Occurrences and removal of pharmaceutical and personal care products from aquatic systems using advanced treatment- A review

Recent progress in electro-Fenton technology for the remediation of pharmaceutical compounds in aqueous environments

The global focus on wastewater treatment has intensified in the contemporary era due to its significant environmental and human health impacts. Pharmaceutical compounds (PCs) have become an emerging concern among various pollutants, as they resist conventional treatment methods and pose a severe environmental threat. Advanced oxidation processes (AOPs) emerge as a potent and environmentally benign approach for treating recalcitrant pharmaceuticals. To address the shortcomings of traditional treatment methods, a technology known as the electro-Fenton (EF) method has been developed more recently as an electrochemical advanced oxidation process (EAOP) that connects electrochemistry to the chemical Fenton process. It has shown effective in treating a variety of pharmaceutically active compounds and actual wastewaters. By producing H2O2 in situ through a two-electron reduction of dissolved O2 on an appropriate cathode, the EF process maximizes the benefits of electrochemistry. Herein, we have critically reviewed the application of the EF process, encompassing diverse reactor types and configurations, the underlying mechanisms involved in the degradation of pharmaceuticals and other emerging contaminants (ECs), and the impact of electrode materials on the process. The review also addresses the factors influencing the efficiency of the EF process, such as (i) pH, (ii) current density, (iii) H2O2 concentration, (iv) and others, while providing insight into the scalability potential of EF technology and its commercialization on a global scale. The review delves into future perspectives and implications concerning the ongoing challenges encountered in the operation of the electro-Fenton process for the treatment of PCs and other ECs.

Enhanced removal of PPCPs and antibiotic resistance genes in saline wastewater using a bioelectrochemical-constructed wetland system

Pharmaceuticals and personal care products (PPCPs) are insufficiently degraded in saline wastewater treatment processes and are found at high concentrations and detection frequencies in aquatic environments. In this study, the wetland plant Thalia dealbata was selected using a screening plant experiment to ensure good salt tolerance and high efficiency in removing PPCPs. An electric integrated vertical-flow constructed wetland (E-VFCW) was developed to improve the removal of PPCPs and reduce the abundance of antibiotic resistance genes (ARGs). The removal efficiency of ofloxacin, enrofloxacin, and diclofenac in the system with anaerobic cathodic and aerobic anodic chambers is higher than that of the control system (41.84±2.88%, 47.29±3.01%, 53.29±2.54%) by approximately 20.31%, 16.04%, and 35.25%. The removal efficiency of ibuprofen in the system with the aerobic anodic and anaerobic cathodic chamber was 28.51% higher than that of the control system (72.41±3.06%) and promotes the reduction of ARGs. Electrical stimulation can increase the activity of plant enzymes, increasing their adaptability to stress caused by PPCPs, and PPCPs are transferred to plants. Species related to PPCPs biodegradation (Geobacter, Lactococcus, Hydrogenophaga, and Nitrospira) were enriched in the anodic and cathodic chambers of the system. This study provides an essential reference for the removal of PPCPs in saline-constructed wetlands.

Toxicity of water-soluble polymers polyethylene glycol and polyvinyl alcohol for fish and frog embryos

Personal Care Products (PCPs) have been one of the most studied chemicals in the last twenty years since they were identified as pseudo-persistent pollutants by the European Union in the early 2000s. The accumulation of PCPs in the aquatic environment and their effects on non-target species make it necessary to find new, less harmful, substances. Polyethylene glycol (PEGs) and polyvinyl alcohol (PVAs) are two polymers that have increased their presence in the composition of PCPs in recent years, but little is known about the effect of their accumulation in the environment on non-target species. Through embryotoxicity tests on two common models of aquatic organisms (Danio rerio and Xenopus laevis), this work aims to increase the knowledge of PEGs and PVAs' effects on non-target species. Animals were exposed to the pollutant for 96 h. The main embryotoxicity endpoint (mortality, hatching, malformations, heartbeat rate) was recorded every 24 h. The most significant results were hatching delay in Danio rerio exposed to both chemicals, in malformations (oedema, body malformations, changes in pigmentation and deformations of spine and tail) in D. rerio and X. laevis and significant change in the heartbeat rate (decrease or increase in the rate) in both animals for all chemicals tested.

Remediation of pharmacophoric laboratory waste by using biodegradable carbon nanoparticles of bacterial biofilm origin

Research laboratories generate a broad range of hazardous pharmacophoric chemical contaminants, from drugs to dyes used during various experimental procedures. In the recent past, biological methods have demonstrated great potential in the remediation of such contaminants. However, the presence of pharmacophoric chemicals containing antibiotics, xenobiotics, and heavy metals suppresses the growth and survivability of used microbial agents, thus decreasing the overall efficiency of biological remediation processes. Bacterial biofilm is a natural arrangement to counter some of these inhibitions but its use in a systemic manner, portable devices, and pollutant remediation plants post serious challenges. This could be countered by synthesizing a biodegradable carbon nanoparticle from bacterial biofilm. In this study, extracellular polymeric substance-based carbon nanoparticles (Bio-EPS-CNPs) were synthesized from bacterial biofilm derived from Bacillus subtilis NCIB 3610, as a model bacterial system. The produced Bio-EPS-CNPs were investigated for physiochemical properties by dynamic light scattering, optical, Fourier-transformed infrared, and Raman spectroscopy techniques, whereas X-ray diffraction study, scanning electron microscopy, and transmission electron microscopy were used to investigate structural and morphological features. The Bio-EPS-CNPs exhibited negative surface charge with spherical morphology having a uniform size of sub-100 nm. The maximum remediation of some laboratory-produced pharmacophoric chemicals was achieved through a five-round scavenging process and confirmed by UV/Vis spectroscopic analysis with respect to the used pharmacophore. This bioinspired remediation of used pharmacophoric chemicals was achieved through the mechanism of surface adsorption via hydrogen bonding and electrostatic interactions, as revealed by different characterizations. Further experiments were performed to investigate the effects of pH, temperature, stirring, and the protocol of scavenging to establish Bio-EPS-CNP as a possible alternative to be used in research laboratories for efficient removal of pharmacophoric chemicals by incorporating it in a portable, filter-based device.

Mechanism of self-supporting montmorillonite composite material for bio-enhanced degradation of chlorotetracycline: Electron transfer and microbial response

The efficient degradation of antibiotics holds significant implications for mitigating environmental pollution. This study synthesized a montmorillonite chitosan composite material (MMT-CS) using the gel template method. Subsequently, a bio-enhanced reactor was constructed to facilitate the degradation of chlorotetracycline (CTC). The addition of MMT-CS composite material enables the degradation of different concentrations of CTC. MMT-CS, a conductive carrier, effectively promotes microbial adhesion and boosts the metabolic activity of functional microorganisms. Additionally, it facilitates the maintenance of microbial activity under CTC pressure by promoting the secretion of extracellular polymeric substances, increasing critical enzyme activity, and enhancing the electron transfer capacity within the system. In this MMT-CS bio-enhanced process, Paracoccus (11.4%) and Bacillus (3.9%) are utilized as essential bacteria genes. The results of metabolic pathways prediction indicated significant enhancements in membrane-transport, nucleotide-metabolism, replication-repair, and lipid-metabolism. Thus, the developed self-supporting MMT-CS bio-enhanced process ensured the stability of the system during the removal of antibiotics.

Occurrence, distribution, and ecological risk assessment of pharmaceuticals and personal care products in the surface water of Lipu River, China

Pharmaceuticals and Personal Care Products (PPCPs) are inadvertently released into the aquatic environment, causing detrimental effects on aquatic ecosystem. There is an urgent need of an in-deep investigation on contamination information of PPCPs in aquatic environment as well as the ecological risks to the aquatic ecosystem. This study was carried out in Lipu River basin, China, to investigate the distribution pattern and ecological risks of PPCPs. Results showed that PPCPs pollution is ubiquitous, 29 out of 30 targeted PPCPs were detected in Lipu River. Fourteen PPCPs were detected with a frequency of 100% in all water samples, and ten PPCPs were detected with a frequency of more than 80%. The cumulated PPCPs concentrations ranged from 33.30 ng/L to 99.60 ng/L, with a median value of 47.20 ng/L in Lipu River. Caffeine, flumequine, nifedipine, and lomefloxacin were the predominant PPCPs in study area. Caffeine showed high ecological risk, five and seven individual PPCP showed medium and low ecological risk to algae.

Influence of vegetation and substrate type on removal of emerging organic contaminants and microbial dynamics in horizontal subsurface constructed wetlands

Constructed wetlands (CWs) offer an efficient alternative technology for removing emerging organic contaminants (EOCs) from wastewater. Optimizing CW performance requires understanding the impact of CW configuration on EOC removal and microbial community dynamics. This study investigated EOC removal and microbial communities in horizontal subsurface flow (HSSF) CWs over a 26-month operational period. Comparison between tuff-filled and gravel-filled CWs highlighted the superior EOC removal in tuff-filled CWs during extended operation, likely caused by the larger surface area of the tuff substrate fostering microbial growth, sorption, and biodegradation. Removal of partially positively charged EOCs, like atenolol (29-98 %) and fexofenadine (21-87 %), remained constant in the different CWs, and was mainly attributed to sorption. In contrast, removal rates for polar non-sorbing compounds, including diclofenac (3-64 %), acyclovir (9-85 %), and artificial sweeteners acesulfame (5-60 %) and saccharin (1-48 %), seemed to increase over time due to enhanced biodegradation. The presence of vegetation and different planting methods (single vs. mixed plantation) had a limited impact, underscoring the dominance of substrate type in the CW performance. Microbial community analysis identified two stages: a startup phase (1-7 months) and a maturation phase (19-26 months). During this transition, highly diverse communities dominated by specific species in the early stages gave way to more evenly distributed and relatively stable communities. Proteobacteria and Bacteroidetes remained dominant throughout. Alphaproteobacteria, Acidobacteria, Planctomycetes, Salinimicrobium, and Sphingomonas were enriched during the maturation phase, potentially serving as bioindicators for EOC removal. In conclusion, this study emphasizes the pivotal role of substrate type and maturation in the removal of EOCs in HSSF CW, considering the complex interplay with EOC physicochemical properties. Insights into microbial community dynamics underscore the importance of taxonomic and functional diversity in assessing CW effectiveness. This knowledge aids in optimizing HSSF CWs for sustainable wastewater treatment, EOC removal, and ecological risk assessment, ultimately contributing to environmental protection.

Machine learning-based exploration of biochar for environmental management and remediation

Biochar has a wide range of applications, including environmental management, such as preventing soil and water pollution, removing heavy metals from water sources, and reducing air pollution. However, there are several challenges associated with the usage of biochar for these purposes, resulting in an abundance of experimental data in the literature. Accordingly, the purpose of this study is to examine the use of machine learning in biochar processes with an eye toward the potential of biochar in environmental remediation. First, recent developments in biochar utilization for the environment are summarized. Then, a bibliometric analysis is carried out to illustrate the major trends (demonstrating that the top three keywords are heavy metal, wastewater, and adsorption) and construct a comprehensive perspective for future studies. This is followed by a detailed review of machine learning applications, which reveals that adsorption efficiency and capacity are the primary utilization targets in biochar utilization. Finally, a comprehensive perspective is provided for the future. It is then concluded that machine learning can help to detect hidden patterns and make accurate predictions for determining the combination of variables that results in the desired properties which can be later used for decision-making, resource allocation, and environmental management.

Synthesis of recyclable and light-weight graphene oxide/chitosan/genipin sponges for the adsorption of diclofenac, triclosan, and microplastics

Emerging micropollutants, such as pharmaceuticals and microplastics (MPs), have become a pressing water environmental concern. The aim of this study is to synthesize chitosan sponges using graphene oxide (GO) and genipin (GP) for the removal of pharmaceuticals (diclofenac (DCF) and triclosan (TCS)) and MPs, verify their adsorption mechanisms, evaluate the effects of temperature, pH, and salinity on their adsorption capacities, and determine their reusability. The GO5/CS/GP sponge exhibited a macroporous nature (porosity = 95%, density = 32.6 mg/cm3). GO and cross-linker GP enhanced the adsorption of DCF, TCS, and polystyrene (PS) MPs onto the CS sponges. The adsorption of DCF, TCS, and PS MPs involved multiple steps: surface diffusion and pore diffusion of the sponge. The adsorption isotherms demonstrated that Langmuir model was the most fitted well model to explain adsorption of TCS (qm = 7.08 mg/g) and PS MPs (qm = 7.42 mg/g) on GO5/CS/GP sponge, while Freundlich model suited for DCF adsorption (qm = 48.58 mg/g). DCF adsorption was thermodynamically spontaneous and endothermic; however, the adsorption of TCS and PS MPs was exothermic (283-313 K). The optimal pH was 5.5-7 due to the surface charge of the GO5/CS/GP sponge (pHzpc = 5.76) and ionization of DCF, TCS, and PS MPs. As the salinity increased, DCF removal efficiency drastically decreased due to the weakening of electrostatic interactions; however, TCS removal efficiency remained stable because TCS adsorption was mainly caused by hydrophobic and π-π interactions rather than electrostatic interaction. The removal of PS MPs was enhanced by the electrostatic screening effects of high Na+ ions. PS nanoplastics (average size = 26 nm) were removed by the GO5/CS/GP sponge at a rate of 73.0%, which was better than that of PS MPs (41.5%). In addition, the GO5/CS/GP sponge could be recycled over five adsorption-desorption cycles.

Current strategies on bioremediation of personal care products and detergents: Sustainability and life cycle assessment

The increased use of personal care products and detergents in modern society has raised concerns about their potential adverse effects on the environment. These products contain various chemical compounds that can persist in water bodies, leading to water pollution and ecological disturbances. Bioremediation has emerged as a promising approach to address these challenges, utilizing the natural capabilities of microorganisms to degrade or remove these contaminants. This review examines the current strategies employed in the bioremediation of personal care products and detergents, with a specific focus on their sustainability and environmental impact. This bioremediation is essential for environmental rejuvenation, as it uses living organisms to detergents and other daily used products. Its distinctiveness stems from sustainable, nature-centric ways that provide eco-friendly solutions for pollution eradication and nurturing a healthy planet, all while avoiding copying. Explores the use of microbial consortia, enzyme-based treatments, and novel biotechnological approaches in the context of environmental remediation. Additionally, the ecological implications and long-term sustainability of these strategies are assessed. Understanding the strengths and limitations of these bioremediation techniques is essential for developing effective and environmentally friendly solutions to mitigate the impact of personal care products and detergents on ecosystems.

Occurrence and fate of pharmaceutical pollutants in wastewater: Insights on ecotoxicity, health risk, and state-of-the-art removal

Pharmaceutical active compound (PhAC) residues are considered an emerging micropollutant that enters the aquatic environment and causes harmful ecotoxicity. The significant sources of PhACs in the environment include the pharmaceutical industry, hospital streams, and agricultural wastes (animal husbandry). Recent investigations demonstrated that wastewater treatment plants (WWTPs) are an important source of PhACs discharging ecosystems. Several commonly reported that PhACs are detected in a range level from ng L-1 to μg L-1 concentration in WWTP effluents. These compounds can have acute and chronic adverse impacts on natural wildlife, including flora and fauna. The approaches for PhAC removals in WWTPs include bioremediation, adsorption (e.g., biochar, chitosan, and graphene), and advanced oxidation processes (AOPs). Overall, adsorption and AOPs can effectively remove PhACs from wastewater aided by oxidizing radicals. Heterogeneous photocatalysis has also proved to be a sustainable solution. Bioremediation approaches such as membrane bioreactors (MBRs), constructed wetlands (CWs), and microalgal-based systems were applied to minimize pharmaceutical pollution. Noteworthy, applying MBRs has illustrated high removal efficiencies of up to 99%, promising prospective future. However, WWTPs should be combined with advanced solutions, e.g., AOPs/photodegradation, microalgae-bacteria consortia, etc., to treat and minimize their accumulation. More effective and novel technologies (e.g., new generation bioremediation) for PhAC degradation must be investigated and specially designed for a low-cost and full-scale. Investigating green and eco-friendly PhACs with advantages, e.g., low persistence, no bioaccumulation, less or non-toxicity, and environmentally friendly, is also necessary.

Endocrine disrupting chemicals in Italian drinking water systems: Insights from a three-year investigation combining chemical and effect-based tools

Drinking water quality can be compromised by endocrine-disrupting chemicals (EDCs). Three phenolic compounds [bisphenol A (BPA), nonylphenol (NP), and 4-octylphenol (OP)] and three hormones [17β-estradiol (E2), estrone (E1), and 17α-ethinylestradiol (EE2)] were analyzed as EDCs potentially occurring in source and drinking water from three full-scale drinking water treatment plants (DWTPs) in the Romagna area (Italy) by a combined approach of HPLC-MS/MS target analysis and effect-based tests for estrogenicity and genotoxicity. The EDC removal efficiency was evaluated at different steps along the treatment process in the most advanced DWTP. NP prevailed in all samples, followed by BPA. Sporadic contamination by OP and E1/E2 appeared only in the source waters; EE2 was never detected. No estrogenic or genotoxic activity was found, except for two samples showing estrogenicity well below the effect-based trigger value suggested for drinking water safety (0.9 ng/L EEQ). BPA and NP levels were largely below the threshold value; however, increases were observed after the intermediate steps of the treatment chain. The good quality of the water relied on the last step, i.e. the activated carbon filtration. DWTPs may represent an extra source of EDCs and monitoring chemical occurrence at all steps of the process is advisable to improve efficiency.

Mobility of antipyretic drugs with different molecular structures in saturated soil porous media

In the post-COVID-19 era, extensive quantities of antipyretic drugs are being haphazardly released from households into the environment, which may pose potential risks to ecological systems and human health. Identification of the mobility behaviors of these compounds in the subsurface environment is crucial to understand the environmental fate of these common contaminants. The mobility properties of three broad-spectrum antipyretic drugs, including ibuprofen (IBF), indometacin (IMC), and acetaminophen (APAP), in porous soil media, were investigated in this study. The results showed that the mobility of the three drugs (the background electrolyte was Na+) through the soil column followed the order of APAP > IBF > IMC. The difference in the physicochemical characteristics of various antipyretic drugs (e.g., the molecular structure and hydrophobicity) could explain this trend. Unlike Na+, Ca2+ ions tended to serve as bridging agents by linking the soil grains and antipyretic molecules, leading to the relatively weak mobility behaviors of antipyretic drugs. Furthermore, for a given antipyretic drug, the antipyretic mobility was promoted when the background solution pH values were raised from 5.0 to 9.0. The phenomenon stemmed from the improved electrostatic repulsion between the dissociated species of antipyretic molecules and soil grains, as well as the weakened hydrophobic interactions between antipyretic drugs and soil organic matter. Furthermore, a two-site non-equilibrium transport model was used to estimate the mobility of antipyretic drugs. The results obtained from this work provide vital information illustrating the transport and retention of various antipyretic drugs in aquifers.

Advances in photocatalytic degradation of organic pollutants in wastewaters: harnessing the power of phthalocyanines and phthalocyanine-containing materials

Access to clean water is increasingly challenging worldwide due to human activities and climate change. Wastewater treatment and utilization offer a promising solution by reducing the reliance on pure underground water. However, it is crucial to develop efficient and sustainable methods for wastewater purification. Among the emerging wastewater treatment strategies, photocatalysis has gained significant attention for decomposing organic pollutants in water, especially when combined with sunlight and a recoverable photocatalyst. Heterogeneous photocatalysts have distinct advantages, as they can be recovered and reused without significant loss of activity over multiple cycles. Phthalocyanine dyes, with their exceptional photophysical properties, are particularly valuable for homogeneous and heterogeneous photocatalysis. By immobilizing these photosensitizers in various supports, hybrid materials extend their light absorption into the visible spectrum, complementing most supports' limited UV light absorption. The novelty and research importance of this review stems from its discussion of the multifaceted approach to treating contaminated wastewater with phthalocyanines and materials containing phthalocyanines. It highlights key aspects of each study, including photocatalytic efficiency, recyclability characteristics, investigation of the generation of oxygen species responsible for degradation, identification of the major degradation byproducts for each pollutant, and others. Moreover, the review includes tables that illustrate and compare the various phthalocyanines and supporting materials employed in each study for pollutant degradation. Additionally, almost all photocatalysts mentioned in this review could degrade at least 5% of the pollutant, and more than 50 photocatalysts showed photocatalytic rates above 50%. When immobilized in some support, the synergistic effect of the phthalocyanine was visible in the photocatalytic rate of the studied pollutant. However, when performing these types of works, it is necessary to understand the degradation products of each pollutant and their relative toxicities. Along with this, recyclability and stability studies are also necessary. Despite the good results presented in this review, some of the works lack those studies. Moreover, none of the works mentions any study in wastewater.

Hydroxylamine enhanced the degradation of diclofenac in Cu(II)/peracetic acid system: Formation and contributions of CH3C(O)O•, CH3C(O)OO•, Cu(III) and •OH

The slow reduction of Cu(II) into Cu(I) through peracetic acid (PAA) heavily limited the widespread application of Cu(II)/PAA system. Herein, hydroxylamine (HA) was proposed to boost the oxidative capacity of Cu(II)/PAA system by facilitating the redox cycle of Cu(I)/Cu(II). HA/Cu(II)/PAA system was quite rapid in the removal of diclofenac within a broad pH range of 4.5-9.5, with a 10-fold increase in the removal rate of diclofenac compared with the Cu(II)/PAA system at an optimal initial pH of 8.5. Results of UV-Vis spectra, electron paramagnetic resonance, and alcohol quenching experiments demonstrated that CH3C(O)O•, CH3C(O)OO•, Cu(III), and •OH were involved in HA/Cu(II)/PAA system, while CH3C(O)OO• was verified as the predominant reactive species of diclofenac elimination. Different from previously reported Cu-catalyzed PAA processes, CH3C(O)OO• mainly generated from the reaction of PAA with Cu(III) rather than CH3C(O)O• and •OH. Four possible elimination pathways for diclofenac were proposed, and the acute toxicity of treated diclofenac solution with HA/Cu(II)/PAA system significantly decreased. Moreover, HA/Cu(II)/PAA system possessed a strong anti-interference ability towards the commonly existent water matrix. This research proposed an effective strategy to boost the oxidative capacity of Cu(II)/PAA system and might promote its potential application, especially in copper-contained wastewater.

Helping WWTP managers to address the volatile methylsiloxanes issue-Behaviour and complete mass balance in a conventional plant

Volatile methylsiloxanes (VMSs) are a group of additives employed in different consumer products that can affect the quality of the biogas produced in wastewater treatment plants (WWTPs). The main objective of this study is to understand the fate of different VMSs along the treatment process of a WWTP located in Aveiro (Portugal). Thus, wastewater, sludge, biogas, and air were sampled in different units for two weeks. Subsequently, these samples were extracted and analyzed by different environment-friendly protocols to obtain their VMS (L3-L5, D3-D6) concentrations and profiles. Finally, considering the different matrix flows at every sampling moment, the mass distribution of VMSs within the plant was estimated. The levels of ∑VMSs were similar to those showed in the literature (0.1-50 μg/L in entry wastewater and 1-100 μg/g dw in primary sludge). However, the entry wastewater profile showed higher variability in D3 concentrations (from non detected to 49 μg/L) than found in previous studies (0.10-1.00 μg/L), likely caused by isolated releases of this compound that could be related to industrial sources. Outdoor air samples showed a prevalence of D5, while indoor air locations were characterized by a predominance of D3 and D4. Differences in sources and the presence of an indoor air filtration system may explain this divergence. Biogas was characterized by ∑VMSs concentrations (8.00 ± 0.22 mg/m3) above the limits recommended by some engine manufacturers and mainly composed of D5 (89%). Overall, 81% of the total incoming mass of VMSs is reduced along the WWTP, being the primary decanter and the secondary treatment responsible for the highest decrease (30.6% and 29.4% of the initial mass, respectively). This reduction, however, is congener dependant. The present study demonstrates the importance of extending sampling periods and matrices (i.e., sludge and air) to improve sample representativity, time-sensitivity, and the accuracy of mass balance exercises.

Advances in Surface-Enhanced Raman Scattering Sensors of Pollutants in Water Treatment

Water scarcity is a world issue, and a solution to address it is the use of treated wastewater. Indeed, in these wastewaters, pollutants such as pharmaceuticals, pesticides, herbicides, and heavy ions can be present at high concentrations. Thus, several analytical techniques were initiated throughout recent years for the detection and quantification of pollutants in different types of water. Among them, the surface-enhanced Raman scattering (SERS) technique was examined due to its high sensitivity and its ability to provide details on the molecular structure. Herein, we summarize the most recent advances (2021-2023) on SERS sensors of pollutants in water treatment. In this context, we present the results obtained with the SERS sensors in terms of detection limits serving as assessment of SERS performances of these sensors for the detection of various pollutants.

Recent advancements on antibiotic bioremediation in wastewaters with a focus on algae: an overview

Antibiotic contamination from hospitals, animal husbandry, and municipal wastewater is graver than imagined, and it possess serious risks to the health of humans and animals, with the emergence of multidrug resistant bacteria; those affect the growth of higher plants too. Conventional wastewater treatment methods adopted today are inadequate for removing antibiotics from wastewater. Intuitively, the remediation process using mixed algae should be effective enough, for which algae-based remediation technologies have emerged as sustainable remedial methods. This review summarized the detection of antibiotics in field water in most countries; a comprehensive overview of algae-based technologies, algal adsorption, accumulation, biodegradation, photodegradation, hydrolysis, and the use of algae-bacteria consortia for the remediation of antibiotics in wastewaters in done. Green algae namely, Chlamydomonas sp., Chlorella sp., C. vulgaris, Spyrogira sp. Scenedesmus quadricauda, S. obliquus, S. dimorphus, Haematoccus pluvialis, and Nannochlopsis sp., had been reporting have 90-100% antibiotic removal efficiency. The integration of bioelectrochemical systems and genetically engineered prokaryotic algal species offer promising avenues for improving antibiotic removal in the future. Overall, this review highlights the need for tenacious research and development of algae-based technologies to reduce antibiotic contamination in aquatic environments, for holistic good.

Catalytic Activity of Rare Earth Elements (REEs) in Advanced Oxidation Processes of Wastewater Pollutants: A Review

In recent years, sewage treatment plants did not effectively remove emerging water pollutants, leaving potential threats to human health and the environment. Advanced oxidation processes (AOPs) have emerged as a promising technology for the treatment of contaminated wastewater, and the addition of catalysts such as heavy metals has been shown to enhance their effectiveness. This review focuses on the use of rare earth elements (REEs) as catalysts in the AOP process for the degradation of organic pollutants. Cerium and La are the most studied REEs, and their mechanism of action is based on the oxygen vacancies and REE ion concentration in the catalysts. Metal oxide surfaces improve the decomposition of hydrogen peroxide to form hydroxide species, which degrade the organics. The review discusses the targets of AOPs, including pharmaceuticals, dyes, and other molecules such as alkaloids, herbicides, and phenols. The current state-of-the-art advances of REEs-based AOPs, including Fenton-like oxidation and photocatalytic oxidation, are also discussed, with an emphasis on their catalytic performance and mechanism. Additionally, factors affecting water chemistry, such as pH, temperature, dissolved oxygen, inorganic species, and natural organic matter, are analyzed. REEs have great potential for enhancing the removal of dangerous organics from aqueous solutions, and further research is needed to explore the photoFenton-like activity of REEs and their ideal implementation for wastewater treatment.

Dynamically driven perovskite La-Fe-modified SrTiO3 nanocubes and their improved photoresponsive activity under visible light: influence of alkaline environment

Visible-light active La-Fe-SrTiO3 (La0.01Sr0.99Fe0.01Ti0.99O3) photocatalysts were synthesized via a dynamic hydrothermal route under different NaOH concentrations (2, 3, 4, 5, and 6 M). The results showed that altering NaOH concentrations changed the physicochemical characteristics of the materials. Namely, the decrease in particle size was observed when the NaOH levels were increased. The specific surface area of the photocatalysts changed with an increased concentration of NaOH, and the maximum value was 17.10 m2/g in 5 M of NaOH. The crystal structure of all prepared samples remained unaffected when altered the NaOH concentration or when incorporated La and Fe in the lattice of SrTiO3. Namely, all samples synthesized under various NaOH concentrations crystallized and maintained in the standard cubic perovskite structure of SrTiO3. The increased NaOH concentration slightly altered the absorption wavelength towards a longer wavelength region. The La atom, replacing some Sr2+ in the structure of modified SrTiO3, was confirmed to be in the La3+ valence state. Simultaneously, Fe atoms demonstrating oxidation states of Fe3+ can also be incorporated into the SrTiO3 network. The photocatalytic degradation of ciprofloxacin antibiotic revealed that the highest performance was approximately 75% within 9 h over the La0.01Sr0.99Fe0.01Ti0.99O3 sample prepared at 5 M of NaOH via the dynamic hydrothermal process. Meanwhile, this photocatalyst also displayed greater activity than the pristine SrTiO3, the single-doped samples (SrFe0.01Ti0.99O3 and La0.01Sr0.99TiO3), and the La0.01Sr0.99Fe0.01Ti0.99O3 sample prepared through a static hydrothermal technique under the same synthesis condition.

Sequestration of steroidal estrogen in aqueous samples using an adsorption mechanism: a systemic scientometric review

Steroidal estrogens (SEs) remain one of the notable endocrine disrupting chemicals (EDCs) that pose a significant threat to the aquatic environment in this era owing to their interference with the normal metabolic functions of the human body systems. They are currently identified as emerging contaminants of water sources. The sources of SEs are either natural or synthetic active ingredients in oral contraceptive and hormonal replacement therapy drugs and enter the environment primarily from excretes in the form of active free conjugate radicals, resulting in numerous effects on organisms in aquatic habitats and humans. The removal of SEs from water sources is of great importance because of their potential adverse effects on aquatic ecosystems and human health. Adsorption techniques have gained considerable attention as effective methods for the removal of these contaminants. A systemic review and bibliometric analysis of the application of adsorption for sequestration were carried out. Metadata for publications on SE removal utilizing adsorbents were obtained from the Web of Science (WoS) from January 1, 1990, to November 5, 2022 (107 documents) and Scopus databases from January 1, 1949, to November 5, 2022 (77 documents). In total, 137 documents (134 research and 4 review articles) were used to systematically map bibliometric indicators, such as the number of articles, most prolific countries, most productive scholars, and most cited articles, confirming this to be a growing research area. The use of different adsorbents, include activated carbon graphene-based materials, single and multi-walled carbon nanotubes, biochar, zeolite, and nanocomposites. The adsorption mechanism and factors affecting the removal efficiency, such as pH, temperature, initial concentration, contact time and adsorbent properties, were investigated in this review. This review discusses the advantages and limitations of different adsorbents, including their adsorption capacities, regenerative potential, and cost-effectiveness. Recent advances and innovations in adsorption technology, such as functionalized materials and hybrid systems, have also been highlighted. Overall, the bibliographic analysis provides a comprehensive overview of the adsorption technique for the removal of SEs from other sources, serving as a valuable resource for researchers and policymakers involved in the development of efficient and sustainable strategies to mitigate the effects of these emerging contaminants.

MXenes and MXene-based materials for removal of pharmaceutical compounds from wastewater: Critical review

The rapid increase in the global population and its ever-rising standards of living are imposing a huge burden on global resources. Apart from the rising energy needs, the demand for freshwater is correspondingly increasing. A population of around 3.8 billion people will face water scarcity by 2030, as per the reports of the World Water Council. This may be due to global climate change and the deficiency in the treatment of wastewater. Conventional wastewater treatment technologies fail to completely remove several emerging contaminants, especially those containing pharmaceutical compounds. Hence, leading to an increase in the concentration of harmful chemicals in the human food chain and the proliferation of several diseases. MXenes are transition metal carbide/nitride ceramics that primarily structure the leading 2D material group. MXenes act as novel nanomaterials for wastewater treatment due to their high surface area, excellent adsorption properties, and unique physicochemical properties, such as high electrical conductivity and hydrophilicity. MXenes are highly hydrophilic and covered with active functional groups (i.e., hydroxyl, oxygen, fluorine, etc.), which makes them efficient adsorbents for a wide range of species and promising candidates for environmental remediation and water treatment. This work concludes that the scaling up process of MXene-based materials for water treatment is currently of high cost. The up-to-date applications are still limited because MXenes are currently produced mainly in the laboratory with limited yield. It is recommended to direct research efforts towards lower synthesis cost procedures coupled with the use of more environmentally friendly materials to avoid secondary contamination.

Advancements in algal membrane bioreactors: Overcoming obstacles and harnessing potential for eliminating hazardous pollutants from wastewater

This paper offers a comprehensive analysis of algal-based membrane bioreactors (AMBRs) and their potential for removing hazardous and toxic contaminants from wastewater. Through an identification of contaminant types and sources, as well as an explanation of AMBR operating principles, this study sheds light on the promising capabilities of AMBRs in eliminating pollutants like nitrogen, phosphorus, and organic matter, while generating valuable biomass and energy. However, challenges and limitations, such as the need for process optimization and the risk of algal-bacterial imbalance, have been identified. To overcome these obstacles, strategies like mixed cultures and bioaugmentation techniques have been proposed. Furthermore, this study explores the wider applications of AMBRs beyond wastewater treatment, including the production of value-added products and the removal of emerging contaminants. The findings underscore the significance of factors such as appropriate algal-bacterial consortia selection, hydraulic and organic loading rate optimization, and environmental factor control for the success of AMBRs. A comprehensive understanding of these challenges and opportunities can pave the way for more efficient and effective wastewater treatment processes, which are crucial for safeguarding public health and the environment.

Novel ZIF-67-derived Co@CNTs nanocomposites as effective adsorbents for removal of tetracycline and sulfadiazine antibiotics

Tetracycline (TCC) and sulfadiazine (SDZ) are two of the most consumed antibiotics for human therapies and bacterial infection treatments in aquafarming fields, but their accumulative residues can result in negative effects on water and aquatic microorganisms. Removal techniques are therefore required to purify water before use. Herein, we concentrate on adsorptive removal of TCC and SDZ using cobalt@carbon nanotubes (Co@CNTs) derived from Co-ZIF-67. The presence of CNTs on the edge of nanocomposites was observed. Taguchi orthogonal array was designed with four variables including initial concentration (5-20 mg L^-1), dosage (0.05-0.2 g L^-1), time (60-240 min), and pH (2-10). Concentration and pH were found to be main contributors to adsorption of tetracycline and sulfadiazine, respectively. The optimum condition was found at concentration 5 mg L^-1, dosage 0.2 g L^-1, contact time 240 min, and pH 7 for both TCC and SDZ removals. Confirmation tests showed that Co@CNTs-700 removed 99.6% of TCC and 97.3% of SDZ with small errors (3-5.5%). Moreover, the kinetic and isotherm were studied, which kinetic and isotherm data were best fitted with pseudo second-order model and Langmuir. Maximum adsorption capacity values for TCC and SDZ were determined at 118.4-174.1 mg g^-1 for 180 min. We also proposed the main role of interactions such as hydrogen bonding, π-π stacking, and electrostatic attraction in the adsorption of antibiotics. With high adsorption performance, Co@CNTs-700 is expected to remove antibiotics efficiently from wastewater.

Green alga Chlamydomonas reinhardtii can effectively remove diclofenac from the water environment - A new perspective on biotransformation

The use of unicellular algae to remove xenobiotics (including drugs) from wastewaters is one of the rapidly developing areas of environmental protection. Numerous data indicate that for efficient phycoremediation three processes are important, i.e. biosorption, bioaccumulation, and biotransformation. Although biosorption and bioaccumulation do not raise any serious doubts, biotransformation is more problematic since its products can be potentially more toxic than the parent compounds posing a threat to organisms living in a given environment, including organisms that made this transformation. Thus, two questions need to be answered before the proper algae strain is chosen for phycoremediation, namely what metabolites are produced during biotransformation, and how resistant is the analyzed strain to a mixture of parent compound and metabolites that appear over the course of culture? In this work, we evaluated the remediation potential of the model green alga Chlamydomonas reinhardtii in relation to non-steroidal anti-inflammatory drugs (NSAIDs), as exemplified by diclofenac. To achieve this, we analysed the susceptibility of C. reinhardtii to diclofenac as well as its capability to biosorption, bioaccumulation, and biotransformation of the drug. We have found that even at a relatively high concentration of diclofenac the algae maintained their vitality and were able to remove (37.7%) DCF from the environment. A wide range of phase I and II metabolites of diclofenac (38 transformation products) was discovered, with many of them characteristic rather for animal and bacterial biochemical pathways than for plant metabolism. Due to such a large number of detected products, 18 of which were not previously reported, the proposed scheme of diclofenac transformation by C. reinhardtii not only significantly contributes to broadening the knowledge in this field, but also allows to suggest possible pathways of degradation of xenobiotics with a similar structure. It is worth pointing out that a decrease in the level of diclofenac in the media observed in this study cannot be fully explained by biotransformation (8.4%). The mass balance analysis indicates that other processes (total 22%), such as biosorption, a non-extractable residue formation, or complete decomposition in metabolic cycles can be involved in the diclofenac disappearance, and those findings open the prospects of further research.

Nanomaterials: a review of emerging contaminants with potential health or environmental impact

Nanotechnologies have been advantageous in many sectors and gaining much concern due to the unique physical, chemical and biological properties of nanomaterials (NMs). We have surveyed peer-reviewed publications related to "nanotechnology", "NMs", "NMs water treatment", "NMs air treatment", and "NMs environmental risk" in the last 23 years. We found that most of the research work is focused on developing novel applications for NMs and new products with peculiar features. In contrast, there are relatively few of publications concerning NMs as environmental contaminants relative to that for NMs applications. Thus, we devoted this review for NMs as emerging environmental contaminants. The definition and classification of NMs will be presented first to demonstrate the importance of unifying the NMs definition. The information provided here should facilitate the detection, control, and regulation of NMs contaminants in the environment. The high surface-area-to-volume ratio and the reactivity of NMs contaminants cause the prediction of the chemical properties and potential toxicities of NPs to be extremely difficult; therefore, we found that there are marked knowledge gaps in the fate, impact, toxicity, and risk of NMs. Consequently, developing and modifying extraction methods, detection tools, and characterization technologies are essential for complete risk assessment of NMs contaminants in the environment. This will help also in setting regulations and standards for releasing and handling NMs as there are no specific regulations. Finally, the integrated treatment technologies are necessary for the removal of NMs contaminants in water. Also, membrane technology is recommended for NMs remediation in air.

Metabolomic response of microalgae towards diclofenac sodium during its removal from water and concomitant recovery of pigments and lipids

The aim of this work was to assess the efficiency of freshwater green microalga, Chlorella sorokiniana for diclofenac sodium (DFS) removal, and metabolic response of alga to comprehend the metabolic pathways involved/affected during DFS decontamination. Results showed 91.51 % removal of DFS could be achieved within 9 days of algal treatment along with recovery of enhanced value-added bioresources i.e. chlorophyll, carotenoids, and lipids from the spent biomass. DFS also had an effect on enzyme activity including superoxide dismutase (SOD), catalase (CAT), and lipid peroxidation (MDA). Furthermore, metabolomics profiling provided an in-depth insight into changes in the metabolic response of C. sorokiniana wherein DFS induced 32 metabolites in microalgae compared to unexposed-control. This study offers microalgae as a green option for DFS removal, and the metabolomics study complemented with DFS could be an approach to understand the stress-induced strategies of C. sorokiniana for concomitant value-added products recovery in presence of DFS.

Current research trends on emerging contaminants pharmaceutical and personal care products (PPCPs): A comprehensive review

Pharmaceutical and personnel care products (PPCPs) from wastewater are a potential hazard to the human health and wildlife, and their occurrence in wastewater has caught the concern of researchers recently. To deal with PPCPs, various treatment technologies have been evolved such as physical, biological, and chemical methods. Nevertheless, modern and efficient techniques such as advance oxidation processes (AOPs) demand expensive chemicals and energy, which ultimately leads to a high treatment cost. Therefore, integration of chemical techniques with biological processes has been recently suggested to decrease the expenses. Furthermore, combining ozonation with activated carbon (AC) can significantly enhance the removal efficiency. There are some other emerging technologies of lower operational cost like photo-Fenton method and solar radiation-based methods as well as constructed wetland, which are promising. However, feasibility and practicality in pilot-scale have not been estimated for most of these advanced treatment technologies. In this context, the present review work explores the treatment of emerging PPCPs in wastewater, via available conventional, non-conventional, and integrated technologies. Furthermore, this work focused on the state-of-art technologies via an extensive literature search, highlights the limitations and challenges of the prevailing commercial technologies. Finally, this work provides a brief discussion and offers future research directions on technologies needed for treatment of wastewater containing PPCPs, accompanied by techno-economic feasibility assessment.

The Application of Polymer Inclusion Membranes for the Removal of Emerging Contaminants and Synthetic Dyes from Aqueous Solutions-A Mini Review

Pollution of the environment, including water resources, is currently one of the greatest challenges due to emerging new contaminants of anthropogenic origin. Of particular concern are emerging organic pollutants such as pharmaceuticals, endocrine disruptors, and pesticides, but also other industrial pollutants, for example, synthetic dyes. The growing demand for environmentally friendly and economical methods of removing emerging contaminants and synthetic dyes from wastewater resulted in increased interest in the possibility of using techniques based on the application of polymer inclusion membranes (PIMs) for this purpose. PIM-based techniques are promising methods for eliminating emerging contaminants and synthetic dyes from aqueous solutions, including wastewater, due to high efficiency, membranes versatility, ease/low cost of preparation, and high selectivity. This review describes the latest developments related to the removal of various emerging contaminants and synthetic dyes from aqueous solutions using PIMs over the past few years, with particular emphasis on research aimed at increasing the effectiveness and selectivity of PIMs, which may contribute to wider use of these methods in the future.

Attitudes and opinions about ecopharmacovigilance from multi-disciplinary perspectives: a cross-sectional survey among academic researchers in China

As a promising upstream strategy to reduce the environmental loads of pharmaceutical emerging contaminants (PECs) through source control, ecopharmacovigilance (EPV) is concerned with the set of activities to identify, evaluate, understand, and prevent against diverse PEC-related problems, and has been accepted as a multi-disciplinary and multi-stakeholder system. This cross-sectional observational survey aimed to assess the attitudes and opinions about EPV from multi-disciplinary perspectives among Chinese academic professors from four main EPV-related disciplines including pharmacy, management, clinical medicine, and environmental and ecological science based on a self-developed questionnaire. Forty-two usable survey instruments were acquired. Results showed that the responding Chinese academic researchers from different disciplines expressed consistently positive attitudes and strong intentions for EPV, in spite of several disparities existing among disciplinary groups showing that pharmacy and medical researchers felt more certain of the environmental adverse effects of PECs, and researchers in pharmacy and environmental and ecological science were more interested in EPV. A multi-disciplinary consensus was achieved in regard to the types of key stakeholders in EPV practices including the pharmaceutical manufacturers, the public, the drug safety authority, hospitals, and the environmental protection agency. The main roles and responsibilities of each stakeholder identity in EPV practices were summarized based on the expert opinions.

Development of Functional Hybrid Polymers and Gel Materials for Sustainable Membrane-Based Water Treatment Technology: How to Combine Greener and Cleaner Approaches

Water quality and disposability are among the main challenges that governments and societies will outside during the next years due to their close relationship to population growth and urbanization and their direct influence on the environment and socio-economic development. Potable water suitable for human consumption is a key resource that, unfortunately, is strongly limited by anthropogenic pollution and climate change. In this regard, new groups of compounds, referred to as emerging contaminants, represent a risk to human health and living species; they have already been identified in water bodies as a result of increased industrialization. Pesticides, cosmetics, personal care products, pharmaceuticals, organic dyes, and other man-made chemicals indispensable for modern society are among the emerging pollutants of difficult remediation by traditional methods of wastewater treatment. However, the majority of the currently used waste management and remediation techniques require significant amounts of energy and chemicals, which can themselves be sources of secondary pollution. Therefore, this review reported newly advanced, efficient, and sustainable techniques and approaches for water purification. In particular, new advancements in sustainable membrane-based filtration technologies are discussed, together with their modification through a rational safe-by-design to modulate their hydrophilicity, porosity, surface characteristics, and adsorption performances. Thus, their preparation by the use of biopolymer-based gels is described, as well as their blending with functional cross-linkers or nanofillers or by advanced and innovative approaches, such as electrospinning.

Novel composite of Zn/Ti-layered double hydroxide coupled with MXene for the efficient photocatalytic degradation of pharmaceuticals

In the present study, a hybrid photocatalyst of Zn/Ti layered double hydroxide (LDH) coupled with MXene - Ti₃C₂ was synthesized for the first time and applied in photocatalytic degradation of acetaminophen and ibuprofen, two commonly present in the natural environment and prone to accumulate in the aquatic ecosystem pharmaceuticals. The effect of MXene content (0.5 wt%, 2.5 wt%, and 5 wt%) on the photocatalytic activity of LDH/MXene composite was investigated. The composite of LDH/MXene containing 2.5 wt% of MXene revealed the highest photocatalytic activity in the degradation of acetaminophen (100% within 40 min) and ibuprofen (99.7% within 60 min). Furthermore, an improvement in acetaminophen and ibuprofen mineralization was observed for the composite material. Meanwhile, the introduction of interfering ions (Na⁺, Ca²⁺, Mg²⁺, Cl^-, SO₄^2-) in the model seawater did not affect the removal efficiency of both pharmaceuticals. The photocatalytic experiment performed in the four subsequent cycles, as well as FTIR, TEM, and XPS analyses after the photodegradation process confirmed the excellent stability and reusability of the prepared composite material. In order to evaluate the effect of various reactive oxidizing species (ROS) on the photocatalytic process, the trapping experiment was applied. It was noticed that •O₂^- had the main contribution in photocatalytic degradation of acetaminophen, while •OH and h⁺ mainly affected the degradation of ibuprofen. Finally, based on the results of Mott Schottky analysis, bandgap calculation, and ROS trapping experiment, the possible mechanism for pharmaceuticals degradation was proposed. This research illustrates the feasibility and novelty of the treatment of pharmaceuticals by LDH/MXene composites, implying that MXene plays a significant role in the electron-hole separation and thus high photocatalytic activity.

Pharmaceutical residues: One of the significant problems in achieving 'clean water for all' and its solution

With the rapid emergence of various metabolic and multiple-drug-resistant infectious diseases, new pharmaceuticals are continuously being introduced in the market. The excess production and use of pharmaceuticals and their untreated/unmetabolized release in the environment cause the contamination of aquatic ecosystem, and thus, compromise the environment and human-health. The present review provides insights into the classification, sources, occurrence, harmful impacts, and existing technologies to curb these problems. A comprehensive detail of various biological and nanotechnological strategies for the removal of pharmaceutical residues from water is critically discussed focusing on their efficiencies, and current limitations to design improved-technologies for their lab-to-field applications. Furthermore, the review highlights and suggests the scope of integrated bionanotechnological methods for enhanced removal of pharmaceutical residues from water to fulfill the United Nations Sustainable Development Goal (UN-SDG) for providing clean potable water for all.

Emerging periodate-based oxidation technologies for water decontamination: A state-of-the-art mechanistic review and future perspectives

With the ever-increasing severity of the ongoing water crisis, it is of great significance to develop efficient, eco-friendly water treatment technologies. As an emerging oxidant in the advanced oxidation processes (AOPs), periodate (PI) has received worldwide attention owing to the advantages of superior stability, susceptible activation capability, and high efficiency for decontamination. This is the first review that conducts a comprehensive analysis of the mechanism, pollutant transformation pathway, toxicity evolution, barriers, and future directions of PI-based AOPs based on the scientific information and experimental data reported in recent years. The pollutant elimination in PI-based AOPs was mainly attributed to the in situ generate reactive oxygen species (e.g., ^•OH, O(³P), ¹O₂, and O₂^•-), reactive iodine species (e.g., IO₃^• and IO₄^•), and high-valent metal-oxo species with exceptionally high reactivity. These reactive species were derived from the PI activated by the external energy, metal activators, alkaline, freezing, hydroxylamine, H₂O_2, etc. It is noteworthy that direct electron transport could also dominate the decontamination in carbon-based catalyst/PI systems. Furthermore, PI was transformed to iodate (IO₃^-) stoichiometrically via an oxygen-atom transfer process in most PI-based AOPs systems. However, the production of I₂, I^-, and HOI was sometimes inevitable. Furthermore, the transformation pathway of typical micropollutants was clarified, and the in silico QSAR-based prediction results indicated that most transformation products retained biodegradation recalcitrance and multi-endpoint toxicity. The barriers faced by the PI-based AOPs were also clarified with potential solutions. Finally, future perspectives and research directions are highlighted based on the current state of PI-based AOPs. This review enhances our in-depth understanding of PI-based AOPs for pollutant elimination and identifies future research needs to focus on the reduction of toxic byproducts.

Removal of Pharmaceuticals and Personal Care Products (PPCPs) by Free Radicals in Advanced Oxidation Processes

As emerging pollutants, pharmaceutical and personal care products (PPCPs) have received extensive attention due to their high detection frequency (with concentrations ranging from ng/L to μg/L) and potential risk to aqueous environments and human health. Advanced oxidation processes (AOPs) are effective techniques for the removal of PPCPs from water environments. In AOPs, different types of free radicals (HO·, SO₄·^-, O₂·^-, etc.) are generated to decompose PPCPs into non-toxic and small-molecule compounds, finally leading to the decomposition of PPCPs. This review systematically summarizes the features of various AOPs and the removal of PPCPs by different free radicals. The operation conditions and comprehensive performance of different types of free radicals are summarized, and the reaction mechanisms are further revealed. This review will provide a quick understanding of AOPs for later researchers.

Activated carbon-chitosan based adsorbent for the efficient removal of the emerging contaminant diclofenac: Synthesis, characterization and phytotoxicity studies

The rise in pharmaceutical pollutants due to their unregulated discharge in pharmaceutical wastewater has landed them as emerging contaminants that would gradually affect the aquatic ecosystem and human life. The current study emphasizes the adsorptive elimination of one such emerging pharmaceutical pollutant, i.e., Diclofenac (DIF), using a synthesized adsorbent vis. Activated carbon-chitosan beads (ACCB). The morphological and physicochemical properties of the prepared adsorbent, ACCB and its interaction with the DIF species were investigated. Process parameters influencing the adsorptive interactions between ACCB and DIF were optimised. DIF was efficiently adsorbed at optimised initial DIF pH of 6.0 and ACCB dosage of 1.5 mg/mL at an incubation temperature of 40 °C. Freundlich isotherm model showed the best fit (R² = 0.98) with the experimental data to conclude that the adsorbent surface is heterogenous, promoting multilayer adsorption. As depicted from the Langmuir isotherm model, the maximum theoretical adsorption capacity was 99.29 mg/g. The seed toxicity assay confirmed the efficacy of ACCB in the adsorptive removal of DIF species from aqueous setups, making the post-treated solution fit enough for seed germination.

Investigation of membrane fouling and mechanism induced by extracellular organic matter during long-term exposure to pharmaceuticals and personal care products

This study investigated ultrafiltration membrane fouling by extracellular organic matter (EOM) and the mechanism operating during long-term exposure to pharmaceuticals and personal care products. The results indicated that carbamazepine and diclofenac in algal-laden water altered the filtration flux and membrane fouling by EOM. Exposure to low-concentration carbamazepine (0.25 μg/L) improved the filtration flux and the total (R_tot) and reversible fouling resistance (R_c), whereas the filtration flux and R_tot and R_c were reduced when EOM was used during long-term exposure to high carbamazepine concentrations (>1 μg/L). Both R_tot and R_c were increased when algae were exposed to 0.25 μg/L diclofenac, whereas the filtration flux and R_tot and R_c were alleviated when algae were exposed to >1 μg/L diclofenac. Moreover, carbamazepine and diclofenac (0.25 μg/L - 1000 μg/L) in water enhanced the irreversible fouling resistance (R_b) when ultrafiltration was used to treat algal-laden waters. The mechanism indicated that membrane fouling induced by standard blocking was transformed to complete blocking when EOM was exposed to high levels of carbamazepine (>0.25 μg/L) in the initial filtration process, whereas cake layer formation played an important role during the later filtration process; with low carbamazepine levels (0.25 μg/L), standard blocking of EOM was dominant during the entire filtration process. The membrane fouling mechanism also changed when algal-laden waters were exposed to diclofenac, the membrane fouling was transformed from complete blocking to standard blocking when DFC was present in the initial filtration process, whereas cake layer formation exerted an important role during the late filtration process. This research provides important information on the long-term risks caused by pharmaceutical and personal care products and potential threats to membrane treatment.

Electro-Chemical Degradation of Norfloxacin Using a PbO2-NF Anode Prepared by the Electrodeposition of PbO2 onto the Substrate of Nickel Foam

A novel three-dimensional network nickel foam/PbO2 combination electrode (PbO2-NF) with high electrochemical degradation efficiency to norfloxacin was successfully fabricated through the electrodeposition of PbO2 on the substrate of nickel foam. The characterization of an PbO2-NF electrode, including surface morphology, elemental components, electrochemical performance, and stability was performed. In electrochemical oxidation tests, the removal efficiency of norfloxacin (initial concentration for 50 mg/L) on PbO2-NF reached 88.64% within 60 min of electrolysis, whereas that of pure nickel foam was only 30%. In the presence of PbO2-NF, the optimum current density, solution pH, electrode spacing for norfloxacin degradation were 30 mA/cm2, 11, and 3 cm, respectively. The electric energy consumption for 80% norfloxacin was approximately 5 Wh/L. Therefore, these results provide a new anode to improve the removal of norfloxacin in the wastewater with high efficiency and low energy consumption.

Ofloxacin Removal from Aqueous Media by Means of Magnetoactive Electrospun Fibrous Adsorbents

Functionalized electrospun polymer microfibrous membranes were fabricated by electrospinning and further surface-functionalized with magnetic iron oxide (Fe_xO_y) nanoparticles to yield magnetoactive nanocomposite fibrous adsorbents. The latter were characterized in respect to their morphology, mechanical properties and magnetic properties while they were further evaluated as substrates for removing Ofloxacin (OFL) from synthetic aqueous media and secondary urban wastewater (UWW) under varying physicochemical parameters, including the concentration of the pharmaceutical pollutant, the solution pH and the membranes' magnetic content. The magnetic-functionalized fibrous adsorbents demonstrated significantly enhanced adsorption efficacy in comparison to their non-functionalized fibrous analogues while their magnetic properties enabled their magnetic recovery and regeneration.

Remediation of wastewater containing 4-nitrophenol using ionic liquid stabilized nanoparticles: Synthesis, characterizations and applications

In the present study, an ionic liquid (IL) based on 1-butyl-3- (trimethoxysilylpropyl) -imidazolium tetrafluoroborate (IL) was prepared using metathesis and anion exchange reactions and used to stabilize silver (AgNPs) nanoparticles. The IL-stabilized silver nanoparticles AgNPs@[BMSI]BF₄ were produced in an aqueous solution with NaBH₄ as a reducing agent. TGA, FTIR, XRD, BET, FSEM, TEM/HRTEM, XPS, and UV-Vis spectra were used to analyze AgNPs@[BMSI]BF₄ and were used for the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH₄. AgNPs@[BMSI]BF₄ showed excellent catalytic properties for the reduction of 4-NP to 4-AP and showed 100% conversion of 4-NP to 4-AP within 6 min and the rate constant (k) was found to be 8.33 × 10^-3 s^-1. The reusability results indicated that 97.8% of 4-NP was converted to 4-AP with highly stable rate constants over six consecutive cycles. The activity factor (AF) and the turn-over frequency (TOF) at room temperature were 3.33 s^-1 gm^-1 and 0.166 s^-1, respectively. This study extends a new approach to the production of stable catalysts for the growing needs in wastewater treatment.

Pharmaceutical and personal care products as emerging environmental contaminants in Nigeria: A systematic review

The increasingly broad and massive use of pharmaceuticals (human, veterinary) and personal care products in industrially developing nations makes their uncontrolled environmental and ecological impact a true concern. Focusing on Nigeria, this systematic literature search (databases: PubMed, ScienceDirect, Google Scholar, EMBASE, Scopus, Cochrane library and African Journals Online) aims to increase visibility to the issue. Among 275 articles identified, 7 were included in this systematic review. Studies indicated the presence of 11 personal care products (15.94 %) and 58 pharmaceutical products (84.06 %) in surface and ground water, leachates, runoffs, sludge, and sediments. The 42.86% (3/7) of reviewed studies reported 17 analgesics; 71.42 % (5/7) reported 16 antibiotics; 28.57 % (2/7) reported 5 lipid lowering drugs; 28.57% reported anti-malaria and fungal drugs; 14.29 % (1/7) reported estrogen drugs. Different studies report on sunscreen products, hormone, phytosterol, insect repellent, and β1 receptor. Gemfibrozil (<4-730 ng/L), Triclosan (55.1-297.7 ng/L), Triclocarban (35.6-232.4 ng/L), Trimethoprim (<1-388 ng/L) and Tramadol (<2-883 ng/L) had the highest range of concentrations. Findings confirm the need of i) legislation for environmental monitoring, including biota, ii) toxicological profiling of new market products, and iii) sensitization on appropriate use and disposal of pharmaceuticals and personal care products.

Desorption of pharmaceuticals and illicit drugs from different stabilized sludge types across pH

Pharmaceutical and illicit drug residues in sewage sludge may present important risks following direct application to agricultural soils, potentially resulting in uptake by plants. Leaching/desorption tests were performed on different types of stabilized sewage sludge originating from multiple treatment technologies in the Slovak Republic. Acid rain and base-rich condition of soil with different pH conditions were simulated to model the effect of widely varying pH (pH 2, 4, 7, 9, and 12) on the leaching/desorption of pharmaceuticals and illicit drugs. Twenty-nine of 93 target analytes were found above the limit of quantification in sludge or associated leachates. Total desorbed amounts of pharmaceuticals and illicit drugs ranged from 810 to 4000 µg/kg, and 110 to 3600 µg/kg of the dry mass of anaerobic and aerobic sludge, respectively. Desorbed fractions were calculated as these values are normalized to initial sludge concentration and, therefore, were more suitable for qualitative description of the behavior of individual compounds. Using principal component analysis, qualitative analysis of the desorbed fraction confirmed the differences among sludge types, pharmaceuticals, and desorption pH. Desorbed fractions could not be related to the octanol/water distribution coefficient. Desorbed fractions also did not reflect the expected ionization of studied molecules unless converted into their relative values. Generally, the lowest mobility was observed within the environmentally relevant pH range of 4-9, and high pH generally resulted in high desorption, especially in anaerobically stabilized sludges.

Novel aspartic-based bio-MOF adsorbent for effective anionic dye decontamination from polluted water

In this study, a cost-effective powdered Zn l-aspartic acid bio-metal organic framework (Zn l-Asp bio-MOF) was reported as an efficient adsorbent for Direct Red 81 (DR-81) as an anionic organic dye. The prepared bio-MOF was characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission transmission electron microscopy (FETEM), surface area analysis (BET), and thermal gravimetrical analysis (TGA). The resulting bio-MOF has a large surface area (180.43 m2 g-1) and large mesopore volume (0.144 cm3 g-1), as well as good chemical inertness and mechanical stability. The optimum dosage from the Zn l-Asp bio-MOF was 1.0 g L-1 at pH = 7 for 95.3% adsorption of 10 ppm DR-81 after 45 min. Thermodynamic analysis results demonstrated that the decontamination processes were done with spontaneous, thermodynamically, and exothermic nature onto the fabricated bio-MOF. Kinetic parameters were well-fitted with pseudo-second-order kinetics, and the adsorption process was described by the Freundlich isotherm. The adsorption data proved that Zn l-Asp bio-MOF is an effective adsorbent for DR-81 from aqueous solutions with high stability and recycling ability for eight cycles, as well as the easy regeneration of the sorbent.

Green Synthesis via Eucalyptus globulus L. Extract of Ag-TiO2 Catalyst: Antimicrobial Activity Evaluation toward Water Disinfection Process

The problem of water pollution by persistent substances and microorganisms requires solutions that materials such as silver-modified titanium dioxide can provide due to their excellent photocatalytic and antimicrobial properties. However, the synthesis methods conventionally used to obtain these materials involve toxic chemical reagents such as sodium borohydride (NaBH₄). The search for alternative synthesis methods that use environmentally friendly substances, such as the biosynthesis method, was evaluated. Silver-titanium dioxide (Ag-TiO₂) was synthesized by a Eucalyptus globulus L. extract as a reductive agent through sol-gel and microwave-assisted sol-gel processes. Four different solvents were tested to extract secondary metabolites to determine their roles in reducing silver nanoparticles. Titanium dioxide nanoparticles with sizes from 11 to 14 nm were obtained in the anatase phase, and no narrowing of the bandgap was observed (3.1–3.2 eV) for the Ag-TiO₂ materials compared with the pure TiO₂. Interestingly, the bacterial inhibition values were close to 100%, suggesting an effective antimicrobial mechanism related to the properties of silver. Finally, by the physicochemical characterization of the materials and their antimicrobial properties, it was possible to obtain a suitable biosynthesized Ag-TiO₂ material as a green option for water disinfection that may be compared to the conventional methods.

Effect of Applied Electrical Stimuli to Interdigitated Electrode Sensors While Detecting 17α-Ethinylestradiol in Water Samples

The effect of impedance measurements of applied voltage on the detection of 17α-ethinylestradiol (EE2) in water samples using interdigitated electrodes (IDE) coated or not with thin films, is described. Firstly, the effect of immersion in EE2 aqueous solutions of layer-by-layer films prepared with poly(allylamine hydrochloride) (PAH), graphene oxide (GO), poly(1-(4-(3-carboxy-4-hydroxyphenylazo) benzene sulfonamido) 1,2 ethanediyl, sodium salt) (PAZO), polyethylenimine (PEI) and poly(sodium 4-styrenesulfonate) (PSS) was analyzed. These results demonstrated that PAH/GO films desorb during the immersion on EE2 solutions, while EE2 adsorbs on PAH/PAZO and PEI/PSS films with characteristic time values of 16.7 and 7.1 min, respectively, demonstrating that both films are adequate for the development of EE2 sensors. However, as the adsorption characteristic time is shorter, and the EE2 adsorbed amount is smaller, the PEI/PSS films are more suitable for the development of sensors. The effect of the applied voltage was analyzed using both IDEs covered with PEI/PSS films as well as those uncoated. The capacitance spectra are best fitted to analyze this effect, and the loss tangent spectra are advantageous to analyze the aqueous media. Furthermore, it was concluded that lower voltage values are best suited to perform measurements of this nature, given that higher voltages lead to less reliable results and cause irreparable damage to the sensors.