Treatment of medical radioactive liquid waste using Forward Osmosis (FO) membrane process

High Removal Efficiency of Radioactive Iodine with In Situ-Synthesized Ag2O-Mg(OH)2 Plate Composites

To promote the capacity of adsorbing radioactive iodine (I-) in acid and alkaline situations, a high-removal-efficiency adsorbent based on silver oxide (Ag2O) and magnesium hydroxide (Mg(OH)2) was synthesized by the in situ method. To determine the mechanism of this novel absorbent, batch experiments related to the temperature, pH, competitive ion (Cl-), and kinetic analysis were carried out. The results showed that the Ag2O-Mg(OH)2 plate composites had high adsorption capacity and efficiency for I- (409 mg/g, 25 °C) with a wide range of pH values (3-9). In addition, the adsorption time from the initial concentration to I- removal (97.36%) was only 20 min. Competitive ion experiments depicted that Cl- influenced the capacity of adsorbing I-. The k value of the pseudo-second-order model and regression factor R 2 were 7.86 × 10-3g mg-1 min-1 and 0.999 at 25 °C, respectively. The kinetics and XPS results proved that the mechanism of adsorption was chemical adsorption. Compared with other commercial adsorbents, the Ag2O-Mg(OH)2 plate composites had potential for application in nuclear wastewater treatment with low cost and high efficiency.

Advances in the management of radioactive wastes and radionuclide contamination in environmental compartments: a review

Several anthropogenic activities produce radioactive materials into the environment. According to reports, exposure to high concentrations of radioactive elements such as potassium (⁴⁰K), uranium (²³⁸U and ²³⁵U), and thorium (²³²Th) poses serious health concerns. The scarcity of reviews addressing the occurrence/sources, distribution, and remedial solutions of radioactive contamination in the ecosystems has fueled data collection for this bibliometric survey. In rivers and potable water, reports show that several parts of Europe and Asia have recorded radionuclide concentrations much higher than the permissible level of 1 Bq/L. According to various investigations, activity concentrations of gamma-emitting radioactive elements discovered in soils are higher than the global average crustal values, especially around mining activities. Adsorption technique is the most prevalent remedial method for decontaminating radiochemically polluted sites. However, there is a need to investigate integrated approaches/combination techniques. Although complete radionuclide decontamination utilizing the various technologies is feasible, future research should focus on cost-effectiveness, waste minimization, sustainability, and rapid radionuclide decontamination. Radioactive materials can be harnessed as fuel for nuclear power generation to meet worldwide energy demand. However, proper infrastructure must be put in place to prevent catastrophic disasters.

Implication of nanotechnology to reduce the environmental risks of waste associated with the COVID-19 pandemic

The COVID-19 pandemic is the largest global public health outbreak in the 21st century so far. It has contributed to a significant increase in the generation of waste, particularly personal protective equipment and hazardous medical, as it can contribute to environmental pollution and expose individuals to various hazards. To minimize the risk of infection, the entire surrounding environment should be disinfected or neutralized regularly. Effective medical waste management can add value by reducing the spread of COVID-19 and increasing the recyclability of materials instead of sending them to landfill. Developing an antiviral coating for the surface of objects frequently used by the public could be a practical solution to prevent the spread of virus particles and the inactivation of virus transmission. Relying on an abundance of engineered materials identifiable by their useful physicochemical properties through versatile chemical functionalization, nanotechnology offers a number of approaches to address this emergency. Here, through a multidisciplinary perspective encompassing various fields such as virology, biology, medicine, engineering, chemistry, materials science, and computer science, we describe how nanotechnology-based strategies can support the fight against COVID-19 well as infectious diseases in general, including future pandemics. In this review, the design of the antiviral coating to combat the spread of COVID-19 was discussed, and technological attempts to minimize the coronavirus outbreak were highlighted.

Highly efficient removal of total nitrogen and dissolved organic compound in waste reverse osmosis concentrate mediated by chlorine radical on 3D Co3O4 nanowires anode

Reverse osmosis concentrate (ROC) from wastewater reclamation has posed significant disposal challenges due to its highly concentrated NH₃-N, chloride ion and bio-refractory organics, and developing technologies for their removal are essential. Herein, we developed an efficient electrochemical system to remove total nitrogen and dissolved organic compound (DOC) simultaneously mediated by chlorine radical (Cl•), which is generated by activation of chloride ion existing in ROC on an inexpensive, three-dimensional Co₃O₄ nanowires. Results showed that the total nitrogen and total organic carbon removal were 98.2% and 56.9% in 60 min for synthetic ROC with 56 mg/L of NH₃-N and 20 mg/L of DOC. The utilization of Co₃O₄ nanowires enhanced NH₃-N degradation by 2.58 times compared with Co₃O₄ nanoplates, which were 1.69 and 17.5 times these of RuO₂ and Pt. We found that structural Co³⁺/Co²⁺ acts as cyclic catalysis to produce Cl• via single-electron transfer, which convert NH₃-N to N₂ and lead to faster DOC degradation. This architecture provides abundant catalytic sites and sufficient accessibility of reactants. Small amount of nitrate generated by oxidation of NH₃-N was further reduced to N₂ on Pd-Cu/NF cathode. These findings provide new insights for utilization of waste Cl^- and development of novel electrochemical system for ROC disposal.

A critical review of advanced nanotechnology and hybrid membrane based water recycling, reuse, and wastewater treatment processes

One of the modern challenges is to provide clean and affordable drinking water. Water scarcity is caused by the growing population in the world and pollutants contaminate all remaining water sources. Innovative water treatment solutions have been provided by nanotechnology. Microorganisms, organic suspensions, and inorganic heavy metal ions, among other things, are common water contaminants. Since antiquity, a wide range of water clean-up methods have been employed to address this issue. Breakthroughs in water purification procedures have occurred during the previous four decades, with the most significant one being the use of nanomaterials and nanomembranes. Nanoparticles and nanomembranes (polymeric membranes) have recently been used in engineered materials (TiO₂, ZnO, CuO, Ag, CNT's and mixed oxide nanoparticles, for example). Engineered nanomembranes, nanocomposites and nanoparticles have been used in this review article's discussion of water purification technologies. The review also discusses the risk and solutions of using nanoparticles and nanocomposites in the future.

Hydroxyapatite nanoparticle functionalized activated carbon particle electrode that removes strontium from spiked soils in a unipolar three-dimensional electrokinetic system

Biohazard performance of Sr radionuclide can be significantly magnified by its release from the contaminated sedimentation. In this study, hydroxyapatite nanoparticle-functionalized activated carbon electrode (AC-HAP) was synthesized and stacked to the cathode compartment of the electrokinetic (EK) system to develop a unipolar three-dimensional (3D) electrochemical process for Sr²⁺ removal from spiked soils. Sr²⁺ adsorption by AC-HAP can be fitted by the pseudo-first-order and pseudo-second-order kinetic models and the Langmuir, Freundlich, and Temkin isotherm models. The largest monolayer adsorption capacity of AC-HAP of 69.49 mg g^-1 was evaluated in the pH range of 10-12 and at 40 °C. 3D EK further intensified the adsorption process of AC-HAP and the corresponding Sr²⁺ removal from aqueous environments. Voltage gradients and proposing time had a significant effect on the migration and transmission of Sr²⁺ in the electrolyzer. The influence of competitive ions on Sr²⁺ removal in the stock solutions followed Al³⁺ < Mg²⁺ < K⁺ < Na⁺ < Ca²⁺ while followed Al³⁺ < Na⁺ < K⁺ < Mg²⁺ < Ca²⁺ in 3D EK. The first three cycles for AC-HAP had taken roughly 50% of the reusability percentage. Sr²⁺ removal from spiked samples in 3D EK was achieved by acid dissolution, electromigration, and selective uptake on particle electrode.

The Role of Electrospun Nanomaterials in the Future of Energy and Environment

Electrospinning is one of the most successful and efficient techniques for the fabrication of one-dimensional nanofibrous materials as they have widely been utilized in multiple application fields due to their intrinsic properties like high porosity, large surface area, good connectivity, wettability, and ease of fabrication from various materials. Together with current trends on energy conservation and environment remediation, a number of researchers have focused on the applications of nanofibers and their composites in this field as they have achieved some key results along the way with multiple materials and designs. In this review, recent advances on the application of nanofibers in the areas-including energy conversion, energy storage, and environmental aspects-are summarized with an outlook on their materials and structural designs. Also, this will provide a detailed overview on the future directions of demanding energy and environment fields.

Removal of strontium by in situ electrochemical synthesis of Zn–Al LDHs using a bidirectional pulse method

The Sr2+ removal rate is 99.26%, and the energy consumption of the reaction process is 5.01 kW h m−3.

Natural and anthropogenic radionuclides in water and wastewater: Sources, treatments and recoveries

Water-energy nexus in the context of changing climate amplifies the importance of comprehending the transport, fate and recovery of radioisotope. While countries have been more interested for zero/low greenhouse gas emission technologies, energy production from nuclear power plant (NPP) can be a prominent solution. Moreover, radioisotopes are also used for other benefits such as in medical science, industrial activities and many more. These radionuclides are blended accidently or intentionally with water or wastewater because of inefficacious management of the nuclear waste; and therefore, it is an imperative task to manage nuclear waste so that the harmful consequences of the waste on environment, ecology and human health can be dispelled. Due to generation of significant amount of waste throughout its utilization, a noticeable number of physical, chemical and biological processes has been introduced as remediation processes although mechanisms of optimum removal process are still under investigation. Removal mechanisms and influencing factors for radionuclide removal are elucidated in this review so that, further, operation and process development can be promoted. Again, resource recovery, opportunities and challenges are also discussed for elevating the removal rates and minimizing the knowledge gaps existing in development and applications of novel decontamination processes.

Membrane processes

This literature review provides a review for publications in 2018 and 2019 and includes information membrane processes findings for municipal and industrial applications. This review is a subsection of the annual Water Environment Federation literature review for Treatment Systems section. The following topics are covered in this literature review: industrial wastewater and membrane. Bioreactor (MBR) configuration, membrane fouling, design, reuse, nutrient removal, operation, anaerobic membrane systems, microconstituents removal, membrane technology advances, and modeling. Other sub-sections of the Treatment Systems section that might relate to this literature review include the following: Biological Fixed-Film Systems, Activated Sludge, and Other Aerobic Suspended Culture Processes, Anaerobic Processes, and Water Reclamation and Reuse. This publication might also have related information on membrane processes: Industrial Wastes, Hazardous Wastes, and Fate and Effects of Pollutants.

Development of ZSM-22/Polyethersulfone Membrane for Effective Salt Rejection

ZSM-22/polyethersulfone membranes were prepared for salt rejection using modelled brackish water. The membranes were fabricated via direct ZSM-22 incorporation into a polymer matrix, thereby inducing the water permeability, hydrophilicity and fouling resistance of the pristine polyethersulfone (PES) membrane. A ZSM-22 zeolite material with a 60 Si/Al ratio, high crystallinity and needle-like morphologies was produced and effectively used as a nanoadditive in the development of ZSM-22/PES membranes with nominal loadings of 0–0.75 wt.%. The characterisation and membrane performance evaluation of the resulting materials with XRD, BET, FTIR, TEM, SEM and contact angle as well as dead-end cell, respectively, showed improved water permeability in comparison with the pristine PES membrane. These ZSM-22/PES membranes were found to be more effective and superior in the processing of modelled brackish water. The salt rejection of the prepared membranes for NaCl and MgCl₂ was effective, while they exhibited quite improved water flux and flux recovery ratios in the membrane permeability and anti-fouling test. This indicates that different amounts of ZSM-22 nanoadditives produce widely divergent influences on the performance of the pristine PES membrane. As such, over 55% of salt rejection is observed, which means that the obtained membranes are effective in salt removal from water.

Organic Fouling in Forward Osmosis: A Comprehensive Review

Organic fouling in the forward osmosis process is complex and influenced by different parameters in the forward osmosis such as type of feed and draw solution, operating conditions, and type of membrane. In this article, we reviewed organic fouling in the forward osmosis by focusing on wastewater treatment applications. Model organic foulants used in the forward osmosis literature were highlighted, which were followed by the characteristics of organic foulants when real wastewater was used as feed solution. The various physical and chemical cleaning protocols for the organic fouled membrane are also discussed. The study also highlighted the effective pre-treatment strategies that are effective in reducing the impact of organic fouling on the forward osmosis (FO) membrane. The efficiency of cleaning methods for the removal of organic fouling in the FO process was investigated, including recommendations on future cleaning technologies such as Ultraviolet and Ultrasound. Generally, a combination of physical and chemical cleaning is the best for restoring the water flux in the FO process.

Physical, chemical, and biological impact (hazard) of hospital wastewater on environment: presence of pharmaceuticals, pathogens, and antibiotic-resistance genes

Hospital wastewater contains various pharmaceuticals and pathogens. Improper management of the wastewater has caused the leakage of these harmful materials to the environment. The presence of pathogens, pharmaceuticals, and their derivatives such as antibiotic resistance genes as the most typical one in the environment leads to physical, chemical, and biological harmful impact. This chapter has reviewed the pharmaceuticals and pathogens in the hospital; discussed the development of antibiotic resistance genes; and revealed the possible impact of these harmful materials in microorganisms, organism, and human being. In addition, the measures that can be taken to prevent the transportation of pharmaceuticals and pathogens into environment have been stated in this chapter.

Recent Progresses of Forward Osmosis Membranes Formulation and Design for Wastewater Treatment

Production of potable water or reclaimed water with higher quality are in demand to address water scarcity issues as well as to meet the expectation of stringent water quality standards. Forward osmosis (FO) provides a highly promising platform for energy-efficient membrane-based separation technology. This emerging technology has been recognized as a potential and cost-competitive alternative for many conventional wastewater treatment technologies. Motivated by its advantages over existing wastewater treatment technologies, the interest of applying FO technology for wastewater treatment has increased significantly in recent years. This article focuses on the recent developments and innovations in FO for wastewater treatment. An overview of the potential of FO in various wastewater treatment application will be first presented. The contemporary strategies used in membrane designs and fabrications as well as the efforts made to address membrane fouling are comprehensively reviewed. Finally, the challenges and future outlook of FO for wastewater treatment are highlighted.

Synthesis of core-shell magnetic titanate nanofibers composite for the efficient removal of Sr(ii)

We report a facile approach for the fabrication of Fe₃O₄@titanate fibers magnetic composite through a hydrothermal method and sol-gel process. The structure and morphology were characterized by X-ray diffraction (XRD), transmission electron microsphere (TEM), scanning electron microscope (SEM) and energy-dispersive X-ray analysis (EDX). Owing to the high ion exchange capacity of the functional titanate layer, the obtained core-shell structured magnetic microspheres exhibited high removal efficiency towards strontium from wastewater. The effects of contact time and Sr(ii) concentration on the uptake amount of strontium were systematically investigated. The results indicated that the adsorption equilibrium can be reached within 30 min, and the maximum exchange capacity was approximately 37.1 mg g^-1. Moreover, the captured Sr(ii) can be eluted using 5 wt% of EDTA(Na), which contributed to the reduction of waste volume. Based on the experimental results of ion exchange process and X-ray photoelectron spectroscopy (XPS), a possible adsorption mechanism was proposed. This work provided a facile approach to synthesize magnetic functional nanocomposites for wastewater treatment.

Fabrication of stable superabsorbent hydrogels for successful removal of crystal violet from waste water

Smart superabsorbent hydrogels consisting of acrylamide/sodium alginate (AS), acrylamide/sodium alginate/2-acrylamido-2-methylpropane sulphonic acid (ASA_x, x = amount of AMPS) were synthesized via free radical polymerization. The swelling behavior of the hydrogels was studied in distilled and tap water. It was found that by increasing the amount of 2-acrylamido-2-methylpropanesulphonic (AMPS) in the hydrogel composition, the hydrogel swelling capability was enhanced from 3685% for AS to 4797% for ASA₁ and 21 175% for ASA₂ in distilled water, while in tap water this property varied from 915% for AS to 988% and 1588% for ASA₁ and ASA₂, respectively. All the samples were found to be efficient for the removal of crystal violet from aqueous solution. The absorption efficiency and % removal increased from 1.78 mg g⁻¹ and 62.6% for AS to 3.31 mg g⁻¹ and 75% for ASA₁ and 3.34 mg g⁻¹ and 82.1% for ASA₂. The effects of pH, contact time, initial dye concentration and hydrogel dosage on the removal process were studied in detail. The mechanism of CV removal occurs according to the Freundlich isotherm following pseudo second order kinetics. The thermodynamic parameters showed that the sorption process is spontaneous and endothermic in nature. The superabsorbent hydrogels were regenerated and reused in six consecutive cycles with 5% decrease in efficiency.

Smart superabsorbent hydrogels consisting of acrylamide/sodium alginate (AS), acrylamide/sodium alginate/2-acrylamido-2-methylpropane sulphonic acid (ASA_x, x = amount of AMPS) were synthesized via free radical polymerization.

A recyclable hydroxyl functionalized polyindole hydrogel for sodium hydroxide extraction via the synergistic effect of cation–π interactions and hydrogen bonding

We have successfully constructed a new type of recyclable indole-based hydrogel, which exhibited highly effective extraction behavior for hydroxide via the synergistic effect of cation–π interactions and hydrogen bonds.