Feed Solution Research Articles

Improved synthesis of metformin hydrochloride-sodium alginate (MH-NaALG) microspheres using ultrasonic spray drying

Metformin Hydrochloride (MH), an orally administered antidiabetic drug from the biguanide family, encounters issues of wide particle size distribution, inefficient dissolution rates and short half-life leading to excess dosage which can result in lactic acidosis. Novel approaches that yield smaller particle size and uniform distribution at higher yields are significant to tackle problems associated with solubility and optimum dosage levels of the administered drugs. In the current research related to microsphere synthesis, a controlled process based on pressure and ultrasonic nozzles for the atomization of liquid, was applied with an objective of optimizing particle size of microspheres of MH in sodium alginate, a biopolymer excipient matrix. The study carried out in spray dryer elucidated parameter optimization using one variable at a time approach by varying important parameters as inlet temperature of air (120°C–150 °C), rate of flow of feed (1.5 mL/min-3 mL/min), aspirator rate (800 rpm–1400 rpm) and polymer content in feed solution (1 g–8 g) using ultrasonic and pressure nozzles for comparison with the target output parameter as particle size and yield. While the particle size at optimum conditions were <10 μm for both types of atomization, ultrasound assisted spray drying exhibited narrower distribution compared to the pressure atomization. Particle characterization performed using SEM, optical microscopy, FTIR, XRD and DSC revealed slight deformation with no chemical interaction and slight decrease in crystalline nature of pure drug. Overall, an improved process based on the use of ultrasound with optimized parameters has been demonstrated for synthesis of MH containing microspheres.

An integrated electrocatalytic membrane reactor and nanofiltration system for highly efficient removal of arsenic (III) from water

Arsenic (As) contamination in drinking water and groundwater has become as a major environmental concern due to extremely strong toxicity of As. Herein, a facile, efficient and energy-saving integrated membrane process via coupling the electrocatalytic membrane reactor (ECMR) and nanofiltration (NF) membrane is developed for the arsenic removal from As(III)-contained water. The ECMR, constructed with the one-dimensional (1D) MnO2 nanowires (NWs) loaded in the flat carbon membrane as anode, exhibits superior catalytic activity for the electro-oxidation of As(III). The maximum conversion rate of As(III) to As(V) achieves 96.0 % in the ECMR. The NF membrane is employed to filter the resultant permeate from ECMR. The concentration of As(V) after NF treatment is reduced to below 10 μg L−1 (99.5 % removal rate of As(V)) even if the As(III) concentration in the feed solution of ECMR is up to 2000 μg L−1, under a reaction temperature of 20 °C, a current density of 0.4 mA cm−2, a residence time of 10 min, an electrolyte Na2SO4 concentration of 15 g L−1 reaction conditions. The energy consumption of the whole integrated process was only 0.00211 kWh/μgAs. The superior catalytic performance of ECMR with 1D MnO2 NWs can be attributed to large electrochemical active surface area, 1D nanostructure with highly exposed (310) plane of 1D MnO2 NWs as well as strong interaction of oxide with the carbon membrane surface and the porous structure.

Incorporating TiO2 nanocages into electrospun nanofibrous membrane for efficient and anti-fouling membrane distillation

In this study, TiO2 nanocages with a hollow structure were integrated into the polyvinylidene fluoride co-hexafluoropropylene (PH) spinning solution, leading to the fabrication of a novel PH/TiO2 electrospun nanofiber membrane (PH/TiO2 ENM) through electrostatic spinning. The incorporation of TiO2 nanocages resulted in the formation of abundant micro-nano structures on the PH nanofiber surface, enhancing membrane roughness and hydrophobicity. Additionally, the hollow nanostructure of TiO2 nanocages effectively reduced the thermal conductivity of the ENMs. This reduction in thermal conductivity mitigated the temperature polarization effect, thereby increasing mass transfer driving force for the ENMs. The maximum water flux of the PH/TiO2 ENM reached ∼57.9 L m−2 h−1 (LMH), which was approximately 3.7 times higher than that of the original PH ENM. In addition to the formation of micro-nano structures on PH nanofibers, the presence of TiO2 nanocages facilitated the attachment of more low-surface-energy FAS molecules, improving the resistance of them to fouling and anti-wetting properties against both inorganic and organic contaminants, even in the presence of SDS, in a composite feed solution during the DCMD process. Moreover, even after prolonged exposure to a composite salt solution, this membrane also exhibited exceptional anti-fouling properties and stable desalination performance during a 168 h long-term stability test.

Removal of furosemide from water by emulsion liquid membrane: Influence of experimental conditions and real water matrices

This work investigates the removal of furosemide (FSM) from low pH aqueous phase by emulsion liquid membrane (ELM). The influence of various experimental conditions on FSM permeation rate and subsequent emulsion stability, such as surfactant concentration, diluent type, stripping solution concentration, feed solution pH, stripping solution/membrane solution volume ratio, emulsification time and speed, stirring rate, initial FSM concentration, and emulsion/feed solution volume ratio, was evaluated. The ability to extract FSM in different natural complex matrices was examined. The ELM system is formed by Span 80 (5% w/w) as surfactant, hexane as diluent, NaOH (0.01 N) as stripping agent, stripping solution/membrane solution volume ratio of 1/1, treatment volume ratio of 20/200, and mixing rate of 200 rpm. The treatment process demonstrates complete removal of FSM within a remarkably short time span of 20 min. In seawater and natural mineral water, the extraction efficiency is 94.3% and 96.8%, respectively, after 20 min. Additionally, the stripping efficiency of FSM is reported to be excellent (100%), demonstrating the remarkable ability of ELM to remove and recover FSM from water. For these reasons, the ELM technique is a particularly interesting process for treating FSM-contaminated water.

Effects of processed duckweed (Lemna paucicostata) meals as protein sources in Oreochromis niloticus (Linnaeus, 1758) diets

Effects of processed duckweed meals as a replacement for toasted soybean meal in the diets of Oreochromis niloticus fingerlings were evaluated. Sun-dried and blanched duckweed meals were used to replaced toasted soybean meal in at 25, 50, 75, and 100% each. Feed Solution Software (version 2022) was used to formulate nine iso-nitrogenous diets at 32% crude protein. 27 Hapa nets of 1 m2 each were used for the feeding trials for six months. Ten fingerlings of Oreochromis niloticus were stocked per Hapa and fed 5% body weight three times per day. The best mean weight gain (460.59 g), viscerosomatic index (9.90) and feed conversion ratio (1.82) were recorded in the fish fed 75% blanched duckweed meal while the fish fed 100% sun-dried duckweed meal and 100% blanched duckweed meal recorded the poor mean weight gain, viscerosomatic index and feed conversion ratio of 401.69 g and 394.03 g, 6.49 and 6.36, 2.06 and 2.10, respectively. The cost-benefit evaluation revealed that 75% blanched duckweed meal gave the highest net profit (₦3,682) and lowest incident cost (₦6.49). This study revealed that soybean meal can be replaced with 75% blanched duckweed meal in the diet of Oreochromis niloticus without any inauspicious effects on the growth and nutrient utilization, and will reduce the cost of production and maximize profit.

In vitro release modeling of beta-carotene from Bene oleosome and electrosprayed Quince seed hydrocolloids loaded with oleosomes containing beta-carotene

This research aimed to extract oleosome from the Bene kernel as a carrier of beta-carotene (3, 5, and 10 % w/w) and then use oleosomes in the Quince seed gum (QSG) electrosprayed nanoparticles for the sustained release of beta-carotene in food simulant. Oleosomes loaded with 5 % w/w beta-carotene had the highest encapsulation efficiency (94.53 % ± 1.23 %) and were used at 1, 3, and 5 % w/w in the QSG electrosprayed nanoparticles. Electrospray feed solutions containing 5 % oleosomes loaded with beta-carotene had the highest zeta potential (−34.45 ± 0.58 mV) and the lowest surface tension (23.47 ± 1.10 mN/m). FESEM images showed that with the increase of oleosomes up to 3 % w/w, the average size of the electrosprayed particles decreases. The Fourier transform infrared (FTIR) test proved the presence of protein in the oleosomes and their successful extraction from Bene seeds. Differential scanning calorimetry (DSC) and FTIR proved the successful entrapment of beta-carotene in the oleosomes structure and the successful placement of oleosomes containing beta-carotene in the electrosprayed nanoparticles. The predominant driving force involving the release of beta-carotene from the designed structures in food simulants was the Fickian release mechanism. The Peleg model was introduced as the best model describing the beta-carotene release.

Removal of Heavy Metals from Contaminated Aquatic Streams Using a Resin Supported Green nZVI

This study addresses the escalating demand for clean water resources driven by population growth and water quality deterioration. The research focuses on evaluating the efficacy of a nanocomposite material, incorporating zero valent iron nanoparticles into a chelating cation exchange resin matrix, for selectively removing heavy metals from polluted aquatic environments. The selected resin, featuring iminodiacetic acid functional groups, demonstrates notable selectivity for heavy metal cations over alkali earth metals. Column experiments were conducted to assess the nanocomposite’s performance, utilizing a feed solution spiked with heavy metals at concentrations ten times higher than Greek legislation limits for wastewater effluent recycling. The nanocomposite exhibited significant effectiveness for Cu, Cr(VI), and Pb, consistently maintaining Cu levels below detection limits and demonstrating limited breakthrough of Cr(VI) and Pb depending on experimental conditions. However, the removal efficiency was lower for Ni and insufficient for Cd, Zn, and As in this complex multicomponent solution. This research contributes valuable insights into the potential application of the developed nanocomposite for targeted removal of specific heavy metals in contaminated water sources, providing a foundation for further exploration and application in water remediation technologies.

Hydrophobic enrichment-induced augmentation of NH2-UiO-66 particle interactions for enhanced pervaporation performance of polydimethylsiloxane membrane

BackgroundIn this research, we aimed to improve the hydrophobic property of NH2-UiO-66 particles by palmitoyl chloride (PC) modification. PC-UiO-66 particles were mixed in the selective layer of PDMS (polydimethylsiloxane)-PVDF (Polyvinylidene fluoride) composite membrane for organo-selective pervaporation. MethodsWe effectively preserved conspicuous crystallinity and high porosity during a conversion from hydrophilic to hydrophobic MOF, as confirmed by XRD and BET studies. The successful incorporation of palmitoyl long alkyl chains into PC-UiO-66 was verified through FTIR, XPS, and EDS studies. PC-UiO-66 particles exhibited an excellent dispersion in PDMS matrix due to a strong interfacial polymer-MOF interaction observed in FESEM and AFM studies. An organophilic pervaporation separation performance of pristine PDMS, NH2-UiO-66/PDMS, and PC-UiO-66/PDMS membranes coated on PVDF support was evaluated for ethanol/water, IPA/water, and 1,5 PDO/IPA feed solution. Significant findingsThe results demonstrated that adding PC-UiO-66 particles significantly improved the separation performance of PC-UiO-66/PDMS membranes, achieving the highest selectivity compared to pristine PDMS and NH2-UiO-66/PDMS membranes.

Removal of High Concentrations of Arsenite from Aqueous Solutions by the Emulsion Liquid Membrane Technique

AbstractAs(III) is a dangerous species that contaminates groundwater resources and therefore water purification from this element is necessary. In this study, the removal of As(III) was investigated by the emulsion liquid membrane (ELM) technique due to the high toxicity levels of this species. The effect of various parameters such as hydrochloric acid and arsenic concentration in the feed solution, emulsion to feed ratio, surfactant concentration and type of carrier was evaluated on the arsenic separation efficiency. The results showed that the best type of carrier in terms of emulsion stability and separation efficiency of arsenic ions was di‐(2‐ethylhexyl) phosphoric acid (D2EHPA), and its optimal concentration was about 5 % (v/v). In addition, paraffin as the organic solvent performed better than the mixture of paraffin and kerosene in the separation of As(III) ions. The optimal conditions were obtained at 8 and 0.1 M HCl concentrations for the feed and the internal phases, respectively. Also, the emulsion to feed ratio of 1 : 4.5, the volume ratio of the internal phase to the membrane phase of 1 : 1 and the surfactant concentration of 5 % (v/v) led to achieving the maximum removal of arsenic ions. This work presents a broad perspective of removing As(III) ions from wastewater by carefully examining the parameters influencing the separation of this hazardous element through the ELM method.

Enhanced Salt Removal of Fresh Water by Recovery-Reduced Ion Concentration Polarization Desalination.

Here, we examine electromembrane systems for low-concentration desalination applicable to ultrapure water production. In addition to electrodialysis and ion concentration polarization (ICP) desalination, we propose a recovery-reduced ICP strategy for reducing the width of the desalted outlet for a higher salt removal ratio (SRR). The correlation between conductivity changes and thickness of the ion depletion zone is identified for electrodialysis, ICPH (1:1), and ICPQ (3:1) with a low-concentration feed solution (10 mM, 1 mM, 0.1 mM NaCl). Based on the experimental results, the scaling law and SRR for the electroconvection zone are summarized, and current efficiency (CE) and energy per ion removal (EPIR) depending on SRR are also discussed. As a result, the SRR of electrodialysis is mostly around 50%, but that of recovery-reduced ICP desalination is observed up to 99% under similar operating conditions. Moreover, at the same SRR, the CE of recovery-reduced ICP is similar to that of electrodialysis, but the EPIR is calculated to be lower than that of electrodialysis. Considering that forming an ion depletion zone up to half the channel width in the electromembrane system typically requires much power consumption, an ICP strategy that can adjust the width of the desalted outlet for high SRR can be preferable.

Isopropanol concentration by osmotically assisted reverse osmosis

Isopropanol (IPA) is a versatile solvent used in a wide range of industrial and consumer applications, and its disposal may pose high costs and environmental concerns. In this work, the osmotically assisted reverse osmosis (OARO) technology was employed to demonstrate the effective treatment and concentration of IPA wastewater. The effect of various operating parameters, including feed solution concentration, number of membrane modules, flow rate, and applied pressure, was systematically investigated. Both permeance and IPA rejection decreased with an increase in IPA concentration, due to increase of feed solution osmotic pressure and occurrence of membrane swelling. By adjusting the feed flow rate and applied pressure, we can effectively control the final IPA concentration. Specifically, lowering the feed flow rate will result in higher IPA concentration, and increasing the applied pressure will also lead to higher IPA concentration. Long-term operational stability was also investigated, and results showed that the OARO process could maintain stable operation over an extended period of 180 days. Lastly, real IPA wastewater sourced from an electronics devices factory was treated using the OARO system and the wastewater sample was concentrated for more than four times. The results of this work exhibit the great practical application potential of the OARO process for the concentration of IPA wastewater.

Thermochemical modeling and performance evaluation of freeze desalination systems

Freeze desalination (FD) is a method in which saline water is cooled below its freezing point and freshwater is separated from the brine in the form of ice crystals. FD is relatively insensitive to the salinity of the feed solution, making it suitable for desalination of high concentration brines such as the brine rejected from the seawater desalination plants. The design of the FD system and the thermochemical behavior of the brine upon freezing are critical factors in the energy performance of this method. To date, thermochemical properties of the concentrated seawater during cooling, such as the threshold of formation of ice and salt-hydrates and their corresponding cooling load of formation, are not well known. Likewise, the optimal configuration of the FD system to achieve the maximum energy efficiency has not been investigated. This work provides comprehensive data about the cooling load of freezing of concentrated brine rejected from seawater desalination plants along with the threshold of formation of ice and salt-hydrates backed-up by validation. Furthermore, the optimal configuration of the FD system is identified and the effects of the compressor isentropic efficiency and effectiveness of the system's heat exchangers on the work consumption of the FD system were investigated.

Insight into the scaling behavior of capacitive deionization for the removal of multiple cation components in the single-pass mode

Capacitive deionization (CDI) can effectively remove various ions in seawater and brackish water. However, due to the complex cation components in natural water, the desalination stability of CDI is challenged by cation scaling. In this study, the scaling behavior of CDI for the removal of multiple cation components in the single-pass mode was investigated. Three feed solutions containing various compositions (FS1 for Na+, FS2 for Na+/Ca2+/Mg2+, and FS3 for Na+/Ca/Mg2+/Fe3+) were tested. The results showed that the desalination stability was affected by cation components. Especially, the salt adsorption capacity for FS3 dramatically decreased from 7.16 to 3.53 mg/g over multiple cycles. Characterization demonstrated that the scaling of Ca and Mg for FS2 was slight while the scaling of Fe for FS3 was noticeable. Additionally, compared to FS2 scale, Fe significantly aggravated the scaling of Ca and Mg. The severe scaling behavior led to a decrease in specific capacitance, and an increase in charge transfer resistance and ion diffusion resistance of CDI electrodes. Finally, the correlation between scaling behavior and Faradaic reactions was comprehensively explored. The study provides insight into the scaling behavior of CDI, which is crucial for desalination stability in actual operation.

Deploy the proboscis!: Functional morphology and kinematics of a novel form of extreme jaw protrusion in the hingemouth, Phractolaemus ansorgii (Gonorynchiformes).

Premaxillary protrusion and the performance advantages it confers are implicated in the success of diverse lineages of teleost fishes, such as Cypriniformes and Acanthomorpha. Although premaxillary protrusion has evolved independently at least five times within bony fishes, much of the functional work investigating this kinesis relates to mechanisms found only in these two clades. Few studies have characterized feeding mechanisms in less-diverse premaxilla-protruding lineages and fewer yet have investigated the distinctive anatomy underlying jaw kinesis in these lineages. Here, we integrated dissection, clearing and staining, histology, micro-CT, and high-speed videography to investigate an isolated and independent origin of jaw protrusion in the hingemouth, Phractolaemus ansorgii, which employs a complex arrangement of bones, musculature, and connective tissues to feed on benthic detritus via a deployable proboscis. Our goals were to provide an integrative account of the underlying architecture of P. ansorgii's feeding apparatus and to assess the functional consequences of this drastic deviation from the more typical teleost condition. Phractolaemus ansorgii's cranial anatomy is distinct from all other fishes in that its adducted lower jaw is caudally oriented, and it possesses a mouth at the terminal end of an elongated, tube-like proboscis that is unique in its lack of skeletal support from the oral jaws. Instead, its mouth is supported primarily by hyaline-cell cartilage and other rigid connective tissues, and features highly flexible lips that are covered in rows of keratinous unculi. Concomitant changes to the adductor musculature likely allow for the flexibility to protrude the mouth dorsally and ventrally as observed during different feeding behaviors, while the intrinsic compliance of the lips allows for more effective scraping of irregular surfaces. From our feeding videos, we find that P. ansorgii is capable of modulating the distance of protrusion, with maximum anterior protrusion exceeding 30% of head length. This represents a previously undescribed example of extreme jaw protrusion on par with many acanthomorph species. Protrusion is much slower in P. ansorgii-reaching an average speed of 2.74 cm/s-compared to acanthomorphs feeding on elusive prey or even benthivorous cypriniforms. However, this reorganization of cranial anatomy may reflect a greater need for dexterity to forage more precisely in multiple directions and on a wide variety of surface textures. Although this highly modified mechanism may have limited versatility over evolutionary timescales, it has persisted in solitude within Gonorynchiformes, representing a novel functional solution for benthic feeding in tropical West African rivers.

Chiral acidic molecularly imprinted polymer for enantio-separation of norepinephrine racemate.

We are looking into how well a copolymeric material made of poly (maleic acid-co-4-vinylpyridine) cross-linked with divinylbenzene can separate L-norepinephrine (L-NEP) from (±)-NEP. The initial step in this direction was the synthesis and subsequent analysis of L-NEP-maleimide chiral derivative. A 4-vinylpyridine/divinylbenzene combination was copolymerized with the resultant chiral maleimide. After heating the polymer materials in a high-alkaline environment to breakdown the connecting imide bonds, they were acidified in an HCl solution to eliminate the incorporated L-NEP species. Fourier transform infrared spectroscopy (FTIR) and a scanning electron microscope were used to examine the imprinted L-NEP-imprinted materials. The manufactured L-NEP-imprinted materials exhibited selectivity characteristics that were over 11 times greater for L-NEP than D-norepinephrine. The highest capacity observed in Langmuir adsorption studies was 170 mg/g at a pH of 7. After optical separation using a column technique, it was determined that the enantiomeric excess levels of D-norepinephrine and L-NEP in the first feeding and subsequent recovery solutions were 95% and 81%, respectively.

An Updated Model Using a Reflection Coefficient for Predicting Performance of Pressure-Retarded Osmosis

Mathematical model was used to predict the performance of membrane process. In this study, an updatedmathematical model has been developed to study the forward osmosis (FO) and pressure-retarded osmosis (PRO) processes. This model has been advanced by taking into consideration the reflection coefficient, internal and external concentration polarizations, and structural membrane parameters, as well as the equations of applied pressure and mass transport for feed and draw solutions together. The model was validated through prediction of the water and salt fluxes using the membrane performance data published in other articles. The estimated values of the reflection coefficient ranged from 0.868 to 0.9 for FO and 0.9 to 0.95 for PRO. For this reason, it is not possible to consider the reflection coefficient to be equal to one as normally assumed in membrane modeling study. Other findings have showed that the varying salt fluxes at different concentrations and cross-flow velocities adversely impacted the FO and PRO modules. Internal and external concentration polarizations have been studied and compared with their effect on the effectiveness of the FO/PRO process. The model has demonstrated its ability to predict flux in the PRO greater than FO because of the model primary reliance on the applied pressure to drive the osmotic process. The ratio of must be effectively managed to correspond with operating limits and the value must also be kept to a minimum in order to avert the drastical drop in the flux, the fouling, and the membrane damage.

Evaluation of commercial nanofiltration and reverse osmosis membrane filtration to remove per-and polyfluoroalkyl substances (PFAS): Effects of transmembrane pressures and water matrices.

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are now widely found in aquatic ecosystems, including sources of drinking water and portable water, due to their increasing prevalence. Among different PFAS treatment or separation technologies, nanofiltration (NF) and reverse osmosis (RO) both yield high rejection efficiencies (>95%) of diverse PFAS in water; however, both technologies are affected by many intrinsic and extrinsic factors. This study evaluated the rejection of PFAS of different carbon chain length (e.g., PFOA and PFBA) by two commercial RO and NF membranes under different operational conditions (e.g., applied pressure and initial PFAS concentration) and feed solution matrixes, such as pH (4-10), salinity (0- to 1000-mM NaCl), and organic matters (0-10mM). We further performed principal component analysis (PCA) to demonstrate the interrelationships of molecular weight (213-499 g·mol-1 ), membrane characteristics (RO or NF), feed water matrices, and operational conditions on PFAS rejection. Our results confirmed that size exclusion is a primary mechanism of PFAS rejection by RO and NF, as well as the fact that electrostatic interactions are important when PFAS molecules have sizes less than the NF membrane pores. PRACTITIONER POINTS: Two commercial RO and NF membranes were both evaluated to remove 10 different PFAS. High transmembrane pressures facilitated permeate recovery and PFAS rejection by RO. Electrostatic repulsion and pore size exclusion are dominant rejection mechanisms for PFAS removal. pH, ionic strength, and organic matters affected PFAS rejection. Mechanisms of PFAS rejection with RO/NF membranes were explained by PCA analysis.

Unveiling the potential of forward osmosis desalination: Multi-objective optimization for peak efficiency

Forward osmosis (FO) has emerged as a promising technology with diverse applications. While recent advancements in FO have primarily focused on developing efficient membranes and draw solutes, studies on process optimization remain scarce. This work aims at identifying optimal operating conditions to use FO in seawater and brackish water desalination. Central Composite Design was conducted to investigate the effects of draw solution concentration, temperature, and flow rate on water flux (Jw), reverse solute flux (RSF), and specific cost index (Isc) responses. Response Surface Methodology analysis was performed to identify factors influencing responses. The desirability function was used to determine the best-input variables. The optimum operating conditions for the FO process are found at a flow rate of 0.6 L/min, a temperature of 32.9 °C, and a concentration of 1.79 mol/l, with corresponding values for water flux, RSF and Isc of 18.16 L/m2h and 41.03 g/m2h and 0.274, respectively. These results were experimentally validated. Experiments were also performed using seawater and brackish water feed solutions.

Hydraulic retention time governed the micro/nanostructures of titanium-incorporated diatoms and their photocatalytic activity

Titanium-incorporated diatoms are promising biomaterials to photodegrade micropollutants such as pharmaceuticals and personal care products (PPCPs). Hydraulic retention time (HRT) is a key parameter for diatom cultivation and the incorporation of titanium into diatom frustules. This study assessed how HRT governs the micro/nanostructures, titania (TiO2) content and distribution, and the photocatalytic activity of titanium-incorporated diatom frustules. We cultivated a diatom strain Stephanodiscus hantzschii using a feed solution containing titanium(IV) in membrane bioreactors (MBRs) at a solids retention time (SRT) of 10 d and staged HRTs from 24 to 12 and to 6 h. The decrease in HRT reduced the porosity of diatom frustules but increased their silicon and titania contents. When the HRT decreased from 24 to 12 and to 6 h, the specific surface areas of the diatom decreased from 37.65 ± 3.19 to 31.53 ± 3.71 and to 18.43 ± 2.69 m2·g−1 frustules, while the titanium (Ti) contents increased from 53 ± 14 to 71 ± 9 and to 85 ± 13 mg Ti·g−1 frustules. The increase in the influent flow rates of the MBRs with decreasing HRTs likely enhanced nutrient diffusion inside the diatom valve pores, facilitating the uptake and incorporation of silicon and titanium. The titanium-incorporated frustules were effective in removing two representative PPCPs, bisphenol A (BPA) and N,N-diethyl-meta-toluamide (DEET), from water. As photocatalytic activity depends on the amount of titanium, decreasing the HRT substantially increased the photocatalytic activity of the titanium-incorporated frustules. In batch tests under ultraviolet light, frustules from the diatom cultivated at HRTs of 24, 12, and 6 h had the pseudo-first-order removal (mainly through photodegradation) rate constants of BPA of 0.376, 0.456, and 0.683 h−1, respectively. Under the same experimental condition, the pseudo-first-order removal rate constants of DEET by the frustules cultivated at HRTs of 24, 12, and 6 h increased from 0.270 to 0.330 and to 0.480 h−1.

Simultaneous Wastewater Treatment and Resources Recovery by Forward Osmosis Coupled with Microbial Fuel Cell: A Review.

Osmotic microbial fuel cells (OsMFCs) with the abilities to simultaneously treat wastewater, produce clean water, and electricity provided a novel approach for the application of microbial fuel cell (MFC) and forward osmosis (FO). This synergistic merging of functions significantly improved the performances of OsMFCs. Nonetheless, despite their promising potential, OsMFCs currently receive inadequate attention in wastewater treatment, water reclamation, and energy recovery. In this review, we delved into the cooperation mechanisms between the MFC and the FO. MFC facilitates the FO process by promoting water flux, reducing reverse solute flux (RSF), and degrading contaminants in the feed solution (FS). Moreover, the water flux based on the FO principle contributed to MFC's electricity generation capability. Furthermore, we summarized the potential roles of OsMFCs in resource recovery, including nutrient, energy, and water recovery, and identified the key factors, such as configurations, FO membranes, and draw solutions (DS). We prospected the practical applications of OsMFCs in the future, including their capabilities to remove emerging pollutants. Finally, we also highlighted the existing challenges in membrane fouling, system expansion, and RSF. We hope this review serves as a useful guide for the practical implementation of OsMFCs.