing sunlight, eliminating the additional energy input. The test results showed that the water production rate of this system was superior to that of most published solar membrane distillation systems, which the flux could reach 2.26 kg/m2/h, and the nanoparticles could be almost completely recycled. The work not only provides a useful method of desalination using solar energy and membrane distillation, but also to reduce the materials consumption and overall operating cost.

Harnessing the power of neural networks for the investigation of solar-driven membrane distillation systems under the dynamic operation mode

Accurate modeling of solar-driven direct contact membrane distillation systems (DCMD) can enhance the commercialization of these promising systems. However, the existing dynamic mathematical models for predicting the performance of these systems are complex and computationally expensive. This is due to the intermittent nature of solar energy and complex heat/mass transfer of different components of solar-driven DCMD systems (solar collectors, MD modules and storage tanks). This study applies a machine learning-based approach to model the dynamic nature of a solar-driven DCMD system for the first time. A small-scale rig was designed and fabricated to experimentally assess the performance of the system over 20 days. The predictive capabilities of two neural network models: multilayer perceptron (MLP) and long short-term memory (LSTM) were then comprehensively examined to predict the permeate flux, efficiency and gain-output-ratio (GOR). The results showed that both models can efficiently predict the dynamic performance of solar-driven DCMD systems, where MLP outperformed the LSTM model overall, especially in the prediction of efficiency. Additionally, it was indicated that the accuracy of the models for the prediction of GOR can be significantly improved by increasing the size of the dataset.

Optimization of a continuous flow electrocoagulation as pretreatment for membrane distillation of the waste stream in vinyl ester resin production

Vinyl ester resin production wastewater (VERW) contains high concentrations of organics particularly, methacrylic acid and bisphenol A, which are hazardous chemicals and harmful to the aquatic environment. Therefore, there is an urgent need to properly treat the effluent before discharge into the aquatic system. In this work, direct contact membrane distillation (DCMD) was explored as an advanced treatment of the VERW pre-treated by a continuous flow electrocoagulation (EC) and peroxi-electrocoagulation (PEC) processes. Optimization of EC and PEC processes were investigated and the DCMD performance was evaluated. Results showed that the optimal value of current density and polyacrylamide (PAM) dosage was 15 mA/cm2 and 1 mg/L, respectively in the EC process. For the PEC process, the optimal addition of hydrogen peroxide (H2O2) dosage was four times of the chemical oxygen demand (COD) concentration of EC effluent. The COD of VERW was effectively removed via EC followed by PEC (EC-PEC), resulting in the significant alleviation of membrane fouling during DCMD filtration of VERW. The initial flux of DCMD filtration of VERW pre-treated via EC-PEC improved by 35%, compared that only pre-treated by EC. Moreover, the concentration factor (CF) of the DCMD system reached up to 8.1 and the conductivity of distillate was less than 33.2 μS/cm. Hence, the EC and membrane distillation hybrid process paves a new way for the effective treatment of waste steam from resin production.

Boron removal from wastewater by direct contact membrane distillation system using two-level factorial design

Numerous industries use boron and its compounds in various applications. In this study, the removal of boron from an aqueous solution by direct contact membrane distillation (DCMD) system. A 23 full factorial experimental design was implemented to determine the optimum values and the degree of importance of the parameters. The experiments were performed at low and high levels of temperature, initial pH, and feed boron concentration. Design variables were evaluated in terms of individual, binary, and triple effects. At the 95% confidence level, the temperature–initial pH interaction was found as the most significant factor. The maximum boron removal efficiency can be achieved either at a low level of temperature (30 °C) and pH (4.0), or a high level of temperature (50°C) and pH (11) combinations at 20 mg/L boron concentration with desirability of 0.957.

Predicting and evaluating the performance of DCMD: The effect of non-ideal morphology and thermal conductivity of porous nanocomposite membranes

The aim of this work is to explore the effects of the factors affecting the thermal conductivity of the porous nanocomposite membranes and their performance in direct contact membrane distillation (DCMD). The thermal conductivity models were evaluated comprehensively for membrane material involving three-phases (filler particle, polymer and interface). Hashemifard-Matsuura-Fauzi (HMF) and Maxwell models were the most reliable models among three-phase and two-phase (nanocomposite material and pores) models, respectively. Thus, the thermal conductivity of the porous nanocomposite membrane was obtained by the combination of three-phase HMF and two-phase Maxwell model. Finally, the performances of PTFE/Silica aerogel (SiAG) and PTFE/CaCO3 porous nanocomposite membranes were disclosed by the heat and mass transfer model in a DCMD system in order to study the effects of particle loading, interlayer thickness and membrane porosity. It was concluded that both membrane thermal conductivity and the DCMD flux approach almost the same values at the high end of interface thickness, regardless of the thermal conductivity of the filler particle. In other words, the heat loss of the system can be controlled by tuning the interface thickness in order to achieve a high DCMD flux even by incorporating fillers with higher thermal conductivity rather than that of the pure polymer. In summary, our findings revealed that next to the membrane material and porosity, the type of the nanoparticle and interface thickness can be highlighted as the most important parameters for controlling membrane thermal conductivity and improving DCMD performance.