Performance and mechanisms for the removal of phthalates and pharmaceuticals from aqueous solution by graphene-containing ceramic composite tubular membrane coupled with the simultaneous electrocoagulation and electrofiltration process

Integrated bipolar electrocoagulation and PVC-based ultrafiltration membrane process for palm oil mill effluent (POME) treatment

In this study, the effectiveness of integrating electrocoagulation (EC) and ultrafiltration (UF) membranes for palm oil mill effluent (POME) wastewater treatment was investigated. The impact of various parameters on contaminant removal efficiency, including electrode configuration (monopolar and bipolar), number of anodes, agitation rate, and current density, was studied. The findings demonstrated that using bipolar (BP) electrodes in the EC reactor improved coagulation efficiency. However, an increase in agitation rate led to a decrease in removal efficiency. The electrode configuration of 2A-2C-2B achieved high contaminant removal with a lower electrode consumption compared to the 4A-2C and 4A-2C-2B configurations. The removal efficiencies for total dissolved solids (TDS), total suspended solids (TSS), chemical oxygen demand (COD), and biological oxygen demand (BOD) were 59.1%, 99.9%, 96.8%, and 96%, respectively. The operating cost for the electrode configuration of 2A-2C-2B was estimated to be 2.71 US$ m-3 at an effluent capacity of 50 m3 d-1 and 20 h d-1 of operating time, while the energy requirement was 6.20 kWh m-3. An increase in operating time from 5 to 24 h d-1 raised the specific operating cost from 2.17 to 2.85 US$ m-3. This study provides valuable insights into optimizing EC and UF processes for POME wastewater treatment, which could have significant implications for sustainable industrial practices.

Structural and performance variation of PES/PVDF membranes after exposure to the pretreated feed water of CECs

In this study, the removal efficiency of chemicals of emerging concerns (CECs) was evaluated under exposure to various doses of UV/H₂O₂-based oxidation processes in combination with membrane filtration for three cleaning cycles. Polyethersulphone (PES) and polyvinylidene fluoride (PVDF) materials based membranes were used for this study. The chemical cleaning of the membranes was performed by immersion of the membranes into 1 N HCl followed by adding 3000 mg.L^-1 NaOCl for 1hr. Degradation and filtration performance was evaluated using Liquid Chromatography with tandem mass spectrometry (LC-MS/MS) and total organic carbon (TOC) analysis. Membrane fouling analysis for assessing the comparative performance of PES and PVDF membranes was determined by specific fouling and fouling indices evaluation. Membrane characterization results show that the alkynes and carbonyl group formation are due to dehydrofluorination and oxidation of PVDF and PES membranes under the attack of foulants and cleaning chemicals, which resulted in a reduction of fluoride percentage and an increase in sulfur percentage in the PVDF and PES membranes. A decrease in the hydrophilicity of the membranes in underexposed conditions was observed and is consistent with an increase in dose. Degradation results of CECs follow with the highest removal efficiency of chlortetracycline (CTC) followed by atenolol (ATL), acetaminophen (ACT), and caffeine (CAF) degradation due to attack on the aromatic ring and the carbonyl group of CECs by OH exposure. Membrane exposed at 3 mg.L-1 dose of UV/H₂O₂-based CECs shows minimum alteration with higher filtration efficiency and lower fouling, particularly in PES membranes.

Recent developments in microplastic contaminated water treatment: Progress and prospects of carbon-based two-dimensional materials for membranes separation

Micro (nano)plastics pollution is a noxious menace not only for mankind but also for marine life, as removing microplastics (MPs) is challenging due to their physiochemical properties, composition, and response toward salinity and pH. This review provides a detailed assessment of the MPs pollution in different water types, environmental implications, and corresponding treatment strategies. With the advancement in nanotechnology, mitigation strategies for aqueous pollution are seen, especially due to the fabrication of nanosheets/membranes mostly utilized as a filtration process. Two-dimensional (2D) materials are increasingly used for membranes due to their diverse structure, affinity, cost-effectiveness, and, most importantly, removal efficiency. The popular 2D materials used for membrane-based organic and inorganic pollutants from water mainly include graphene and MXenes however their effectiveness for MPs removal is still in its infancy. Albeit, the available literature asserts a 70- 99% success rate in micro/nano plastics removal achieved through membranes fabricated via graphene oxide (GO), reduced graphene oxide (rGO) and MXene membranes. This review examined existing membrane separation strategies for MPs removal, focusing on the structural properties of 2D materials, composite, and how they adsorb pollutants and underlying physicochemical mechanisms. Since MPs and other contaminants commonly coexist in the natural environment, a brief examination of the response of 2D membranes to MPs removal was also conducted. In addition, the influencing factors regulate MPs removal performance of membranes by impacting their two main operating routes (filtration and adsorption). Finally, significant limitations, research gaps, and future prospects of 2D material-based membranes for effectively removing MPs are also proposed. The conclusion is that the success of 2D material is strongly linked to the types, size of MPs, and characteristics of aqueous media. Future perspectives talk about the problems that need to be solved to get 2D material-based membranes out of the lab and onto the market.

Recent innovation and impacts of nano-based technologies for wastewater treatment on humans: a review

Sustainable wastewater management requires environment-friendly, efficient, and cost-effective methods of water treatment. The ever-growing list of emerging contaminants in municipal wastewater requires advanced, efficient, and cost-effective techniques for its treatment to combat the increasing water demand. The nano-based technologies hold great potential in improving water treatment efficiency and augmenting the water supply. However, the environmental effects of these technologies are still questionable among the public and scientific community. The present review discusses risks to human health due to the use of nano-based technology for the removal of emerging contaminants in water. The discussion will be about the impacts of these technologies on humans. Recommendations about safe and environmentally friendly options for nano-based technology for water treatment have been included. Safest options of nano-based technologies for water treatment and steps to minimize the risk associated with them have also been incorporated in this article. Since all biological systems are different, separate risk analyses should be performed at the environmentally relevant concentration for different durations. There is little/no information on the quantitative impact on humans and requires more understanding. The quantitative measurement of the cellular uptake of nanoparticles is usually difficult. We hope this article will serve its purpose for water researchers, medical researchers, environmentalists, policymakers, and the government.

Next-generation graphene oxide additives composite membranes for emerging organic micropollutants removal: Separation, adsorption and degradation

In the past two decades, membrane technology has attracted considerable interest as a viable and promising method for water purification. Emerging organic micropollutants (EOMPs) in wastewater have trace, persistent, highly variable quantities and types, develop hazardous intermediates and are diffusible. These primary issues affect EOMPs polluted wastewater on an industrial scale differently than in a lab, challenging membranes-based EOMP removal. Graphene oxide (GO) promises state-of-the-art membrane synthesis technologies and use in EOMPs removal systems due to its superior physicochemical, mechanical, and electrical qualities and high oxygen content. This critical review highlights the recent advancements in the synthesis of next-generation GO membranes with diverse membrane substrates such as ceramic, polyethersulfone (PES), and polyvinylidene fluoride (PVDF). The EOMPs removal efficiencies of GO membranes in filtration, adsorption (incorporated with metal, nanomaterial in biodegradable polymer and biomimetic membranes), and degradation (in catalytic, photo-Fenton, photocatalytic and electrocatalytic membranes) and corresponding removal mechanisms of different EOMPs are also depicted. GO-assisted water treatment strategies were further assessed by various influencing factors, including applied water flow mode and membrane properties (e.g., permeability, hydrophily, mechanical stability, and fouling). GO additive membranes showed better permeability, hydrophilicity, high water flux, and fouling resistance than pristine membranes. Likewise, degradation combined with filtration is two times more effective than alone, while crossflow mode improves the photocatalytic degradation performance of the system. GO integration in polymer membranes enhances their stability, facilitates photocatalytic processes, and gravity-driven GO membranes enable filtration of pollutants at low pressure, making membrane filtration more inexpensive. However, simultaneous removal of multiple contaminants with contrasting characteristics and variable efficiencies in different systems demands further optimization in GO-mediated membranes. This review concludes with identifying future critical research directions to promote research for determining the GO-assisted OMPs removal membrane technology nexus and maximizing this technique for industrial application.

Cost and efficiency perspectives of ceramic membranes for water treatment

More robust ceramic membranes with tailorable structures and functions are increasingly employed for water treatment, particularly in some harsh applications for their ultra-long service lifespan due to their high mechanical, structural, chemical and thermal stability and anti-fouling properties. Decreasing cost and enhancing efficiency are two key but quite challenging application-oriented issues for broader and larger-scale engineering application of current ceramic membranes, and are required to make ceramic membranes a highly efficient and economic water treatment technique. In this review, we critically discuss these two significant concerns of both cost and efficiency for water treatment ceramic membranes, focusing on an overview of various advanced strategies and mechanism insights. A brief up-to-date discussion is first introduced about recent developments of ceramic membranes covering the major advances of novel membranes and applications. Then some promising strategies for decreasing the cost of ceramic membranes are discussed, including membrane material cost and processing cost. To fully address the issue of moderate efficiency with single separation function, valuable and considerable insights are provided into recent major progress and mechanism understandings in application with other unit processes, such as advanced oxidation and electrochemistry techniques, to significantly enhance treatment efficiency. Subsequently, a review of recent ceramic membrane applications emphasizing harsh operating environments is presented, such as oil-water separation, saline water, refractory organic and emerging contaminant wastewater treatment. Finally, engineering application, conclusions, and future perspectives of ceramic membrane for water treatment applications are critically discussed offering new insight based on understanding the issues of cost and efficiency.

Biochar-based composites for remediation of polluted wastewater and soil environments: Challenges and prospects

Pharmaceuticals, heavy metals, pesticides, and dyes are the main environmental contaminants that have serious effects on both land and aquatic lives and necessitate the development of effective methods to mitigate these issues. Although some conventional methods are in use to tackle soil contamination, but biochar and biochar-based composites represent a reliable and sustainable means to deal with a spectrum of toxic organic and inorganic pollutants from contaminated environments. The capacity of biochars and derived constructs to remediate inorganic dyes, pesticides, insecticides, heavy metals, and pharmaceuticals from environmental matrices is attributed to their extensive surface area, surface functional groups, pore size distribution, and high sorption capability of these pollutants in water and soil environments. Application conditions, biochar feedstock, pyrolysis conditions and precursor materials are the factors that influence the capacity and functionality of biochar to adsorb pollutants from wastewater and soil. These factors, when improved, can benefit biochar in agrochemical and heavy metal remediation from various environments. However, the processes involved in biochar production and their influence in enhancing pollutant sequestration remain unclear. Therefore, this paper throws light on the current strategies, operational conditions, and sequestration performance of biochar and biochar-based composites for agrochemical and heavy metal in soil and water environments. The main challenges associated with biochar preparation and exploitation, toxicity evaluation, research directions and future prospects for biochar in environmental remediation are also outlined.

Persistence, environmental hazards, and mitigation of pharmaceutically active residual contaminants from water matrices

Pharmaceutical compounds are designed to elicit a biological reaction in specific organisms. However, they may also elicit a biological response in non-specific organisms when exposed to ambient quantities. Therefore, the potential human health hazards and environmental effects associated with pharmaceutically active compounds presented in aquatic environments are being studied by researchers all over the world. Owing to their broad-spectrum occurrence in various environmental matrices, direct or indirect environmental hazardous impacts, and human-health related consequences, several pharmaceutically active compounds have been categorized as emerging contaminants (ECs) of top concern. ECs are often recalcitrant and resistant to abate from water matrices. In this review, we have examined the classification, occurrence, and environmental hazards of pharmaceutically active compounds. Moreover, because of their toxicity and the inefficiency of wastewater treatment plants to remove pharmaceutical pollutants, novel wastewater remediation technologies are urgently required. Thus, we have also analyzed the recent advances in microbes-assisted bioremediation as a suitable, cost-effective, and eco-friendly alternative for the decontamination of pharmaceutical pollutants. Finally, the most important factors to reach optimal bioremediation are discussed.

Phthalates removal from wastewater by different methods - a review

Phthalate esters are commonly used as plasticizers to improve the durability and workability of polymeric materials, locating and identifying them in various contexts has become a major challenge. Because of their ubiquitous use in plastic packaging and personal care items, as well as their tendency to leach out of these materials, phthalates have been detected in a variety of aquatic situations, including surface water, groundwater, drinking water, and wastewater. Phthalate esters have been shown to affect reproductive health and physical growth by disrupting the endocrine system. As a result, developing energy-efficient and effective technologies to eliminate these harmful substances from the atmosphere has become more important and urgent. This paper examines the existing techniques for treating phthalates and degradation mechanisms, as well as knowledge gaps and future research directions. These technologies include adsorption, electrochemical, photocatalysis, membrane filtration and microbial degradation. Adsorption and photo catalysis are the most widely used techniques for phthalate removal, according to the literature survey papers.

A review on electrocoagulation process for the removal of emerging contaminants: theory, fundamentals, and applications

Electrocoagulation (EC) is an excellent and promising technology in wastewater treatment, as it combines the benefits of coagulation, flotation, and electrochemistry. During the last decade, extensive researches have focused on removal of emerging contaminants by using electrocoagualtion, due to its several advantages like compactness, cost-effectiveness, efficiency, low sludge production, and eco-friendness. Emerging contaminants (ECs) are micropollutants found in trace amounts that discharging into conventional wastewater treatment (WWT) plants entering surface waters and imposing a high threat to human and aquatic life. Various studies reveal that about 90% of emerging contaminants are disposed unscientifically into water bodies, creating problems to public health and environment. The studies on removal of emerging contaminants from wastewater are by global researchers are critically reviewed. The core findings proved that still more research required into optimization of parameters, system design, and economic feasibility to explore the potential of EC combined systems. This review has introduced an innovative collection of current knowledge on electro-coagulation for the removal of emerging contaminants.

Modern Carbon-Based Materials for Adsorptive Removal of Organic and Inorganic Pollutants from Water and Wastewater

Currently, a serious threat for living organisms and human life in particular, is water contamination with persistent organic and inorganic pollutants. To date, several techniques have been adopted to remove/treat organics and toxic contaminants. Adsorption is one of the most effective and economical methods for this purpose. Generally, porous materials are considered as appropriate adsorbents for water purification. Conventional adsorbents such as activated carbons have a limited possibility of surface modification (texture and functionality), and their adsorption capacity is difficult to control. Therefore, despite the significant progress achieved in the development of the systems for water remediation, there is still a need for novel adsorptive materials with tunable functional characteristics. This review addresses the new trends in the development of new adsorbent materials. Herein, modern carbon-based materials, such as graphene, oxidized carbon, carbon nanotubes, biomass-derived carbonaceous matrices-biochars as well as their composites with metal-organic frameworks (MOFs) and MOF-derived highly-ordered carbons are considered as advanced adsorbents for removal of hazardous organics from drinking water, process water, and leachate. The review is focused on the preparation and modification of these next-generation carbon-based adsorbents and analysis of their adsorption performance including possible adsorption mechanisms. Simultaneously, some weak points of modern carbon-based adsorbents are analyzed as well as the routes to conquer them. For instance, for removal of large quantities of pollutants, the combination of adsorption and other methods, like sedimentation may be recommended. A number of efficient strategies for further enhancing the adsorption performance of the carbon-based adsorbents, in particular, integrating approaches and further rational functionalization, including composing these adsorbents (of two or even three types) can be recommended. The cost reduction and efficient regeneration must also be in the focus of future research endeavors. The targeted optimization of the discussed carbon-based adsorbents associated with detailed studies of the adsorption process, especially, for multicomponent adsorbate solution, will pave a bright avenue for efficient water remediation.

Modification of Ceramic Membranes with Carbon Compounds for Pharmaceutical Substances Removal from Water in a Filtration-Adsorption System

The aim of this work is to develop a new type of carbon-ceramic membranes for the removal of pharmaceutical substances from water. The membranes were prepared by the chemical modification method using an organosilicon precursor—octadecyltrichlorosilane (ODTS). Graphene oxide, multi-walled carbon nanotubes with carboxylic groups, and single-walled carbon nanotubes were used in the modification process. The filtration properties and adsorption properties of the developed membranes were tested. In order to characterize the membrane, the water permeability, the change of the permeate flux in time, and the adsorbed mass of the substance were determined. Additionally, the surface properties of the membranes were characterized by contact angle measurements and porosimetry. The antibiotic tetracycline was used in the adsorption tests. Based on the results, the improved adsorption properties of the modified membrane in relation to the unmodified membrane were noticed. Novel ceramic membranes modified with MWCNT are characterized by 45.4% removal of tetracycline and permeate flux of 520 L·h·m⁻²·bar⁻¹. We demonstrated the ability of modified membranes to adsorb pharmaceuticals from water streams that are in contact with the membrane. Novel membranes retain their filtration properties. Therefore, such membranes can be used in an integrated filtration–adsorption process.

Nano-adsorbents an effective candidate for removal of toxic pharmaceutical compounds from aqueous environment: A critical review on emerging trends

Advancements in medical research has resulted in the modernization of healthcare facilities, subsequently leading to a higher level of production and usage of pharmaceuticals to sustain better quality of life. Pharmaceutical active compounds (PhACs) possess high genotoxicity and eco-toxicity thus presenting numerous side effects to living beings on long-term exposure. The fate and toxicity of PhACs were explored in detail, aiming to elucidate their occurrence and transmission in wastewater treatment systems (WWTPs). Adsorption of pharmaceutical compounds using Nano-adsorbents has gained momentum in recent years owing to their low-cost, high surface area and effectiveness. This review has been conducted in order to widen the utilization of Nano adsorbents in the adsorption of pharmaceutical compounds with a focus on the aqueous environment. The synthesis routes and properties of Nano-adsorbents for removal of PhACs were assessed in a comprehensive way. The recovery and reuse ability of nano-adsorbents also forms an integral part of its application in the removal of PhACs and has hence been delineated.

Biochar for remediation of agrochemicals and synthetic organic dyes from environmental samples: A review

Application of agrochemicals in farming sector to control insects and pests; and use of synthetic organic dyes to color the products are increasing continuously due to the rapid growth of industries. During the application process many industries releases toxic agrochemicals and dyes in to the aquatic environment and on land without the proper treatment. Due to their toxicity the disposal of such chemicals is of utmost importance. Biochar offers the ability to remediate these substances from environmental matrices because of their high sorption ability of pollutants from water and soil. This review highlights the development and advancement of biochar-based treatment for abatement of agrochemicals and synthetic organic dyes, involving its technical aspects and the variables connected with removing these kinds of pollutants. Several optimization parameters like temperature, pH, chemical concentration, biochar properties, time, and co-existing ions have been elaborated. Literature survey shows that most of the researches on biochar application have been conducted in the batch mode. Hence there is an urgent need to apply this beneficial technique for the remediation of pollutants at the larger scale in the real water and soil samples. A comprehensive summary on sorption kinetics and adsorption isotherms with regards to pollutant removal is also presented. This review also covers the cost analysis of various techniques where biochar has been used as an adsorbent. Thus this review makes an easy roadmap for the further development in biochar and biochar based composites and expansion of these demanding areas of research in biochar and their applications.

Chitosan-Based Nanocomposite Polymeric Membranes for Water Purification-A Review

During the past few years, researchers have focused their attention on developing innovative nanocomposite polymeric membranes with applications in water purification. Natural and synthetic polymers were considered, and it was proven that chitosan-based materials presented important features. This review presents an overview regarding diverse materials used in developing innovative chitosan-based nanocomposite polymeric membranes for water purification. The first part of the review presents a detailed introduction about chitosan, highlighting the fact that is a biocompatible, biodegradable, low-cost, nontoxic biopolymer, having unique structure and interesting properties, and also antibacterial and antioxidant activities, reasons for using it in water treatment applications. To use chitosan-based materials for developing nanocomposite polymeric membranes for wastewater purification applications must enhance their performance by using different materials. In the second part of the review, the performance's features will be presented as a consequence of adding different nanoparticles, also showing the effect that those nanoparticles could bring on other polymeric membranes. Among these features, pollutant's retention and enhancing thermo-mechanical properties will be mentioned. The focus of the third section of the review will illustrate chitosan-based nanocomposite as polymeric membranes for water purification. Over the last few years, researchers have demonstrated that adsorbent nanocomposite polymeric membranes are powerful, important, and potential instruments in separation or removal of pollutants, such as heavy metals, dyes, and other toxic compounds presented in water systems. Lastly, we conclude this review with a summary of the most important applications of chitosan-based nanocomposite polymeric membranes and their perspectives in water purification.

Graphene Oxide Membranes for Trace Hydrocarbon Contaminant Removal from Aqueous Solution

The aim of this paper is to shed light on the application of graphene oxide (GO) membranes for the selective removal of benzene, toluene, and xylene (BTX) from wastewater. These molecules are present in traces in the water produced from oil and gas plants and are treated now with complex filtration systems. GO membranes are obtained by a simple, fast, and scalable method. The focus of this work is to prove the possibility of employing GO membranes for the filtration of organic contaminants present in traces in oil and gas wastewater, which has never been reported. The stability of GO membranes is analyzed in water solutions with different pH and salinity. Details of the membrane preparation are provided, resulting in a crucial step to achieve a good filtration performance. Material characterization techniques such as electron microscopy, x-ray diffraction, and infrared spectroscopy are employed to study the physical and chemical structure of GO membranes, while gas chromatography, UV-visible spectroscopy, and gravimetric techniques allow the quantification of their filtration performance. An impressive rejection of about 90% was achieved for 1 ppm of toluene and other pollutants in water, demonstrating the excellent performance of GO membranes in the oil and gas field.

A comprehensive review on contaminants removal from pharmaceutical wastewater by electrocoagulation process

The pharmaceuticals are emergent contaminants, which can create potential threats for human health and the environment. All the pharmaceutical contaminants are becoming enormous in the environment as conventional wastewater treatment cannot be effectively implemented due to toxic and intractable action of pharmaceuticals. For this reason, the existence of pharmaceutical contaminants has brought great awareness, causing significant concern on their transformation, occurrence, risk, and fate in the environments. Electrocoagulation (EC) treatment process is effectively applied for the removal of contaminants, radionuclides, pesticides, and also harmful microorganisms. During the EC process, an electric current is employed directly, and both electrodes are dissoluted partially in the reactor under the special conditions. This electrode dissolution produces the increased concentration of cation, which is finally precipitated as hydroxides and oxides. Different anode materials usage like aluminum, stainless steel, iron, etc. are found more effective in EC operation for efficient removal of pharmaceutical contaminants. Due to the simple procedure and less costly material, EC method is extensively recognized for pharmaceutical wastewater treatment over further conventional treatment methods. The EC process has more usefulness to destabilize the pharmaceutical contaminants with the neutralization of charge and after that coagulating those contaminants to produce flocs. Thus, the review places particular emphasis on the application of EC process to remove pharmaceutical contaminants. First, the operational parameters influencing EC efficiency with the electroanalysis techniques are described. Second, in this review emerging challenges, current developments and techno-economic concerns of EC are highlighted. Finally, future recommendations and prospective on EC are envisioned.

Are pharmaceuticals removal and membrane fouling in electromembrane bioreactor affected by current density?

Pharmaceutical active compounds (PhACs) have been detected at significant concentrations in various natural and artificial aquatic environments. In this study, electro membrane bioreactor (eMBR) technology was used to treat simulated municipal wastewater containing widely-used pharmaceuticals namely amoxicillin (AMX), diclofenac (DCF) and carbamazepine (CBZ). The effects of varying current density on the removal of PhACs (AMX, DCF and CBZ) and conventional pollutants (chemical oxygen demand (COD), dissolved organic carbon (DOC), humic substances, ammonia nitrogen (NH₄-N), nitrate nitrogen (NO₃-N) and orthophosphate (PO₄-P) species) were examined. High COD and DOC removal efficiencies (~100%) were obtained in all the experimental runs regardless of applied current density. In contrast, enhanced removal efficiencies for AMX, DCF and CBZ were achieved at high current densities. Membrane fouling rate in eMBR with respect to conventional MBR was reduced by 24, 44 and 45% at current densities of 0.3, 0.5 and 1.15 mA/cm², respectively. The mechanism for pharmaceutical removal in this study proceeded by: (1) charge neutralization between negatively-charged pharmaceutical compounds and positive electro-generated aluminium coagulants to form larger particles and (2) size exclusion by membrane filtration.

Control of quorum sensing signals and emerging contaminants in electrochemical membrane bioreactors

The present study investigated the influence of electric field on the removal of quorum sensing (QS) and emerging contaminants using an electrochemical membrane bioreactor (eMBR). A significant reduction of N-octanoyl-L-homoserine lactone signal molecules (∼76%) was achieved in the eMBR, with respect to the level observed in the conventional MBR as the control. Furthermore, the intermittent electric current supply (0.5 mA/cm²) was found to be effective for the removal of atrazine and estrone. The degradation of key pharmaceutical compounds, such as diclofenac, carbamazepine, and amoxicillin, was also possible, confirming the applicability of the eMBR system for removing the priority chemical compounds of public health concern.

Submerged low-cost pyrophyllite ceramic membrane filtration combined with GAC as fluidized particles for industrial wastewater treatment

Submerged ceramic membrane reactor treating industrial wastewater was combined with granular activated carbon (GAC) particles to control membrane fouling and organic removal efficiency. The GAC particles were suspended along the membrane surface under bulk recirculation only through the reactor without any gas sparging. Membrane support coated with Al₂O₃ layer (CPM) and uncoated one (UPM) was compared at constant flux mode of filtration. The membrane support consisted of 80% of pyrophyllite and 20% of alumina. Under up-flow velocity of 0.031 m s^-1 through bulk recirculation only without GAC particles, the fouling rates were observed as 0.011 and 0.013 bar h^-1 for the CPM and UPM, respectively. With suspension of GAC particles, fouling mitigation was enhanced considerably and this effect was more pronounced with CPM than UPM under the same upflow velocity (90 vs. 57%). In addition, the GAC suspension increased critical flux by 46% higher with CPM than that observed without the carbon particles. The organic removal efficiency of the UPM was lower than that of CPM while the fouling rate was much greater probably due to pore blocking caused by organic dye compounds. For the both membranes, suspension of GAC particles along the membrane surface increased organic removal efficiency higher than 90%. The organic removal efficiency was enhanced by increasing permeate flux, but it became lower as upflow velocity was higher.

Progress of Nanocomposite Membranes for Water Treatment

The use of membrane-based technologies has been applied for water treatment applications; however, the limitations of conventional polymeric membranes have led to the addition of inorganic fillers to enhance their performance. In recent years, nanocomposite membranes have greatly attracted the attention of scientists for water treatment applications such as wastewater treatment, water purification, removal of microorganisms, chemical compounds, heavy metals, etc. The incorporation of different nanofillers, such as carbon nanotubes, zinc oxide, graphene oxide, silver and copper nanoparticles, titanium dioxide, 2D materials, and some other novel nano-scale materials into polymeric membranes have provided great advances, e.g., enhancing on hydrophilicity, suppressing the accumulation of pollutants and foulants, enhancing rejection efficiencies and improving mechanical properties and thermal stabilities. Thereby, the aim of this work is to provide up-to-date information related to those novel nanocomposite membranes and their contribution for water treatment applications.

Removal of micropollutants from municipal wastewater by graphene adsorption and simultaneous electrocoagulation/electrofiltration process

In this work the optimal operating conditions for removing selected micropollutants (also known as emerging contaminants, ECs) from actual municipal wastewater by graphene adsorption (GA) and simultaneous electrocoagulation/electrofiltration (EC/EF) process, respectively, were first determined and evaluated. Then, performance and mechanisms for the removal of selected phthalates and pharmaceuticals from municipal wastewater simultaneously by the GA and EC/EF process were further assessed. ECs of concern included di-n-butyl phthalate (DnBP), di-(2-ethylhexyl) phthalate (DEHP), acetaminophen (ACE), caffeine (CAF), cefalexin (CLX) and sulfamethoxazole (SMX). It was found that GA plus EC/EF process yielded the following removal efficiencies: DnBP, 89 ± 2%; DEHP, 85 ± 3%; ACE, 99 ± 2%; CAF, 94 ± 3%; CLX, 100 ± 0%; and SMX, 98 ± 2%. Carbon adsorption, size exclusion, electrostatic repulsion, electrocoagulation, and electrofiltration were considered as the main mechanisms for the removal of target ECs by the integrated process indicated above.

New magnetic graphene-based inorganic-organic sol-gel hybrid nanocomposite for simultaneous analysis of polar and non-polar organophosphorus pesticides from water samples using solid-phase extraction

A new graphene-based tetraethoxysilane-methyltrimethoxysilane sol-gel hybrid magnetic nanocomposite (Fe₃O₄@G-TEOS-MTMOS) was synthesised, characterized and successfully applied in magnetic solid-phase extraction (MSPE) for simultaneous analysis of polar and non-polar organophosphorus pesticides from several water samples. The Fe₃O₄@G-TEOS-MTMOS nanocomposite was characterized using Fourier transform-infrared spectroscopy, energy-dispersive X-ray spectroscopy, field emission scanning electron microscopy and X-ray diffraction. Separation, determination and quantification were achieved using gas chromatography coupled with micro electron capture detector. Adsorption capacity of the sorbent was calculated using Langmuir equation. MSPE was linear in the range 100-1000 pg mL^-1 for phosphamidon and dimethoate, and 10-100 pg mL^-1 for chlorpyrifos and diazinon, with limit of detection (S/N = 3) of 19.8, 23.7, 1.4 and 2.9 pg mL^-1 for phosphamidon, dimethoate, diazinon and chlorpyrifos, respectively. The LODs obtained is well below the maximum residual level (100 pg mL^-1) as set by European Union for pesticides in drinking water. Acceptable precision (%RSD) was achieved for intra-day (1.3-8.7%, n = 3) and inter-day (7.6-17.8%, n = 15) analyses. Fe₃O₄@G-TEOS-MTMOS showed high adsorption capacity (54.4-76.3 mg g^-1) for the selected OPPs. No pesticide residues were detected in the water samples analysed. Excellent extraction recoveries (83-105%) were obtained for the spiked OPPs from tap, river, lake and sea water samples. The newly synthesised Fe₃O₄@G-TEOS-MTMOS showed high potential as adsorbent for OPPs analysis.