Emerging pollutant treatments in wastewater: Cases of antibiotics and hormones

Degradation of cefixime by photocatalysis via Ba-doped BiFeO3 nanomaterial using RSM analysis under LED light source

In the current work, Response Surface Methodology (RSM)-a statistical method-is used to optimize procedures like photocatalysis with the least amount of laboratory testing. However, to determine the most effective model for achieving the maximum rate of removal efficiency, the Response Surface Methodology was employed. The Ba-doped BiFeO3 photocatalyst was synthesized by the co-precipitation method, and its intrinsic properties were investigated by utilizing a range of spectroscopic techniques, such as FESEM, EDX, XRD, FTIR, and UV-vis. Herein, four independent factors such as, pH, contact time, pollutant concentration, and catalyst dosage were chosen. The results revealed that under acidic conditions with a contact duration of 2 min, a moderate catalyst dosage, and higher pollutant concentration, a degradation rate of 89.8% was achieved. The regression coefficient (R2) and probability value (P) were determined to be 0.99551 and 0.0301, respectively, therefore confirming the excellent fit of the RSM model. Furthermore, this research investigated the potential photocatalytic degradation mechanisms of cefixime, demonstrating that the removal efficiency of cefixime is greatly influenced by the functional parameters.

Advances in Algomics technology: Application in wastewater treatment and biofuel production

Advanced sustainable bioremediation is gaining importance with rising global pollution. This review examines microalgae's potential for sustainable bioremediation and process enhancement using multi-omics approaches. Recently, microalgae-bacterial consortia have emerged for synergistic nutrient removal, allowing complex metabolite exchanges. Advanced bioremediation requires effective consortium design or pure culture based on the treatment stage and specific roles. The strain potential must be screened using modern omics approaches aligning wastewater composition. The review highlights crucial research gaps in microalgal bioremediation. It discusses multi-omics advantages for understanding microalgal fitness concerning wastewater composition and facilitating the design of microalgal consortia based on bioremediation skills. Metagenomics enables strain identification, thereby monitoring microbial dynamics during the treatment process. Transcriptomics and metabolomics encourage the algal cell response toward nutrients and pollutants in wastewater. Multi-omics role is also summarized for product enhancement to make algal treatment sustainable and fit for sustainable development goals and growing circular bioeconomy scenario.

Synthesis and Characterization of a Photocatalytic Material Based on Raspberry-like SiO2@TiO2 Nanoparticles Supported on Graphene Oxide

A raspberry-like SiO2@TiO2 new material supported on functionalized graphene oxide was prepared to reduce titania's band gap value. The material was characterized through different analytical methods such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HR-TEM). The band gap value was studied via UV-Vis absorption spectra and determined through the Kubelka-Munk equation. A theoretical study was also carried out to analyze the interaction between the species.

Adsorption performance of GO-doped activated ATP composites towards tetracycline

Antibiotic-related environmental contamination directly threatens ecosystems and human health. Adsorption is an efficient and simple treatment process for removing antibiotics from water environments. Attapulgite (ATP) is a natural clay mineral extensively researched as a promising adsorbent material in the food industry, pharmaceutical sanitation, and organic wastewater treatment. Graphene oxide (GO) is widely employed in the treatment of organic wastewater due to its superior physicochemical properties. Here, using high temperature and HCl, ATP was activated (a-ATP), and a GO/a-ATP composite was prepared via hydrothermal synthesis. Using an adsorbent dosage of 0.75 g L-1, pH = 5, reaction time of 120 min, initial temperature = 35 °C, and initial TC concentration of 50 mg L-1, the adsorption capacity of GO/a-ATP for TC was 38.8 mg g-1. The pseudo-first-order model (PFO) and pseudo-second-order (PSO) model were fitted to the kinetic data, and yielded an R 2-value of PSO (0.99991) > PFO (0.9389), indicating that the adsorption process is related to chemisorption. Adsorption was also well described by the mixed-order (MO) model (R 2 = 0.9827), demonstrating that two rate-limiting adsorption reaction steps, diffusion and adsorption, occur; the former exerting greater influence. Equilibrium data was fitted to Langmuir, Freundlich, and Temkin isotherm models; the Langmuir model gave the best fit, suggesting the adsorption process is a homogeneous and monolayer adsorption process. Various thermodynamic parameters such as standard Gibbs free energy (ΔG 0) and standard enthalpy (ΔH 0) were also calculated, these results indicate the adsorption reaction is an endothermic process. Our study shows that GO/a-ATP is a promising adsorbent material for use in the adsorption of tetracycline in aquatic environments.

Insight into using a novel ultraviolet/peracetic acid combination disinfection process to simultaneously remove antibiotics and antibiotic resistance genes in wastewater: Mechanism and comparison with conventional processes

In this study, the simultaneous removal mechanism of antibiotics and antibiotic resistance genes (ARGs) was investigated using the novel ultraviolet/peracetic acid (UV/PAA) combination disinfection process and conventional disinfection processes were also applied for comparison. The results showed that UV/PAA disinfection with a high UV dosage (UV/PAA-H) was most effective for the removal of tetracyclines, quinolones, macrolides and β-lactams; their average removal efficiencies ranged from 25.7% to 100%, while NaClO disinfection was effective for the removal of sulfonamides (∼81.6%). The majority of ARGs were well removed after the UV/PAA-H disinfection, while specific genes including tetB, tetC, ermA and bla_TEM significantly increased after NaClO disinfection. In addition, β-lactam resistance genes (-35.9%) and macrolides resistance genes (-12.0%) remarkably augmented after UV/NaClO disinfection. The highly reactive oxidation species generated from UV/PAA process including hydroxyl radicals (•OH) and carbon-centered organic radicals (R-C•), were responsible for the elimination of antibiotics and ARGs. Correlation analysis showed that tetracycline, sulfonamide and macrolide antibiotics removal showed a positive correlation with the corresponding ARGs, and a low dose of antibiotic residues played an important role in the distribution of ARGs. Metagenomic sequencing analysis showed that UV/PAA disinfection could not only greatly decrease the abundance of resistant bacteria but also downregulate the expression of key functional genes involved in ARGs propagation and inhibit the signal transduction of the host bacteria, underlying that its removal mechanism was quite different from that of NaClO-based disinfection processes. Our study provides valuable information for understanding the simultaneous removal mechanism of antibiotics and ARGs in wastewater during the disinfection processes, especially for the novel UV/PAA combination process.

Bloom of tetracycline resistance genes in mudflats following fertilization is attributed to the increases in the shared potential hosts between soil and organic fertilizers

A field experiment was carried out in mudflats adjacent to the Yellow Sea, China, amended with sewage sludge and vermicompost by one-time input at different rates to reveal the fates of tetracycline resistance genes (TRGs) and their potential hosts in the soils. Quantitative PCR results showed that soils added with either sludge or vermicompost had more abundant TRGs compared with the non-fertilized soil. This situation was more obvious in sludge fertilized soils especially at high application rates. Vermicompost exhibited a promising outlook for improvement of the mudflats. The abundances of intI1 in the non-fertilized soils were significantly higher than those in fertilizers and fertilized soils. The potential hosts for intI1 were not shared with other TRGs-contained hosts, indicating that intI1 had little effects on the dissemination of TRGs in the mudflats. Moreover, the exclusive hosts for TRGs in fertilizers were not higher than those in the non-fertilized soils, illustrating little effects of fertilization on the introduction of exogenous TRGs into soil. The shared hosts between soil and fertilizers were highest among four possible sources, contributing vastly to the bloom of TRGs following fertilization. It was also shown that different organic fertilizers caused distinct categories of shared potential hosts for TRGs. RDA analysis further indicated that the abundances of the shared potential hosts were affected by soil nutrients. These results suggested that the development of TRGs in soil following fertilization depended on the shared potential hosts with similar ecological niches between soil and fertilizers.

Development in nanomembrane-based filtration of emerging contaminants

Recently, the concentration of emerging contaminants is increasing in drinking water sources, industrial wastewater, and reclaimed water. It is not possible to remove the emerging contaminants using conventional methods, and the interest to use nanomembrane-based filtration is getting attention. A nanomembrane-based filtration can be manipulated without the use of any special equipment. Different research findings reported better removal of emerging contaminants has been achieved using nanomembrane-based filtration. Moreover, new developments have been examined and implemented at different levels and are expected to continue. Therefore, this chapter provides a brief overview of recent developments on nanomembrane-based filtration processes in the removal of emerging contaminants from drinking water sources, industrial wastewater, and reclaimed water.

Can use of hydroxychloroquine and azithromycin as a treatment of COVID-19 affect aquatic wildlife? A study conducted with neotropical tadpole

The impacts on human health and the economic and social disruption caused by the pandemic COVID-19 have been devastating. However, its environmental consequences are poorly understood. Thus, to assess whether COVID-19 therapy based on the use of azithromycin (AZT) and hydroxychloroquine (HCQ) during the pandemic affects wild aquatic life, we exposed (for 72 h) neotropical tadpoles of the species Physalaemus cuvieri to the water containing these drugs to 12.5 μg/L. We observed that the increase in superoxide dismutase and catalase in tadpoles exposed to AZT (alone or in combination with HCQ) was predominant to keep the production of NO, ROS, TBARS and H2O2 equitable between the experimental groups. In addition, the uptake of AZT and the strong interaction of AZT with acetylcholinesterase (AChE), predicted by the molecular docking analysis, were associated with the anticholinesterase effect observed in the groups exposed to the antibiotic. However, the unexpected increase in butyrylcholinesterase (BChE) in these same groups suggests its constitutive role in maintaining cholinergic homeostasis. Therefore, taken together, our data provide a pioneering evidence that the exposure of P. cuvieri tadpoles to AZT (alone or in combination with HCQ) in a predictably increased environmental concentration (12.5 μg/L) elicits a compensatory adaptive response that can have, in the short period of exposure, guaranteed the survival of the animals. However, the high energy cost for maintaining physiological homeostasis, can compromise the growth and development of animals and, therefore, in the medium-long term, have a general negative effect on the health of animals. Thus, it is possible that COVID-19 therapy, based on the use of AZT, affects wild aquatic life, which requires greater attention to the impacts that this drug may represent.

Treatment Processes for Microbial Resistance Mitigation: The Technological Contribution to Tackle the Problem of Antibiotic Resistance

Advances generated in medicine, science, and technology have contributed to a better quality of life in recent years; however, antimicrobial resistance has also benefited from these advances, creating various environmental and health problems. Several determinants may explain the problem of antimicrobial resistance, such as wastewater treatment plants that represent a powerful agent for the promotion of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARG), and are an important factor in mitigating the problem. This article focuses on reviewing current technologies for ARB and ARG removal treatments, which include disinfection, constructed wetlands, advanced oxidation processes (AOP), anaerobic, aerobic, or combined treatments, and nanomaterial-based treatments. Some of these technologies are highly intensive, such as AOP; however, other technologies require long treatment times or high doses of oxidizing agents. From this review, it can be concluded that treatment technologies must be significantly enhanced before the environmental and heath problems associated with antimicrobial resistance can be effectively solved. In either case, it is necessary to achieve total removal of bacteria and genes to avoid the possibility of regrowth given by the favorable environmental conditions at treatment plant facilities.

Bibliometric approach to the perspectives and challenges of membrane separation processes to remove emerging contaminants from water

The presence of contaminants in water is concerning due to the potential impacts on human health and the environment, and ingested contaminants cause harm in various ways. The conventional water treatment systems are not efficient to remove these contaminants. Therefore, novel techniques and materials for the removal of contaminants are increasingly being developed. The separation process using modified membranes can remove these micropollutants; therefore, they have attracted significant research attention. Among the materials used for manufacturing of these membranes, composites based on graphene oxide and reduced graphene oxide are preferred owing to their promising properties, such as mechanical resistance, thermal and chemical stability, antifouling capacity, water permeability, high thermal and electrical conductivity, high optical transmittance and high surface area. Membrane separation processes (MSP) can be used as secondary or tertiary treatment during the supply of wastewater. However, the efficient and accessible applications of these technologies are challenging. This study aims to demonstrate the main concepts of membrane separation processes and their application in the removal of emerging contaminants. This study reports bibliometric mapping, relevant data on studies using membranes as water treatment processes, and their viability in industrial applications. The main challenges and perspectives of these technologies are discussed in detail as well.

Putative environmental levels of levofloxacin facilitate the dissemination of antibiotic-resistant Escherichia coli via plasmid-mediated transformability

Antibiotic residues in the environment pose a great risk to global public health. They increase antibiotic resistance by enhancing plasmid conjugation among bacteria or mutations within bacterial genomes. However, little is known about whether the putative environmental levels of antibiotics are sufficient to influence plasmid-mediated transformability. In this study, we explored the effect of eight kinds of representative antibiotics and several other compounds on the plasmid transformability of competent Escherichia coli. Only levofloxacin (LEV) at the putative environmental levels was found to facilitate the frequency of PBR322-or RP4-plasmid-mediated transformation by up to 5.3-fold. Additionally, PBR322 transformation frequency could be further enhanced by copper ion or ammonia nitrogen but inhibited by humic acid. However, when competent E. coli was exposed to the minimal inhibitory concentrations (MIC) of the antibiotics, an enhanced plasmid-assimilation ability was observed and plasmid transformation frequency was increased by up to 98.6-fold for all the tested antibiotics. Furthermore, E. coli exhibited a preference for the uptake of plasmids harbouring the resistance genes to the antibiotics it had been exposed to. Among these antibiotics, cephalexin, tetracycline, and kanamycin induced the highest uptake of RP4. The putative environmental levels of LEV enhanced plasmid transformability regardless of the presence of corresponding antibiotic resistance gene (ARG) on the genetic elements, suggesting environmental LEV residues may facilitate dissemination of antibiotic resistance by any plasmid-mediated transformability, thereby posing a great risk to health.

Current Trends in the Application of Nanomaterials for the Removal of Emerging Micropollutants and Pathogens from Water

Water resources contamination has a worldwide impact and is a cause of global concern. The need for provision of clean water is becoming more and more demanding. Nanotechnology may support effective strategies for the treatment, use and reuse of water and the development of next-generation water supply systems. The excellent properties and effectiveness of nanomaterials make them particularly suitable for water/wastewater treatment. This review provides a comprehensive overview of the main categories of nanomaterials used in catalytic processes (carbon nanotubes/graphitic carbon nitride (CNT/g-C₃N₄) composites/graphene-based composites, metal oxides and composites, metal–organic framework and commercially available nanomaterials). These materials have found application in the removal of different categories of pollutants, including pharmaceutically active compounds, personal care products, organic micropollutants, as well as for the disinfection of bacterial, viral and protozoa microbial targets, in water and wastewater matrices. Apart from reviewing the characteristics and efficacy of the aforementioned nanoengineered materials for the removal of different pollutants, we have also recorded performance limitations issues (e.g., toxicity, operating conditions and reuse) for their practical application in water and wastewater treatment on large scale. Research efforts and continuous production are expected to support the development of eco-friendly, economic and efficient nanomaterials for real life applications in the near future.

Exclusion of Estrogenic and Androgenic Steroid Hormones from Municipal Membrane Bioreactor Wastewater Using UF/NF/RO Membranes for Water Reuse Application

In the context of water scarcity, domestic secondary effluent reuse may be an option as a reliable source for alleviating acute water shortage. The increasing risks linked with the presence of natural steroid hormones and many emerging anthropogenic micropollutants (MPs) passing through municipal wastewater treatment works (MWWTWs) are of concern for their endocrine-disrupting activities. In this study, domestic wastewater treated by a full-scale membrane bioreactor (MBR) at an MWWTW in the Western Cape Province, South Africa, was used directly as the influent to a reverse osmosis (RO) pilot plant for the removal of selected natural steroid hormones 17β-estradiol (E₂) and testosterone (T) as a potential indirect water recycling application. Estrogenicity and androgenicity were assessed using the enzyme-linked immunosorbent assays (ELISA) and the recombinant yeast estrogen receptor binding assays (YES). The influent pH and flux did not influence the rejection of E₂ and T, which was most likely due to adsorption, size exclusion, and diffusion simultaneously. RO and nanofiltration (NF) exhibited excellent removal rates (>95%) for E₂ and T. All the E₂ effluent samples with MBR/ultrafiltration (UF), MBR/NF, and MBR/RO were lower than the US EPA and WHO trigger value of 0.7 ng/L, as well as the predicted no-effect concentration (PNEC) values for fish (1 ng E₂/L).

Organic Contaminant Biodegradation by Oxidoreductase Enzymes in Wastewater Treatment

Organic contaminants (OCs), such as pharmaceuticals, personal care products, flame retardants, and plasticisers, are societally ubiquitous, environmentally hazardous, and structurally diverse chemical compounds whose recalcitrance to conventional wastewater treatment necessitates the development of more effective remedial alternatives. The engineered application of ligninolytic oxidoreductase fungal enzymes, principally white-rot laccase, lignin peroxidase, and manganese peroxidase, has been identified as a particularly promising approach for OC remediation due to their strong oxidative power, broad substrate specificity, low energy consumption, environmental benignity, and cultivability from lignocellulosic waste. By applying an understanding of the mechanisms by which substrate properties influence enzyme activity, a set of semi-quantitative physicochemical criteria (redox potential, hydrophobicity, steric bulk and pKa) was formulated, against which the oxidoreductase degradation susceptibility of twenty-five representative OCs was assessed. Ionisable, compact, and electron donating group (EDG) rich pharmaceuticals and antibiotics were judged the most susceptible, whilst hydrophilic, bulky, and electron withdrawing group (EWG) rich polyhalogenated compounds were judged the least susceptible. OC susceptibility scores were in general agreement with the removal rates reported for experimental oxidoreductase treatments (R2 = 0.60). Based on this fundamental knowledge, and recent developments in enzyme immobilisation techniques, microbiological enzymic treatment strategies are proposed to formulate a new generation of biological wastewater treatment processes for the biodegradation of environmentally challenging OC compounds.

Oxidation of Flame Retardant Tetrabromobisphenol A by a Biocatalytic Nanofiber of Chloroperoxidase

Background: Tetrabromobisphenol (TBBPA), a flame retardant compound, is considered a ubiquitous pollutant, with potential impact on the environment and human health. Several technologies have been applied to accelerate its degradation and minimize environmental impacts. Due to its aromaticity character, peroxidase enzymes may be employed to carry out its transformation in mild conditions. Therefore, the purpose of this work was to determine the capacity of the enzyme chloroperoxidase (CPO) to oxidize TBBPA in several water samples. Methods: The oxidation capacity of CPO was evaluated in catalytic conditions using water samples from surface and groundwater, as well as effluents from wastewater treatment plants. The biocatalytic performance of CPO was improved due to its immobilization on nanofibers composed of polyvinyl alcohol and chitosan (PVA/chitosan). Results: Free and immobilized CPO were able to transform more than 80% in short reaction times (60 min); producing more biodegradable and less toxic products. Particularly, the immobilized enzyme was catalytically active in a wider range of pH than the free enzyme with the possibility of reusing it up to five times. Conclusions: The biocatalytic oxidation of TBBPA under environmental conditions is highly efficient, even in complex media such as treated effluents of wastewater treatment plants.

Simultaneous oxidation of ammonium and tetracycline in a membrane aerated biofilm reactor

The membrane aerated biofilms reactor (MABR) is an emerging technology in wastewater treatment with particular advantages including high rate nitrification, and very high oxygen transfer efficiencies. In this study a synthetic feed water incorporating tetracycline (TC) was investigated in a MABR. Simultaneous removal of ammonium and tetracycline (TC) in the reactor, formation of TC transformation products (TPs), and microbial community analysis in the biofilm growing on the membrane were performed. A range of TC and ammonium loading rates and the effect of different intra-membrane oxygen pressures were on treatment performance were systematically investigated. Successful nitrification and TC degradation were achieved with the highest TC removal (63%) obtained at a HRT of 18 h HRT and 0.41 bar gas pressure. It has shown that different operating conditions (HRT and gas pressure) do not cause a significant change in ammonium removal. The concentration of TPs such as ETC, EATC, and ATC was determined to be at the ppb level. Molecular results showed that MABR reactor was mainly dominated by β-proteobacteria. The relative abundance of this group decreased in parallel with the increasing ammonium and TC loading.

Removal of priority and emerging pollutants from aqueous media by adsorption onto synthetic organo-funtionalized high-charge swelling micas

In this work, the removal of different types of emerging pollutants (four perfluoroalkyl compounds, two preservatives, three surfactants and nine pharmaceutical compounds) from aqueous solution by adsorption onto two novel synthetic clays, a high-charge swelling mica (Na-Mica-4) and an organo-functionalized mica (C₁₈-Mica-4), was evaluated. Na-Mica-4 and C₁₈-Mica- 4 were prepared and characterized by X-Ray diffraction, Zeta potential, specific surface area, thermogravimetric analysis and transmission electron microscopy, before and after adsorption experiments. The influence of the aqueous sample pH, salt addition and extraction time in the removal were evaluated. The results showed the high adsorption affinity of C₁₈-Mica-4 for most of the emerging pollutants analysed after a removal time of 24 h (14 out of 18 pollutants were effectively removed [70-100%]). A high correlation was observed between the log K_ow of the selected emerging pollutants and the adsorption onto C₁₈-Mica-4. The results also indicate that adsorption occurs in the interlayer space. While the removal rates with Na-Mica-4 were in the range 8-97% after seven days, some of the compounds, perfluorobutanoic acid and most of pharmaceutically active compounds, were not adsorbed onto the high-charge mica. C₁₈-Mica- 4 was effectively used for the removal of contaminants from four types of water samples.

Elucidating the Photocatalytic Behavior of TiO₂-SnS₂ Composites Based on Their Energy Band Structure

TiO₂-SnS₂ composite semiconducting photocatalysts with different building component ratios were prepared by hydrothermal synthesis (TiO₂-SnS₂-HT) and by immobilization of commercial TiO₂ and SnS₂ particles (TiO₂-SnS₂-COMM). The band gap values, which determine the catalysts’ photoactivity, were examined by diffuse reflectance spectroscopy and Kubelka–Munk transformations. The catalysts’ surface properties: specific surface area, charge and adsorption capacitance at the solid–solution interface were characterized using BET analysis, potentiometric titration and electrochemical impedance spectroscopy, respectively. The electronic band structure of TiO₂-SnS₂ photocatalyst, as the key property for the solar-driven photocatalysis, was deduced from the thermodynamic data and the semiconducting parameters (type of semiconductivity, concentration of the charge carriers, flat band potential) obtained by Mott–Schottky analysis. The photoactivity of both composites was studied in photocatalytic treatment of diclofenac (DCF) under simulated solar irradiation and was compared to the benchmark photocatalyst (TiO₂ P25) activity. The influence of process parameters, such as pH, H₂O₂, and composite formulation on the effectiveness of DCF removal and conversion was investigated and discussed by employing response surface modeling (RSM) approach. The photocatalytic efficiency of both composite materials was discussed on the basis of the hetereojunction formation that facilitated the photoelectron transfer, promoting more efficient photocatalytic degradation of DCF.