A comparative study among catalytic wet air oxidation, Fenton, and Photo-Fenton technologies for the on-site treatment of hospital wastewater

Innovative laccase-based hollow packed-bed reactor for continuous treatment of hospital wastewater

This study reports on laccase-mediated removal of trace organic compounds (TrOCs) from real hospital wastewater (HWW) in a packed-bed reactor (PBR). The reactor column consisted of a catalytic bed of amino-functionalized mesoporous silica microspheres attached to a hollow polyethylene packing on which a Trametes hirsuta laccase was immobilized. This bed material had the advantage of significantly limiting pressure drop, which is one of the major drawbacks of PBRs operating in continuous mode. The PBR was fed with HWW, previously filtered through a 0.45-µm PTFE filter. The HWW was used either unspiked or spiked at 1 µg L-1 with acetaminophen, ibuprofen, naproxen, ketoprofen, mefenamic acid, indomethacin, and carbamazepine. A kinetic model combining the substrate conversion (1st-order kinetic) and the biocatalyst inactivation (1st-order kinetic) was developed and implemented, using acetaminophen as a model phenolic compound. After validation, the model showed good fit with experimental data and robustness regarding extended time operation with real HWW under uncontrolled conditions (pH, unbuffered media, ambient temperature). After 6 h of contact time, more than 95% of acetaminophen and mefenamic acid were removed in the PBR. In addition, toxicity tests showed that the laccase-based treatment resulted in a reduction in toxicity to Daphnia magna. The treated HWW did not significantly affect the mobility of Daphnia magna, unlike untreated HWW.

Selected emerging contaminants in water: Global occurrence, existing treatment technologies, regulations and associated risk

Emerging contaminants (ECs) in aquatic environments have recently attracted the attention of researchers due to their ubiquitous occurrence and the potential risk they may pose to life. While advance analytical methods have improved global reporting in water matrices, additional information is needed to compile data on their occurrence, existing legislation, treatment technologies and associated human health risks. Therefore, the present study provides an overview of the occurrence of selected ECs, including personal care product, antibiotics, NSAIDs, EDCs and psychiatric drugs, the existing regulatory framework and their toxicological effects on human health. The water matrices under review are the treated wastewater, surface water, groundwater and, in a few cases, drinking water. The study also highlights different treatment technologies available, and evaluates their performance based on the removal efficiency for different classes of ECs. For removal of almost all ECs considered, ozonation integrated with gamma radiation was reported highly efficient. Risk analysis was also performed for selected ECs including diclofenac, ibuprofen, naproxen, carbamazepine, estrone, 17 β-estradiol, bisphenol A, sulfamethoxazole, erythromycin and triclosan. The human health risk analysis indicated the highest number of locations with potential risk due to the EDCs, with South America, Europe and Asia having multiple risks due to estrone and Bisphenol A. The results of this study will give a better insight into the current situation of ECs in the global water matrices, the performance assessment of treatment technologies and the risk analysis will describe the need for more robust regulatory structures around the world to prevent the occurrence of such contaminants in the aquatic environment.

Catalytic wet air oxidation removal of tetracycline by La2O3 immobilized on recycled polyethylene terephthalate using the response surface methodology

This study investigated the removal of tetracycline from the aqueous solutions by lanthanum oxide nanoparticles covered with polyethylene terephthalate (PET) using a low-cost and facile co-precipitation method, via catalytic wet air oxidation process (CWAO) by response surface methodology (RSM). XRD, FTIR, SEM, and EDX-map techniques have been employed to investigate the crystal structure, functional groups on the surface, morphologic characteristics, and elemental composition, respectively. Under optimum conditions (pH= 9, initial TC concentration= 20 mg L-1, nanocomposite dosage= 1.5 g L-1, pressure= 4 bar, temperature= 70 °C, and time= 90 min), TC removal efficiency by La2O3-PET was achieved at about 99.9%. The environmental parameters were assessed to determine tetracycline catalytic wet air oxidation degradation rate, which included cleaning gases, hydrogen peroxide, type of organic compounds, anions, radical scavenger and reusability. The ANOVA results indicated that the polynomial model proves that the model is entirely meaningful (F-value> 0.001 and P-value< 0.0001) and has high coefficient values of adjusted R2 (0.7404) and predicted R2 (0.5940). The findings indicated that the variables of time, pH, temperature, dosage, and TC concentration have the greatest role in removing tetracycline, respectively. However, pressure as a factor does not have a considerable influence on the performance of the system. In general, due to the presence of the role of additional anionics, the effectiveness of this method for removing tetracycline from drinking water was 82.76%. The catalyst indicated pleasing stability and recycling power during eight testing cycles. Further, the estimated electrical energy per order consumption (EEO) for the CWAO/La2O3-PET system was calculated as 5.31 kWh m-3 with an operational cost (OC) utilization of 1.78 USD kg-1 and it has been shown that this process is feasible and economically comparable to other CWAO processes. The breakdown intermediate products of tetracycline in the CWAO were examined using gas chromatography/mass spectrometry (GC-MS) analysis. The toxicity analyses for the removal of TC were carried out using Daphnia magna and the CWAO process achieved a remarkable decrease in the presence of La2O3-PET nanocomposite (LC50 and toxicity unit (TU) 48 h equal to 0.634 and 157.72 vol percent).

A review on hazards and treatment methods of released antibiotics in hospitals wastewater during the COVID-19 pandemic

Drugs and related goods are widely used in order to promote public health and the quality of life. One of the most serious environmental challenges affecting public health is the ongoing presence of antibiotics in the effluents generated by pharmaceutical industries and hospitals. Antibiotics cannot be entirely removed from wastewater using the traditional wastewater treatment methods. Unmetabolized antibiotics generated by humans can be found in urban and livestock effluent. The antibiotic present in effluent contributes to issues with resistance to antibiotics and the creation of superbugs. Over the recent 2 years, the coronavirus disease 2019 pandemic has substantially boosted hospital waste volume. In this situation, a detailed literature review was conducted to highlight the harmful effects of untreated hospital waste and outline the best approaches to manage it. Approximately 50 to 70% of the emerging contaminants prevalent in the hospital wastewater can be removed using traditional treatment strategies. This paper emphasizes the numerous treatment approaches for effectively eliminating emerging contaminants and antibiotics from hospital wastewater and provides an overview of global hospital wastewater legislation and guidelines on hospital wastewater administration. Around 90% of ECs might be eliminated by biological or physical treatment techniques when used in conjunction with modern oxidation techniques. According to this research, hybrid methods are the best approach for removing antibiotics and ECs from hospital wastewater. The document outlines the many features of effective hospital waste management and might be helpful during and after the coronavirus disease 2019 outbreak, when waste creation on all hospitals throughout the globe has considerably increased.

Catalytic Ozonation of Pharmaceuticals Using CeO2-CeTiOx-Doped Crossflow Ultrafiltration Ceramic Membranes

The removal of persistent organic micropollutants (OMPs) from secondary effluent in wastewater treatment plants is critical for meeting water reuse standards. Traditional treatment methods often fail to adequately degrade these contaminants. This study explored the efficacy of a hybrid ozonation membrane filtration (HOMF) process using CeO2 and CeTiOx-doped ceramic crossflow ultrafiltration ceramic membranes for the degradation of OMPs. Hollow ceramic membranes (CM) with a 300 kDa molecular weight cut-off (MWCO) were modified to serve as substrates for catalytic nanosized metal oxides in a crossflow and inside-out operational configuration. Three types of depositions were tested: a single layer of CeO2, a single layer of CeTiOx, and a combined layer of CeO2 + CeTiOx. These catalytic nanoparticles were distributed uniformly using a solution-based method supported by vacuum infiltration to ensure high-throughput deposition. The results demonstrated successful infiltration of the metal oxides, although the yield permeability and transmembrane flow varied, following this order: pristine > CeTiOx > CeO2 > CeO2 + CeTiOx. Four OMPs were examined: two easily degraded by ozone (carbamazepine and diclofenac) and two recalcitrant (ibuprofen and pCBA). The highest OMP degradation was observed in demineralized water, particularly with the CeO2 + CeTiOx modification, suggesting O3 decomposition to hydroxyl radicals. The increased resistance in the modified membranes contributed to the adsorption phenomena. The degradation efficiency decreased in secondary effluent due to competition with the organic and inorganic load, highlighting the challenges in complex water matrices.

Insights into the efficient mineralization of antibiotic trimethoprim in aqueous media by Fe2+ catalytically enhanced vacuum-UV irradiation: Kinetics, mechanisms, and toxicity evaluation

The widespread existence of antibiotics in the environment has attracted growing concerns regarding the potential adverse effects on aquatic organisms, ecosystems, and human health even at low concentrations. Extensive efforts have been devoted to developing new methods for effective elimination of antibiotics from wastewater. Herein, a novel process of Fe2+ catalytically enhanced vacuum ultraviolet (VUV) irradiation was proposed as a promising approach for the removal of antibiotic trimethoprim (TMP) in water. Compared with UVC photolysis, VUV photolysis, and UVC/Fe2+, VUV/Fe2+ could increase the pseudo-first-order reaction rate constant of TMP removal by 6.6-38.4 times and the mineralization rate by 36.5%-59.9%. The excellent performance might originate from the synergistic effect of VUV and Fe2+, i.e., VUV irradiation could effectively split water and largely accelerate the Fe3+/Fe2+ cycle to generate more reactive oxygen species (ROS). EPR results indicated that •OH and O2•- were identified as the main ROS in the UVC/Fe2+ and VUV/Fe2+ processes, while •OH, O2•-, and 1O2 were involved in the VUV process. The operating parameters, such as Fe2+ dosage and initial TMP contents, were evaluated and optimized. Up to 8 aromatic intermediates derived from hydroxylation, demethylation, carbonylation, and methylene group cleavage were identified by UPLC-QTOF-MS/MS technique, the possible pathways of TMP degradation were proposed. Finally, the acute and chronic toxicity of intermediates formed during TMP degradation in the VUV/Fe2+ process were also evaluated.

Boosted Electrocatalytic Degradation of Levofloxacin by Chloride Ions: Performances Evaluation and Mechanism Insight with Different Anodes

As chloride (Cl-) is a commonly found anion in natural water, it has a significant impact on electrocatalytic oxidation processes; yet, the mechanism of radical transformation on different types of anodes remains unexplored. Therefore, this study aims to investigate the influence of chlorine-containing environments on the electrocatalytic degradation performance of levofloxacin using BDD, Ti4O7, and Ru-Ti electrodes. The comparative analysis of the electrode performance demonstrated that the presence of Cl- improved the removal and mineralization efficiency of levofloxacin on all the electrodes. The enhancement was the most pronounced on the Ti4O7 electrode and the least significant on the Ru-Ti electrode. The evaluation experiments and EPR characterization revealed that the increased generation of hydroxyl radicals and active chlorine played a major role in the degradation process, particularly on the Ti4O7 anode. The electrochemical performance tests indicated that the concentration of Cl- affected the oxygen evolution potentials of the electrode and consequently influenced the formation of hydroxyl radicals. This study elucidates the mechanism of Cl- participation in the electrocatalytic degradation of chlorine-containing organic wastewater. Therefore, the highly chlorine-resistant electrocatalytic anode materials hold great potential for the promotion of the practical application of the electrocatalytic treatment of antibiotic wastewater.

Microalgal-based bioremediation of emerging contaminants: Mechanisms and challenges

Emerging contaminants (ECs) in different ecosystems have consistently been acknowledged as a global issue due to toxicity, human health implications, and potential role in generating and disseminating antimicrobial resistance. The existing wastewater treatment system is incompetent at eliminating ECs since the effluent water contains significant concentrations of ECs, viz., antibiotics (0.03-13.0 μg L-1), paracetamol (50 μg L-1), and many others in varying concentrations. Microalgae are considered as a prospective and sustainable candidate for mitigating of ECs owing to some peculiar features. In addition, the microalgal-based processes also offer cost and energy-efficient solutions for the bioremediation of ECs than conventional treatment systems. It is pertinent that, microalgal-based processes also provides waste valorization benefits as microalgal biomass obtained after ECs treatment can be potentially applied to generate biofuels. Moreover, microalgae can effectively utilize alternative metabolic (cometabolism) routes for enhanced degradation of ECs. Additionally, the ECs removal via the microalgal biodegradation route is highly promising as it can transform the ECs into less toxic compounds. The present review comprehensively discusses different mechanisms involved in removing ECs and various factors that affect their removal. Also, the technoeconomic feasibility of microalgae than other conventional wastewater treatment methods is summarised. The review also highlighted the different molecular and genetic tools that can augment the activity and robustness of microalgae for better removal of organic contaminants. Finally, we have summarised the challenges and future research required towards microalgal-based bioremediation of emerging contaminants (ECs) as a holistic approach.

Pharmaceutical residues in the ecosystem: Antibiotic resistance, health impacts, and removal techniques

Hospital wastewater has emerged as a major category of environmental pollutants over the past two decades, but its prevalence in freshwater is less well documented than other types of contaminants. Due to compound complexity and improper operations, conventional treatment is unable to remove pharmaceuticals from hospital wastewater. Advanced treatment technologies may eliminate pharmaceuticals, but there are still concerns about cost and energy use. There should be a legal and regulatory framework in place to control the flow of hospital wastewater. Here, we review the latest scientific knowledge regarding effective pharmaceutical cleanup strategies and treatment procedures to achieve that goal. Successful treatment techniques are also highlighted, such as pre-treatment or on-site facilities that control hospital wastewater where it is used in hospitals. Due to the prioritization, the regulatory agencies will be able to assess and monitor the concentration of pharmaceutical residues in groundwater, surface water, and drinking water. Based on the data obtained, the conventional WWTPs remove 10-60% of pharmaceutical residues. However, most PhACs are eliminated during the secondary or advanced therapy stages, and an overall elimination rate higher than 90% can be achieved. This review also highlights and compares the suitability of currently used treatment technologies and identifies the merits and demerits of each technology to upgrade the system to tackle future challenges. For this reason, pharmaceutical compound rankings in regulatory agencies should be the subject of prospective studies.

Global trends in the research and development of medical/pharmaceutical wastewater treatment over the half-century

The COVID-19 pandemic has severely impacted public health and the worldwide economy. The overstretched operation of health systems around the world is accompanied by potential and ongoing environmental threats. At present, comprehensive scientific assessments of research on temporal changes in medical/pharmaceutical wastewater (MPWW), as well as estimations of researcher networks and scientific productivity are lacking. Therefore, we conducted a thorough literature study, using bibliometrics to reproduce research on medical wastewater over nearly half a century. Our primary goal is systematically to map the evolution of keyword clusters over time, and to obtain the structure and credibility of clusters. Our secondary objective was to measure research network performance (country, institution, and author) using CiteSpace and VOSviewer. We extracted 2306 papers published between 1981 and 2022. The co-cited reference network identified 16 clusters with well-structured networks (Q = 0.7716, S = 0.896). The main trends were as follows: 1) Early MPWW research prioritized sources of wastewater, and this cluster was considered to be the mainstream research frontier and direction, representing an important source and priority research area. 2) Mid-term research focused on characteristic contaminants and detection technologies. Particularly during 2000-2010, a period of rapid developments in global medical systems, pharmaceutical compounds (PhCs) in MPWW were recognized as a major threat to human health and the environment. 3) Recent research has focused on novel degradation technologies for PhC-containing MPWW, with high scores for research on biological methods. Wastewater-based epidemiology has emerged as being consistent with or predictive of the number of confirmed COVID-19 cases. Therefore, the application of MPWW in COVID-19 tracing will be of great interest to environmentalists. These results could guide the future direction of funding agencies and research groups.

Detection and removal technologies for ammonium and antibiotics in agricultural wastewater: Recent advances and prospective

With the extensive development of industrial livestock and poultry production, a considerable part of agricultural wastewater containing tremendous ammonium and antibiotics have been indiscriminately released into the aquatic systems, causing serious harms to ecosystem and human health. In this review, ammonium detection technologies, including spectroscopy and fluorescence methods, and sensors were systematically summarized. Antibiotics analysis methodologies were critically reviewed, including chromatographic methods coupled with mass spectrometry, electrochemical sensors, fluorescence sensors, and biosensors. Current progress in remediation methods for ammonium removal were discussed and analyzed, including chemical precipitation, breakpoint chlorination, air stripping, reverse osmosis, adsorption, advanced oxidation processes (AOPs), and biological methods. Antibiotics removal approaches were comprehensively reviewed, including physical, AOPs, and biological processes. Furthermore, the simultaneous removal strategies for ammonium and antibiotics were reviewed and discussed, including physical adsorption processes, AOPs, biological processes. Finally, research gaps and the future perspectives were discussed. Through conducting comprehensive review, future research priorities include: (1) to improve the stabilities and adaptabilities of detection and analysis techniques for ammonium and antibiotics, (2) to develop innovative, efficient, and low cost approaches for simultaneous removal of ammonium and antibiotics, and (3) to explore the underlying mechanisms that governs the simultaneous removal of ammonium and antibiotics. This review could facilitate the evolution of innovative and efficient technologies for ammonium and antibiotics treatment in agricultural wastewater.

A critical review of textile industry wastewater: green technologies for the removal of indigo dyes

The denim textile industry represents an important productive sector. It generates wastewater with low biodegradability due to the presence of persistent pollutants, which can produce toxic and carcinogenic compounds; therefore, wastewater treatment reduces risks to aquatic life and public health. This paper presents a review of 172 papers regarding textile industry wastewater treatment for the removal of contaminants, especially indigo dyes used in the denim industry, in the context of green technologies. The physicochemical characteristics of textile wastewater, its environmental and health impacts, and the permissible limit regulations in different countries were reviewed. Biological, physicochemical and advanced oxidation processes for the removal of indigo dyes were reviewed. The goal of this study was to analyze the characteristics of green technologies; however, the research does not clearly demonstrate an effect on energy consumption savings, carbon footprint decreases, and/or waste generation. Advanced oxidation processes showed the highest color removal efficiency (95 and 97% in synthetic or real wastewater, respectively). Photocatalysis and Fenton reactions were the most efficient processes. None of the revised works presented results regarding upscaling for industrial application, and the results should be discussed in terms of the guidelines and maximum permissible limits established by international legislation. New technologies need to be developed and evaluated in a sustainable context with real wastewater.

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.

Towards Effective, Sustainable Solution for Hospital Wastewater Treatment to Cope with the Post-Pandemic Era

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has spread across the globe since the end of 2019, posing significant challenges for global medical facilities and human health. Treatment of hospital wastewater is vitally important under this special circumstance. However, there is a shortage of studies on the sustainable wastewater treatment processes utilized by hospitals. Based on a review of the research trends regarding hospital wastewater treatment in the past three years of the COVID-19 outbreak, this review overviews the existing hospital wastewater treatment processes. It is clear that activated sludge processes (ASPs) and the use of membrane bioreactors (MBRs) are the major and effective treatment techniques applied to hospital wastewater. Advanced technology (such as Fenton oxidation, electrocoagulation, etc.) has also achieved good results, but the use of such technology remains small scale for the moment and poses some side effects, including increased cost. More interestingly, this review reveals the increased use of constructed wetlands (CWs) as an eco-solution for hospital wastewater treatment and then focuses in slightly more detail on examining the roles and mechanisms of CWs' components with respect to purifying hospital wastewater and compares their removal efficiency with other treatment processes. It is believed that a multi-stage CW system with various intensifications or CWs incorporated with other treatment processes constitute an effective, sustainable solution for hospital wastewater treatment in order to cope with the post-pandemic era.

Treatment of thiocyanate-containing wastewater: a critical review of thiocyanate destruction in industrial effluents

Thiocyanate is a common pollutant in gold mine, textile, printing, dyeing, coking and other industries. Therefore, thiocyanate in industrial wastewater is an urgent problem to be solved. This paper reviews the chemical properties, applications, sources and toxicity of thiocyanate, as well as the various treatment methods for thiocyanate in wastewater and their advantages and disadvantages. It is emphasized that biological systems, ranging from laboratory to full-scale, are able to successfully remove thiocyanate from factories. Thiocyanate-degrading microorganisms degrade thiocyanate in autotrophic manner for energy, while other biodegrading microorganisms use thiocyanate as a carbon or nitrogen source, and the biochemical pathways and enzymes involved in thiocyanate metabolism by different bacteria are discussed in detail. In the future, degradation mechanisms should be investigated at the molecular level, with further research aiming to improve the biochemical understanding of thiocyanate metabolism and scaling up thiocyanate degradation technologies from the laboratory to a full-scale.

Removal of organic micropollutans by adsorptive membrane

Various emerging organic micropollutants, such as pharmaceuticals, have attracted the interest of the water industry during the last two decades due to their insufficient removal during conventional water and wastewater treatment methods and increasing demand for pharmaceuticals projected to climate change-related impacts and COVID-19, nanosorbents such as carbon nanotubes (CNTs), graphene oxides (GOs), and metallic organic frameworks (MOFs) have recently been extensively explored regarding their potential environmental applications. Due to their unique physicochemical features, the use of these nanoadsorbents for organic micropollutans in water and wastewater treatment processes has been a rapidly growing topic of research in recent literature. Adsorptive membranes, which include these nanosorbents, combine the benefits of adsorption with membrane separation, allowing for high flow rates and faster adsorption/desorption rates, and have received a lot of publicity in recent years. The most recent advances in the fabrication of adsorptive membranes (including homogeneous membranes, mixed matrix membranes, and composite membranes), as well as their basic principles and applications in water and wastewater treatment, are discussed in this review. This paper covers ten years, from 2011 to 2021, and examines over 100 published studies, highlighting that micropollutans can pose a serious threat to surface water environments and that adsorptive membranes are promising, particularly in the adsorption of trace substances with fast kinetics. Membrane fouling, on the other hand, should be given more attention in future studies due to the high costs and restricted reusability.

A critical review on paracetamol removal from different aqueous matrices by Fenton and Fenton-based processes, and their combined methods

Paracetamol (PCT), also known as acetaminophen, is a drug used to treat fever and mild to moderate pain. After consumption by animals and humans, it is excreted through the urine to the sewer systems, wastewater treatment plants, and other aquatic/natural environments. It has been detected in trace amounts in effluents of wastewater plant treatments, sewage sludge, hospital wastewaters, surface waters, and drinking water. PCT can cause genetic code damage, oxidative degradation of lipids, and denaturation of protein in cells, and its toxicity has been well-proven in bacteria, algae, macrophytes, protozoan, and fishes. To avoid its harmful health problems over living beings, powerful Fenton and Fenton-based treatments as pre-eminent advanced oxidation processes (AOPs) have been developed because of the inefficient treatment by conventional treatments. This paper presents a comprehensive and critical review over the application of such Fenton technologies to remove PCT from natural waters, synthetic wastewaters, and real wastewaters. The characteristics and main results obtained using Fenton, photo-Fenton, electro-Fenton, and photoelectro-Fenton are described, making special emphasis in the oxidative action of the generated reactive oxygen species. Hybrid processes based on the coupling with ultrasounds, gamma radiation, photocatalysis, photoelectrocatalysis, zero-valent iron-activated persulfate, adsorption, and microbial fuel cells, are analyzed. Sequential treatments involving the initiation with plasma gliding arc discharge and post-biological process are detailed. Comparative results with other available AOPs are also described and discussed. Finally, 13 aromatic by-products and 9 short-linear aliphatic carboxylic acid detected during the PCT removal by Fenton and Fenton-based processes are reported, with the proposal of three parallel pathways for its initial degradation.

New trends on green energy and environmental technologies, with special focus on biomass valorization, water and waste recycling: editorial of the special issue

In this editorial piece, the Editors of the Virtual Special Issue (VSI) "New Trends on Green Energy and Environmental Technologies, with Special Focus on Biomass Valorization, Water and Waste Recycling", present summarized data corresponding to the accepted submissions, as well as additional comments regarding the thematic of the VSI. Overall, 83 manuscripts were received, with final publication of those having the highest quality, accepted after peer-reviewing. The Editors think that the result is a set of very interesting papers that increase the knowledge on the matter, and which would be useful for researchers and the whole society.

An assessment of hospital wastewater and biomedical waste generation, existing legislations, risk assessment, treatment processes, and scenario during COVID-19

Hospitals release significant quantities of wastewater (HWW) and biomedical waste (BMW), which hosts a wide range of contaminants that can adversely affect the environment if left untreated. The COVID-19 outbreak has further increased hospital waste generation over the past two years. In this context, a thorough literature study was carried out to reveal the negative implications of untreated hospital waste and delineate the proper ways to handle them. Conventional treatment methods can remove only 50%-70% of the emerging contaminants (ECs) present in the HWW. Still, many countries have not implemented suitable treatment methods to treat the HWW in-situ. This review presents an overview of worldwide HWW generation, regulations, and guidelines on HWW management and highlights the various treatment techniques for efficiently removing ECs from HWW. When combined with advanced oxidation processes, biological or physical treatment processes could remove around 90% of ECs. Analgesics were found to be more easily removed than antibiotics, β-blockers, and X-ray contrast media. The different environmental implications of BMW have also been highlighted. Mishandling of BMW can spread infections, deadly diseases, and hazardous waste into the environment. Hence, the different steps associated with collection to final disposal of BMW have been delineated to minimize the associated health risks. The paper circumscribes the multiple aspects of efficient hospital waste management and may be instrumental during the COVID-19 pandemic when the waste generation from all hospitals worldwide has increased significantly.

High-efficiency oxidation of norfloxacin by Fe3+/H2O2 process enhanced via vacuum ultraviolet irradiation: Role of newly formed Fe2

Fluoroquinolones in water environments have caused worldwide concern due to negative effects on human health and ecological environment. Heretofore, synergistic mechanisms of Fe³⁺/H₂O₂ process enhanced via vacuum ultraviolet (VUV) irradiation for fluoroquinolones removal, and generation ways and contribution evaluations of reactive oxygen species (ROS) in integrated VUV/Fe³⁺/H₂O₂ were not reported systematically. This work comparatively investigated norfloxacin (NOR, typical fluoroquinolones) degradation in VUV/Fe³⁺/H₂O₂ and its sub-processes. Compared with its sub-processes, VUV/Fe³⁺/H₂O₂ process could not only increase degradation rate constant by 2.1-10.2 times and increase mineralization rate by 14.5%-49.5%, but also reduce energy consumption by 53.1%-89.9% and reduce economic cost by 33.3%-68.0%. Effect mechanisms of Fe³⁺ and H₂O₂ doses on decontamination capability of VUV/Fe²⁺/H₂O₂ were elaborated, and 3 mM H₂O₂ and 90 μM Fe³⁺ were determined as optimal doses. The synergetic factor in integrated VUV/Fe³⁺/H₂O₂ was 3.33, which was mainly ascribed to VUV photons accelerating iron cycle. In VUV/Fe³⁺/H₂O₂ process, superoxide radical and hydroxyl radical were confirmed as primary ROS, contributing 20.86% and 76.32% to NOR oxidation, separately. Organic and inorganic products of NOR and its degradation pathways in integrated VUV/Fe³⁺/H₂O₂ were also investigated. Besides, the synergistic reaction pathways in VUV/Fe³⁺/H₂O₂ were elaborated. Effects of water matrices on decontamination capability of VUV/Fe³⁺/H₂O₂ were also studied. All results indicated VUV/Fe³⁺/H₂O₂ as an efficient and cost-effective process suitable for NOR removal.

Electrocatalytic Degradation of Levofloxacin, a Typical Antibiotic in Hospital Wastewater

Presently, in the context of the novel coronavirus pneumonia epidemic, several antibiotics are overused in hospitals, causing heavy pressure on the hospital’s wastewater treatment process. Therefore, developing stable, safe, and efficient hospital wastewater treatment equipment is crucial. Herein, a bench-scale electrooxidation equipment for hospital wastewater was used to evaluate the removal effect of the main antibiotic levofloxacin (LVX) in hospital wastewater using response surface methodology (RSM). During the degradation process, the influence of the following five factors on total organic carbon (TOC) removal was discussed and the best reaction condition was obtained: current density, initial pH, flow rate, chloride ion concentration, and reaction time of 39.6 A/m², 6.5, 50 mL/min, 4‰, and 120 min, respectively. The TOC removal could reach 41% after a reaction time of 120 min, which was consistent with the result predicted by the response surface (40.48%). Moreover, the morphology and properties of the electrode were analyzed. The degradation pathway of LVX was analyzed using high-performance liquid chromatography–mass spectrometry (LC–MS). Subsequently, the bench-scale electrooxidation equipment was changed into onboard-scale electrooxidation equipment, and the onboard-scale equipment was promoted to several hospitals in Dalian.