Machine learning toward improving the performance of membrane-based wastewater treatment: A review

Machine learning (ML) is a data-driven approach that can be applied to design, analyze, predict, and optimize a process based on existing data. Recently, ML has found its application in improving membrane separation performance for wastewater treatment. Models have been developed to predict the performance of membranes to separate contaminants from wastewater, design optimum conditions for membrane fabrication for greater membrane separation performance and predict backwashing membranes and membrane fouling. This review summarizes the progress of ML-based membrane separation modeling and explores the direction of the future development of ML in membrane separation-based wastewater treatment. The strengths and drawbacks of the ML algorithms extensively used in membrane separation-based wastewater treatment are summarized. Artificial neural network (ANN) was the most used algorithm for modeling membrane separation-based wastewater treatment. Future research is recommended to focus on the development of integrated ML algorithms and on combining ML algorithms with other modeling approaches (e.g., process-based models and statistical models). This will serve to achieve higher accuracy and better performance of the ML application

Volatile organic compounds (VOCs) recovery from aqueous solutions via pervaporation with vinyltriethoxysilane-grafted-silicalite-1/polydimethylsiloxane mixed matrix membrane

Recovery of volatile organic compounds (VOCs) from industrial wastewaters is important for the prevention of environmental pollution. This study investigated pervaporative recovery of VOCs by vinyltriethoxysilane (VTES)-grafted-silicalite-1/PDMS mixed matrix membrane (MMM) from the methanol-containing binary, ternary and quaternary wastewater solutions. The separation of methanol/water binary mixtures was first conducted. The influence of feed concentration and temperature on the membrane performance, such as permeation fluxes and VOC/water separation factor, was investigated. It was observed that with the increase of VOC concentration in the feed, the total permeation flux increased and the selectivity changed slightly first, then decreased. At a feed methanol concentration of 10.51 wt% at 65 degrees C, the maximum PSI of 5346 g/m(2) h with a separation factor of over 10 were obtained with the VTES-g-silicalite-1/PDMS MMM, which makes it among the best in the literature and is very competitive for methanol recovery from aqueous solutions. The apparent activation energies of water and VOC during the pervaporation process was calculated based on Arrhenius equation. Thai the mixed matrix membrane was applied to ternary and quaternary wastewater model solutions. Compared with binary methanol/water mixture, the addition of ethanol and/or acetone led to a decrease of the total flux, methanol flux, and methanol/water separation factor, but increased the total VOCs flux and the permeate VOCs concentration. Separation factors of individual VOC towards water follow the order of acetone &gt; ethanol &gt; methanol, which is consistent with those in binary aqueous mixtures. (c) 2016 Elsevier B.V. All rights reserved.</p

Separation performance of novel vinyltriethoxysilane (VTES)-g-silicalite-1/PDMS/PAN thin-film composite membrane in the recovery of bioethanol from fermentation broths by pervaporation

Organophilic pervaporation (OPV) has been considered as one of the most promising separation processes for the recovery of biofuels from fermentation broths, however, in addition to preferred target product liquid biofuels, the yeast cells and fermentation nutrients could affect the recovery efficiency of biofuels from broths by pervaporation. In this paper, the influence of the yeast cells and the fermentation nutrient components such as the sources of carbon, nitrogen and salts on the separation performance of the vinyltriethoxysilane (VTES)grafted- (VTES-g-) silicalite-1/PDMS/PAN thin-film composite membrane was conducted systematically. The results revealed that glucose, xylose, protein, and salts cannot permeate through the membrane. Glucose concentration in the fermentation broth should be kept at a lower level (less than 20 g/L) to eliminate its deleterious influence on ethanol flux and membrane selectivity. Xylose and corn steep liquor (CSL) have little effect on the pervaporation performance of the composite membrane. The addition of NaCI improved the membrane selectivity and ethanol flux but slightly lowered down total permeation flux. Adding dry yeast cells to the ethanol solution can enhance the turbulence in the feed mixtures, resulting an increase of the membrane flux and selectivity. The pervaporation performance of fermentation broths was also studied. The results showed that the nutrients and the deposition of yeast cells on the membrane surface didn&#39;t deteriorate the pervaporation performance, indicating excellent fouling resistance of the novel VTES-g-silicalite-1/PDMS/ PAN composite membrane in operation with fermentation broths. The continuous ethanol fermentation can be directly connected to the in-situ pervaporative recovery system without requiring prior removal of yeast cells.</p

Effects of fermentation by-products and inhibitors on pervaporative recovery of biofuels from fermentation broths with novel silane modified silicalite-1/PDMS/PAN thin film composite membrane

The influence of different bioethanol fermentation broths components (fermentation by-products, and the common inhibitory compounds present in lignocellulosic hydrolysates) on the pervaporation performance of the vinyltriethoxysilane (VTES) modified silicalite-1/PDMS/PAN thin-film composite membrane was detailedly investigated in this work. The results showed that succinic acid and glycerol are impermeable components, whereas formic acid, acetic acid, and furfural can permeate through the membrane. Succinic acid have no obvious influence on the membrane performance. Meanwhile, the composite membrane can effectively remove formic acid, acetic acid, and furfural present in lignocellulosic hydrolysates. The maximum furfural/water selectivity of 95 and furfural flux of 130 g/m(2) h were obtained with adding 15 g/L furfural into 2 wt.% ethanol binary solution at the feed temperature of 35 degrees C. This research reveals a novel detoxification method of lignocellulosic hydrolysates and a potential approach for furfural production as well. (C) 2015 Elsevier B.V. All rights reserved

Preparation and characterization of vinyltriethoxysilane (VTES) modified silicalite-1/PDMS hybrid pervaporation membrane and its application in ethanol separation from dilute aqueous solution

To improve the affinity between silicalite-1 and polydimethylsiloxane (PDMS), the silicalite-1 particles were modified by a silane coupling agent vinyltriethoxysilane (VTES) and incorporated into polydimethylsiloxane (PDMS) matrix for the preparation of silicalite-1/PDMS hybrid membranes. The modified silicalite-1 particles were examined by XRD, FT-IR and TGA, and the results showed that the silane coupling agent was bonded to the surface of silicalite-1 particles through chemical bonds and the modification did not influence the framework of silicalite-1 crystals. VTES could enhance the interaction of silicalite-1 particles with PDMS through chemical bonds and hence suppressed the formation of microvoids at polymer-silicalite-1 interface, as a result, the thermal stability of the hybrid membrane could be improved. The effect of silicalite-1 loading on the pervaporation performances of the hybrid membranes with dilute ethanol solutions was investigated. As compared with the unmodified hybrid membranes, the VTES modified silicalite-1/PDMS hybrid membranes effectively improved the pervaporation selectivity at different silicalite-1 loadings. With increasing silicalite-1 loading, membrane selectivity increased for both unmodified and VTES modified silicalite-1/PDMS hybrid membranes, and a selectivity of 32 was obtained when VETS modified silicalite-1 loadings was 67%. It was also found that with increasing silicalite-1 loading, the total flux of both unmodified and VTES modified silicalite-1/PDMS hybrid membranes decreased while the ethanol flux of both hybrid membranes increased. With increasing the feed ethanol concentration at a given temperature, the total flux, ethanol flux, and ethanol concentration in permeate increased almost proportionally, while water flux decreased and the separation factor decreased slightly. An increase in temperature increased the permeation fluxes of both ethanol and water, while the separation factor was more or less constant at a given ethanol concentration. (C) 2010 Elsevier B.V. All rights reserved

Application of response surface methodology and central composite rotatable design in optimizing the preparation conditions of vinyltriethoxysilane modified silicalite/polydimethylsiloxane hybrid pervaporation membranes

Response surface methodology (RSM) based on a five-level-three-variable central composite rotatable design (CCRD) was employed for optimization of preparation conditions of vinyltriethoxysilane (VTES)modified silicalite/polydimethylsiloxane (PDMS) hybrid pervaporation membranes. The three variables considered were silicalite loading, crosslinker/prepolymer weight ratio and polymer concentration. With a feed containing 5.0 wt% ethanol as a model solution, the main effects, quadratic effects and interactions of the three variables on the selectivity and total flux of hybrid membranes were investigated by the analysis of variance (ANOVA). The results showed that the main effect of silicalite loading was the most significant factor that influenced the hybrid membrane's selectivity, followed by the quadratic effect of silicalite loading, the main effect of crosslinker/prepolymer weight ratio and polymer concentration. The most significant factor that influenced the total flux was the main effect of polymer concentration. Regression equations between the preparation variables and the performance of the hybrid membranes were also established. Predicted values from the regression equations were found to be in good agreement with observed values, indicating that the regression equations could be used to predict and optimize the performance of the VTES modified silicalite/PDMS hybrid membranes. Under the preparation conditions of 66.8% silicalite loading, 0.098 crosslinker/prepolymer weight ratio and 23.7% polymer concentration, the maximum selectivity of 34.3 could be obtained with the feed containing 5.0 wt% ethanol at 323 K. (C) 2009 Elsevier B.V. All rights reserved

Modification of silicalite-1 by vinyltrimethoxysilane (VTMS) and preparation of silicalite-1 filled polydimethylsiloxane (PDMS) hybrid pervaporation membranes

In preparation of inorganic particles filled polymer membranes, coupling agents can help to improve the compatibility between inorganic filler and polymer matrix. In this paper, surface modification of silicalite-1 was performed by a coupling agent, vinyltrimethoxysilane (VTMS), and hybrid pervaporation membranes were prepared by incorporating the unmodified or VTMS-modified silicalite-1 into polydimethylsiloxane (PDMS). The VTMS-modified silicalite-1 particles and hybrid membranes were characterized by FT-IR, (29)Si CP MAS NMR, DSC, TGA, XRD and SEM. The results showed that the coupling agent VTMS was readily grafted on the surface of silicalite-1 by hydrolysis reaction and condensation reaction, and the chemical linking between the -CH=CH(2) group on the surface-modified silicalite-1 and -Si-H on the PDMS substantially eliminated the nonselective voids inside the membrane. When used to separate acetone, butanol, ethanol (ABE) from aqueous solution, a higher selectivity was obtained with the VTMS-modified silicalite-1/PDMS hybrid membrane. Moreover, the surface modification of silicalite-1 improved its dispersion in PDMS and increased the maximal loading of silicalite-1 in membrane preparation, and thus further enhanced the separation factor of the membrane. (C) 2010 Elsevier B.V. All rights reserved

Cross-sectional association between red blood cell distribution width and regional cerebral tissue oxygen saturation in preterm infants in the first 14 days after birth

BackgroundHypoxia can threaten the metabolic functions of different systems in immature neonates, particularly the central nervous system. The red blood cell distribution width (RDW) has recently been reported as a prognostic factor in neurologic diseases. Herein, we examined the correlation between RDW and regional cerebral tissue oxygen saturation (rcSO2).MethodsThis cross-sectional study included 110 preterm infants born at a gestational age (GA) of &lt;32 weeks, or with a birth weight (BW) of &lt;1,500 g at our institution between January and June 2,022. The rcSO2 was monitored using near-infrared spectroscopy, and RDW was extracted from the complete blood count during the first 14 days after birth. RDW and rcSO2 measurements were analyzed using a cross-sectional research method.ResultsWe divided the study population into two groups, with a mean rcSO2 value over the first 14 days. Fifty-three preterm had rcSO2 ≥ 55% and 57% &lt; 55%. The 14-days-mean in the study population showing an association of lower rcSO2 values with higher RDW values. Significantly higher RDW values were observed in the low rcSO2 group compared with those in the high rcSO2 group. Threshold effect analysis showed that rcSO2 decreased with RDW values ≥18% (β, −0.03; 95% CI, −0.04 and −0.02; p ≥ 0.0001). After adjusting for potential confounders, an RDW of ≥18% was determined as the predictive cutoff value for preterm infants with low rcSO2 (Model I: OR, 3.31; 95% CI, 1.36–8.06; p = 0.009; and Model II: OR, 3.31; 95% CI, 1.28–8.53; p = 0.013).ConclusionsAn RDW of ≥18% in the first 14 days is associated with rcSO2 of &lt;55% in preterm infants

State-of-the-Art Organic- and Inorganic-Based Hollow Fiber Membranes in Liquid and Gas Applications: Looking Back and Beyond

The aggravation of environmental problems such as water scarcity and air pollution has called upon the need for a sustainable solution globally. Membrane technology, owing to its simplicity, sustainability, and cost-effectiveness, has emerged as one of the favorable technologies for water and air purification. Among all of the membrane configurations, hollow fiber membranes hold promise due to their outstanding packing density and ease of module assembly. Herein, this review systematically outlines the fundamentals of hollow fiber membranes, which comprise the structural analyses and phase inversion mechanism. Furthermore, illustrations of the latest advances in the fabrication of organic, inorganic, and composite hollow fiber membranes are presented. Key findings on the utilization of hollow fiber membranes in microfiltration (MF), nanofiltration (NF), reverse osmosis (RO), forward osmosis (FO), pervaporation, gas and vapor separation, membrane distillation, and membrane contactor are also reported. Moreover, the applications in nuclear waste treatment and biomedical fields such as hemodialysis and drug delivery are emphasized. Subsequently, the emerging R&D areas, precisely on green fabrication and modification techniques as well as sustainable materials for hollow fiber membranes, are highlighted. Last but not least, this review offers invigorating perspectives on the future directions for the design of next-generation hollow fiber membranes for various applications. As such, the comprehensive and critical insights gained in this review are anticipated to provide a new research doorway to stimulate the future development and optimization of hollow fiber membranes