Removal of Antibiotics in Biological Wastewater Treatment Systems-A Critical Assessment Using the Activated Sludge Modeling Framework for Xenobiotics (ASM-X)

Recent advances and challenges in mechanistic modelling of photosynthetic processes for wastewater treatment

Phototrophy-based wastewater treatment has the potential to reduce wastewater bioremediation costs, improving environmental impacts and allowing for enhanced resource recovery. Microbial interactions occurring in phototrophic-chemotrophic consortia treating wastewater are particularly complex, and with varying impact on each microbial clade by different chemical, biological and physical factors, including light-related aspects. For this reason, mechanistic mathematical modelling of these systems is challenging, and the resulting models are especially complex. The present study focuses particularly on the extension of microalgae-focused models to the simulation of phototrophic-chemotrophic systems, especially as for (i) microalgae-bacteria consortia and (ii) purple bacteria-enriched communities. The review identifies model structures and typical modelling choices, as well as the potential applications and limitations of available experimental protocols for model calibration, identifying relevant research needs and requirements. Simplified models have been proposed, which allow assessment of dominant mechanisms, but may not represent more complex behaviour, including nutrient removal and response to light cycling. These models have been largely applied to simple (oxygen and carbon dioxide) exchange between algae and aerobic heterotrophs. More comprehensive models, including all relevant microbial clades, have been recently published, which consider nutrient cycling, competitive uptake, and other features, including temperature, pH, and gas transfer. These models have comparable structures, but a quantitative comparison between these models is often challenging due to different fundamental stoichiometry (e.g., in the assumed algae composition), or in differing approaches to storage compounds. Particularly for models with a high complexity, it is often difficult to properly estimate biokinetic species-specific parameters for the different phototrophic and chemotrophic populations involved. Several methods have been proposed for model calibration, among which photo-respirometry has shown considerable potential. However, photo-respirometric methods do not follow a standardised approach, which has limited their application and comparability between studies. Finally, the validation of models on long-term data sets, demonstrating the impact of seasonality, as well as long-term population adaptation, is rare.

Regulation of surface-bound radicals enhanced Fenton-like activities via radicals confined on Fe3O4/MXenes

The low yield and efficiency of surface-bound radicals seriously affect the Fenton-like activity of the catalyst. In this study, novel Fe3O4/MXenes (V2C and Ti3C2) composites are designed for structural domain regulation of surface-bound radicals. The MXenes with multilayer structure enhance the adsorption energy and electron transfer of the Fe3O4/peroxodisulfate (PDS) system. In the Fe3O4/V2C and Fe3O4/Ti3C2 systems, the adsorption energies of PDS at Fe sites are 8.27 and 4.36 eV, the electron transfer amounts are 0.303 and 0.115 e, and the lengths of the OO bond on PDS adsorbed are 2.965 and 1.503 Å, respectively. The enhanced adsorption and electron transfer properties make PDS more easily to be adsorbed on Fe3O4/V2C and broken to generate free radicals. The generated free radicals are confined to the structure of Fe3O4/V2C to form more surface-bound radicals, resulting in higher degradation efficiency. The contribution of surface-bound radicals to tetracycline (TC) degradation in Fe3O4/V2C/PDS reaches 45 %, while that of Fe3O4/Ti3C2/PDS is less than 15 %. The removal efficiency of Fe3O4/V2C-mediated surface-bound hydroxyl radical on TC reaches 93.3 % in 30 min, which is higher than that of Fe3O4/Ti3C2-mediated hydroxyl radical (•OH) and sulfate radical (SO4•-) (79.5 %). Fe3O4/V2C has excellent stability and reusability, and the surface-bound radicals produced by Fe3O4/V2C can degrade TC into non-toxic products. This study provides a new strategy for structural domain regulation of surface-bound radicals to enhance Fenton-like activities.

A framework to assess pharmaceutical accumulation in crops: from wastewater irrigation to consumption

The reuse of treated wastewater for irrigation can inadvertently introduce a suite of emerging contaminants such as pharmaceuticals into agri-ecosystems. However, current monitoring efforts to characterise exposure usually focus on a limited range of analytes. A modelling framework was developed that employs a sequence of pre-developed models to predict accumulative potential in a model crop, Zea mays (corn), using chemical structure and excretion rate as the only model inputs. Z. mays was selected as the model crop as it is a major food source, stands as one of the highest cultivated crops globally, and is characterised as having a medium uptake potential. The framework was used to predict uptake in Z. mays in three regions characteristic of high wastewater reuse (Australia, the US and the Middle East). Despite regional and plant specific differences, 72.7 % of the calculated concentrations were within a factor of ten of those reported in the literature. Topiramate, furosemide, and gemfibrozil were observed to accumulate to the greatest extent in Z. mays, predicted concentrations ranged between 50.27 and 418.01 ng/g (dw) for the top 10. Acids predominantly accumulated in leaves and fruit whereas a higher proportion of bases were predicted to accumulate in the roots. To the best of our knowledge 56.7 % of the 30 highest-ranked pharmaceuticals have not been previously documented in existing literature or monitoring campaigns. This presented framework demonstrates a method to assess risk posed by pharmaceutical compounds with limited experimental data.

Antimicrobial risk assessment-Aggregating aquatic chemical and resistome emissions

Urban water systems receive and emit antimicrobial chemicals, resistant bacterial strains, and resistance genes (ARGs), thus representing "antimicrobial hotspots". Currently, regional environmental risk assessment (ERA) is carried out using drug consumption data and threshold concentrations derived based on chemical-specific minimum inhibitory concentration values. A legislative proposal by the European Commission released in 2022 addresses the need to include selected ARGs besides the chemical concentration-based ERAs. The questions arise as to (A) how to improve chemical concentration-based risk assessment and (B) how to integrate resistome-related information with chemical-based risk - the main focal areas of this study. A tiered chemical risk prediction method is proposed by considering effluents of sewer networks and water resource recovery facilities (WRRFs). To improve predicted environmental concentrations (PEC in recipient water bodies), the impact of antimicrobial bio- and re-transformation in WRRFs is assessed using reliable global data. To combine chemical and genetic risks, a new parameter, i.e., the gene response efficiency (GRE) is proposed. A regression analysis show four orders of magnitude differences in GRE values amongst the seven antimicrobial classes studied. Higher GRE values in wastewater are obtained for antimicrobials with relatively low consumption rate levels.

Potentialities of semi-continuous anaerobic digestion for mitigating antibiotics in sludge

The behavior and removal of roxithromycin (ROX), oxytetracycline (OTC), chlortetracycline (CTC), and enrofloxacin (ENR) were investigated during the steady state of sludge anaerobic digestion (AD) in semi-continuous mode (37 °C). Sludge was spiked at realistic concentrations (50 μg/L of each antibiotic) and then used to feed the bioreactor for 80 days. Antibiotics were extracted from the substrate and digested sludge samples by accelerated solvent extraction (ASE). Accurate determination of antibiotics was obtained by the standard addition method (SAM) associated with the liquid chromatography-tandem mass spectrometry (LC-MS/MS). The presence of antibiotics at a concentration of 2.5 μg/g TS had no inhibitory effects on methane (CH4) production, total and volatile solids (TS and VS) removal as well as chemical oxygen demand (COD) removal. During the steady-state, antibiotics were removed significantly by 50, 100, and 59% respectively for the ROX, OTC, and CTC. Furthermore, ENR removal was not statistically significant and was estimated at 36%. This study highlighted that AD process could partially remove parent compounds, but ROX, CTC, and ENR persisted in the digested sludge. Hence, AD could be considered as a sludge treatment for mitigating, but not suppressing, the release of antibiotics through sludge application.

Insights into the role of electrochemical stimulation on sulfur-driven biodegradation of antibiotics in wastewater treatment

The presence of antibiotics in wastewater poses significant threat to our ecosystems and health. Traditional biological wastewater treatment technologies have several limitations in treating antibiotic-contaminated wastewaters, such as low removal efficiency and poor process resilience. Here, a novel electrochemical-coupled sulfur-mediated biological system was developed for treating wastewater co-contaminated with several antibiotics (e.g., ciprofloxacin (CIP), sulfamethoxazole (SMX), chloramphenicol (CAP)). Superior removal of CIP, SMX, and CAP with efficiencies ranging from 40.6 ± 2.6 % to 98.4 ± 1.6 % was achieved at high concentrations of 1000 μg/L in the electrochemical-coupled sulfur-mediated biological system, whereas the efficiencies ranged from 30.4 ± 2.3 % to 98.2 ± 1.4 % in the control system (without electrochemical stimulation). The biodegradation rates of CIP, SMX, and CAP increased by 1.5∼1.9-folds under electrochemical stimulation compared to the control. The insights into the role of electrochemical stimulation for multiple antibiotics biodegradation enhancement was elucidated through a combination of metagenomic and electrochemical analyses. Results showed that sustained electrochemical stimulation significantly enriched the sulfate-reducing and electroactive bacteria (e.g., Desulfobulbus, Longilinea, and Lentimicrobiumin on biocathode and Geobactor on bioanode), and boosted the secretion of electron transport mediators (e.g., cytochrome c and extracellular polymeric substances), which facilitated the microbial extracellular electron transfer processes and subsequent antibiotics removal in the sulfur-mediated biological system. Furthermore, under electrochemical stimulation, functional genes associated with sulfur and carbon metabolism and electron transfer were more abundant, and the microbial metabolic processes were enhanced, contributing to antibiotics biodegradation. Our study for the first time demonstrated that the synergistic effects of electrochemical-coupled sulfur-mediated biological system was capable of overcoming the limitations of conventional biological treatment processes. This study shed light on the mechanism of enhanced antibiotics biodegradation via electrochemical stimulation, which could be employed in sulfur-mediated bioprocess for treating antibiotic-contaminated wastewaters.

Sulfamethoxazole degradation in tri-electrode microbial electrochemical systems: Metabolomic and Metagenomic insights into organic pollution effects

Organic pollutants can alter the physicochemical properties and microbial communities of water bodies. In water contaminated with organic pollutants, the unique extracellular electron transfer mechanisms that promote sulfamethoxazole (SMX) degradation in tri-electrode microbial electrochemical systems (TE-MES) may be impacted. To simulate biodegradable organic matter contamination, glucose (GLU) was added. Metagenomics and metabolomics were used to analyze changes in microbial community structure, metabolism, and function on the electrodes. GLU addition accelerated water quality deterioration, and enhanced SMX degradation. Microbial taxa on the electrodes experienced selective enrichment. Notably, methanogens and SMX-degrading bacteria were enriched, while denitrifying bacteria and antibiotic-resistant bacteria were suppressed. Enriched metabolites were linked to 15 metabolic pathways and other functions like microbial signaling and genetics. Non-redundant genes also clustered in metabolic pathways, aligning with metabolite enrichment results. Additional pathways involved life cycle processes and protein interactions. Enzymes related to carbon metabolism, particularly glycoside hydrolases, increased significantly, indicating a shift in carbon metabolism on microbial electrodes after GLU addition. The abundance of intracellular electron transfer enzymes rose, while outer membrane proteins decreased. This contrasts with the typical TE-MES mechanism where outer membrane proteins facilitate SMX degradation. The presence of organic pollution may shift SMX degradation from an extracellular electrochemical process to an intracellular metabolic process, possibly involving co-metabolism with simple organic compounds. This study provides mechanistic insights and theoretical guidance for using TE-MES with embedded microbial electrodes to treat antibiotic-contaminated water affected by organic pollution.

Effect of secondary and tertiary wastewater treatment methods on opioids and the subsequent environmental impact of effluent and biosolids

Opioids are widely distributed, potent prescription analgesics that are known to be diverted for illicit use. Their prevalence of use is reflected by high concentrations of parent compounds and/or metabolites found in samples collected from wastewater treatment plants. Given that treatment byproducts enter the environment through several routes, the consequences of insufficient removal by treatment methods include unwanted environmental exposure and potential to disrupt ecosystems. Activated sludge treatment has been widely investigated for a large suite of prescription opioids but the same cannot be said for UV and chlorination. Additionally, the biosolid cycle of opioids has been overlooked previously. This study aimed to determine the extent to which secondary and tertiary wastewater treatment methods remove opioids from influent, and the associated environmental exposure for those persistent, as well as the fate of opioids in biosolids. Membrane bioreactor treatment proved effective for natural and semi-synthetic opioids while the effect of UV treatment was negligible. Chlorination was the most effective treatment method resulting in effluent with concentrations below theoretical predicted no-effect concentration. Biosolids are not subjected to any additional biological or chemical treatment after membrane bioreactor treatment and the levels detected in biosolid used as fertiliser had several opioids at potentially hazardous concentrations, indicated by a QSAR theoretical model. This data indicates a potential issue regarding the treatment process of biosolids and reliance on chlorination for effluent treatment that should be investigated in other treatment plants.

A Review of the Dissemination of Antibiotic Resistance through Wastewater Treatment Plants: Current Situation in Sri Lanka and Future Perspectives

The emergence of antibiotic resistance (AR) poses a significant threat to both public health and aquatic ecosystems. Wastewater treatment plants (WWTPs) have been identified as potential hotspots for disseminating AR in the environment. However, only a limited number of studies have been conducted on AR dissemination through WWTPs in Sri Lanka. To address this knowledge gap in AR dissemination through WWTP operations in Sri Lanka, we critically examined the global situation of WWTPs as hotspots for transmitting antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs) by evaluating more than a hundred peer-reviewed international publications and available national publications. Our findings discuss the current state of operating WWTPs in the country and highlight the research needed in controlling AR dissemination. The results revealed that the impact of different wastewater types, such as clinical, veterinary, domestic, and industrial, on the dissemination of AR has not been extensively studied in Sri Lanka; furthermore, the effectiveness of various wastewater treatment techniques in removing ARGs requires further investigation to improve the technologies. Furthermore, existing studies have not explored deeply enough the potential public health and ecological risks posed by AR dissemination through WWTPs.

A sustainable carbon aerogel from waste paper with exceptional performance for antibiotics removal from water

In this work, a sustainable 3D carbon aerogel (AO-WPC) is prepared from waste paper (WP), and used for efficient antibiotics removal from water. The AO-WPC aerogel shows good mechanical property and can recover after 100th of 30 % compression strain. The specific surface area of AO-WPC aerogel is up to 654.58 m2/g. More importantly, this aerogel reveals proper pore size distribution, including micro sized macropores between carbon fibers and intrinsic nano scale mesopores (11.86 nm), which is conducive to remove antibiotics from water. Taking tetracycline (Tc) as an example, the maximum adsorption capacity and adsorption rate of AO-WPC for Tc are as high as 384.6 mg/g and 0.510 g/(mg‧min), respectively, which exhibits significant advantages over most of the recent absorbents, and the adsorption toward Tc reveals good resistance to various environmental factors, including pH, various ions, and dissolved organic matter (DOM). Moreover, good thermal stability enables the AO-WPC aerogel to be regenerated through simple burning, and the adsorption capacity of Tc only decreases by 10.4 % after 10 cycles. Mechanism research shows that hydrogen bonding and π-π electron-donor-acceptor (EDA) interaction play the important role in the adsorption. The excellent mechanical property and adsorption performance imply good practical prospect of the AO-WPC aerogel.

Physiological adaptation and population dynamics of a nitrifying sludge exposed to ampicillin

Antibiotics in wastewater treatment plants can alter the physiological activity and the structure of microbial communities through toxic and inhibitory effects. Physiological adaptation, kinetic, and population dynamics behavior of a nitrifying sludge was evaluated in a sequential batch reactor (SBR) fed with 14.4 mg/L of ampicillin (AMP). The addition of AMP did not affect ammonium consumption (100 mg NH4+-N/L) but provoked nitrite accumulation (0.90 mg NO2--N formed/mg NH4+-N consumed) and an inhibition of up to 67% on the nitrite oxidizing process. After 30 cycles under AMP feeding, the sludge recovered its nitrite oxidizing activity with a high nitrate yield (YNO3-) of 0.87 ± 0.10 mg NO3--N formed/mg NH4+-N consumed, carrying out again a stable and complete nitrifying process. Increases in specific rate of nitrate production (qNO3-) showed the physiological adaptation of the nitrite oxidizing bacteria to AMP inhibition. Ampicillin was totally removed since the first cycle of addition. Exposure to AMP had effects on the abundance of bacterial populations, promoting adaptation of the nitrifying sludge to the presence of the antibiotic and its consumption. Nitrosomonas and Nitrosospira always remained within the dominant genera, keeping the ammonium oxidizing process stable while an increase in Nitrospira abundance was observed, recovering the stability of the nitrite oxidizing process. Burkholderia, Pseudomonas, and Thauera might be some of the heterotrophic bacteria involved in AMP consumption.

Intelligent management of carbon emissions of urban domestic sewage based on the Internet of Things

Domestic wastewater is one of the major carbon sources that cannot be ignored by human society. Against the background of carbon peaking & carbon neutrality (Double Carbon) goals, the continuous urbanization has put heavy pressure on urban drainage systems. Nevertheless, the complex subjective and objective conditions of drainage systems restrict the field monitoring, measurement, and analysis of drainage systems, which has become a great obstacle to the study of carbon emissions from drainage system. In this paper, 3389 sensor terminals of Internet of Things (IoT) are used to build a field monitoring IoT for urban domestic wastewater methane (CH4) carbon emission, with 21 main districts of Chongqing Municipality in China as the study area. Incorporating Fick's law of diffusion, this field monitoring IoT derives a measurement model for methane carbon emissions based on measured concentrations, and solves the problems of long-term and stable monitoring and measurement of methane gas in complex underground environment. With GIS spatio-temporal analysis used to analyze the spatial and temporal evolution patterns of carbon emissions from septic tanks in drainage systems, it successfully reveals the spatial and temporal distribution of methane carbon emissions from drainage systems in different seasons, as well as the relationship between methane carbon emissions from drainage systems and the latitude of direct sunlight. Applying the DTW method, it quantifies the stability of methane monitoring in drainage systems and evaluates the effects of Sampling Frequency (SF) and Number of Devices Terminal (NDT) on the stability of methane monitoring. Consequently, an intelligent management system for carbon emissions from urban domestic wastewater is constructed on the base of IoT, which integrates methane monitoring, measurement and analysis in septic tanks of drainage systems.

Occurrence, removal efficiency, and emission of antibiotics in the sewage treatment plants of a low-urbanized basin in China and their impact on the receiving water

Sewage treatment plants (STPs) are primary sources of antibiotics in aquatic environments. However, limited research has been conducted on antibiotic attenuation in STPs and their downstream waters in low-urbanized areas. This study analyzed 15 antibiotics in the STP sewage and river water in the Zijiang River basin to quantify antibiotic transport and attenuation in the STPs and downstream. The results showed that 14 target antibiotics, except leucomycin, were detected in the STP sewage, dominated by amoxicillin (AMOX), ofloxacin, and roxithromycin. The total antibiotic concentration in the influent and effluent ranged from 158 to 1025 ng/L and 99.9 to 411 ng/L, respectively. The removal efficiency of total antibiotics ranged from 54.7 % to 75.7 % and was significantly correlated with total antibiotic concentration in the influent. The antibiotic emission from STPs into rivers was 78 kg/yr and 4.6 g/km2yr in the Zijiang River basin. The total antibiotic concentration downstream of the STP downstream was 23.6 to 213 ng/L and was significantly negatively correlated with the transport distance away from the STP outlets. Antibiotics may pose a high ecological risk to algae and low ecological risk to fish in the basin. The risk of AMOX and ciprofloxacin resistance for organisms in the basin was estimated to be moderate. This study established antibiotic removal and attenuation models in STPs and their downstream regions in a low-urbanized basin, which is important for simulating antibiotic transport in STPs and rivers worldwide.

Fate and transport modelling for evaluating antibiotic resistance in aquatic environments: Current knowledge and research priorities

Antibiotics have revolutionised medicine in the last century and enabled the prevention of bacterial infections that were previously deemed untreatable. However, in parallel, bacteria have increasingly developed resistance to antibiotics through various mechanisms. When resistant bacteria find their way into terrestrial and aquatic environments, animal and human exposures increase, e.g., via polluted soil, food, and water, and health risks multiply. Understanding the fate and transport of antibiotic resistant bacteria (ARB) and the transfer mechanisms of antibiotic resistance genes (ARGs) in aquatic environments is critical for evaluating and mitigating the risks of resistant-induced infections. The conceptual understanding of sources and pathways of antibiotics, ARB, and ARGs from society to the water environments is essential for setting the scene and developing an appropriate framework for modelling. Various factors and processes associated with hydrology, ecology, and climate change can significantly affect the fate and transport of ARB and ARGs in natural environments. This article reviews current knowledge, research gaps, and priorities for developing water quality models to assess the fate and transport of ARB and ARGs. The paper also provides inputs on future research needs, especially the need for new predictive models to guide risk assessment on AR transmission and spread in aquatic environments.

Biological degradation and mineralization of tetracycline antibiotic using SBR equipped with a vertical axially rotating biological bed (SBR-VARB)

Tetracycline (TC) is a widely used antibiotic with a complex aromatic chemical structure and is highly resistant to biodegradation. In this study, an SBR equipped with a vertical axially rotating biological bed (SBR-VARB) was used for the biodegradation and mineralization of TC. SBR-VARB showed high efficiency in removing TC (97%), total phenolic compounds (TP) (95%), and COD (85%) under optimal operating conditions (TC = 50 mg/L, HRT = 1.75 d, and OLR = 36 g COD/m3 d). The SBR-VARB was able to treat higher concentrations of TC in shorter HRT than reported in previous studies. The contribution of VARB to improve SBR efficiency in removing TC, TP, and COD was 16, 36, and 48%, respectively. Intermediate compounds formed during the biodegradation of TC were identified using GC-MS under the optimal operating conditions of the bioreactor. These are mainly organic compounds with linear chemical structures. Based on the complete biodegradation of TC under the optimal operating conditions of the bioreactor, 93% and 36% of the chlorine and nitrogen atoms in the chemical structure of TC appeared in the wastewater, respectively. According to the sequence analysis of 16SrDNA, Pseudomonas sp., Kocuria Polaris, and Staphylococcus sp. were identified in the biofilm of VARB and the suspended biomass of the bioreactor. Therefore, SBR-VARB showed high efficiency in the biodegradation and mineralization of TC and can be used as a suitable option for treating wastewater containing antibiotics and other toxic compounds.

Pyrolysis temperature affects the physiochemical characteristics of lanthanum-modified biochar derived from orange peels: Insights into the mechanisms of tetracycline adsorption by spectroscopic analysis and theoretical calculations

Biochar (BC) derived from orange peels was modified using LaCl₃ to enhance its tetracycline (TC) adsorption capacity. SEM-EDS, FT-IR, XRD, and BET were used to characterize the physiochemical characteristics of La-modified biochar (La-BC). Batch experiments were conducted to investigate the effects of several variables like pyrolysis temperature, adsorbent dosage, initial pH, and coexisting ions on the adsorption of TC by La-BC. XPS and density functional theory (DFT) were used to elucidate the TC adsorption mechanism of La-BC. The results demonstrated that La was uniformly coated on the surface of the La-BC. The physiochemical characteristics of La-BC highly depended on pyrolysis temperature. Higher temperature increased the specific surface area and functional groups of La-BC, thus enhancing its TC adsorption capacity. La-BC prepared at 700 °C (BC@La-700) achieved the maximum adsorption capacity of 143.20 mg/g, which was 6.8 and 4.6 times higher than that of BC@La-500 and BC@La-600, respectively. The mechanisms of TC adsorption by La-BC were most accurately described by the pseudo-second-order kinetic model. Furthermore, the adsorption isotherm of La-BC was consistent with the Freundlich model. BC@La-700 achieved good TC adsorption efficiencies even at a wide pH range (pH 4-10). Humic acid significantly inhibited TC adsorption by La-BC. The presence of coexisting ions (NH₄⁺, Ca²⁺, NO₃^-) did not significantly affect the adsorption capacity of La-BC, particularly BC@La-700. Moreover, BC@La-700 also exhibited the best recycling performance, which achieved relative high adsorption capacity even after 5 cycles. The XPS results showed that π-π bonds, oxygen-containing functional groups, and La played a major role in the adsorption of TC on La-BC. The result of DFT showed that the adsorption energy of La-BC was the greatest than that of other functional groups on biochar. Collectively, our findings provide a theoretical basis for the development of La-BC based materials to remove TC from wastewater.

Impact of GSTT1 and GSTM1 Polymorphisms in the Susceptibility to Philadelphia Negative Chronic Myeloid Leukaemia

BACKGROUND

Our research aimed to clarify the role of genetic polymorphisms in GST (T1 and M1) in the development of Ph-ve CML.

MATERIALS AND METHODS

We report on a case-control study with 126 participants, divided into 26 patients with Ph-ve CML (57.7% male, 42.3% female) and 100 healthy volunteers (51% male, 49% female) with no medical history of cancer as a control population. All Ph-ve CML patients were diagnosed according to standard hematologic and cytogenetic criteria based on CBC, confirmed by Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) to determine the presence or absence of the BCRABL gene, followed by bone marrow (BM) examination.

RESULTS

Of the 26 studied cases, 50% had the GSTT1 null genotype against 21% of the control group, a statistically significant difference (CI= 1.519 - 9.317; p-value= 0.004). The GSTM1 null genotype was detected in 23.1% of cases and 35% of controls, a difference not statistically significant (OR= 0.557; CI= 0.205-1.515; p-value= 0.252). The distribution of GSTT1 and GSTM1 polymorphisms was also examined according to gender, age and ethnic grouping; these findings revealed no statistically significant differences.

CONCLUSION

Our study reveals a strong correlation between GSTT1 polymorphism and Ph-ve CML, whereas the data for GSTM1 polymorphisms indicates no role in the initial development of the disease. More studies are required to further clarify these and other genes' roles in disease development.

Efficient removal of ibuprofen and ofloxacin pharmaceuticals using biofilm reactors for hospital wastewater treatment

Hospital wastewater is harmful to the environment and human health due to its complex chemical composition and high potency towards becoming a source of disease outbreaks. Due to these complexities, its treatment is neither efficient nor cost-effective. It is a challenging issue that requires immediate attention. This effort focuses on the treatment of hospital wastewater (HWW) by removing two selected drugs, namely ibuprofen (IBU) and ofloxacin (OFX) using individual biological treatment methods, such as moving bed biofilm reactors (MBBR) and physicochemical treatment, such as ozonation and peroxane process. The both methods are compared to find the best method overall based on effectiveness and removal efficiency. The optimal removal for ozone dosing range was nitrate (9.00% and 62.00%), biological oxygen demand (BOD) (92.00% and 64.00%), and chemical oxygen demand (COD) (96.00% and 92.00%) that required at least 10 min to reach considerable degradation. The MBBR process assured a better performance for ibuprofen removal, overall. The IBU and OFX removal was found to be 14.32-96.00% at a higher COD value and 11.33-94.00% at a lower COD value due to its biodegradation. This work strives to pave the way forward to build an HWW treatment technology using integrated MBBR processes for better efficiency and cost-effectiveness.

Spatiotemporal urban water profiling for the assessment of environmental and public exposure to antimicrobials (antibiotics, antifungals, and antivirals) in the Eerste River Catchment, South Africa

Antimicrobial agent (AA) usage, excretion, and persistence are all important factors in association with the occurrence and dissemination of antimicrobial resistance. Urban water profiling was utilised in the Eerste River catchment (South Africa) to establish AA usage in a region where comprehensive prescription records were not readily available and where portions of the community did not have sufficient access to sanitation. This technique enabled the environmental exposure to be quantified throughout the catchment area and the identification of contamination hotspots. Monitoring occurred over a 11-month period. 812 samples were processed using UPLC-MS/MS for the quantitation of 56 antimicrobials and 26 of their metabolites. Spatiotemporal trends were established, with consideration to community behaviour, seasonal changes, and physiochemical properties of the analytes. The Eerste River samples collected upstream from the town of Stellenbosch had the lowest AA loads (<4 g/day), unafflicted by industrial presence and with only small impact from farming activities. This was followed by sites downstream from a wastewater treatment plant (serving 178 K people). The measurement of low AA loads (influent: 500-800 g/day and effluent 50-100 g/day), indicates a high efficiency of wastewater treatment, allowing for an effective reduction of AA and a lower environmental burden. This is compared to river sites that receive untreated waste from communities in informal settlements (6-12 K people) that are not connected to the sewer infrastructure (with AA levels accounting for 100-600 g/day). Temporal trends exhibited reduced daily loads during the summer to early autumn (Nov-May). This is likely due to seasonal patterns in community health and/or notable changes in rainfall and temperatures at the sampling locations throughout the year. However, weather patterns are also important to consider - particularly for the river sites. South Africa has notable rainfall and temperature seasonality. Antiretrovirals (ARV), emtricitabine and lamivudine, were the most prevalent drugs throughout the monitoring campaign, followed by tuberculosis drugs and sulfonamides. ARVs were, however, effectively reduced via wastewater treatment processes (>97%). This was also the case for beta-lactams, nitrofurantoin, and trimethoprim. The treatment efficacy for other drugs was more variable, that did not appear to have temporal significance.

Degradation of chloramphenicol by Ti/PbO2-La anodes and alteration in bacterial community and antibiotics resistance genes

Antibiotics accumulation in the environment has given rise to multi-drug resistant 'superbugs' and antibiotics resistence genes (ARGs). Chloramphenicol (CAP), a kind of widely used antibiotics, was chosen as the model compound to investigate its degradation during electrochemical treatment process. The prepared Ti/PbO₂-La electrodes had a denser surface and a more complete PbO₂ crystal structure than Ti/PbO₂ electrode. The doping of La increased the onset potential and the overpotential, increased the current value of the oxidation peak and the reduction peak, reduced the impedance, and increased the lifetime. The reactions CAP degradation and TOC removal on Ti/PbO₂-La electrode was both primary kinetic reactions. CAP degradation rate increased with current density, and TOC obtained the highest removal at current density of 25 mA cm^-2. The electrolyte concentration had a small effect in the range of 0.050-0.150 mol L^-1. The effects under acidic and neutral conditions were better than under alkaline conditions. CAP was mainly directly oxidized at the electrode surface and indirect oxidation also took place via generated ·OH and SO₄^·-. 15 intermediates and 2 degradation pathways have been postulated. The entry of CAP and CAP intermediates into the environment caused the alteration in bacterial community and ARGs, while complete degradation products had little effect on them. Redundancy analysis showed that intI1 was the dominant factor affecting ARGs, and Actinobacteria and Patescibacteria were the main factors affecting the abundances of ARGs in the microbial community.

Forward-Looking Roadmaps for Long-Term Continuous Water Quality Monitoring: Bottlenecks, Innovations, and Prospects in a Critical Review

Long-term continuous monitoring (LTCM) of water quality can bring far-reaching influences on water ecosystems by providing spatiotemporal data sets of diverse parameters and enabling operation of water and wastewater treatment processes in an energy-saving and cost-effective manner. However, current water monitoring technologies are deficient for long-term accuracy in data collection and processing capability. Inadequate LTCM data impedes water quality assessment and hinders the stakeholders and decision makers from foreseeing emerging problems and executing efficient control methodologies. To tackle this challenge, this review provides a forward-looking roadmap highlighting vital innovations toward LTCM, and elaborates on the impacts of LTCM through a three-hierarchy perspective: data, parameters, and systems. First, we demonstrate the critical needs and challenges of LTCM in natural resource water, drinking water, and wastewater systems, and differentiate LTCM from existing short-term and discrete monitoring techniques. We then elucidate three steps to achieve LTCM in water systems, consisting of data acquisition (water sensors), data processing (machine learning algorithms), and data application (with modeling and process control as two examples). Finally, we explore future opportunities of LTCM in four key domains, water, energy, sensing, and data, and underscore strategies to transfer scientific discoveries to general end-users.

Occurrence and removal of 25 antibiotics during sewage treatment processes and potential risk analysis

The occurrence and removal of 25 antibiotics, including ten quinolones (QNs), four macrolides (MLs), four tetracyclines (TCs) and seven sulfonamides (SNs), were analysed at two sewage treatment plants (STPs) with different treatment units in Guangxi Province, China. The results showed that 14 and 16 antibiotics were detected in the influent of the two STPs, with concentrations ranging from 13.7-4265.2 ng/L and 14.5-10761.7 ng/L, respectively. Among the antibiotics, TCs were the main type in the study area, accounting for more than 79% of the total concentration of all antibiotics. The antibiotic removal efficiencies of the different process units ranged from -56.73% to 100.0%. It was found that the SN removal efficiency of the multistage composite mobile bed membrane bioreactor (MBBR) process was better than that of the continuous-flow Intermission biological reactor (IBR) process, while the IBR process was better than the MBBR process in terms of removing TCs and MLs; however, there was no obvious difference in the QN removal efficiencies of these two processes. Redundancy analysis (RDA) showed a strong correlation between antibiotic concentration and chemical oxygen demand (COD). Risk assessments indicated that algae, followed by invertebrates and fish, were the most sensitive aquatic organisms to the detected antibiotics.

Chitin-biocalcium as a novel superior composite for ciprofloxacin removal: Synergism of adsorption and flocculation

The ubiquitous present antibiotics in aquatic environment is attracting increasing concern due to the dual problems of bioaccumulation toxicity and antibiotic resistance. In this study, a low-cost chitin-biocalcium (CC) composite was developed by a facile alkali activation process from shell waste for typical antibiotics ciprofloxacin (CIP) removal. Response surface methodology (RSM) was utilized to optimize synthesis methodology. The optimized CC products featured superior CIP removal capacity of 2432 mg/g at 25 °C (adsorption combined with flocculation), rapid adsorption kinetics, high removal efficiency (95.58%) and wide pH adaptability (under pH range 4.0-10.0). The functional groups in chitin and high content of biocalcium (Ca²⁺) endowed CC abundant active sites. The kinetic experimental data was fitted well by pseudo-second-order and intraparticle diffusion model at different concentrations, revealing the removal was controlled by chemisorption and mass transport step. From the macroscopic aspect, flocs were produced with the increase of CIP concentration during the reaction, adsorption combined with flocculation were related to the CIP removal. From the microcosmic aspect, the superior removal performance was attributed to cation bridging, cation complexation among biocalcium-CIP and hydrogen bond between functional groups of chitin and CIP.

An innovative biofilter technology for reducing environmental spreading of emerging pollutants and odour emissions during municipal sewage treatment

Wastewater treatment plants (WWTPs) are known sources of contaminants of emerging concern (CECs) spreading into the environment, as well as, of unpleasant odors. CECs represent a potential hazard for human health and the environment being pharmaceutical or biologically active compounds and they are acquiring relevance in European directives. Similarly, the public concern about odour emissions from WWTPs is also increasing due to the decreasing distance between WWTP and residential areas. This study focuses on the effectiveness of the recently developed MULESL technology (MUch LEss SLudge; WO2019097463) in removing CECs and limiting odour emissions from WWTPs. MULESL technology has been developed for its ability to reduce up to 80% the sludge production from WWTPs. However, it is ought to evaluate if the benefits coming from sludge production reduction do not invalidate CECs removal or negatively affect odour emissions. Thus, the performances of a MULESL and a conventional WWTP (flow rate of 375 m³/d and 3600 m³/d, respectively) were compared while treating the same municipal sewage. Whereas both plants succeeded in removing the traditional gross parameters characterizing wastewaters (e.g. chemical oxygen demand, nitrogen), the MULESL was much more effective than the conventional one in terms of CECs removal for about 60% of the identified compounds showing, however, the same or lower effectiveness for about 30% and 10% of them, respectively. This result was attributed to the high sludge retention time and biomass concentration in the MULESL (enabling enrichment of slow growing microorganisms and forcing biomass to use unusual substrates, respectively), and to the biomass feature to grow in the form of biofilm and granules (favoring micropollutants absorption on biomass). Furthermore, odour impact analysis has shown that the MULESL was characterized by a much lower impact, i.e. 45% lower than that of primary and secondary treatments of the conventional WWTP.

Effective electrocatalytic elimination of chloramphenicol: mechanism, degradation pathway, and toxicity assessment

The residual antibiotics in different environmental media pose a serious threat to human health and the ecosystem. The high-efficient elimination of antibiotics is one of the foremost works. In this study, chloramphenicol (CAP) was eliminated efficiently by electrocatalytic advanced oxidation process with carbon nanotubes/agarose/indium tin oxide (CNTs/AG/ITO) electrode. The influences of different experimental parameters on the degradation efficiency were systematically studied. Under the optimal conditions (4 V potential, 10 wt% CNTs dosage, and pH = 10), the maximum degradation efficiency of CAP (20 mg L-1) achieved 88% within 180 min. Besides, the electrocatalytic degradation pathway and mechanism for CAP were also investigated, •O2- played a major role in the process of electrocatalytic degradation. Based on the QSAR (quantitative structure-activity relationship) model, the toxicities of CAP and identified intermediates were analyzed. Compared with the parent compound, the maximal chronic toxicity of intermediate ((E)-3-(4-nitrophenyl)prop-1-ene-1,3-diol) for daphnid increased 197-fold. Besides, the hybrid toxicity of the degradation system was further confirmed via disk agar biocidal tests with Escherichia coli ATCC25922, which changed slightly during the degradation process. Based on the above results, it is worth noting that the degradation pathway and toxicity assessment should be paid more attention to the treatment of antibiotic wastewater.

Elimination from wastewater of antibiotics reserved for hospital settings, with a Fenton process based on zero-valent iron

The Fenton process activated by Zero Valent Iron (ZVI-Fenton) is shown here to effectively remove antibiotics reserved for hospital settings (specifically used to treat antibiotic-resistant infections) from wastewater, thereby helping in the fight against bacterial resistance. Effective degradation of cefazolin, imipenem and vancomycin in real urban wastewater was achieved at pH 5, which is quite near neutrality when compared with classic Fenton that works effectively at pH 3-4. The possibility to operate successfully at pH 5 has several advantages compared to operation at lower pH values: (i) lower reagent costs for pH adjustment; (ii) insignificant impact on wastewater conductivity, because lesser acid is required to acidify and lesser or no base for neutralization; (iii) undetectable release of dissolved Fe, which could otherwise be an issue for wastewater quality. The cost of reagents for the treatment ranges between 0.04 and 0.07 $ m^-3, which looks very suitable for practical applications. The structures of the degradation intermediates of the studied antibiotics and their likely abundance suggest that, once the primary compound is eliminated, most of the potential to trigger antibiotic action has been removed. Application of the ZVI-Fenton technique to wastewater treatment could considerably lower the possibility for antibiotics to trigger the development of resistance in bacteria.

A Review on Occurrence and Spread of Antibiotic Resistance in Wastewaters and in Wastewater Treatment Plants: Mechanisms and Perspectives

This paper reviews current knowledge on sources, spread and removal mechanisms of antibiotic resistance genes (ARGs) in microbial communities of wastewaters, treatment plants and downstream recipients. Antibiotic is the most important tool to cure bacterial infections in humans and animals. The over- and misuse of antibiotics have played a major role in the development, spread, and prevalence of antibiotic resistance (AR) in the microbiomes of humans and animals, and microbial ecosystems worldwide. AR can be transferred and spread amongst bacteria via intra- and interspecies horizontal gene transfer (HGT). Wastewater treatment plants (WWTPs) receive wastewater containing an enormous variety of pollutants, including antibiotics, and chemicals from different sources. They contain large and diverse communities of microorganisms and provide a favorable environment for the spread and reproduction of AR. Existing WWTPs are not designed to remove micropollutants, antibiotic resistant bacteria (ARB) and ARGs, which therefore remain present in the effluent. Studies have shown that raw and treated wastewaters carry a higher amount of ARB in comparison to surface water, and such reports have led to further studies on more advanced treatment processes. This review summarizes what is known about AR removal efficiencies of different wastewater treatment methods, and it shows the variations among different methods. Results vary, but the trend is that conventional activated sludge treatment, with aerobic and/or anaerobic reactors alone or in series, followed by advanced post treatment methods like UV, ozonation, and oxidation removes considerably more ARGs and ARB than activated sludge treatment alone. In addition to AR levels in treated wastewater, it examines AR levels in biosolids, settled by-product from wastewater treatment, and discusses AR removal efficiency of different biosolids treatment procedures. Finally, it puts forward key-points and suggestions for dealing with and preventing further increase of AR in WWTPs and other aquatic environments, together with a discussion on the use of mathematical models to quantify and simulate the spread of ARGs in WWTPs. Mathematical models already play a role in the analysis and development of WWTPs, but they do not consider AR and challenges remain before models can be used to reliably study the dynamics and reduction of AR in such systems.

Oxygen vacancy-rich 2D/0D BiO1-XBr/AgBr Z-scheme photocatalysts for efficient visible light driven degradation of tetracycline

Semiconductor-based photocatalytic technology, as a green and promising avenue in response to the abuse of antibiotic pollution and human health crisis, is restricted by the limited photo-absorption and fast recombination of photogenerated carriers. In this paper, all these challenges were settled by AgBr particles incorporated into oxygen-deficient BiOBr nanosheets, forming novel oxygen vacancy (OV)-rich 2D/0D Z-scheme heterojunctions. Z-scheme photocatalytic system has an effective separation rate of photogenerated carriers and an ability to maintain original redox capacity. Moreover, introducing OVs in the Z-scheme can not only improve the visible light absorption ability, but also serve as recombination centers, thus promoting the separation of electrons and holes. Notably, the photocatalytic activity of 2D/0D BiO_1-XBr/AgBr (2:1) was significantly improved under the irradiation of visible light, removing 81% of tetracycline after 25 min, which was about 2.62 times and 2.03 times as high as those of BiO_1-XBr and AgBr, respectively. In addition, the 2D/0D BiO_1-XBr/AgBr (2:1) indicated high photocatalytic stability and reusability, and its tetracycline degradation efficiency remained stable after five cycles. In summary, this work suggests that the photocatalysts have a great potential to remove TC and provides a possible strategy for purifying water.

A Mechanistic Model to Assess the Fate of Naphthalene and Benzo(a)pyrene in a Chilean WWTP

Polycyclic aromatic hydrocarbons (PAHs) are a family of organic compounds of widespread presence in the environment. They are recalcitrant, ubiquitous, prone to bioaccumulation, and potentially carcinogenic. Effluent from wastewater treatment plants (WWTPs) constitutes a major source of PAHs into water bodies, and their presence should be closely monitored, especially considering the increasing applications of potable and non-potable reuse of treated wastewater worldwide. Modeling the fate and distribution of PAHs in WWTPs is a valuable tool to overcome the complexity and cost of monitoring and quantifying PAHs. A mechanistic model was built to evaluate the fate of PAHs in both water and sludge lines of a Chilean WWTP. Naphthalene and benzo(a)pyrene were used as models of low-MW and high-MW PAHs. As there were no reported experimental data available for the case study, the influent load was determined through a statistical approach based on reported values worldwide. For both naphthalene and benzo(a)pyrene, the predominant mechanism in the water line was sorption to sludge, while that in the sludge line was desorption. Compared to other studies in the literature, the model satisfactorily describes the mechanisms involved in the fate and distribution of PAHs in a conventional activated sludge WWTP. Even though there is evidence of the presence of PAHs in urban centers in Chile, local regulatory standards do not consider PAHs in the disposal of WWTP effluents. Monitoring of PAHs in both treated effluents and biosolids is imperative, especially when considering de facto reuse and soil amendment in agricultural activities are currently practiced downstream of the studied WWTP.

Bioremoval and tolerance study of sulfamethoxazole using whole cell Trichoderma harzianum isolated from rotten tree bark

Antibiotic contamination raises concerns over antibiotic resistance genes (ARGs), which can severely impact the human health and environment. Sulfamethoxazole (SMX) is a widely used antibiotic that is incompletely metabolized in the body. In this study, the research objectives were (1) to isolate the native strain of Trichoderma sp. from the environment and analyze the tolerance toward SMX concentration by evaluating fungal growth, and (2) to investigate the potential of SMX removal by fungi. The potential fungi isolated from rotten tree bark showed 97% similarity to Trichoderma harzianum (Accession no. MH707098.1). The whole cell of fungi was examined in vitro; the strain Trichoderma harzianum BGP115 eliminated 71% of SMX after 7 days, while the white rot fungi Trametes versicolor, demonstrated 90% removal after 10 days. Furthermore, the tolerance of fungal growth toward SMX concentration at 10 mg L^-1 was analyzed, which indicated that Trichoderma harzianum BGP115 (the screened strain) exhibited more tolerance toward SMX than Trametes versicolor (the reference strain). The screened fungi isolated from rotted tree bark demonstrated the ability of SMX bioremoval and the potential to be tolerant to high concentrations of SMX.

Instantaneous Sonophotocatalytic Degradation of Tetracycline over NU-1000@ZnIn2S4 Core-Shell Nanorods as a Robust and Eco-friendly Catalyst

The universal pollution of diverse water bodies and declined water quality represent very important environmental problems. The development of new and efficient photocatalytic water treatment systems based on the Z-scheme mechanisms can contribute to tackling such problems. This study reports the preparation, full characterization, and detailed sonophotocatalytic activity of a new series of hybrid NU@ZIS nanocomposites, which comprise a p-n heterojunction of 3D Zr(IV) metal-organic framework nanorods (NU-1000) and photoactive ZnIn₂S₄ (ZIS) nanostars. Among the obtained materials with varying content of ZIS (5, 10, 20, and 30%) on the surface of NU-1000, the NU@ZIS20 nanocomposite revealed an ultrahigh catalytic performance and recyclability in a quick visible-light-induced degradation of the tetracycline antibiotic in water under sonophotocatalytic conditions. Moreover, increased activity of NU@ZIS20 can be ascribed to the formation of a p-n heterojunction between NU-1000 and ZIS, and a synergistic effect of these components, leading to a high level of radical production, facilitating a Z-scheme charge carrier transfer and reducing the recombination of charge carriers. The radical trapping tests revealed that ^•OH, ^•O₂^-, and h⁺ are the major active species in the sonophotocatalytic degradation of tetracycline. Possible mechanism and mineralization pathways were introduced. Cytotoxicity of NU@ZIS20 and aquatic toxicity of water samples after tetracycline degradation were also assessed, showing good biocompatibility of the catalyst and efficacy of sonophotocatalytic protocols to produce water that does not affect the growth of bacteria. Finally, the obtained nanocomposites and developed photocatalytic processes can represent an interesting approach toward diverse environmental applications in water remediation and the elimination of other types of organic pollutants.

Industrialization as a source of heavy metals and antibiotics which can enhance the antibiotic resistance in wastewater, sewage sludge and river water

The spread of antibiotic resistance is closely related with selective pressure in the environment. Wastewater from industrialized regions is characterized by higher concentrations of these pollutants than sewage from less industrialized areas. The aim of this study was to compare the concentrations of contaminants such as antibiotics and heavy metals (HMs), and to evaluate their impact on the spread of genes encoding resistance to antimicrobial drugs in samples of wastewater, sewage sludge and river water in two regions with different levels of industrialization. The factors exerting selective pressure, which significantly contributed to the occurrence of the examined antibiotic resistance genes (ARGs), were identified. The concentrations of selected gene copy numbers conferring resistance to four groups of antibiotics as well as class 1 and 2 integron-integrase genes were determined in the analyzed samples. The concentrations of six HMs and antibiotics corresponding to genes mediated resistance from 3 classes were determined. Based on network analysis, only some of the analyzed antibiotics correlated with ARGs, while HM levels were correlated with ARG concentrations, which can confirm the important role of HMs in promoting drug resistance. The samples from a wastewater treatment plant (WWTP) located an industrialized region were characterized by higher HM contamination and a higher number of significant correlations between the analyzed variables than the samples collected from a WWTP located in a less industrialized region. These results indicated that treated wastewater released into the natural environment can pose a continuous threat to human health by transferring ARGs, antibiotics and HMs to the environment. These findings shed light on the impact of industrialization on antibiotic resistance dissemination.

Novel sodium bicarbonate activation of cassava ethanol sludge derived biochar for removing tetracycline from aqueous solution: Performance assessment and mechanism insight

NaHCO₃ was used as a novel activator to produce cassava ethanol sludge-based biochar. The NaHCO₃-activated biochar showed superior adsorption capacity for tetracycline (154.45 mg/g) than raw biochar (34.04 mg/g). Orthogonal experiments confirmed the optimal preparation conditions of biochar. Increasing adsorbent dosage and temperature facilitated tetracycline removal. The maximum removal was 92.60% at pH = 3.0. Calcium ions and alkalinity decreased tetracycline removal. The time for attaining equilibrium was extended with increasing tetracycline concentration, but the equilibrium could be completed within 24 h. Langmuir model fitted the equilibrium data well. Kinetics process followed the Elovich model. The adsorption rate was controlled by both intraparticle and liquid film diffusion and the process was endothermic and spontaneous. The electrostatic attraction, hydrogen bonding, π-π interactions, and pore-filling were involved in the adsorption mechanism. The findings may provide an underlying guide for sludge disposal and removal of tetracycline from wastewater in practical application.

Occurrence and fate of pharmaceuticals in effluent and sludge from a wastewater treatment plant in Brazil

A wide variety of pharmaceuticals are discharged in water courses on a daily basis due to their incomplete removal from effluent in treatment plants. The aim of the current study was to assess the occurrence, fate and removal of pharmaceuticals from effluent and sludge samples collected in the biggest sanitary sewer plant in Southern Brazil. In total, 13 pharmaceuticals were detected in the influent through UHPLC-MS/M - paracetamol and caffeine recorded the highest concentrations, 137.98 and 35.29 µg L^-1, respectively. The treated effluent presented 11 compounds. Antibiotics were the class recording the widest diversity; metronidazole showed the lowest concentration (0.023 µg L^-1) and sulfamethoxazole presented the highest concentration (1.374 µg L^-1) in influent samples. Seven pharmaceuticals were absorbed by the sludge; among them, one finds caffeine, ciprofloxacin and ofloxacin, which were quantified both in the effluent and in the sludge. On the other hand, doxycycline, fenbendazole, norfloxacin and tetracycline were only detected in sludge samples - their concentrations ranged from 0.026 to 5.034 mg kg^-1. Clindamycin, oxytetracycline, sulfathiazole and trimethoprim concentrations increased throughout the treatment. There were high paracetamol and caffeine removal rates (>97%), and it may have happened due to degradation, photodegradation or chemical reaction. Ciprofloxacin and ofloxacin removal rate exceeded 83% mainly due to their sorption by sludge. Finally, the mass balance analysis highlighted high pharmaceutical loads (511.466 g d^-1) discharged into recipient waterbodies. This outcome demands broadening the removal of these pharmaceuticals from sewage.

Fate of antibiotics in engineered wastewater systems and receiving water environment: A case study on the coast of Hangzhou Bay, China

The occurrence of man-made antibiotics in natural environment has aroused attentions from both scientists and publics. However, few studies tracked antibiotics from their production site to the end of disposal environment. Taking the coastal region of Hangzhou Bay as the study area, the fate of 77 antibiotics from 6 categories in two-step wastewater treatment plants (WTPs, i.e. pharmaceutical WTP and integrated WTP) was focused; and the antibiotics in both dissolved and adsorbed phases were investigated simultaneously in this study. The ubiquitous occurrence of antibiotics was observed in the two-step WTPs, with antibiotic concentrations following the order of PWTP (LOQ - 1.0 × 10⁵ ng·L^-1) > IWTP_i (for industrial wastewater treatment, LOQ - 3.7 × 10³ ng·L^-1) > IWTP_d (for domestic sewage treatment, LOQ - 1.3 × 10³ ng·L^-1). And the types of antibiotics detected in excess sludge and suspended particles were in accordance with those in wastewater. Quinolones were invariably dominant in both dissolved and adsorbed fractions. High removal efficiencies (median values >50.0%) were acquired for the dissolved quinolones (except for DFX), tetracyclines, β-lactams, and lincosamides. Anaerobic/anoxic/oxic achieved the highest aqueous removal of antibiotics among the investigated treatment technologies in the three WTPs. PWTP and IWTP removed 9797 and 487 g·d^-1 of antibiotics, respectively; and a final effluent with 126.4 g·d^-1 of antibiotics was discharged into the effluent-receiving area (ERA) of Hangzhou Bay. Source apportionment analysis demonstrated that the effluents of IWTP_d and IWTP_d contributed respectively 39.3% and 8.9% to the total antibiotics in the ERA. The results illustrate quantitatively the antibiotic flows from engineered wastewater systems to natural water environment, on the basis of which the improvements of wastewater treatment technologies and discharge management would be put forward.

Antibiotic residues in the aquatic environment - current perspective and risk considerations

Antimicrobial resistance is a major concern for human and animal health, projected to deteriorate with time and given current trends of antimicrobial usage. Antimicrobial use, particularly in healthcare and agriculture, can result in the release of antimicrobials into surface waters, promoting the development of antibiotic resistance in the environment, and potentially leading to human health risks. This study reviews relevant literature, and investigates current European and Irish antimicrobial usage trends in humans and animals, as well as potential pathways that antibiotics can take into surface waters following use. Reported levels in the aquatic environment are summarized, with particular focus on Ireland. There are relatively few studies examining Irish water bodies or sewage effluent for antibiotic residues, however, five antibiotics, namely azithromycin, ciprofloxacin, clarithromycin, metronidazole, and trimethoprim, have been measured in Irish waters, in concentrations predicted to select for resistance. Numerous isolates of multi-drug resistant bacteria have also been found in water bodies throughout Ireland and Europe. The value of risk assessment methodologies in understanding risks posed by antibiotic residues is reviewed including the advantages and disadvantages of specific approaches. Hazard quotient and bespoke Monte Carlo approaches are predominant risk assessment tools used to examine antimicrobial release and their complex pathways. This study highlights the need for monitoring of antimicrobial releases and the potential for resistance development, persistence and transmission while highlighting the role of risk assessment methodologies in assessing potential human and environmental health impacts.

Removal efficiency of emerging micropollutants in biofilter wastewater treatment plants in tropical areas

We studied the removal of 61 emerging micropollutants, including illicit drugs, in a biofilter wastewater treatment plant located in the French Indies (Martinique). Raw wastewater concentrations were the highest for paracetamol followed by caffeine, naproxen, ibuprofen, its metabolite 2-hydroxyibuprofen, atenolol, ketoprofen, furosemide, methylparaben, cocaine, benzoylecgonine, and 11-nor-delta-9-carboxytetrahydrocannabinol (THC-COOH). The calculated removals were better than those reported in the literature, while the cumulative removal efficacy (i.e., removal of the total mass load) was estimated to be 92 ± 4%. However, this good performance may be partly explained by the removal of paracetamol (also named acetaminophen) and caffeine, which represented 86.4% of the total mass load. Our results point to the adsorption of some molecules on sludge, thus raising the question about local soil pollution from sludge spreading.

Perspectives on the antibiotic contamination, resistance, metabolomics, and systemic remediation

Antibiotics have been regarded as the emerging contaminants because of their massive use in humans and veterinary medicines and their persistence in the environment. The global concern of antibiotic contamination to different environmental matrices and the emergence of antibiotic resistance has posed a severe impact on the environment. Different mass-spectrometry-based techniques confirm their presence in the environment. Antibiotics are released into the environment through the wastewater steams and runoff from land application of manure. The microorganisms get exposed to the antibiotics resulting in the development of antimicrobial resistance. Consistent release of the antibiotics, even in trace amount into the soil and water ecosystem, is the major concern because the antibiotics can lead to multi-resistance in bacteria which can cause hazardous effects on agriculture, aquaculture, human, and livestock. A better understanding of the correlation between the antibiotic use and occurrence of antibiotic resistance can help in the development of policies to promote the judicious use of antibiotics. The present review puts a light on the remediation, transportation, uptake, and antibiotic resistance in the environment along with a novel approach of creating a database for systemic remediation, and metabolomics for the cleaner and safer environment.

Zero-valent iron enhanced in-situ advanced anaerobic digestion for the removal of antibiotics and antibiotic resistance genes in sewage sludge

The in-situ advanced anaerobic digestion (AAD) enhanced with zero-valent iron powder (ZVI) under mesophilic condition was investigated to remove 5 antibiotics (sulfamerazine (SMR), sulfamethoxazole (SMZ), ofloxacin (OFL), tetracycline (TC), and roxithromycin (ROX)) and 11 antibiotic resistance genes (ARGs) (AAC (6')-IB-CR, qnrS, ermF, ermT, ermX, sul1, sul2, sul3, tetA, tetB, and tetG) in sewage sludge. The effects of different ZVI dosages, antibiotic concentrations, and solid retention time (SRTs) on the removal were explored. Also, the correlation coefficient of antibiotics and ARGs, microbial community structure, biogas production and methane yield were analyzed. All conducted treatments operated stably, and the modified Gompertz model described the cumulative methane yield well. The antibiotics, with the exception of OFL, were effectively removed in the sewage sludge at a dosage of 1000 mg/L ZVI, SRT 20 d, and an antibiotic concentration of 20 μg/L during AAD. The removal rates of SMZ, SMR, TC, and ROX reached 97.39%, 74.54%, 78.61%, and 56.58%, respectively. AAC (6')-IB-CR and tetB could be effectively reduced during the in-situ AAD. Through the redundancy analysis, AAC (6')-IB-CR, ermT, ermX, sul2, tetB, and tetG had strong positive correlations with the antibiotics in the reactor. The principle component analysis revealed that the community structure was similar when the SRT was 10 d and 20 d at the same amount of ZVI and antibiotic concentrations in the sludge. Under the operating parameters of 1000 mg/L ZVI dosage, SRT 20 d, and an antibiotic concentration of 20 μg/L, Erysipelotrichia, Verrucomicrobia, Clostridia, Caldiserica, and Alphaproteobacteria of the class were dominated microorganisms in the anaerobic digestion.

Removal of pharmaceuticals by ammonia oxidizers during nitrification

The adverse effect of pharmaceuticals on ecosystem and human health raises great interest for the removal of pharmaceuticals in wastewater treatment plants (WWTPs). Enhanced removal of pharmaceuticals by ammonia oxidizers (AOs) has been observed during nitrification. This review provides a comprehensive summary on the removal of pharmaceuticals by AOs-ammonia oxidizing bacteria (AOB), ammonia oxidizing archaea (AOA), and complete ammonia oxidizer (comammox) during nitrification in pure ammonia oxidizing culture and mixed microbes systems. The superior removal of pharmaceuticals by AOs in conditions with nitrifying activity compared with the conditions without nitrifying activity was proposed. The contribution of AOs on pharmaceuticals removal in pure and mixed microbe systems was discussed and activated sludge modeling was suggested as the proper measure on assessing the contribution of AOs on the removal of pharmaceuticals in mixed microbe culture. Three transformation processes and the involved reaction types of pharmaceuticals transformation during nitrification were reviewed. The present paper provides a systematical summary on pharmaceuticals removal by different AOs across pure and mixed microbes culture during nitrification, which opens up the opportunity to optimize the wastewater biological treatment systems for enhanced removal of pharmaceuticals. KEY POINTS: • The superior removal of pharmaceuticals by ammonia oxidizers (AOs) was summarized. • The removal contribution of pharmaceuticals attributed by AOs was elucidated. • The transformation processes and reaction types of pharmaceuticals were discussed.

Occurrence, distribution, and risk assessment of pharmerciuticals in wastewater and open surface drains of peri-urban areas: Case study of Juja town, Kenya

The occurrence of Active Pharmaceutical Ingredients (APIs) in the environment is becoming a major area of concern due to their undesirable effects on non-target organisms. This study investigated the occurrence and risk of contamination by five antibiotics and three antiretrovirals drugs in a fast-growing peri-urban area in Kenya, with inadequate sewer system coverage. Due to poor sewage connectivity and poorly designed decentralized systems, wastewater is directly released in open drains. Water and sediment samples were collected from open surface water drains, while wastewater samples were collected from centralized wastewater treatment plants (WWTP). Solid-phase extraction and ultrasonic-assisted extraction for the aqueous and sediment samples respectively were carried out and extracts analyzed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) using isotopically labeled internal standards. APIs were observed with the detection frequency ranging from 36% to 100%. High mean concentrations of 48.7 μg L^-1, 108 μg L^-1, and 532 μg L^-1 were observed in surface drains for Lamivudine (3 TC), Sulfamethoxazole (SMX), Ciprofloxacin (CIP) respectively. Drain sediments also showed high concentrations of APIs ranging from 2.1 to 13,100 μg kg^-1. APIs in this study exceeded those observed in existing literature studies. JKUAT WWTP removal efficiencies varied from -90.68% to 72.67%. Total APIs emission load of the study area was 3550 mg d^-1 with WWTP effluent contributing higher loads (2620 mg d^-1) than surface water drains (640 mg d^-1). Zidovudine (ZDV), nevirapine (NVP), and trimethoprim (TMP) loads in drains, however, exceeded WWTP effluent. Low to high ecotoxicity risk of the individual APIs were observed to the aquatic environment, with high risks for the development of antibiotic resistance in microbiome as determined by the risk quotient (RQ) approach. Risk management through efficient wastewater collection, conveyance, and treatment is necessary to suppress the measured concentrations.

Co-occurrence of multidrug resistance, β-lactamase and plasmid mediated AmpC genes in bacteria isolated from river Ganga, northern India

Wastewater effluents released in surface water provides suitable nutrient rich environment for the growth and proliferation of antibiotic resistant bacteria (ARB) and genes (ARG). Consequently, bacterial resistance has highly evolved over the recent years and diversified that each antibiotic class is inhibited by a distinct mechanism. In the present study, the prevalence of Multidrug resistant (MDR), extended spectrum β-lactamases (ESBL) and plasmid mediated Amp-C producing strains was analyzed in 28 surface water samples collected near domestic effluent discharge sites in river Ganga located across 11 different geographical indices of Uttar Pradesh, India. A total of 243 bacterial strains with different phenotypes were isolated. Among 243 isolates, 206 (84.77%) exhibited MDR trait displaying maximum resistance towards β-lactams (P = 78.19%; AMX = 72.84%), glycopeptides (VAN = 32.92%; TEI = 79.42%), cephalosporins (CF = 67.90%; CFX = 38.27%), and lincosamides (CD = 78.18%) followed by sulfonamide, macrolide and tetracycline. ESBL production was confirmed in 126 (51.85%) isolates that harbored the genes: blaTEM (95.24%), blaSHV (22.22%), blaOXA (11.90%) and blaCTX-M group (14.28%). The presence of plasmid mediated AmpC was detected only in 6.17% of isolates. The existence of such pathogenic strains in the open environment generates an urgent need for incorporating stringent measures to reduce the antibiotic consumption and hence its release.

Mass loading, distribution, and removal of antibiotics and antiretroviral drugs in selected wastewater treatment plants in Kenya

The discharge of active pharmaceutical ingredients (APIs) into the aquatic environment from wastewater effluents is a concern in many countries. Although many studies have been conducted to evaluate the APIs removal efficiencies and emissions to the environment in wastewater treatment plants (WWTPs), most of these studies considered the aqueous and sludge phases, disregarding the suspended particulate matter (SPM) phase. To try to understand the role of the SPM, the occurrence of five most common antibiotics and three antiretroviral drugs (ARVDs) commonly used in Kenya were investigated in this study. APIs partitioning and mass loading in influents and effluents of three different WWTPs: trickling filters, stabilization ponds, and decentralized fecal sludge system, were evaluated. API concentration levels ranging from ˂LOQ (limit of quantification) to 92 μgL^-1 and ˂LOQ to 82.2 mgkg^-1 were observed in aqueous samples and solid samples respectively, with SPM accounting for most of the higher concentrations. The use of the aqueous phase alone for determination of removal efficiencies showed underestimations of API removal as compared to when solid phases are also considered. Negative removal efficiencies were observed, depending on the compound and the type of WWTP. The negative removals were associated with deconjugation of metabolites, aggregated accumulation of APIs in the WWTPs, as well as unaccounted hydraulic retention time during sampling. Compound characteristics, environmental factors, and WWTPs operation influenced WWTPs removal efficiencies. Wastewater stabilization ponds had the poorest removals efficiencies with an average of -322%. High total mass loads into the WWTPs influent and effluent of 22,729 and 22,385 mg day^-1 1000 PE^-1 were observed respectively. The results aims at aiding scientists and engineers in planning and designing of WWTPs. Findings also aim at aiding policy-making on pharmaceutical drug use and recommend proper wastewater management practices to manage the high mass loading observed in the WWTPs.

A systematic approach of method development for analysis of multiple classes of emerging contaminants in wastewater: a case study of a biological nutrient removal based plant

Pharmaceuticals, personal care products, synthetic hormones, and industrial manufacturing additives are used worldwide, and their residues are frequently detected in wastewater. In this study, a sensitive and selective method was developed and validated for the detection and quantification of 14 Emerging Contaminants (ECs) with various physico-chemical properties frequently found in wastewater. Solid Phase Extraction (SPE) allowed for extraction and concentration of the compounds. Liquid chromatography-mass spectrometry in both positive and negative electrospray ionization mode was used for the analysis. Three different combinations of mobile phase, water + 0.1% formic acid : acetonitrile + 0.1% formic acid (3 compounds), water + 0.1% formic acid : methanol (5) and 10 mM ammonium acetate buffer : acetonitrile + 0.1% formic acid (6) gave the best chromatographic conditions to analyze the contaminants in real wastewater samples. Four different eluents at acidic and basic sample pH values were tested to optimize the SPE methodology, and three different dilution ratios (1 : 1, 2 : 1, and 5 : 1) were tested to reduce the matrix effect. Data validation was conducted using linearity, intra and inter-day repeatability, LOD/LOQ, percentage recovery, and percentage process efficiency studies. As a case study, a biological nutrient removal (BNR) based plant was tested for the presence of ECs using the developed method. Removal efficiency at different treatment stages was assessed. Most of the treatment occurred at the secondary treatment stage, whereas primary treatment and disinfection had little effect on removal. All the contaminants were found in the inlet wastewater. Estrone (E1), an endocrine disrupting compound, was reported for the first time in Indian wastewater at 376.2 ng L-1. Seven, four, and two ECs were removed at high, medium, and low efficiencies, respectively. Carbamazepine showed negative removal. This study enhanced our understanding of the occurrence and fate of several ECs in BNR based treatment systems.

Effects of Sulfamethoxazole on the Microbial Community Dynamics During the Anaerobic Digestion Process

Anaerobic digestion (AD) treatment of cattle manure and slurry makes it possible to produce biogas, a renewable and storable biofuel, as well as digestate, a residual organic matter that can be used to replace chemical fertilizers. On the other hand, the intense use of antibiotics (e.g., sulfamethoxazole) in animal husbandry practices is showing increasing negative impacts resulting from the release of still metabolically active molecules into agroecosystems. In the present study, cattle manure collected from an AD plant-feeding tank was used as feedstock for AD experiments in which some batches were spiked with 5 mg L^-1 of sulfamethoxazole (SMX). Adding the antibiotic affected the microbial community dynamic; in particular, the efficiency of the acidogenic and acetogenic phases of the process corresponded to higher CH₄ and H₂ production than in the control. SMX was also degraded, and at the end of the experiment (69 days), just 20% of its initial concentration was found. The relative abundance (ARG/16S) of resistance genes sul1, sul2, and the proxy intI1 initially found in the ingestate decreased during the AD in both the spiked and control batches, suggesting that this process lowers the likelihood of antibiotic resistance genes spreading.

Environmental Dissemination of Selected Antibiotics from Hospital Wastewater to the Aquatic Environment

The environmental dissemination of selected antibiotics from hospital wastewater into municipal wastewater and lastly to a receiving water body was investigated. Selected antibiotics (azithromycin (AZM), ciprofloxacin (CIP), clindamycin (CDM), doxycycline (DXC) and sulfamethoxazole (SMZ)) present in effluents of academic hospital wastewater, influents, sewage sludge, and effluents of municipal wastewater, receiving water, and its benthic sediment samples were quantified using the Acquity^® Waters Ultra-Performance Liquid Chromatography System hyphenated with a Waters Synapt G2 coupled to a quadrupole time-of-flight mass spectrometer. The overall results showed that all assessed antibiotics were found in all matrices. For solid matrices, river sediment samples had elevated concentrations with mean concentrations of 34,834, 35,623, 50,913, 55,263, and 41,781 ng/g for AZM, CIP, CDM, DXC, and SMZ, respectively, whereas for liquid samples, hospital wastewater and influent of wastewater had the highest concentrations. The lowest concentrations were observed in river water, with mean concentrations of 11, 97, 15, and 123 ng/L, except for CDM, which was 18 ng/L in the effluent of wastewater. The results showed that the highest percentages of antibiotics removed was SMZ with 90%, followed by DXC, AZM and CIP with a removal efficiency of 85%, 83%, and 83%, respectively. The antibiotic that showed the lowest removal percentage was CDM with 66%. However, the calculated environmental dissemination analysis through the use of mass load calculations revealed daily release of 15,486, 14,934, 1526, 922, and 680 mg/d for SMZ, CIP, AZM, DXC, and CDM, respectively, indicating a substantial release of selected antibiotics from wastewater to the river system, where they are possibly adsorbed in the river sediment. Further research into the efficient removal of antibiotics from wastewater and the identification of antibiotic sources in river sediment is needed.