Performance of secondary wastewater treatment methods for the removal of contaminants of emerging concern implicated in crop uptake and antibiotic resistance spread: A review

Characterisation of microbial communities and quantification of antibiotic resistance genes in Italian wastewater treatment plants using 16S rRNA sequencing and digital PCR

The spread of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in humans, animals and environment is a growing threat to public health. Wastewater treatment plants (WWTPs) are crucial in mitigating the risk of environmental contamination by effectively removing contaminants before discharge. However, the persistence of ARB and ARGs even after treatment is a challenge for the management of water system. To comprehensively assess antimicrobial resistance dynamics, we conducted a one-year monitoring study in three WWTPs in central Italy, both influents and effluents. We used seasonal sampling to analyze microbial communities by 16S rRNA, as well as to determine the prevalence and behaviour of major ARGs (sul1, tetA, blaTEM, blaOXA-48, blaCTX-M-1 group, blaKPC) and the class 1 Integron (int1). Predominant genera included in order: Arcobacter, Acinetobacter, Flavobacterium, Pseudarcobacter, Bacteroides, Aeromonas, Trichococcus, Cloacibacterium, Pseudomonas and Streptococcus. A higher diversity of bacterial communities was observed in the effluents compared to the influents. Within these communities, we also identified bacteria that may be associated with antibiotic resistance and pose a significant threat to human health. The mean concentrations (in gene copies per liter, gc/L) of ARGs and int1 in untreated wastewater (absolute abundance) were as follows: sul1 (4.1 × 109), tetA (5.2 × 108), blaTEM (1.1 × 108), blaOXA-48 (2.1 × 107), blaCTX-M-1 group (1.1 × 107), blaKPC (9.4 × 105), and int1 (5.5 × 109). The mean values in treated effluents showed reductions ranging from one to three log. However, after normalizing to the 16S rRNA gene (relative abundance), it was observed that in 37.5 % (42/112) of measurements, the relative abundance of ARGs increased in effluents compared to influents. Furthermore, correlations were identified between ARGs and bacterial genera including priority pathogens. This study improves our understanding of the dynamics of ARGs and provides insights to develop more effective strategies to reduce their spread, protecting public health and preserving the future efficacy of antibiotics.

Determination of antibiotics during treatment of hospital wastewater using automated solid-phase extraction followed by UHPLC-MS: occurrence, removal and environmental risks

The extent of removal of pharmaceuticals by African-based wastewater treatment plants (WWTPs) is relatively unknown with various studies observing high concentrations in effluents. This is mainly due to WWTPs still utilising the traditional treatment methods which are known to be less effective. In this study, 15 selected antibiotics (amoxicillin, ampicillin, azithromycin, ciprofloxacin, doxycycline, erythromycin, gentamicin, metronidazole, norfloxacin, ofloxacin, penicillin, sulfamethoxazole, sulfapyridine, tetracycline and trimethoprim) were monitored in wastewater as it goes through sedimentation (primary and secondary), aeration and chlorination stages of a WWTP. Analytical method involved solid-phase extraction followed by liquid chromatographic determination. Removal efficiencies during sedimentation were generally positive with doxycycline achieving 80-95.8%, while negative removal efficiencies were observed for penicillin V (-46.4 to -17.1%) and trimethoprim (-26.2 to -18.9%). The aeration and agitation stage resulted in concentration enhancement for several antibiotics with seven of them ranging between -273 and -15.5%. This stage was responsible for the relatively low overall removal efficiencies in which only 4 antibiotics (doxycycline, tetracycline, ciprofloxacin, and erythromycin) experienced overall removal efficiencies above 50%. The recorded effluent concentrations ranging between 0.0130 and 0.383 ng/mL were translated to low potential for development of antibiotic resistance genes in the receiving environments while ecotoxicity risk was high for only amoxicillin, ampicillin and sulfapyridine. The study has provided an overview of the performance of common wastewater treatment processes in South Africa and hopes that more monitoring and environmental risk data can be made available towards drafting of antibiotic priority lists that cater for Africa.

In situ activation of peroxymonosulfate with bioelectricity for sulfamethoxazole sustainable removal

Conventional electrochemical activation of peroxymonosulfate (PMS) is not very cost-effective and practical by the excessive input of energy. The electricity generated by photosynthetic microalgae fuel cells (MFCs) is utilized to activate PMS, which would achieve the combination of green bioelectricity and advanced oxidation processes for sustainable pollutants degradation. In this study, a novel dual-chamber of MFCs was constructed by using microalgae as anode electron donor and PMS as cathode electron acceptor, which was operating under both close-circuit and open-circuit conditions. Under close-circuit condition, 1-12 mM PMS in cathode was successfully in situ activated, where 32.00%-99.83% of SMX was removed within 24 h, which was about 1.21-1.78 times of that in the open-circuit of MFCs. Meanwhile, a significant increase in bioelectricity generation in MFCs was observed after the accumulation of microalgae biomass (4.65-5.37 mg/L), which was attributed to the efficient electron separation and transfer. Furthermore, the electrochemical analysis demonstrated that SMX or its products were functioned as electronic shuttles, facilitating the electrochemical reaction and altering the electrical capacitance. The quenching experiments and voltage output results reflected that complex active radical (SO4⋅-, ⋅OH, and 1O2) were involved in SMX removal. Seven degradation products of SMX were detected and S-N bond cleavage was the main degradation pathway. Predicted toxicity values calculated by ECOSAR program showed that all the products were less toxic or nontoxic. Finally, the density functional theory (DFT) calculations revealed that the O and N atoms on SMX were more susceptible to electrophilic reactions, which were more vulnerable to be attacked by reactive species. This study provided new insights into the activation of PMS by bioelectricity for SMX degradation, proposing the mechanisms for PMS activation and degradation sites of SMX.

Continuous UV-C/H2O2 and UV-C/Chlorine applied to municipal secondary effluent and nanofiltration retentate: Removal of contaminants of emerging concern, ecotoxicity, and reuse potential

As global effects of water scarcity raise concerns and environmental regulations evolve, contemporary wastewater treatment plants (WWTPs) face the challenge of effectively removing a diverse range of contaminants of emerging concern (CECs) from municipal effluents. This study focuses on the assessment of advanced oxidation processes (AOPs), specifically UV-C/H2O2 and UV-C/Chlorine, for the removal of 14 target CECs in municipal secondary effluent (MSE, spiked with 10 μg L-1 of each CEC) or in the subsequent MSE nanofiltration retentate (NFR, no spiking). Phototreatments were carried out in continuous mode operation, with a hydraulic retention time of 3.4 min, using a tube-in-tube membrane photoreactor. For both wastewater matrices, UV-C photolysis (3.3 kJ L-1) exhibited high efficacy in removing CECs susceptible to photolysis, although lower treatment performance was observed for NFR. In MSE, adding 10 mg L-1 of H2O2 or Cl2 enhanced treatment efficiency, with UV-C/H2O2 outperforming UV-C/Chlorine. Both UV-C/AOPs eliminated the chronic toxicity of MSE toward Chlorella vulgaris. In the NFR, not only was the degradation of target CECs diminished, but chronic toxicity to C. vulgaris persisted after both UV-C/AOPs, with UV-C/Chlorine increasing toxicity due to potential toxic by-products. Nanofiltration permeate (NFP) exhibited low CECs and microbial content. A single chlorine addition effectively controlled Escherichia coli regrowth for 3 days, proving NFP potential for safe reuse in crop irrigation (<1 CFU/100 mL for E. coli; <1 mg L-1 for free chlorine). These findings provide valuable insights into the applications and limitations of UV-C/H2O2 and UV-C/Chlorine for distinct wastewater treatment scenarios.

Biochemical responses in Pacific oysters Magallana gigas (Thunberg, 1793): Tools to evaluate the environmental quality of aquaculture areas

The discharge of sanitary sewage into the bays of the Florianópolis Metropolitan Area (Southern Brazil), has led to the contamination of oyster farms. Consequently, linear alkylbenzenes (LABs) were quantified in the sediment, and the biochemical responses in gills and digestive gland of oysters from six farms were assessed. Our findings revealed elevated levels of LABs in the sediment of the Imaruim and Serraria farms. Additionally, alterations were observed in the antioxidant enzymes: catalase, glutathione peroxidase and superoxide dismutase in both oyster tissue from the Serraria, Santo Antonio de Lisboa and Sambaqui farms. Furthermore, correlation analyses indicated strong and moderate associations between biochemical responses, organic contaminants, and certain physicochemical parameters. Consequently, our results demonstrated the activation of the antioxidant system in oysters, representing a protective response to the presence of sanitary sewage and other contaminants. Therefore, we propose the utilization of biochemical biomarkers for monitoring the environmental quality of farms.

Exposure of Danio rerio to environmental sulfamethoxazole may contribute to neurobehavioral abnormalities via gut microbiome disturbance

The neurotoxic effects and mechanisms of low-dose and long-term sulfamethoxazole (SMZ) exposure remain unknown. This study exposed zebrafish to environmental SMZ concentrations and observed behavioral outcomes. SMZ exposure increased hyperactivity and altered the transcript levels of 17 genes associated with neurological function. It impaired intestinal function by reducing the number of intestinal goblet cells and lipid content. Metabolomic results indicated that the contents of several lipids and amino acids in the gut were altered, which might affect the expression levels of neurological function-related genes. Metagenomic results demonstrated that SMZ exposure substantially altered the composition of the gut microbiome. Zebrafish receiving a transplanted fecal microbiome from the SMZ group were also found to exhibit abnormal behavior, suggesting that the gut microbiome is an important target for SMZ exposure-induced neurobehavioral abnormalities. Multi-omics correlation analysis revealed that gut micrometabolic function was related to differential gut metabolite levels, which may affect neurological function through the gut-brain-axis. Reduced abundance of Lefsonia and Microbacterium was strongly correlated with intestinal metabolic function and may be the key bacterial genera in neurobehavioral changes. This study confirms for the first time that SMZ-induced neurotoxicity in zebrafish is closely mediated by alterations in the gut microbiome.

An evaluation of conventional and nature-based technologies for controlling antibiotic-resistant bacteria and antibiotic-resistant genes in wastewater treatment plants

Antibiotic resistance is a globally recognized health concern which leads to longer hospital stays, increased morbidity, increased mortality, and higher medical costs. Understanding how antibiotic resistance persists and exchanges in environmental systems like soil, water, and wastewater are critically important for understanding the emergence of pathogens with new resistance profiles and the subsequent exposure of people who indirectly/directly come in contact with these pathogens. There are concerns about the widespread application of prophylactic antibiotics in the clinical and agriculture sectors, as well as chemicals/detergents used in food and manufacturing industries, especially the quaternary ammonium compounds which have been found responsible for the generation of resistant genes in water and soil. The rates of horizontal gene transfer increase where there is a lack of proper water/wastewater infrastructure, high antibiotic manufacturing industries, or endpoint users - such as hospitals and intensive agriculture. Conventional wastewater treatment technologies are often inefficient in the reduction of ARB/ARGs and provide the perfect combination of conditions for the development of antibiotic resistance. The wastewater discharged from municipal facilities may therefore be enriched with bacterial communities/pathogens and provide a suitable environment (due to the presence of nutrients and other pollutants) to enhance the transfer of antibiotic resistance. However, facilities with tertiary treatment (either traditional/emerging technologies) provide higher rates of reduction. This review provides a synthesis of the current understanding of wastewater treatment and antibiotic resistance, examining the drivers that may accelerate their possible transmission to a different environment, and highlighting the need for tertiary technologies used in treatment plants for the reduction of resistant bacteria/genes.

Antibiotics and antibiotic resistance genes removal in biological aerated filter

Two laboratory-level biological aerated filters (BAF) were constructed to explore their treatment capacity for simulated antibiotic wastewater at high (1 - 16 mg/L) and low (0 - 0.5 mg/L) concentrations. Results showed that BAF was capable of removing both sulfonamides and tetracyclines with an efficiency of over 90 % at 16 mg/L. The main mechanism for removing antibiotics was found to be biodegradation followed by adsorption. Paenarthrobacter was identified as the key genus in sulfonamides degradation, while Hydrogenophaga played a crucial role in tetracyclines degradation. Antibiotics resistant genes such as intI1, sul1, sul2, tetA, tetW and tetX were frequently detected in the effluent, with interception rates ranging from 105 - 106 copies/mL. The dominated microorganisms obtained in the study could potentially be utilized to enhance the capacity of biological processes for treating antibiotics contaminated wastewater. These findings contribute to a better understanding of BAF treating wastewater containing antibiotics and resistant genes.

Occurrence and environmental risks of contaminants of emerging concern across the River Athi Basin, Kenya, in dry and wet seasons

Globally, the environmental occurrence of Contaminants of Emerging Concern (CECs) including pharmaceuticals (PhACs), personal care products (PCPs) and modern polar pesticides has raised ecological and human health awareness. However, as the developed world races against time to establish regulatory measures to mitigate their effects, developing nations including Kenya are lagging behind, partly due to unavailability of adequate data. In this work, a multi-residue analysis of 86 CECs was carried out on 198 surface water and 18 effluent samples collected at 24 sites across the River Athi basin area, Kenya, in both dry and rainy seasons. Overall, 57 CECs comprising 31 PhACs (0.4 ng L-1-142 μg L-1), 6 PCPs (0.7-570 ng L-1) and 20 pesticides (0.3 ng L-1-8.3 μg L-1) were detected. The maximum loads varied from 217 g day-1 (PCPs) to 46 kg day-1 (PhACs). Individually, carbamazepine, nevirapine, sulfamethoxazole and DEET were the most ubiquitous CECs, with detection frequencies (DF) higher than 80 %. The highest concentrations were observed at river sites that are heavily impacted by informal settlements, highlighting the critical role of slums in urban rivers pollution. At least 8 CECs including acetamiprid, alachlor, atrazine, diuron, nevirapine and paracetamol show potential risk to algae, Daphnia magna and fish, as exemplified by Risk Quotients (RQ) up to 174. Similarly, potential risk of antibiotic resistant bacteria development is evident (RQ up to 64), being driven by metronidazole, sulfamethoxazole and trimethoprim. Ultimately, further studies on the occurrence and distribution of antibiotic resistant bacteria within the basin and among the communities consuming untreated river water for drinking is merited.

Removal of selected sulfonamides and sulfonamide resistance genes from wastewater in full-scale constructed wetlands

Sulfonamides are high-consumption antibiotics that reach the aquatic environment. The threat related to their presence in wastewater and the environment is not only associated with their antibacterial properties, but also with risk of the spread of drug resistance in bacteria. Therefore, the aim of this work was to evaluate the occurrence of eight commonly used sulfonamides, sulfonamide resistance genes (sul1-3) and integrase genes intI1-3 in five full-scale constructed wetlands (CWs) differing in design (including hybrid systems) and in the source of wastewater (agricultural drainage, domestic sewage/surface runoff, and animal runs runoff in a zoo). The CWs were located in low-urbanized areas in Poland and in Czechia. No sulfonamides were detected in the CW treating agricultural tile drainage water. In the other four systems, four sulfonamide compounds were detected. Sulfamethoxazole exhibited the highest concentration in those four CWs and its highest was 12,603.23 ± 1000.66 ng/L in a CW treating a mixture of domestic sewage and surface runoff. Despite the high removal efficiencies of sulfamethoxazole in the tested CWs (86 %-99 %), it was still detected in the treated wastewater. The sul1 genes occurred in all samples of raw and treated wastewater and their abundance did not change significantly after the treatment process and it was, predominantly, at the level 105 gene copies numbers/mL. Noteworthy, sul2 genes were only found in the influents, and sul3 were not detected. The sulfonamides can be removed in CWs, but their elimination is not complete. However, hybrid CWs treating sewage were superior in decreasing the relative abundance of genes and the concentration of SMX. CWs may play a role in the dissemination of sulfonamide resistance genes of the sul1 type and other determinants of drug resistance, such as the intI1 gene, in the environment, however, the magnitude of this phenomenon is a matter of further research.

Microbial biofilm metabolization of benzalkonium compounds (benzyl dimethyl dodecyl ammonium & benzyl dimethyl tetradecyl ammonium chloride)

Benzalkonium chlorides (BACs) are quaternary ammonium compounds (QUATs) that are used as biocides. The degradation of these compounds in wastewater treatment plants is essential to reduce their spread into the environment and thus prevent the development of QUAT-resistant genes. The biodegradation of two BACs (BAC-12 and BAC-14) was investigated in moving bed biofilm reactors (MBBRs). Degradation half-lives of 12 and 20 h for BAC-12 and - 14, respectively, were detected as well as the formation of 42 metabolites. Two new degradation pathways for the BACs were identified in this study: 1) one involving an ω-oxidation, followed by β-oxidation and 2) one via an ω-oxidation followed by an α-oxidation that was succeeded by β-oxidation. Similar metabolites were detected for both BAC-12 and BAC-14. Additional metabolites were detected in the study, that could not be assigned to the above-mentioned pathways, revealing even more metabolic pathways in the MBBR which is probably due to the complexity of the microbial community in the biofilm. Interestingly, both TP194 (Benzyl-(carboxymethyl)-dimethylazanium) and TP208B (Benzyl-(2-carboxyethyl)-dimethylazanium) were identified as end products of the ω/β-pathway and the α/β-pathway. TP208B, TP152 and TP250 that were identified in this study, as well as the known BDMA were discovered in the effluent of a wastewater treatment plant.

Integrated control strategy for dual sludge ages in the high-concentration powder carrier bio-fluidized bed (HPB) technology: Enhancing municipal wastewater treatment efficiency

The high-concentration powder carrier bio-fluidized bed (HPB) technology is an emerging approach that enables on-site upgrading of wastewater treatment plants (WWTPs). HPB technology promotes the formation of biofilm sludge with micron-scale composite powder carriers as the core and suspended sludge mainly composed of flocs surrounding the biofilm sludge. This study proposed a novel integrated strategy for assessing and controlling the sludge ages in suspended/bio-film activated sludge supported by micron-scale composite powder carrier. Utilizing the cyclone unit and the corresponding theoretical model, the proposed strategy effectively addresses the sludge ages contradiction between denitrifying bacteria and polyphosphate-accumulating organisms (PAOs), thereby enhancing the efficiency of municipal wastewater treatment. The sludge age of the suspended (25 d) and bio-film (99 d) sludge, calculated using the model, contribute to the simultaneous removal of nitrogen and phosphorus. Meanwhile, the model further estimates distinct contributions of suspended and bio-film sludge to chemical oxygen demand (COD) and total nitrogen (TN), which are 55% and 42% for COD, 20% and 57% for TN of suspended sludge and bio-film sludge, respectively. This suggests that the contribution of suspended sludge and bio-film sludge to COD and TN removal efficiency can be determined and controlled by the operational conditions of the cyclone unit. Additionally, the simulation values for COD, ammonia nitrogen (NH4+-N), TN and total phosphorus (TP) closely align with the actual values of WWTPs over 70 days (p < 0.001) with the correlation coefficients (R2) of 0.9809, 0.9932, 0.9825, and 0.837, respectively. These results support the theoretical foundation of HPB technology for simultaneous nitrogen and phosphorus removal in sewage treatment plants. Therefore, this model serves as a valuable tool to guide the operation, design, and carrier addition in HPB technology implementation.

A case study on pharmaceutical residues and antimicrobial resistance genes in Costa Rican rivers: A possible route of contamination for feline and other species

In this investigation, the presence of antibiotics and pharmaceuticals in Costa Rican surface waters, specifically in regions near feline habitats, was examined. The study revealed that 47% of the water samples contained detectable traces of at least one antibiotic. Ciprofloxacin and norfloxacin were the most frequently detected compounds, each with a detection rate of 27%. Other antibiotics, such as erythromycin, roxithromycin, and trimethoprim, were also found but at lower frequencies, around 14%. Notably, all antibiotic concentrations remained below 10 ng/L, with ciprofloxacin, norfloxacin, and erythromycin showing the highest concentrations. Furthermore, the investigation revealed the presence of non-antibiotic pharmaceutical residues in the water samples, typically at concentrations below 64 ng/L. Tramadol was the most frequently detected compound, present in 18% of the samples. The highest concentrations were observed for acetaminophen and tramadol, measuring 64 and 10 ng/L, respectively. Comparing these findings with studies conducted in treated wastewater and urban rivers, it became evident that the concentrations of antibiotics and pharmaceuticals were notably lower in this study. While previous research reported higher values, the limited number of studies conducted in protected areas raises concerns about the potential environmental impact on biodiversity. In summary, these results emphasize the importance of monitoring pharmaceutical residues and antimicrobial resistance genes ARGs in vulnerable ecosystems, especially those in close proximity to feline habitats in Costa Rica. Additionally, the study delved into the detection of (ARGs). All tested water samples were positive for at least one ARG, with the blaTEM gene being the most prevalent at 82%, followed by tetS at 64% and qnrB at 23%. Moreover, this research shed light on the complexity of evaluating ARGs in environmental samples, as their presence does not necessarily indicate their expression. It also highlighted the potential for co-selection and co-regulation of ARGs, showcasing the intricate behaviors of these genes in aquatic environments.

Multi-target assessment of advanced oxidation processes-based strategies for indirect potable reuse of tertiary wastewater: Fate of compounds of emerging concerns, microbial and ecotoxicological parameters

Two advanced oxidation processes (AOPs), namely ozone/H2O2 and UV/H2O2, were tested at pilot scale as zero-liquid-discharge alternative treatments for the removal of microbiological (bacteria and viruses), chemical (compounds of emerging concern (CECs)) and genotoxic responses from tertiary municipal wastewater for indirect potable reuse (IPR). The AOP treated effluents were further subjected to granular activated carbon (GAC) adsorption and UV disinfection, following the concept of multiple treatment barriers. As a reference, a consolidated advanced wastewater treatment train consisting of ultrafiltration, UV disinfection, and reverse osmosis (RO) was also employed. The results showed that, for the same electrical energy applied, the ozone/H2O2 treatment was more effective than the UV/H2O2 treatment in removing CECs. Specifically, the ozone/H2O2 treatment, intensified by high pressure and high mixing, achieved an average CECs removal efficiency higher than UV/H2O2 (66.8% with respect to 18.4%). The subsequent GAC adsorption step, applied downstream the AOPs, further improved the removal efficiency of the whole treatment trains, achieving rates of 98.5% and 96.8% for the ozone/H2O2 and UV/H2O2 treatments, respectively. In contrast, the ultrafiltration step of the reference treatment train only achieved a removal percentage of 22.5%, which increased to 99% when reverse osmosis was used as the final step. Microbiological investigations showed that all three wastewater treatment lines displayed good performance in the complete removal of regulated and optional parameters according to both national and the European Directive 2020/2184. Only P. aeruginosa resulted resistant to all treatments with a higher removal by UV/H2O2 when higher UV dose was applied. In addition, E. coli STEC/VTEC and enteric viruses, were found to be completely removed in all tested treatments and no genotoxic activity was detected even after a 1000-fold concentration. The obtained results suggest that the investigated treatments are suitable for groundwater recharge to be used as a potable water source being such a procedure an IPR. The intensified ozone/H2O2 or UV/H2O2 treatments can be conveniently incorporated into a multi-barrier zero-liquid-discharge scheme, thus avoiding the management issues associated with the retentate of the conventional scheme that uses reverse osmosis. By including the chemical cost associated with using 11-12 mg/L of H2O2 in the cost calculations, the overall operational cost (energy plus chemical) required to achieve 50% average CECs removal in tertiary effluent for an hypothetical full-scale plant of 250 m3/h (or 25,000 inhabitants) was 0.183 €/m3 and 0.425 €/m3 for ozone/H2O2 and UV/H2O2 treatment train, respectively.

Removal of pharmaceutical compounds from the liquid phase of anaerobic sludge in a pilot-scale high-rate algae-bacteria pond

This study evaluates the effectiveness of a pilot-scale high-rate algae-bacteria pond (HRAP) to remove pharmaceutical compounds (PhACs) from municipal centrate. The studied PhACs belonged to different classes of synthetic active compounds: antihypertensives, antiepileptics, antidepressants, neuroprotectors, and anti-inflammatory drugs. The HRAP, growing a mixed microalgal consortium made of Chlorella spp. and Scenedesmus spp., was operated in continuous mode (6 days hydraulic retention time) from May to November 2021. Removal efficiencies were high (>85 %) for Sulfamethoxazole and Lamotrigine, promising (65-70 %) for Metoprolol, Fluoxetine, and Diclofenac but low (30-40 %) for Amisulpride, Ofloxacin, Carbamazepine, and Clarithromycin. Propyphenazone and Irbesartan were not removed, and their concentrations increased after the treatment. The combination of abiotic and biotic drivers (mostly global radiation and the synergy between microalgae and bacteria metabolisms) fostered photo and biodegradation processes. Overall, results suggest that microalgae-based systems can be a valuable solution to remove PhACs from wastewater.

Tertiary/quaternary treatment of urban wastewater by UV/H2O2 or ozonation: Microplastics may affect removal of E. coli and contaminants of emerging concern

The aim of this study was to investigate the interference of polyethylene microplastics (MPs) on ultraviolet irradiation/hydrogen peroxide (UV/H2O2) and ozonation processes in the inactivation of E. coli bacteria (tertiary treatment) and removal of contaminants of emerging concern (CECs) (quaternary treatment) from simulated and real secondary treated urban wastewater. Three pharmaceuticals were investigated as model CECs, namely carbamazepine, sulfamethoxazole and trimethoprim. Experimental results showed that disinfection efficiency of UV/H2O2 treatment decreased (2.4, 1.8 and 1.3 log reductions of E. coli, initial H2O2 dose of 30 mg/L, 2.5 min treatment) as the initial concentration of MPs was increased (0.25, 0.5 and 1.0 g/L, respectively). Similarly, an increase in MPs concentration (0.25, 0.5 and 1.0 g/L) reduced the inactivation (4.7, 4.1 and 3.7 log reductions) of the target bacteria after 60 min of ozonation treatment. Although the disinfection efficiency of both treatment processes was negatively affected by the presence of MPs, UV/H2O2 was more effective than the ozonation, despite ozonation being investigated at high doses to better discriminate the effect of MPs. Noteworthy, CECs degradation by UV/H2O2 under realistic operating conditions was affected to some extent by MPs, while a lower effect was observed for ozonation, at not realistic ozone dose.

Current challenges and future perspectives for the full circular economy of water in European countries

This paper reviews the current problems and prospects to overcome circular water economy management challenges in European countries. The geopolitical paradigm of water, the water economy, water innovation, water management and regulation in Europe, environmental and safety concerns at water reuse, and technological solutions for water recovery are all covered in this review, which has been prepared in the frame of the COST ACTION (CA, 20133) FULLRECO4US, Working Group (WG) 4. With a Circular Economy approach to water recycling and recovery based on this COST Action, this review paper aims to develop novel, futuristic solutions to overcome the difficulties that the European Union (EU) is currently facing. The detailed review of the current environmental barriers and upcoming difficulties for water reuse in Europe with a Circular Economy vision is another distinctive aspect of this study. It is observed that the biggest challenge in using and recycling water from wastewater treatment plants is dealing with technical, social, political, and economic issues. For instance, geographical differences significantly affect technological problems, and it is effective in terms of social acceptance of the reuse of treated water. Local governmental organizations should support and encourage initiatives to expand water reuse, particularly for agricultural and industrial uses across all of Europe. It should not also be disregarded that the latest hydro politics approach to water management will actively contribute to addressing the issues associated with water scarcity.

Solar heterogeneous photo-Fenton for complete inactivation of Escherichia coli and Salmonella typhimurium in secondary-treated wastewater effluent

In this work, complete elimination of Escherichia coli and Salmonella typhimurium was achieved in 120 min using a heterogeneous photo-Fenton process under sunlight at pH 6.5 in distilled water. A face-centered composite central design 22 with one categoric factor and three replicates at the central point was used to evaluate the effect of iron (III) oxide concentration (0.8-3.4 mg L-1), H2O2 (2-10 mg L-1), and the type of iron oxide phase (maghemite and hematite) on the inactivation of both bacteria. The results showed that the amount of catalyst, H2O2 concentration and their interaction were significant factors (p < 0.05) in the elimination of the microorganisms. Thus, under the best conditions (3.4 mg L-1 of iron (III) oxide and 10 mg L-1 of H2O2) in the experimental ranges, complete inactivation of E. coli and S. typhimurium was achieved (6-log reduction) in 120 min using the photo-Fenton treatment with both iron-oxide phases. Furthermore, the photocatalytic elimination of both bacteria by the photo-Fenton process using hematite and maghemite in secondary-treated wastewater effluent was performed obtaining slower inactivation rates (1.2-5.9 times) than in distilled water due to the matrix effect of the effluent from a wastewater treatment plant. Nevertheless, the process continued to be effective in the effluent, achieving complete bacterial elimination in 150 min using the hematite phase. Additionally, the SEM images of the bacterial cells showed that the heterogeneous photo-Fenton treatment generated permanent and irreversible cell damage, resulting in complete cell death.

Continuous solar photo-Fenton for wastewater reclamation in operational environment at demonstration scale

For the first time, a continuous flow solar photo-Fenton demonstration plant has been assessed for wastewater reclamation according to the EU 2020/741 regulation. The treated water qualities achieved under two operating strategies (acidic and neutral pH) in a 100-m2 raceway pond reactor were explored in terms of liquid depth, iron source, reagent concentrations, and hydraulic residence time over three consecutive days of operation. The results obtained at acidic pH showed removal percentages of contaminants of emerging concern (CECs) > 75% and water quality classes B, C and D according to EU regulation at both assessed operating conditions, with treatment capacities up to 1.92 m3 m-2 d-1. At neutral pH with ferric nitrilotriacetate (Fe3+-NTA), 50% of CEC removal and only water quality class D were achieved with the most oxidizing condition assessed, giving a treatment capacity of 0.80 m3 m-2 d-1. The treatment capacities obtained in this work, which have never been achieved with solar water treatments, demonstrate the potential of this technology for commercial-scale application.

Solar photo-Fenton optimization at neutral pH for microcontaminant removal at pilot plant scale

The increasing occurrence of micropollutants in natural water bodies has medium to long-term effects on both aquatic life and human health. The aim of this study is to optimize the degradation of two pharmaceutical pollutants of emerging concern: amoxicillin and acetaminophen in aqueous solution at laboratory and pilot scale, by solar photo-Fenton process carried out at neutral pH using ethylenediamine-N,N'-disuccinic acid (EDDS) as a complexing agent to maintain iron in solution. The initial concentration of each compound was set at 1 mg/L dissolved in a simulated effluent from a municipal wastewater treatment plant (MWTP). A factorial experimental design and its surface response analysis were used to optimize the operating parameters to achieve the highest initial degradation rate of each target. The evolution of the degradation process was measured by ultra-performance liquid chromatography (UPLC/UV), obtaining elimination rates above 90% for both contaminants. Statistical study showed the optimum concentrations of Fe(III) at 3 mg/L at an Fe-EDDS ratio of 1:2 and 2.75 mg/L H2O2 for the almost complete removal of the target compounds by solar photo-Fenton process. Validation of the experimental design was successfully carried out with actual MWTP effluent spiked with 100 μg/L of amoxicillin and acetaminophen, each at pilot plant scale.

Microbiome and Resistome Profiles along a Sewage-Effluent-Reservoir Trajectory Underline the Role of Natural Attenuation in Wastewater Stabilization Reservoirs

Antibiotic-resistant bacteria and antibiotic resistance gene (ARGs) loads dissipate through sewage treatment plants to receiving aquatic environments, but the mechanisms that mitigate the spread of these ARGs are not well understood due to the complexity of full-scale systems and the difficulty of source tracking in downstream environments. To overcome this problem, we targeted a controlled experimental system comprising a semicommercial membrane-aerated bioreactor (MABR), whose effluents fed a 4,500-L polypropylene basin that mimicked effluent stabilization reservoirs and receiving aquatic ecosystems. We analyzed a large set of physicochemical measurements, concomitant with the cultivation of total and cefotaxime-resistant Escherichia coli, microbial community analyses, and quantitative PCR (qPCR)/digital droplet PCR (ddPCR) quantification of selected ARGs and mobile genetic elements (MGEs). The MABR removed most of the sewage-derived organic carbon and nitrogen, and simultaneously, E. coli, ARG, and MGE levels dropped by approximately 1.5- and 1.0-log unit mL-1, respectively. Similar levels of E. coli, ARGs, and MGEs were removed in the reservoir, but interestingly, unlike in the MABR, the relative abundance (normalized to 16S rRNA gene-inferred total bacterial abundance) of these genes also decreased. Microbial community analyses revealed the substantial shifts in bacterial and eukaryotic community composition in the reservoir relative to the MABR. Collectively, our observations lead us to conclude that the removal of ARGs in the MABR is mainly a consequence of treatment-facilitated biomass removal, whereas in the stabilization reservoir, mitigation is linked to natural attenuation associated with ecosystem functioning, which includes abiotic parameters, and the development of native microbiomes that prevent the establishment of wastewater-derived bacteria and associated ARGs. IMPORTANCE Wastewater treatment plants are sources of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), which can contaminate receiving aquatic environments and contribute to antibiotic resistance. We focused on a controlled experimental system comprising a semicommercial membrane-aerated bioreactor (MABR) that treated raw sewage, whose effluents fed a 4,500-L polypropylene basin that mimicked effluent stabilization reservoirs. We evaluated ARB and ARG dynamics across the raw-sewage-MABR-effluent trajectory, concomitant with evaluation of microbial community composition and physicochemical parameters, in an attempt to identify mechanisms associated with ARB and ARG dissipation. We found that removal of ARB and ARGs in the MABR was primarily associated with bacterial death or sludge removal, whereas in the reservoir it was attributed to the inability of ARBs and associated ARGs to colonize the reservoir due to a dynamic and persistent microbial community. The study demonstrates the importance of ecosystem functioning in removing microbial contaminants from wastewater.

Chelating agents supported solar photo-Fenton and sunlight/H2O2 processes for pharmaceuticals removal and resistant pathogens inactivation in quaternary treatment for urban wastewater reuse

In this work, Fe³⁺-iminodisuccinic acid (Fe:IDS) based solar photo Fenton (SPF), an Italian patented method, was investigated in quaternary treatment of real urban wastewater and compared to Fe³⁺-ethylenediamine-N,N'-disuccinic acid (Fe:EDDS) for the first time. Three pharmaceuticals (PCs) (sulfamethoxazole, carbamazepine and trimethoprim) and four pathogens (Escherichia coli, somatic and F-plus coliphages, Clostridium perfringens, consistently with the new EU regulation for wastewater reuse (2020/741)), were chosen as target pollutants. SPF with Fe:EDDS was more effective in PCs removal (80%, 10 kJ L^-1) than the SPF with Fe:IDS (58%), possibly due to the higher capability of generating hydroxyl radicals. On the contrary, Fe:IDS was more effective (4.3 log inactivation for E. coli) than Fe:EDDS (1.9 log) in pathogens inactivation, possibly due to a lower iron precipitation and turbidity which finally promoted an improved intracellular photo-Fenton mechanism. Fe:L based SPF was subsequently coupled to sunlight/H₂O₂. Interestingly, while its combination with Fe:EDDS based SPF slightly increased disinfectant efficacy (2.3 vs 1.9 log inactivation for E. coli), the combination with Fe:IDS decreased inactivation efficiency (3.4 vs 4.3 log reduction). In conclusion, due to the good compromise between PCs removal and disinfection efficiency, Fe:IDS SPF alone is an attractive option for quaternary treatment for urban wastewater reuse.

Environmental risks of antibiotic resistance genes released from biological laboratories and its control measure

Antibiotic resistance genes (ARGs) are a growing global threat to public health. Biological laboratory wastewater contains large amounts of free ARGs. It is important to assess the risk of free ARGs from biological laboratories and to find appropriate treatments to control their spread. The fate of plasmids in the environment and the effect of different thermal treatments on their persistence activity were tested. The results showed that untreated resistance plasmids could exist in water for more than 24 h (the special 245 bp fragment). Gel electrophoresis and transformation assays showed that the plasmids boiled for 20 min retained 3.65% ± 0.31% transformation activity of the intact plasmids, while autoclaving for 20 min at 121 °C could effectively degrade the plasmids and that NaCl, bovine serum albumin, and EDTA-2Na affected the degradation efficiency of the plasmids during boiling. In the simulated aquatic system, using 10⁶ copy/μL of plasmids after autoclaving, only 10² copies/μL of the fragment after only 1-2 h could be detected. By contrast, boiled plasmids for 20 min were still detectable after plunging them into water for 24 h. These findings suggest that untreated and boiled plasmids can remain in the aquatic environment for a certain time resulting in the risk of disseminating ARGs. However, autoclaving is an effective way of degrading waste free resistance plasmids.

Spatial Distribution and Risk Assessment of Antibiotics in 15 Pharmaceutical Plants in the Pearl River Delta

Pharmaceutical plants are an essential source of antibiotics emitted into the aqueous environment. The monitoring of target antibiotics in pharmaceutical plants through various regions is vital to optimize contaminant release. The occurrence, distribution, removal, and ecological risk of 30 kinds of selected antibiotics in 15 pharmaceutical plants in the Pearl River Delta (PRD) were investigated in this study. Lincomycin (LIN) showed the highest concentration (up to 56,258.3 ng/L) in the pharmaceutical plant influents from Zhongshan city. Norfloxacin (NFX) showed a higher detection frequency than other antibiotics. In addition, the spatial distribution of antibiotics in pharmaceutical plants showed significant differences, with higher concentrations of total antibiotics found in pharmaceutical plant influents in Shenzhen City than those of different regions in PRD. The treatment processes adopted by pharmaceutical plants were commonly ineffective in removing antibiotics, with only 26.7% of antibiotics being effectively removed (average removal greater than 70%), while 55.6% of antibiotics had removal rates of below 60%. The anaerobic/anoxic/oxic (AAO)-membrane bioreactor (MBR) combined process exhibited better treatment performance than the single treatment process. Sulfamethoxazole (SMX), ofloxacin (OFL), erythromycin-H₂O (ETM-H₂O), sulfadiazine (SDZ), sulfamethazine (SMZ), norfloxacin (NFX), and ciprofloxacin (CIP) in pharmaceutical plant effluents posed high or moderate ecological risk and deserve particular attention.

Emerging environmental contaminants: A global perspective on policies and regulations

Emerging contaminants include many synthetic or natural substances, such as pharmaceuticals and personal care products, hormones, and flame retardants that are not often controlled or monitored in the environment. The consumption or use of these substances is on an ever-rising trend, which dangerously increases their prevalence in practically all environmental matrices. These contaminants are present in low environmental concentrations and cause severe effects on human health and the biota. The present review analyzed 2012-2022 years papers via PubChem, science direct, National Center for Biotechnology Information, web of science on the legislations and policies of emerging contaminants globally. A state-of-the-art review of several studies in the literature focus on examining and evaluating the emerging contaminants and the frameworks adopted by developed and developing countries to combat the release of emerging contaminants and form footprints towards water sustainability which includes water availability, usage patterns, generation and pollution management, the health of aquatic systems, and societal vulnerability. The paper aims to provide a comprehensive view of current global policies and framework regarding evaluating and assessing the chemicals, in light of being a threat to the environment and biota. The review also highlights the future global prospects, including current governmental activities and emerging contaminant policy measures. The review concludes with suggestions and way forward to control the inventory and disposal of emerging contaminants in the environment.

Using integrative samplers to estimate the removal of pharmaceuticals and personal care products in a WWTP and by soil aquifer treatment enhanced with a reactive barrier

The need and availability of freshwater is a major environmental issue, aggravated by climate change. It is necessary to find alternative sources of freshwater. Wastewater could represent a valid option but requires extensive treatment to remove wastewater-borne contaminants, such as contaminants of emerging concern (CECs). It is urgent to develop not only sustainable and effective wastewater treatment techniques, but also water quality assessment methods. In this study, we used polar organic chemical integrative samplers (POCIS) to investigate the presence and abatement of contaminants in an urban wastewater treatment plant (WWTP) and in soil aquifer treatment (SAT) systems (a conventional one and one enhanced with a reactive barrier). This approach allowed us to overcome inter-day and intraday variability of the wastewater composition. Passive sampler extracts were analyzed to investigate contamination from 56 pharmaceuticals and personal care products (PPCPs). Data from the POCIS were used to estimate PPCPs' removal efficiency along the WWTP and the SAT systems. A total of 31 compounds, out of the 56 investigated, were detected in the WWTP influent. Removal rates along WWTP were highly variable (16-100 %), with benzophenone-3, benzophenone-1, parabens, ciprofloxacin, ibuprofen, and acetaminophen as the most effectively removed chemicals. The two SAT systems yielded much higher elimination rates than those achieved through the primary and secondary treatments together. The SAT system that integrated a reactive barrier, based on sustainable materials to promote enhanced elimination of CECs, was significantly more efficient than the conventional one. The removal of the recalcitrant carbamazepine and its epoxy- metabolite was especially remarkable in this SAT, with removal rates between 69-81 % and 63-70 %, respectively.

Evaluation of the bacterial contamination of face masks worn by personnel in a center of COVID 19 hospitalized patients: A cross-sectional study

Background

During the Coronavirus Pandemic, the use of masks has increased significantly. The lack of control on hygiene protocols and the need to use PPE properly increases the spread of bacterial infection. The purpose of this study was to investigate the degree of contamination and frequency of bacterial species isolated from surgical and N95 masks used by hospital personnel.

Methods

A total number of 175 masks were collected from staff working in Sina hospital (Hamadan province, Iran) during the first six months of 2022. The bacterial contamination of masks were evaluated and identified using biochemical kits. Antimicrobial susceptibility testing of the isolates were done using Kirby-Bauer methods and MIC were assessed for each isolate against different disinfectants (Sodium hypochlorite 5%, Hydrogen Peroxide 3%, Ethanol 70% and Deconex).

Results

Of 175 masks, 471 bacterial isolates were detected including 9 species. The most prevalent strain were Coagulase negative Staphylococcus (28%) followed by Acinetobacter (20.8%) and Pseudomonas (13.8%), while, Klebsiealla and Enterococcus were the least frequent species with the rate of 3.8% and 1.2%, respectively. The results of MIC methods indicated that all 471 strains were resistant to ehtanol70% and sensitive to hydrogen peroxide 3%. Furthermore, the mean average of Deconex inhibitory effect is lower than Sodium hypochlorite 5%.

Conclusions

According to the results of this study, there was a high prevalence of CoNS, Acinetobacter and Pseudomonas in hospital with a high resistance pattern against antibiotics especially Ampicillin and disinfectants.

Review of hospital effluents: special emphasis on characterization, impact, and treatment of pollutants and antibiotic resistance

Health care institutions generate large volumes of liquid effluents from specific activities related to healthcare, analysis, and research. Their direct discharge into the environment has various negative effects on aquatic environments and human health, due to their high organic matter charges and the presence of various emerging contaminants such as disinfectants, drugs, bacteria, viruses, and parasites. Moreover, hospital effluents, by carrying antibiotics, contribute to the development of antibiotic-resistant microorganisms in the environment. This resistance has become a global issue that manifests itself variously in different countries, causing the transmission of different infections. In this respect, an effort is provided to protect water resources by current treatment methods that imply physical-chemical processes such as adsorption and advanced oxidation processes, biological processes such as activated sludge and membrane bioreactors and other hybrid techniques. The purpose of this review is to improve the knowledge on the composition and impact of hospital wastewater on man and the environment, highlighting the different treatment techniques appropriate to this type of disposal before discharge into the environment.

Roles of substrates in removing antibiotics and antibiotic resistance genes in constructed wetlands: A review

Antibiotics and corresponding antibiotic resistance genes (ARGs) are emerging pollutants in wastewater that pose a significant threat to the environment and human health. Constructed wetlands (CWs) are a cost-effective technology for eliminating these pollutants through substrates, plants, and microorganisms. Detailed reviews of the roles of CW substrates on antibiotic and ARG removal and recent progress in the field are lacking. This paper reviews the mechanisms influencing antibiotic and ARG (intracellular and extracellular) removal in CWs, and natural, biomass, chemical, modified, industrial, novel, and combined substrates on their removal efficiencies. Generally, substrates remove antibiotics and ARGs mainly through adsorption, biodegradation, chemical oxidation, and filtration. Other mechanisms, such as photolysis, may also contribute to removal. Natural substrates (e.g., gravel, zeolite) are more frequently employed than other types of substrates. The removal performance of antibiotics and intracellular ARGs by zeolite was better than that of gravel through enhanced substrate adsorption, filtration, and biodegradation processes. Moreover, Mn ore showed promising high capability to remove high concentration of antibiotics through various removal pathways. In addition, combined substrates of soil/sand/gravel and other substrates further facilitate antibiotic removal. Future research is suggested to explore the mechanisms of competitive adsorption and redox-controlled biodegradation, investigate the effect of Fe/Mn oxides on the removal of antibiotics and ARGs via chemical oxidation, evaluate the removal of extracellular ARGs by CWs with different substrates, and investigate the effect of substrates on removal of antibiotics and ARGs in full-scale CWs.

Periodic mesoporous organosilicas containing naphthalenediimides as organic sensitizers for sulfadiazine photodegradation

In this work, periodic mesoporous organosilicas (PMO) functionalized with the organic sentisizer naphthalenediimide (NDI) were employed as heterogeneous catalysts for the photodegradation of the antibiotic sulfadiazine (SDZ), taken as a model for contaminants of emerging concern (CECs). The catalysts, designated as PMONDI, were prepared by surfactant-directed co-condensation of the precursor N,N'-bis(3-triethoxysilylpropyl)- 1,4,5,8-naphthalenediimide with tetraethoxysilane. The synthesized PMONDI were characterized using transmission electron microscopy, nitrogen adsorption isotherms and small and large angle x-ray scattering. The performance of PMONDI catalysts in the photodegradation of SDZ was compared to that of TiO₂ nanoparticles impregnated into SBA-15 mesoporous silica (TiO₂/SBA-15), under irradiation with a Hg lamp with a bandpass filter of 320-500 nm. Under optimal conditions, PMONDI degraded 100% of the SDZ in 45 min, while the total degradation of SDZ was achieved only after 150 min with TiO₂/SBA-15. PMONDI also performed better than TiO₂/SBA-15 in reuse tests. The mechanism of photodegradation with PMONDI involves the formation of excited triplet states of NDI (³NDI*) upon irradiation, which can then react with molecular oxygen to form reactive oxygen species, which degrade SDZ. Analysis of the SDZ degradation products indicated two main pathways: (1) hydroxylation of the aniline ring and (2) SO₂ extrusion and rearrangement, followed by oxidation of the aniline ring to nitrobenzene. In conclusion, the great potential of the PMONDI materials as photocatalysts for CECs degradation was demonstrated in this work, encouraging further research on these materials for the degradation of pollutants.

Removal effect of trihalomethanes (THMs) and halogenated acetic acids (HAAs) precursors in reclaimed water by polyaluminum chloride (PACl) coagulation

This study analyzed the removal effect of various doses of polyaluminum chloride (PACI) on wastewater treatment plants at pH 7. The sewage plant's secondary effluent organic matter (EfOM) separates into four components: hydrophobic base (HOB), hydrophilic (HI), hydrophobic acid (HOA), and hydrophobic neutral (HON). The removal effect for various forms of organic waste is optimum at 16 mg/L and that halogenated acetic acids (HAAs) and trihalomethanes (THMs) are formed simultaneously. After PACI treatment, hydrophobic organic compounds were converted to humic acid (HA), fulvic acid (FA), soluble microbial products (SMPs), and other HI organic compounds, increasing the amount of HAAs produced by HI fractions. Removal rate of hydrophobic organic compounds, particularly HON, is 92.8% when using PAC. Moreover, after EfOM coagulation, most HAAs are trichloroacetic acid (TCAA), followed by bromochloroacetic acid (BCAA) and bromodichloroacetic acid (BDCAA). Only HOB can produce monochloroacetic acid (MCAA), whereas HA and SMPs with HOA are primary components of dichloroacetic acid (DCAA). The toughest removable byproduct of THMs is CHBr₃, and after condensation of each THM component, only HOA and HON produce CHBr₃, while HI produces only a minimal quantity of CHBrCl₂ and CHCl₃.This finding is critical for understanding how disinfection byproducts are produced after chlorinating EfOM.

Modelling and prediction of the effect of operational parameters on the fate of contaminants of emerging concern in WWTPs

Wastewater treatment plants (WWTPs) provide a barrier against the discharge of contaminants of emerging concern (CECs) into the environment. The removal of CECs is highly WWTP-specific and the underlying mechanisms are still poorly understood, hampering the optimization of biological treatment steps for their removal. To fill this knowledge gap, we assessed the influence of four operational parameters of activated sludge biological treatment, namely total suspended solids, temperature, pH and redox conditions, on the sorption and biodegradation of four CECs under controlled laboratory conditions. Design of Experiments was used to better address the factors influencing CECs removal and interactions among operational parameters. The derived statistical models showed results in concordance with previous studies and indicated how sorption and biodegradation of the investigated CECs depend on most tested parameters and few of their interactions. The predictions of the developed models have been compared with literature values, indicating how the tested parameters are responsible for most of the variability of sorption, while they could not reliably generalize biodegradation rates. The developed models were also implemented as an extension of a mechanistic biological treatment model, successfully describing the dynamic behaviour of a large-scale WWTP, which was observed during a three-day continuous monitoring campaign. Compared to a traditional modelling approach, the one including the developed models showed on average almost a three-fold uncertainty reduction, favouring its use to aid WWTP managers and regulators for improved assessment of CEC fate and removal. Finally, the models highlighted that, while higher temperatures and solids concentrations generically favoured CECs removal, removal efficiency vary significantly due to operational parameters and no globally optimum conditions for CECs removal exist. The use of these models opens the door to the combined dynamic management of both traditional contaminants and CECs in WWTPs.

Contaminant Exposure and Transport from Three Potential Reuse Waters within a Single Watershed

Global demand for safe and sustainable water supplies necessitates a better understanding of contaminant exposures in potential reuse waters. In this study, we compared exposures and load contributions to surface water from the discharge of three reuse waters (wastewater effluent, urban stormwater, and agricultural runoff). Results document substantial and varying organic-chemical contribution to surface water from effluent discharges (e.g., disinfection byproducts [DBP], prescription pharmaceuticals, industrial/household chemicals), urban stormwater (e.g., polycyclic aromatic hydrocarbons, pesticides, nonprescription pharmaceuticals), and agricultural runoff (e.g., pesticides). Excluding DBPs, episodic storm-event organic concentrations and loads from urban stormwater were comparable to and often exceeded those of daily wastewater-effluent discharges. We also assessed if wastewater-effluent irrigation to corn resulted in measurable effects on organic-chemical concentrations in rain-induced agricultural runoff and harvested feedstock. Overall, the target-organic load of 491 g from wastewater-effluent irrigation to the study corn field during the 2019 growing season did not produce substantial dissolved organic-contaminant contributions in subsequent rain-induced runoff events. Out of the 140 detected organics in source wastewater-effluent irrigation, only imidacloprid and estrone had concentrations that resulted in observable differences between rain-induced agricultural runoff from the effluent-irrigated and nonirrigated corn fields. Analyses of pharmaceuticals and per-/polyfluoroalkyl substances in at-harvest corn-plant samples detected two prescription antibiotics, norfloxacin and ciprofloxacin, at concentrations of 36 and 70 ng/g, respectively, in effluent-irrigated corn-plant samples; no contaminants were detected in noneffluent irrigated corn-plant samples.

Removal of pharmaceutical active compounds in wastewater by constructed wetlands: Performance and mechanisms

The occurrence of pharmaceutical active compounds (PhACs) in aquatic environments is a cause for concern due to potential adverse effects on human and ecosystem health. Constructed wetlands (CWs) are cost-efficient and sustainable wastewater treatment systems for the removal of these PhACs. The removal processes and mechanisms comprise a complex interplay of photodegradation, biodegradation, phytoremediation, and sorption. This review synthesized the current knowledge on CWs for the removal of 20 widely detected PhACs in wastewater. In addition, the major removal mechanisms and influencing factors are discussed, enabling comprehensive and critical understanding for optimizing the removal of PhACs in CWs. Consequently, potential strategies for intensifying CWs system performance for PhACs removal are discussed. Overall, the results of this review showed that CWs performance in the elimination of some pharmaceuticals was on a par with conventional wastewater treatment plants (WWTPs) and, for others, it was above par. Furthermore, the findings indicated that system design, operational, and environmental factors played important but highly variable roles in the removal of pharmaceuticals. Nonetheless, although CWs were proven to be a more cost-efficient and sustainable technology for pharmaceuticals removal than other engineered treatment systems, there were still several research gaps to be addressed, mainly including the fate of a broad range of emerging contaminants in CWs, identification of specific functional microorganisms, transformation pathways of specific pharmaceuticals, assessment of transformation products and the ecotoxicity evaluation of CWs effluents.

A step forward on site-specific environmental risk assessment and insight into the main influencing factors of CECs removal from wastewater

The presence of Contaminants of Emerging Concern (CECs) in water systems has been recognized as a potential source of risk for human health and the ecosystem. The present paper aims at evaluating the effects of different characteristics of full-scale Wastewater Treatment Plants (WWTPs) on the removal of 14 selected CECs belonging to the classes of caffeine, illicit drugs and pharmaceuticals. Particularly, the investigated plants differed because of the treatment lay-out, the type of biological process, the value of the operating parameters, the fate of the treated effluent (i.e. release into surface water or reuse), and the treatment capacity. The activity consisted of measuring concentrations of the selected CECs and also traditional water quality parameters (i.e. COD, phosphorous, nitrogen species and TSS) in the influent and effluent of 8 plants. The study highlights that biodegradable CECs (cocaine, methamphetamine, amphetamine, benzoylecgonine, 11-nor-9carboxy-Δ9-THC, lincomycin, trimethoprim, sulfamethoxazole, sulfadiazine, sulfadimethoxine, carbamazepine, ketoprofen, warfarin and caffeine) were well removed by all the WWTPs, with the best performance achieved by the MBR for antibiotics. Carbamazepine was removed at the lowest extent by all the WWTPs. The environmental risk assessed by using the site-specific value of the dilution factor resulted to be high in 3 out of 8 WWTPs for carbamazepine and less frequently for caffeine. However, the risk was reduced when the dilution factor was assumed equal to the default value of 10 as proposed by EU guidelines. Therefore, a specific determination of this factor is needed taking into account the hydraulic characteristics of the receiving water body.

Occurrence and risk assessment of pharmaceuticals in surface waters of the Middle East and North Africa: A review

Pharmaceutical compounds in surface water are perceived as contaminants of emerging concern due to their impacts on the aquatic environment and human health. The risk associated with these compounds has not been quantified in the Middle East and North Africa (MENA). This review identified that 210 pharmaceutical compounds have been analyzed in MENA water compartments between 2008 and 2022. In fact, 151 of these substances were detected in at least one of 13 MENA countries where occurrence studies had been conducted. Antibiotics claimed the highest number of pharmaceuticals detected with concentrations ranging between 0.03 and 66,400 ng/L (for Thiamphenicol and Spiramycin respectively). To investigate whether any of these compounds exert an ecological, human health, or antibiotic resistance risk, a screening-level risk assessment was performed in surface water matrices using maximum, median, and minimum concentrations. 39 and 8 detected pharmaceuticals in MENA surface waters posed a possible risk on aquatic ecosystems and human health respectively. Extremely high risk quotients (>1000) for six pharmaceuticals (17β estradiol, spiramycin, diclofenac, metoprolol, ethinylestradiol, and carbamazepine) were enumerated based on maximal concentrations implying an alarming risk on aquatic toxicity. Moreover, hormones posed the highest possible risk on human health whether ingested through drinking water or fish (e.g., 17β-estradiol had a health risk quotient of 2880 for children). Spiramycin showed a high risk of antibiotic resistance with a risk quotient of 133. This review serves as a basis for future prioritization studies and regulatory guidelines in the MENA region to minimize the risks of the identified compounds.

Antibiotic resistant genes in the environment-exploring surveillance methods and sustainable remediation strategies of antibiotics and ARGs

Antibiotic Resistant Genes (ARGs) are an emerging environmental health threat due to the potential change in the human microbiome and selection for the emergence of antibiotic resistant bacteria. The rise of antibiotic resistant bacteria has caused a global health burden. The WHO (world health organization) predicts a rise in deaths due to antibiotic resistant infections. Since bacteria can acquire ARGs through horizontal transmission, it is important to assess the dissemination of antibioticresistant genes from anthropogenic sources. There are several sources of antibiotics, antibiotic resistant bacteria and genes in the environment. These include wastewater treatment plants, landfill leachate, agricultural, animal industrial sources and estuaries. The use of antibiotics is a worldwide practice that has resulted in the evolution of resistance to antibiotics. Our review provides a more comprehensive look into multiple sources of ARG's and antibiotics rather than one. Moreover, we focus on effective surveillance methods of ARGs and antibiotics and sustainable abiotic and biotic remediation strategies for removal and reduction of antibiotics and ARGs from both terrestrial and aquatic environments. Further, we consider the impact on public health as this problem cannot be addressed without a global transdisciplinary effort.

Pharmaceuticals in water as emerging pollutants for river health: A critical review under Indian conditions

The wastewaters from pharmaceutical manufacturing units, hospitals, and domestic sewage contaminated with excretal matters of medicine users are the prime sources of pharmaceutical pollutants (PPs) in natural water bodies. In the present study, PPs have been considered one of the emerging pollutants (EPs) and a cause of concern in river health assessment. Beyond the reported increase in antibiotic-resistant bacteria (ABRB), PPs have been found adversely affecting the biotic diversity in such water environments. Considering Algae, Macroinvertebrates, and Fishes as three distinct trophic level indicators, the present study puts forward a framework for showing River Health Condition (RHC) based on the calculation of a River Health Index (RHI). The RHI is calculated using six Indicator Group Scores (IGS) which individually reflect river health in a defined category of water quality characteristics. While Dissolved Oxygen Related Parameters (DORP), Nutrients (NT), and PPs are taken as causative agents affecting RHCs, scores of Algal-Bacterial (AB) symbiosis, Macroinvertebrates (MI), and Fishes (F) are considered as an effect of such environmental conditions. Current wastewater treatment technologies are also not very effective in the removal of PPs. The objective of the present study is to review the harmful effects of PPs on the aquatic environment, particularly on the chemical and biotic indicators of river health. Based on predicted no-effect concentrations (PNEC) for algae, macroinvertebrates, and fishes in the aquatic environment and measured environmental concentration (MEC) in the river, the estimated risk quotient (RQ) for norfloxacin in the Isakavagu-Nakkavagu stream of river Godavari, Hyderabad is found 293 for algae, 39 for MI, and 335 for fish. Among PPs, in Indian rivers, the presence of caffeine is the most frequent, with algae at the highest level of risk (RQ_max= 24.5). Broadly six PPs, including azithromycin, caffeine, diclofenac, naproxen, norfloxacin, and sulfamethoxazole are found above PNEC values in Indian rivers. The application of IGS and RHI in understanding and presenting the river health condition (RHC) through colored hexagons has been demonstrated for the river Ganga near Varanasi (India) as an example. Identification of critical indicator groups, based on IGS provides a scientific basis for planned intervention for river health restoration to achieve an acceptable category.

Antibiotic resistant bacteria: A bibliometric review of literature

Antibiotic-resistant bacteria (ARB) are a serious threat to the health of people and the ecological environment. With this problem becoming more and more serious, more countries made research on the ARB, and the research number has been sharply increased particularly over the past decade. Therefore, it is quite necessary to globally retrace relevant researches on the ARB published from 2010 to 2020. This will help researchers to understand the current research situation, research trends and research hotspots in this field. This paper uses bibliometrics to examine publications in the field of ARB from 2010 to 2020 that were retrieved from the Web of Science (WOS). Our study performed a statistical analysis of the countries, institutions, journals, authors, research areas, author keywords, Essential Science Indicators (ESI) highly cited papers, and ESI hotspots papers to provide an overview of the ARB field as well as research trends, research hotspots, and future research directions in the field. The results showed that the number of related studies is increasing year by year; the USA is most published in the field of ARB; China is the most active in this field in the recent years; the Chinese Acad Sci published the most articles; Sci. Total Environ. published the greatest number of articles; CM Manaia has the most contributions; Environmental Sciences and Ecology is the most popular research area; and "antibiotic resistance," "antibiotics," and "antibiotic resistance genes" were the most frequently occurring author keywords. A citation analysis showed that aquatic environment-related antibiotic resistance is a key research area in this field, while antimicrobial nanomaterial-related research is a recent popular topic.

Antibiotics in the Basque coast (N Spain): Occurrence in waste and receiving waters, and risk assessment (2017-2020)

The study of the presence of antibiotics in the aquatic environment is a preliminary step to analyse their possible harmful effects on aquatic ecosystems. In order to monitor their occurrence in the aquatic environment, the European Commission established in 2015, 2018, and 2020 three Watch Lists of substances for Union-wide monitoring (Decisions (EU) 2015/495, 2018/840, and 2020/1161), where some antibiotics within the classes of macrolides, fluoroquinolones and penicillins were included. In the Basque coast, northern Spain, three macrolide antibiotics (erythromycin, clarithromycin, azithromycin) and ciprofloxacin were monitored quarterly from 2017 to 2020 (covering a period before and after the COVID19 outbreak), in water samples collected from two Waste Water Treatment Plants (WWTPs), and three control points associated with receiving waters (transitional and coastal water bodies). This work was undertaken for the Basque Water Agency (URA). The three macrolide antibiotics in water showed a frequency of quantification >65 % in the Basque coast, with higher concentrations in the WWTP emission stations than in receiving waters. Their frequency of quantification decreased from 2017 to 2020, as did the consumption of antibiotics in Spanish primary care since 2015. Ciprofloxacin showed higher frequencies of quantification in receiving waters than in wastewaters, but the highest concentrations were observed in the WWTP emission stations. Although consumption of fluoroquinolones (among which is ciprofloxacin) in primary care in the Basque Country has decreased in recent years, this trend was not observed in the waters sampled in the present study. On the other hand, concentrations of clarithromycin, azithromycin, and ciprofloxacin in receiving waters exceeded their respective Predicted No-Effect Concentrations, so they could pose an environmental risk. These substances are widely used in human and animal medicine, so, although only ciprofloxacin is included in the third Watch List, it would be advisable to continue monitoring macrolides in the Basque coast as well.

Synergetic effect of green synthesized reduced graphene oxide and nano-zero valent iron composite for the removal of doxycycline antibiotic from water

In this work, the synthesis of an rGO/nZVI composite was achieved for the first time using a simple and green procedure via Atriplex halimus leaves extract as a reducing and stabilizing agent to uphold the green chemistry principles such as less hazardous chemical synthesis. Several tools have been used to confirm the successful synthesis of the composite such as SEM, EDX, XPS, XRD, FTIR, and zeta potential which indicated the successful fabrication of the composite. The novel composite was compared with pristine nZVI for the removal aptitude of a doxycycline antibiotic with different initial concentrations to study the synergistic effect between rGO and nZVI. The adsorptive removal of bare nZVI was 90% using the removal conditions of 25 mg L^-1, 25 °C, and 0.05 g, whereas the adsorptive removal of doxycycline by the rGO/nZVI composite reached 94.6% confirming the synergistic effect between nZVI and rGO. The adsorption process followed the pseudo-second order and was well-fitted to Freundlich models with a maximum adsorption capacity of 31.61 mg g^-1 at 25 °C and pH 7. A plausible mechanism for the removal of DC was suggested. Besides, the reusability of the rGO/nZVI composite was confirmed by having an efficacy of 60% after six successive cycles of regeneration.

Rapid Microwave-Assisted Synthesis of N/TiO2/rGO Nanoparticles for the Photocatalytic Degradation of Pharmaceuticals

Nanocomposites comprising nitrogen-doped TiO₂ and reduced graphene oxide (N/TiO₂/rGO), with different rGO loading qualities, were prepared by a cost-effective microwave-assisted synthesis method. The synthesized materials were broadly characterized by Raman spectroscopy, X-ray diffraction (XRD), infrared spectroscopy (FTIR), photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), electron microscopy (SEM-EDS), and nitrogen adsorption/desorption isotherms. Anatase was the only crystalline phase observed for all synthesized materials. The rGO loading did not affect the morphological properties, but it positively influenced the photocatalytic activity of the nanocomposite materials, especially at low rGO loading. Photocatalysts were evaluated via the degradation of specific organic micropollutant (OMP) pharmaceuticals: ciprofloxacin (CIP), diclofenac (DCF), and salicylic acid (SA), under different radiation sources: ultraviolet A (UVA), solar light simulator (SLS), blue visible light (BVL) and cold visible light (CVL). CIP and SA were removed effectively via the synergy of adsorption and photocatalysis, while DCF degradation was achieved solely by photocatalysis. After implementing scavenger agents, photocatalytic degradation processes mainly depended on the specific pollutant type, while irradiation sources barely defined the photocatalytic mechanism. On the other hand, changes in irradiation intensity significantly influenced the photolysis process, while photocatalysis was slightly affected, indicating that irradiation spectra are more relevant than intensity.

Potential of low-cost bio-adsorbents to retain amoxicillin in contaminated water

Sewage sludge as agricultural amendment is the main route of human-medicine antibiotics to enter soils. When reaching environmental compartments, these compounds can cause significant risks to human and ecological health. Specifically, the antibiotic amoxicillin (AMX) is highly used in medicine, and the fact that more than 80% of the total ingested is excreted increases the chances of causing serious environmental and public health problems. As the use of low-cost bio-adsorbents could help to solve these issues, this research focuses on the retention of AMX onto four by-products of the forestry industry (eucalyptus leaf, pine bark, pine needles, and wood ash) and one from food industry (mussel shell). To carry out this study, batch-type tests were performed, where increasing concentrations of the antibiotic (0, 2.5, 5, 10, 20, 30, 40 and 50 μmol L^-1) were added to samples of 0.5 g of each bio-adsorbent. Eucalyptus leaf, pine needle and wood ash showed adsorption scores higher than 80%, while it was up to 39% and 48% for pine bark and mussel shell, respectively. For pine bark, wood ash and mussel shell, adsorption data showed good adjustment to the Freundlich and Linear models, while pine needles and eucalyptus leaf did not fit to any model. There was not desorption when the maximum concentration of AMX (50 μmol L^-1) was added. Overall, eucalyptus leaf, pine needles and wood ash can be considered good bio-adsorbents with high potential to retain AMX, which has significant implications regarding their eventual use to reduce risks of environmental pollution by this antibiotic.

Metronidazole Degradation by UV and UV/H2O2 Advanced Oxidation Processes: Kinetics, Mechanisms, and Effects of Natural Water Matrices

Advanced oxidation technology represented by hydroxyl radicals has great potential to remove residual antibiotics. In this study, we systematically compared the metronidazole (MTZ) degradation behavior and mechanism in the UV and UV/H₂O₂ systems at pH 3.00 condition. The results show that the initial reaction rates were 0.147 and 1.47 µM min^-1 in the UV and UV/H₂O₂ systems, respectively. The main reason for the slow direct photolysis of MTZ is the relatively low molar absorption coefficient (2645.44 M^-1 cm^-1) and quantum yield (5.9 × 10^-3 mol Einstein^-1). Then, we measured kMTZ,OH&nbsp;• as 2.79 (±0.12) × 10⁹ M^-1 s^-1 by competitive kinetics, and calculated kMTZ,OH&nbsp;• and [OH&nbsp;•]SS as 2.43 (±0.11) × 10⁹ M^-1 s^-1 and 2.36 × 10^-13 M by establishing a kinetic model based on the steady-state hypothesis in our UV/H₂O₂ system. The contribution of direct photolysis and ^•OH to the MTZ degradation was 9.9% and 90.1%. ^•OH plays a major role in the MTZ degradation, and ^•OH was the main active material in the UV/H₂O₂ system. This result was also confirmed by MTZ degradation and radicals' identification experiments. MTZ degradation increases with H₂O₂ dosage, but excessive H₂O₂ had the opposite effect. A complex matrix has influence on MTZ degradation. Organic matter could inhibit the degradation of MTZ, and the quenching of the radical was the main reason. NO3- promoted the MTZ degradation, while SO42- and Cl^- had no effect. These results are of fundamental and practical importance in understanding the MTZ degradation, and to help select preferred processes for the optimal removal of antibiotics in natural water bodies, such as rivers, lakes, and groundwater.

Sodium Alginate/Modified Bentonite Composite Bead Adsorptive Removal of Norfloxacin: Static and Dynamic Adsorption

The low-cost calcium-based bentonite modified with anionic and cationic surfactants was granulated by cross-linking to sodium alginate (SA) to promote the adsorption efficiencies of norfloxacin (NOR). The characterization studies illustrated that the intercalation of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl benzene sulfonate (SDBS) was successful. The modification improved the pore structure and the granular SA/organically modified bentonite composite (GOMBt) exhibited a lamellar structure with some roughness. The adsorption kinetics and isotherms indicated that adsorption of NOR on GOMBt was an endothermic process. The effects of various factors on the adsorption of NOR suggested that the maximum adsorption capacity was obtained under acidic conditions and cations improved the adsorption process. A fixed-bed column was employed to investigate the dynamic adsorption characteristics of NOR by GOMBt. The breakthrough time and bed height had a positive correlation; however, the relation of flow rate, pH, and breakthrough time had a negative correlation. The results showed that the dynamic adsorption data of NOR on GOMBt fitted Thomas and Yoon–Nelson models. The internal and external diffusion in GOMBt dynamic adsorption was not a rate-limiting step.

Advanced wastewater treatment with ozonation and granular activated carbon filtration: Inactivation of antibiotic resistance targets in a long-term pilot study

The inactivation of antibiotic resistant bacteria (ARB) and genes (ARGs) in an advanced plant combining ozonation and granular activated carbon (GAC) filtration applied for effluent after conventional activated sludge treatment at a full-scale urban wastewater treatment plant was investigated for over 13 consecutive months. The nitrite compensated specific ozone dose ranged between 0.4 and 0.7 g O₃/g DOC with short-time sampling campaigns (0.2-0.9 g O₃/g DOC). Samples were analysed with culture-dependent methods for bacterial targets and with qPCR for genes. The log removal values were correlated with a decrease of the matrix UV absorption at 254 nm (ΔUV₂₅₄) and indicated a range of ΔUV₂₅₄ that corresponds to a sufficient membrane damage to affect DNA. For trimethoprim/sulfamethoxazole resistant E. coli, sul1, ermB and tetW, this phase was observed at ΔUV₂₅₄ of ~30 % (~0.5 g O₃/g DOC). For ampicillin resistant E. coli and bla_TEM-1, it was observed around 35-40 % (~0.7 g O₃/g DOC), which can be linked to mechanisms related to oxidative damages in bacteria resistant to bactericidal antibiotics. GAC treatment resulted in a further abatement for trimethoprim/sulfamethoxazole E. coli, sul1 and tetW, and in increase in absolute and relative abundance of ermB and bla_TEM-1.

A review on antibiotics removal: Leveraging the combination of grey and green techniques

Antibiotics are currently a major source of concern around the world due to the serious risks posed to human health and the environment. The performance of the secondary wastewater treatment processes/technologies (representing grey process) and constructed wetlands (CWs) (typical green process) in removing antibiotics and antibiotic resistance genes (ARG) was reviewed. The result showed that the grey process mainly removes antibiotics, but does not significantly remove ARG, and some processes may even cause ARG enrichment. The overall treatment in CWs is better than WWTPs, especially for ARG. Vertical subsurface flow CWs (VFCWs) are more conductive to antibiotics removal, while horizontal subsurface flow CWs (HFCWs) have a better ARG removal. More importantly, this review admits and suggests that the combination of grey process with green process is an effective strategy to remove antibiotics and ARG. The most advantage of the combination lies in realizing complementary advantages, i.e. the grey process as the primary treatment while CWs as the polishing stage. The efficiency of such the hybrid system is much higher than either single treatment process.

Antibiotic resistant bacteria and genes in wastewater treatment plants: From occurrence to treatment strategies

This study aims to discuss the following: (1) occurrence and proliferation of antibiotic resistance in wastewater treatment plants (WWTPs); (2) factors influencing antibiotic resistance bacteria and genes in WWTPs; (3) tools to assess antibiotic resistance in WWTPs; (4) environmental contamination of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) from WWTPs; (5) effects of ARB and ARGs from WWTPs on human health; and (6) treatment strategies. In general, resistant and multi-resistant bacteria, including Enterobacteriaceae, Pseudomonas aeruginosa, and Escherichia coli, exist in various processes of WWTPs. The existence of ARB and ARGs results from the high concentration of antibiotics in wastewater, which promote selective pressures on the local bacteria present in WWTPs. Thus, improving wastewater treatment technology and avoiding the misuse of antibiotics is critical to overcoming the threat of proliferation of ARBs and ARGs. Numerous factors can affect the development of ARB and ARGs in WWTPs. Abiotic factors can affect the bacterial community dynamics, thereby, affecting the applicability of ARB during the wastewater treatment process. Furthermore, the organic loads and other nutrients influence bacterial survival and growth. Specifically, molecular methods for the rapid characterization and detection of ARBs or their genes comprise DNA sequencing, real-time PCR, simple and multiplex PCR, and hybridization-based technologies, including micro- and macro-arrays. The reuse of effluent from WWTPs for irrigation is an efficient method to overcome water scarcity. However, there are also some potential environmental risks associated with this practice, such as increase in the levels of antibiotic resistance in the soil microbiome. Human mortality rates may significantly increase, as ARB can lead to resistance among several types of antibiotics or longer treatment times. Some treatment technologies, such as anaerobic and aerobic treatment, coagulation, membrane bioreactors, and disinfection processes, are considered potential techniques to restrict antibiotic resistance in the environment.