Hospital wastewater treatment by sponge membrane bioreactor coupled with ozonation process

Deciphering the removal of antibiotics and the antibiotic resistome from typical hospital wastewater treatment systems

Hospital wastewater treatment systems (HWTSs) are a significant source and reservoir of antibiotic resistance genes (ARGs) and a crucial hub for transmitting ARGs from clinical to natural environments. However, there is a lack of research on the antibiotic resistome of clinical wastewater in HWTSs. In this study, we used metagenomics to analyze the prevalence and abundance of ARGs in five typical HWTSs. A total of 17 antibiotics from six categories were detected in the five HWTSs; β-lactam antibiotics were found at the highest concentrations, with up to 4074.08 ng·L-1. We further found a total of 21 ARG types and 1106 subtypes of ARGs with the highest percentage of multi-drug resistance genes (evgS, msbA, arlS, and baeS). The most abundant last-resort ARGs were mcr, which were detected in 100 % of the samples. HWTSs effluent is a major pathway for the transmission of last-resort ARGs into urban wastewater networks. The removal of antibiotics, antibiotic-resistant bacteria, and ARGs from HWTSs was mainly achieved by tertiary treatment, i.e., chlorine disinfection, but antibiotics and ARGs were still present in the HWTSs effluent or even increased after treatment. Moreover, antibiotics and heavy metals (especially mercury) in hospital effluents can exert selective pressure for antibiotic resistance, even at low concentrations. Qualitative analyses based on metagenome-assembled genome analysis revealed that the putative hosts of the identified ARGs are widely distributed among Pseudomonas, Acidovorax, Flavobacterium, Polaromonas, and Arcobacter. Moreover, we further assessed the clinical availability of ARGs and found that multidrug ARGs had the highest clinical relevance values. This study provides new impulses for monitoring and removing antibiotics and ARGs in the hospital sewage treatment process.

A thorough analysis of the occurrence, removal and environmental risks of organic micropollutants in a full-scale hybrid membrane bioreactor fed by hospital wastewater

The Urban Wastewater Treatment Directive recent draft issued last October 2022 pays attention to contaminants of emerging concern including organic micropollutants (OMPs) and requires the removal of some of them at large urban wastewater treatment plants (WWTPs) calling for their upgrading. Many investigations to date have reported the occurrence of a vast group of OMPs in the influent and many technologies have been tested for their removal at a lab- or pilot-scale. Moreover, it is well-known that hospital wastewater (HWW) contains specific OMPs at high concentration and therefore its management and treatment deserves attention. In this study, a 1-year investigation was carried out at a full-scale membrane bioreactor (MBR) treating mainly HWW. To promote the removal of OMPs, powdered activated carbon (PAC) was added to the bioreactor at 0.1 g/L and 0.2 g/L which resulted in the MBR operating as a hybrid MBR. Its performance was tested for 232 target and 90 non-target OMPs, analyzed by UHPLC-QTOF-MS using a direct injection method. A new methodology was defined to select the key compounds in order to evaluate the performance of the treatments. It was based on their frequency, occurrence, persistence to removal, bioaccumulation and toxicity. Finally, an environmental risk assessment of the OMP residues was conducted by means of the risk quotient approach. The results indicate that PAC addition increased the removal of most of the key OMPs (e.g., sulfamethoxazole, diclofenac, lidocaine) and OMP classes (e.g., antibiotics, psychiatric drugs and stimulants) with the highest loads in the WWTP influent. The hybrid MBR also reduced the risk in the receiving water as the PAC dosage increased mainly for spiramycin, lorazepam, oleandomycin. Finally, uncertainties and issues related to the investigation being carried out at full-scale under real conditions are discussed.

Molecular insights into enhanced nitrogen removal induced by trace fluoroquinolone antibiotics in an anammox system

It has been widely reported that fluoroquinolones (FQs) can affect the anaerobic ammonium oxidization (anammox) microorganisms, which interferes with the performance of nitrogen removal from wastewater. However, the metabolic mechanism of anammox microorganisms responding to FQs has rarely been explored. In this study, it was found that 20 μg/L FQs promoted the nitrogen removal performance of anammox microorganisms in batch exposure assays, and 36-51% of FQs were removed simultaneously. Combined metabolomics and genome-resolved metagenomic analysis revealed up-regulated carbon fixation in anammox bacteria (AnAOB), while purine and pyrimidine metabolism, protein generation and transmembrane transport were enhanced in AnAOB and symbiotic bacteria by 20 μg/L FQs. Consequently, hydrazine dehydrogenation, nitrite reduction, and ammonium assimilation were bolstered, improving the nitrogen removal efficiency of the anammox system. These results revealed the potential roles of specific microorganisms in response to emerging FQs and provided further information for practical application of anammox technology in wastewater treatment.

Recent trends in the applications of sonochemical reactors as an advanced oxidation process for the remediation of microbial hazards associated with water and wastewater: A critical review

Water is one of the major sources that spread human diseases through contamination with bacteria and other pathogenic microorganisms. This review focuses on microbial hazards as they are often present in water and wastewater and cause various human diseases. Among the currently used disinfection methods, sonochemical reactors (SCRs) that produce free radicals combined with advanced oxidation processes (AOPs) have received significant attention from the scientific community. Also, this review discussed various types of cavitation reactors, such as acoustic cavitation reactors (ACRs) utilizing ultrasonic energy (UE), which had been widely employed, involving AOPs for treating contaminated waters. Besides ACRs, hydrodynamic cavitation reactors (HCRs) also effectively destroy and deactivate microorganisms to varying degrees. Cavitation is the fundamental phenomenon responsible for initiating many sonochemical reactions in liquids. Bacterial degradation occurs mainly due to the thinning of microbial membranes, local warming, and the generation of free radicals due to cavitation. Over the years, although extensive investigations have focused on the antimicrobial effects of UE (ultrasonic energy), the primary mechanism underlying the cavitation effects in the disinfection process, inactivation of microbes, and chemical reactions involved are still poorly understood. Therefore, studies under different conditions often lead to inconsistent results. This review investigates and compares other mechanisms and performances from greener and environmentally friendly sonochemical techniques to the remediation of microbial hazards associated with water and wastewater. Finally, the energy aspects, challenges, and recommendations for future perspectives have been provided.

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.

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.

Hospital wastewater treatment and the role of membrane filtration - removal of micropollutants and pathogens: A review

Dissemination of multiresistant bacteria and high concentrations of micropollutants by hospitals and other medical facilities can be significantly reduced by a wide variety of on-site treatment approaches. Membrane filtration technologies, ranging from microfiltration to reverse osmosis, have been adapted in many studies and offer multiple purposes in advanced wastewater treatment configurations. While the direct rejection of pharmaceutical compounds and pathogens can only be achieved with nanofiltration and reverse osmosis processes, porous membranes are known for their pathogen removal capabilities and can be used in combination with other advanced treatment approaches, such as oxidation and adsorption processes. This review was conducted to systematically assess studies with membrane filtration technologies that are used as either stand-alone or hybrid systems for the treatment of hospital wastewater. In this review, four different databases were screened with a pre-set of search strings to thoroughly investigate the application of membrane filtration technology in hospital wastewater treatment. Hybrid systems that combine multiple treatment technologies seem to be the most promising way of consistently removing micropollutants and pathogens from hospital wastewater, but additional economic assessments are needed for an extensive evaluation.

Critical review of technologies for the on-site treatment of hospital wastewater: From conventional to combined advanced processes

This review aims to assess different technologies for the on-site treatment of hospital wastewater (HWW) to remove pharmaceutical compounds (PhCs) as sustances of emerging concern at a bench, pilot, and full scales from 2014 to 2020. Moreover, a rough characterisation of hospital effluents is presented. The main detected PhCs are antibiotics and psychiatric drugs, with concentrations up to 1.1 mg/L. On the one hand, regarding the presented technologies, membrane bioreactors (MBRs) are a good alternative for treating HWW with PhCs removal values higher than 80% in removing analgesics, anti-inflammatories, cardiovascular drugs, and some antibiotics. Moreover, this system has been scaled up to the pilot plant scale. However, some target compounds are still present in the treated effluent, such as psychiatric and contrast media drugs and recalcitrant antibiotics (erythromycin and sulfamethoxazole). On the other hand, ozonation effectively removes antibiotics found in the HWW (>93%), and some studies are carried out at the pilot plant scale. Even though, some families, such as the X-ray contrast media, are recalcitrant to ozone. Other advanced oxidation processes (AOPs), such as Fenton-like or UV treatments, seem very effective for removing pharmaceuticals, Antibiotic Resistance Bacteria (ARBs) and Antibiotic Resistance Genes (ARGs). However, they are not implanted at pilot plant or full scale as they usually consider extra reactants such as ozone, iron, or UV-light, making the scale-up of the processes a challenging task to treat high-loading wastewater. Thus, several examples of biological wastewater treatment methods combined with AOPs have been proposed as the better strategy to treat HWW with high removal of PhCs (generally over 98%) and ARGs/ARBs (below the detection limit) and lower spending on reactants. However, it still requires further development and optimisation of the integrated processes.

Recent advances in aqueous virus removal technologies

The COVID-19 outbreak has triggered a massive research, but still urgent detection and treatment of this virus seems a public concern. The spread of viruses in aqueous environments underlined efficient virus treatment processes as a hot challenge. This review critically and comprehensively enables identifying and classifying advanced biochemical, membrane-based and disinfection processes for effective treatment of virus-contaminated water and wastewater. Understanding the functions of individual and combined/multi-stage processes in terms of manufacturing and economical parameters makes this contribution a different story from available review papers. Moreover, this review discusses challenges of combining biochemical, membrane and disinfection processes for synergistic treatment of viruses in order to reduce the dissemination of waterborne diseases. Certainly, the combination technologies are proactive in minimizing and restraining the outbreaks of the virus. It emphasizes the importance of health authorities to confront the outbreaks of unknown viruses in the future.

QuEChERS-based analysis and ecotoxicological risk of select antibiotics in dumpsite leachates, hospital wastewater and effluent receiving water in Ibadan, Nigeria

There is currently a dearth of information on the determination, occurrence and ecotoxicological risk of antibiotics in dumpsite leachates and hospital wastewater in Africa. A quick, easy, cheap, effective, rugged and safe (QuEChERS) protocol which combines extraction and clean-up in one step was optimized for the determination of antibiotics sulfadoxine, sulfamethazine and trimethoprim in dumpsite leachates and hospital wastewater. The occurrence and ecotoxicological risk of target antibiotics were investigated in wastewater from two hospitals, effluent receiving water and leachates from three dumpsites in Ibadan, Nigeria. Recoveries in hospital wastewater ranged from 53 to 116% while recoveries ranged from 50 to 89% in leachates. Method limits of quantification ranged from 0.7 to 12.1 µg L^-1 in hospital wastewater and from 6.2 to 38.8 µg L^-1 in leachates. Intra-day precisions (% RSD) were ≤ 21%. High concentrations of target antibiotics were measured: up to 475 µg L^-1 for sulfamethazine in leachates, 118 µg L^-1 for trimethoprim in hospital wastewater and 117 µg L^-1 for sulfadoxine in effluent receiving water. Sulfadoxine presented high risk to algae, daphnid and fish in hospital wastewater, effluent receiving water and leachates. This work highlights the need for adequate and sound management of wastes containing pharmaceuticals in Nigeria.

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.

How anammox process resists the multi-antibiotic stress: Resistance gene accumulation and microbial community evolution

The effects of multiple antibiotics on the anaerobic ammonia oxidation (anammox) process were investigated. The resistance of the anammox system to high-concentration antibiotics was also demonstrated through gradual acclimation experiments. Inhibition of the anammox process (R₁) occurred when the concentrations of erythromycin (ERY), sulfamethoxazole (SMX) and tetracycline (TC) were 0.1, 5.0 and 0.1 mg L^-1, respectively. The nitrogen removal efficiency (NRE) of R₁ was reduced from 97.2% to 60.7% within 12 days and then recovered to 88.9 ± 9.5% when the nitrogen loading declined from 4.52 ± 0.69 to 2.11 ± 0.58 kg N m^-3 d^-1. Even when the concentrations of ERY, SMX and TC were as high as 1.0, 15.0 and 1.0 mg L^-1, respectively, R₁ maintained stable operation. The increases in the abundance of antibiotic resistance genes (ARGs) and in extracellular polymeric substances (EPS) content showed that the anammox process alleviated stress from multiple antibiotics mainly by producing ARGs and secreting EPS. The molecular docking simulation results illustrated the potential binding sites between ammonium transporter and different antibiotics. The upregulation of functional gene expression and the stable abundance of Candidatus Kuenenia in R₁ compared with that in the control suggested that the R₁ reactor generally maintained more stable long-term operation. This work provides a new understanding of the application of the anammox process to treat wastewater containing multiple antibiotics.

Phycoremediation integrated approach for the removal of pharmaceuticals and personal care products from wastewater - A review

Pharmaceuticals and personal care products (PPCPs) are of emerging concerns because of their large usage, persistent nature which promised their continuous disposal into the environment, as these pollutants are stable enough to pass through wastewater treatment plants causing hazardous effects on all the organisms through bioaccumulation, biomagnification, and bioconcentration. The available technologies are not capable of eliminating all the PPCPs along with their degraded products but phycoremediation has the advantage over these technologies by biodegrading the pollutants without developing resistant genes. Even though phycoremediation has many advantages, industries have found difficulty in adapting this technology as a single-stage treatment process. To overcome these drawbacks recent research studies have focused on developing technology that integrated phycoremediation with the commonly employed treatment processes that are in operation for treating the PPCPs effectively. This review paper focuses on such research approaches that focused on integrating phycoremediation with other technologies such as activated sludge process (ASP), advanced oxidation process (AOP), Up-flow anaerobic sludge blanket reactor (UASBR), UV irradiation, and constructed wetland (CW) with the advantages and limitations of each integration processes. Furthermore, augmenting phycoremediation by co-metabolic mechanism with the addition of sodium chloride, sodium acetate, and glucose for the removal of PPCPs has been highlighted in this review paper.

Biodegradability, environmental risk assessment and ecological footprint in wastewater technologies for pharmaceutically active compounds removal

Several studies have investigated the removal of pharmaceutically active compounds (PhACs) by wastewater treatment technologies due to the risk that these compounds pose to the environment. In this sense, advanced biological processes have been developed for micropollutants removal, such as membrane bioreactors and moving bed biofilm reactors. Thus, this review holistically evaluated the biodegradation of 18 environmentally hazardous PhACs. Biological processes were assessed including removal efficiencies, environmental risk, and ecological footprint (consumption of resources and energy, atmospheric emissions, and waste generation). The maximum concentration of PhACs for a low or negligible risk scenario in treated wastewater and the potential of biological processes to meet this goal were assessed. Among the evaluated PhACs, the most biodegradable was paracetamol, while the most recalcitrant was diclofenac. Combination of conventional processes and advanced biological processes proved to be the most efficient way to remove several PhACs, mainly the osmotic membrane bioreactor.

Phthalates in the environment: characteristics, fate and transport, and advanced wastewater treatment technologies

Phthalates are well-known emerging contaminants that harm human health and the environment. Therefore, this review aims to discuss about the occurrence, fate, and phthalates concentration in the various environmental matrices (e.g., aquatic, sediment, soil, and sewage sludge). Hence, it is necessary to treat sources containing phthalates before discharging them to aqueous environment. Various advanced wastewater treatments including adsorption process (e.g., biochar, activated carbon), advanced oxidation processes (e.g., photo-fenton, ozonation, photocatalysis), and biological treatment (membrane bioreactor) have been successfully to address this issue with high removal efficiencies (70-95%). Also, the degradation mechanism was discussed to provide a comprehensive understanding of the phthalate removal for the reader. Additionally, key factors that influenced the phthalates removal efficiency of these technologies were identified and summarized with a view towards pilot-scale and industrial applications.

Monitoring COVID-19 through SARS-CoV-2 quantification in wastewater: progress, challenges and prospects

Wastewater‐Based Epidemiology (WBE) is widely used to monitor the progression of the current SARS‐CoV‐2 pandemic at local levels. In this review, we address the different approaches to the steps needed for this surveillance: sampling wastewaters (WWs), concentrating the virus from the samples and quantifying them by qPCR, focusing on the main limitations of the methodologies used. Factors that can influence SARS‐CoV‐2 monitoring in WWs include: (i) physical parameters as temperature that can hamper the detection in warm seasons and tropical regions, (ii) sampling methodologies and timetables, being composite samples and Moore swabs the less variable and more sensitive approaches, (iii) virus concentration methodologies that need to be feasible and practicable in simpler laboratories and (iv) detection methodologies that should tend to use faster and cost‐effective procedures. The efficiency of WW treatments and the use of WWs for SARS‐CoV‐2 variants detection are also addressed. Furthermore, we discuss the need for the development of common standardized protocols, although these must be versatile enough to comprise variations among target communities. WBE screening of risk populations will allow for the prediction of future outbreaks, thus alerting authorities to implement early action measurements.

The promotions on radical formation and micropollutant degradation by the synergies between ozone and chemical reagents (synergistic ozonation): A review

The combination of ozone (O₃) and chemical reagents (such as H₂O₂) shows synergies on the radical formation and micropollutant degradation. The promoting performance was associated with various parameters including chemical reagents, micropollutants, solution pH, and the water matrix. In this review, we summarized existing knowledge on radical formation pathways, radical yields, and radical oxidation for different synergistic ozonation processes in various water matrices (such as groundwater, surface water, and wastewater). The increase of radical yields by synergistic ozonation processes was positively related to the increase of O₃-decay, with the increase being 1.1-4.4 folds than ozonation alone (0.2). Thus, synergistic ozonation can promote the degradation rate and efficiency of O₃-resistant micropollutants (second order rate constant, k_P,O3 < 200 M^-1 s^-1), but only slightly affects or even minorly inhibits the degradation of O₃-reactive micropollutants (k_P,O3 > 200 M^-1 s^-1). The water matrices^, such as the dissolved organic matters, negatively suppressed the degradation of micropollutant by quenching O₃-oxidation and radical oxidation (i.e. maximum promoting was decreased by 1.3 times), but may positively extend the promoting effects of synergistic ozonation to micropollutants that are more reactive to O₃ (i.e. k_P,O3 was extended from <200 to <2000 M^-1 s^-1). The formation of bromate would be increased through increasing radical oxidation by synergistic ozonation, but can be depressed by relative higher H₂O₂ as the reducing agent of HOBr/OBr^- intermediate. The increase in bromate formation by O₃/permononsulfate is a considerable concern due to permononsulfate cannot reduce the HOBr/OBr^- intermediate.

Hospital Wastewater-Source of Specific Micropollutants, Antibiotic-Resistant Microorganisms, Viruses, and Their Elimination

Municipal wastewaters can generally provide real-time information on drug consumption, the incidence of specific diseases, or establish exposure to certain agents and determine some lifestyle consequences. From this point of view, wastewater-based epidemiology represents a modern diagnostic tool for describing the health status of a certain part of the population in a specific region. Hospital wastewater is a complex mixture of pharmaceuticals, illegal drugs, and their metabolites as well as different susceptible and antibiotic-resistant microorganisms, including viruses. Many studies pointed out that wastewater from healthcare facilities (including hospital wastewater), significantly contributes to higher loads of micropollutants, including bacteria and viruses, in municipal wastewater. In addition, such a mixture can increase the selective pressure on bacteria, thus contributing to the development and dissemination of antimicrobial resistance. Because many pharmaceuticals, drugs, and microorganisms can pass through wastewater treatment plants without any significant change in their structure and toxicity and enter surface waters, treatment technologies need to be improved. This short review summarizes the recent knowledge from studies on micropollutants, pathogens, antibiotic-resistant bacteria, and viruses (including SARS-CoV-2) in wastewater from healthcare facilities. It also proposes several possibilities for improving the wastewater treatment process in terms of efficiency as well as economy.

Augmentation of microbial fuel cell and photocatalytic polishing technique for the treatment of hazardous dimethyl phthalate containing wastewater

In the present paper, the potentiality of integrating microbial fuel cells (MFCs) with a photocatalytic reactor to maximize the wastewater treatment efficiency with concurrent power generation was explored. Dimethyl phthalate (DMP) and acetic acid (AA) were the employed substrate and the co-substrate, respectively, using Pseudomonas aeruginosa as a biocatalyst. MFCs operated by single substrate showed the maximum power generation of 0.75-3.84 W m^-3 whereas an addition of AA as the co-substrate yielded 3-12 fold higher power generation. Pseudomonas aeruginosa produced phenazine-1-carboxylic acid in DMP-fed MFC as the metabolite whereas AA along with DMP yielded pyocyanin which reduced the charge transfer resistance. Chemical oxygen demand (COD) removal efficiency in the MFCs was circa 62% after 11 days of operation. Thereafter, it further increased albeit with a drastic reduction in power generation. Subsequently, the MFC anolyte was treated in a photocatalytic reactor under visible light irradiation and catalyzed by CuO-gC₃N₄. The performance of photocatalytic reactor was evaluated, with COD and total organic carbon (TOC) removal efficiency of 88% and 86% after 200 min of light irradiation. The present work suggests that the MFC can be integrated with photocatalysis as a sustainable wastewater treatment method with concurrent power generation.

Tetracyclines in the environment: An overview on the occurrence, fate, toxicity, detection, removal methods, and sludge management

Tetracyclines (TCs) are a group of broad-spectrum antibiotics having vast human, veterinary, and aquaculture applications. The continuous release of TCs residues into the environment and the inadequate removal through the conventional treatment systems result in its prevalent occurrence in soil, surface water, groundwater, and even in drinking water. As aqueous TCs contamination is the tip of the iceberg, and TCs possess good sorption capacity towards soil, sediments, sludge, and manure, it is insufficient to rely on the sorptive removal in the conventional water treatment plants. The severity of the TCs contamination is evident from the emergence of TCs resistance in a wide variety of microorganisms. This paper reviews the recent research on the TCs occurrence in the environmental matrices, fate in natural systems, toxic effects, and the removal methods. The high performance liquid chromatography (HPLC) determination of TCs in environmental samples and the associated technology developments are analyzed. The benefits and limitations of biochemical and physicochemical removal processes are also discussed. This work draws attention to the inevitability of proper TC sludge management. This paper also gives insight into the limitations of TCs related research and the future scope of research in environmental contamination by TCs residues.

Trends, new insights and perspectives in the treatment of hospital effluents

Recently, investigations of hospital effluent management and treatment have not only interested research groups with acquired experience in the field, but have also attracted the interest of new groups over the world. The most recent literature provides new insights into the occurrence of pharmaceuticals and other contaminants of emerging concern, pathogens, viruses, and antibiotic-resistant bacteria and genes in hospital effluent in various new developing and developed countries. It also provides information on the effective removal of key compounds (mainly antibiotics, analgesics, beta-blockers and chemotherapy drugs) by means of enhanced biological treatments and advanced oxidation processes. The current debate among the scientific community is mainly about the proper treatment to reduce the spread of antibiotic-resistant bacteria and genes and about the feasibility (from a technical and economic point of view) of treatment trains tested at lab and pilot scales.

Powdered activated carbon - Membrane bioreactor (PAC-MBR): Impacts of high PAC concentration on micropollutant removal and microbial communities

In this study, the effect of a high concentration of powdered activated carbon (PAC) on pollutant removal and microbial communities was systematically investigated. Micropollutant removal by the 'control' MBR (without PAC addition) was pollutant-specific and was mainly controlled by their molecular properties. The PAC-MBR achieved enhanced removal of micropollutant by 10% (ofloxacin) to 40% (caffeine). Analysis of the microbial communities in the sludge samples collected from both MBRs indicated an increase in the abundance of 24 (out of 31) genera following PAC addition. Notably, bacterial diversity enriched, particularly in the anoxic zone of the PAC-MBR, indicating a positive impact of recirculating mixed liquor containing PAC from the aerobic to the anoxic zone. In addition, PAC improved the abundance of Comamonas and Methanomethylovorans (up to 2.5%) that can degrade recalcitrant micropollutants. According to the quantitative PCR (qPCR) analysis, the copies of functional genes (nirS, nosZ and narG) increased in PAC-MBR. This study demonstrated that MBR could be operated at a high PAC concentration without compromising the pollutant removal and microbial community evolution during wastewater treatment.

Treatment of hospital wastewater by supercritical water oxidation process

Hospital wastewater contains several micro and macro pollutants that cannot be removed efficiently by conventional treatment processes. Thus, generally hybrid and multistage treatment methods are suggested for the treatment of hospital wastewater. Supercritical water oxidation (SCWO) is a promising method for the removal of emerging organic pollutants from hospital wastewater in one step and a very short reaction time. In this study, supercritical water oxidation (SCWO) process was used for the removal of pharmaceuticals in addition to conventional pollutants from real hospital wastewater. As a result of a series of preliminary studies, the optimum conditions were selected as 450 °C, 60 s, and 1:1 for temperature, reaction time, and oxidant ratio (H₂O₂/COD), respectively, for the treatment of hospital wastewater at 25 ± 1 MPa. The removal rates were determined above 90% for COD, BOD, TOC, TN, and SS from hospital wastewater. Phosphorus removal was greater than 90%, while the removal rates were around 80% for phenol, AOX, and surfactants in hospital wastewater. A total of 9 pharmaceuticals were observed in the real hospital wastewater samples. The highest removal rate was obtained for Paracetamol as 99.9%, while the lowest removal rate was obtained for Warfarin as 72% after SCWO treatment of hospital wastewater. As a result, it can be concluded that SCWO process is sufficient for the treatment of hospital wastewater without the need of additional treatment steps, with high removal rates in a short reaction time.

Removal of sulfadiazine from simulated industrial wastewater by a membrane bioreactor and ozonation

Ozonation can be used as a polishing treatment for degrading low-concentration pharmaceutical compounds recalcitrant to biological treatment, when large amounts of biodegradable organics have been previously removed by biological processes. Nevertheless, a systematic investigation has not yet been carried out for the coupled MBR + O₃ process through an experimental design approach. Thereby, the purpose of this study is to evaluate the performance of different processes (membrane bioreactor-MBR, ozonation; and integrated MBR + O₃) for removing the antibiotic sulfadiazine (SDZ) from a synthetic wastewater matrix of industrial interest. The MBR behavior was monitored over seven months for different parameters (pH, temperature, permeate flow, transmembrane pressure, biological oxygen demand-BOD₅, chemical oxygen demand-COD, total organic carbon-TOC, solids, and SDZ concentration). Additionally, the amount of SDZ sorbed onto the sludge was characterized, an issue which is scarcely addressed in most research works. Ozonation experiments were conducted in batch mode in a 2-L glass reactor provided with openings for gas flow. For the MBR + O₃ process, the effects of gas flow rate (0.1-1.5 L min^-1) and inlet ozone concentration (4-12 mg L^-1) on SDZ removal from the MBR permeate were systematically assessed using a Doehlert experimental design and response surface methodology. The results indicated that the MBR system showed good performance regarding organic matter removal efficiency, evaluated in terms of BOD₅ (91.5%), COD (93.1%) and TOC (96.3%). In contrast, SDZ was partially removed (33%) by the MBR; in that case, the results indicated that the antibiotic was moderately removed with the sludge and partially biodegraded. In turn, the MBR + O₃ system showed excellent performance for removing SDZ (100%), TOC (97%), BOD₅ (94%) and COD (97%). The statistical analysis confirmed that the influence of ozone gas flow rate upon the SDZ removal rate was more important than that exhibited by inlet ozone concentration. Therefore, coupling MBR and ozone can be considered a promising alternative for point source treatment of antibiotic production wastewater.

Microbial degradation of tetracycline in the aquatic environment: a review

Tetracycline residues have frequently been detected in multi-environmental media, and it could induce antibiotic resistance genes (ARGs) in microorganisms, which has attracted great attention. Where biodegradation processes may be a promising strategy to remove tetracycline. Thus, this study mainly considers: (i) the degradation of tetracycline by microorganisms including single microorganisms and microbial flora; (ii) the elimination of tetracycline during biochemical treatment processes and advanced treatment systems in wastewater treatment plants (WWTPs) and constructed wetlands (CWs); (iii) the degradation of tetracycline by biological coupling processes; (iv) the confusion and problem of tetracycline biodegradation. Furthermore, the characteristics and comparison of tetracycline biodegradation have been discussed in detail. Additionally, future research directions are suggested to reduce tetracycline in the aquatic environment, especially tetracycline biodegradation and the nitrogen conversion process. Highlights Degradation of tetracycline by pure culture strains and microflora was significant. Degradation of tetracycline by biochemical treatment process was summarized. Advanced treatment process in CWs could eliminate tetracycline. Future research directions on biodegradation of tetracycline are proposed.

Improving the biodegradability of hospital urines polluted with chloramphenicol by the application of electrochemical oxidation

This work focuses on improving the biodegradability of hospital urines polluted with antibiotics by electrochemical advanced oxidation processes (EAOPs). To do this, chloramphenicol (CAP) has been used as a model compound and the influence of anodic material (Boron Doped Diamond (BDD) and Mixed Metal Oxide (MMO)) and current density (1.25-5 mA cm^-2) on the toxicity and the biodegradability was evaluated. Results show that a complete CAP removal was attained using BDD anodes, being the process more efficient at the lowest current density tested (1.25 mA cm^-2). Conversely, after passing 4 Ah dm^-3, only 35% of CAP removal is reached using MMO anodes, regardless of the current density applied. Furthermore, a kinetic study demonstrated that there is a clear competitive oxidation between the target antibiotic and the organic compounds naturally contained in urine, regardless the current density and the anode material used. During the first stages of the electrolysis, acute toxicity is around 1% EC₅₀ but it increases once CAP and its organic intermediates have been degraded. The formation and accumulation of inorganic oxidants may justify the remaining acute toxicity. This also helps to explain the trend observed in the rapid biodegradability assays. Finally, a 60% of standard biodegradability (Zahn-Wellens test) was achieved which suggests that electrochemical oxidation with BDD anodes could be the most appropriate technology to reduce the hazard of hospital urines at the operating conditions tested.

Evaluation of TiO2 and SnO Supported on Graphene Oxide (TiO2-GO and SnO-GO) Photocatalysts for Treatment of Hospital Wastewater

The effectiveness of two photocatalysts, TiO2 and SnO, supported on graphene oxide (TiO2-GO and SnO-GO) on the removal of organic matter from hospital wastewater effluent was evaluated at laboratory scale. The results of the experimental design allow us to conclude that variables such as catalyst type and catalyst concentration have a significant effect on the organic matter removal efficiency of the photocatalytic process. The highest levels of removal efficiencies—for chemical oxygen demand, 85%, for phenols, 80%, and for dissolved organic carbon, 94%—were achieved using a TiO2-GO catalyst with a concentration in the wastewater of 1.5 g/L.

Acetaminophen micropollutant: Historical and current occurrences, toxicity, removal strategies and transformation pathways in different environments

Acetaminophen (ACT) is commonly used as a counter painkiller and nowadays, it is increasingly present in the natural water environment. Although its concentrations are usually at the ppt to ppm levels, ACT can transform into various intermediates depending on the environmental conditions. Due to the complexity of the ACT degradation products and the intermediates, it poses a major challenge for monitoring, detection and to propose adequate treatment technologies. The main objectives of this review study were to assess (i) the occurrences and toxicities, (2) the removal technologies and (3) the transformation pathways and intermediates of ACT in four environmental compartments namely wastewater, surface water, ground water, and soil/sediments. Based on the review, it was observed that the ACT concentrations in wastewater can reach up to several hundreds of ppb. Amongst the different countries, China and the USA showed the highest ACT concentration in wastewater (≤300 μg/L), with a very high detection frequency (81-100%). Concerning surface water, the ACT concentrations were found to be at the ppt level. Some regions in France, Spain, Germany, Korea, USA, and UK comply with the recommended ACT concentration for drinking water (71 ng/L). Notably, ACT can transform and degrade into various metabolites such as aromatic derivatives or organic acids. Some of them (e.g., hydroquinone and benzoquinone) are toxic to human and other life forms. Thus, in water and wastewater treatment plants, tertiary treatment systems such as advanced oxidation, membrane separation, and hybrid processes should be used to remove the toxic metabolites of ACT.