Imipenem-metal complexes: Computational analysis and toxicity studies with wastewater model microorganisms.

The occurrence of antibiotic residues in diverse water sources has long been acknowledged as a potential health concern due to the emergence and spread of antibiotic-resistant bacteria and genes. However, there have been limited studies into the presence of antibiotic-metal complexes (AMCs) in real-time wastewater matrices, and their impact on wastewater microbial communities. The present work, in this regard, investigated the stability of Imipenem-metal complexes (Me = Mg (II), Ca (II), Fe (II), Cu (II), and Al (III)) with computational studies, stoichiometry with potentiometric measurements, and their antibacterial activity towards wastewater model microorganisms- Bacillus subtilis (B. subtilis) and Escherichia coli (E. Coli) by Colony Forming Unit (CFU) method. The lower energy of Imipenem-metal complexes than the parent antibiotic- Imipenem, during energy optimization using density functional (DFT) methods, revealed that metal interactions of Imipenem stabilize the drug by minimizing its energy. Further, CFU studies indicated that these complexes display higher antimicrobial activity than parent antibiotics. The electron delocalization over the entire chelated system (AMCs) reduces polarity and increases the lipophilicity of the complexes, thereby facilitating stronger interaction between AMCs and the bacterial cell membrane. Results indicate increased antibacterial activity of Imipenem-metal complexes for both E. coli and B. subtilis. The antibacterial activity, was however, more pronounced in B. subtilis, with >97% growth inhibition for metal complexes of Imipenem (at a Minimum Inhibitory Concentration of 20 nM or 6 ppb (i.e., MIC90)), for both the stoichiometric ratios (metal to ligand) ratios (M: L 1: 1 and 2: 1). All around, with increased stability and toxicity, AMCs are emerging as contaminants of concern and demand immediate attention to devise methods for their removal.

Microplastic pollution and associated health hazards: Impact of COVID-19 pandemic.

The COVID-19 pandemic led to an increase in plastic used for medical purposes such as personal protective equipment and packaging materials. A very low share of plastics is recycled while the majority is sent to landfills. This plastic may degrade over time to form microplastics which may pollute land, air, and water sources. An increase in microplastics can increase the disease risk in human well-being's. The ultimate fate of microplastic is accumulation inside the human body posing the risk of different health conditions like cancer, diabetes, and allergic reactions. Hence, proper detection and disposal methods should be devised to deal with the rise in microplastic pollution.

Spatial and temporal variability of contaminants of emerging concern in a drinking water source.

The spatial-temporal behaviour of contaminants of emerging concern (CECs) are not well-documented in drinking water sources, including in Quebec, Canada. In this study, a set of seven contaminants, which are more frequently reported in water sources, were monitored from May 2016 to August 2017 at ten locations within an urbanized watershed (lakes and rivers) in Quebec, Canada. Samples were collected between a wastewater plant discharge (upstream) and the intake of a drinking water plant (downstream). The results showed that three (acetaminophen, salicylic acid, caffeine) out of seven CECs were consistently detected at a range of up to a few hundred ng L-1 at all sampling stations throughout the sampling period with a detection frequency between 51% and 94%. Upstream of two wastewater plant discharge locations, six CECs were measured above the detection limit compared to other locations where only three CECs (acetaminophen, salicylic acid, caffeine) were detected. Most of the CEC concentrations were higher (a few ng L-1) during late winter in comparison with the summer, in both years 2016 and 2017. The results highlight that the wastewater effluents and septic system effluents are significant sources of CECs that are released into the surface water. Moreover, the results help to identify the spatio-temporal patterns, which is a crucial element to understand the fate of CECs in water sources submitted to extreme weather conditions during the year. This research also provides baseline data for CEC occurrence at different points across lakes, rivers, and tributaries which will be useful for future ecotoxicological studies.

A comprehensive review on current technologies for removal of endocrine disrupting chemicals from wastewaters.

In the recent years, endocrine disrupting compounds (EDCs) has received increasing attention due to their significant toxic effects on human beings and wildlife by affecting their endocrine systems. As an important group of emerging pollutant, EDCs have been detected in various aquatic environments, including surface waters, groundwater, wastewater, runoff, and landfill leachates. Their removal from water resources has also been an emerging concern considering growing population as well as reducing access to fresh water resources. EDC removal from wastewaters is highly dependent on physicochemical properties of the given EDCs present in each wastewater types as well as various aquatic environments. Due to chemical, physical and physicochemical diversities in these parameters, variety of technologies consisting of physical, biological, electrochemical, and chemical processes have been developed for their removal. This review highlights that the effectiveness of EDC removal is highly dependent of selecting the appropriate technology; which decision is made upon a full wastewater chemical characterization. This review aims to provide a comprehensive perspective about all the current technologies used for EDCs removal from various aquatic matrices along with rising challenges such as the antimicrobial resistance gene transfer during EDC treatment.

Biodegradation of microplastics: Better late than never.

Plastics use is growing due to its applications in the economy, human health and aesthetics. The major plastic particles in the form of microplastics (MPs) released into the environment are made up of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), and polyethylene terephthalate (PET). Tremendous usage and continuous accumulation of MPs in the environment pose a global threat to ecosystems and human health. The current knowledge of biotechnological, aerobic and aerobic biodegradation approaches emphasizes the microbial culture's potential towards MPs removal. This review selectively provides recent biotechnological advances such as biostimulation, bioaugmentation and enzymatic biodegradation that can be applied for MPs removal by biodegradation and bioaccumulation. This review summarizes the knowledge and the research exploration on the biodegradation of synthetic organic MPs with different biodegradability. However, further research is still needed to understand the underlying mechanism of MPs biodegradation in soil and water systems, leading to the development of an effective method for MPs removal.

Probabilistic framework for assessing ecological risk of Contaminants of Emerging Concern: Application to a Canadian lake system.

Contaminants of Emerging Concern (CECs) in natural water pose risks to ecosystems. The concentration of CECs varies spatially and temporally, and their estimated ecotoxicities differ widely by toxicological studies. This study extensively reviewed literature on ecological risk assessment and proposed a probabilistic framework for assessing ecological risk and its uncertainties (aleatory and epistemic). The framework integrated Adverse Outcome Pathway in risk assessment and was applied to a Canadian lake system for seven CECs: salicylic acid, acetaminophen, caffeine, carbamazepine, ibuprofen, drospirenone, and sulfamethoxazole. Altogether 264 water samples were collected and analyzed from 15 sites May 2016 to September 2017. Phytoplankton, zooplankton, and fish were also sampled and analyzed. The results show ecological risk estimates (Risk Quotient, RQ) varied considerably indicating a range of uncertainty. Based on the conservative estimate, the central tendency estimate of the ecological risk of mixture compounds was medium (RQ = 0.6) including drospirenone. However, the reasonably maximum estimate of the risk was high (RQ = 1.4) for mixture compounds including drospirenone. The high risk is primarily due to drospirenone as its individual risk was high (RQ = 1.1) to fish. The specific site and time of high drospirenone exposure was identified for implementing control measures. Classification of ecotoxicity values based on environmental parameters such as climate and water quality, can reduce uncertainty in the risk estimate.

Antibiotic-metal complexes in wastewaters: fate and treatment trajectory.

Unregulated usage, improper disposal, and leakage from pharmaceutical use and manufacturing sites have led to high detection levels of antibiotic residues in wastewater and surface water. The existing water treatment technologies are insufficient for removing trace antibiotics and these residual antibiotics tend to interact with co-existing metal ions and form antibiotic-metal complexes (AMCs) with altered bioactivity profile and physicochemical properties. Typically, antibiotics, including tetracyclines, fluoroquinolones, and sulphonamides, interact with heavy metals such as Fe2+, Co2+, Cu2+, Ni2+, to form AMCs which are more persistent and toxic than parent compounds. Although many studies have reported antibiotics detection, determination, distribution and risks associated with their environmental persistence, very few investigations are published on understanding the chemistry of these complexes in the wastewater and sludge matrix. This review, therefore, summarizes the structural features of both antibiotics and metals that facilitate complexation in wastewater. Further, this work critically appraises the treatment methods employed for antibiotic removal, individually and combined with metals, highlights the knowledge gaps, and delineates future perspectives for their treatment.

Science-society-policy interface for microplastic and nanoplastic: Environmental and biomedical aspects.

The global concern over the possible consequences of the downsizing of plastic to microplastics (MPs) and nano plastics (NPs) needs to be addressed with a new conceptual framework. The transformation of plastics to MPs and NPs can be discussed in terms of fundamental physics principles applicable to micro and nanophase matter and colloidal science principles. Further, accurate and reliable detection and characterization of MPs and NPs are crucial for an extensive understanding of their environmental and ecological impacts. The other decisive factor that can classify MPs and NPs as hazardous to existing nanomaterials is discussing the cytotoxicity study on human cell lines. The human health risk assessment that might arise from the ingestion of MPs and NPs can be addressed about contrast agents used for medical imaging. However, the lack of standard analytical techniques for MPs and NPs measurement is an emerging challenge for analytical scientists due to their complex physicochemical properties, especially in environmental samples. This review article navigates readers through the point of origin of MPs and NPs and their interdisciplinary aspects. Biomedical applications of plastics and concerns over the toxicity of MPs and NPs are further analyzed. Moreover, the analytical challenges of MPs and NPs have been discussed with critical inputs. Finally, the worldwide efforts being made for creating a common platform of discussion on a different aspect of plastic pollution were taken into account.

A year into the COVID-19 pandemic: Rethinking of wastewater monitoring as a preemptive approach.

Under the current pandemic situation caused by the novel coronavirus SARS-CoV-2, wastewater monitoring has been increasingly investigated as a surveillance tool for community-wide disease prevalence. After a year into the pandemic, this review critically discusses the real progress made in the detection of SARS-CoV-2 using wastewater monitoring. The limitations and the key challenges faced in improving the detection methods are highlighted. As per the literature, the complex nature of the wastewater matrix poses problems in processing the samples and achieving high sensitivity at low loads of viral RNA using the current detection methods. Furthermore, in the absence of a gold standard analytical method for wastewater, the validation of the generated data for use in wastewater-based epidemiological modeling of the disease becomes practically difficult. However, research is advancing in adopting clinical methods to the wastewater by using appropriate processing controls, and recovery methods. Besides, the technological advances made by the industry including the development of PCR kits with improved detection limits, easy-to-use viral RNA concentration methods, ability to detect the coronavirus variants, and artificial intelligence and advanced data modeling for continuous and remote monitoring greatly help to debottleneck some of these problems. Currently, these technologies are limited to healthcare systems, however, their use for wastewater monitoring is expected to provide opportunities for wide-scale applications of wastewater-based epidemiology (WBE). Moreover, the data from wastewater monitoring act as the initial checkpoint for human health even before the appearance of symptoms, hence WBE needs more attention to manage current and future infectious transmissions.

Occurrence and seasonality of raw and drinking water contaminants of emerging interest in five water facilities.

The goal of this work was to investigate the occurrence of contaminants of emerging interest (CEI) in source surface water (SW; river water) and drinking water (DW; tap water) from five drinking water treatment plants (DWTPs) in the Province of Québec, Canada. A total of 28 sampling campaigns were conducted to collect SW and DW samples from each DWTP from June 2016 to July 2017. The seven targeted CEI, including acetaminophen, salicylic acid, caffeine, carbamazepine, ibuprofen, sulfamethoxazole and drospirenone, were analyzed using solid-phase extraction-ultra pressure liquid chromatography-mass spectrometry (SPE-UPLC-MS/MS) for all collected water samples. The selected CEI were detected in all SW and DW samples, with the exception of drospirenone, which occurred in amounts that were below the limit of detection in one DWTP in June and July 2016. In all the SW samples, caffeine was detected and had the highest median concentration range (12.3-91.0 ng/L), followed by acetaminophen (7.9-85.0 ng/L) and salicylic acid (21.6-39.0 ng/L). In the DW samples, salicylic acid was detected and had the highest median concentration range (20.5-50 ng/L), followed by caffeine (5.2-21.8 ng/L), and acetaminophen (5.0-7.7 ng/L). Carbamazepine, ibuprofen, and sulfamethoxazole primarily occurred in amounts between the limit of detection and limit of quantification in SW and occurred below the limit of detection in DW. All the DWTPs exhibited a similar trend in the removal of CEI, which include acetaminophen (≤97.6%), followed by caffeine (71.0-86.5%) and salicylic acid (<50.0%). Varying levels of efficiencies were observed among the removal strategies for CEI under study, which were mainly associated with the contaminant concentration in SW in the case of acetaminophen, and with the treatment processes in the case of caffeine and salicylic acid.

Non-steroidal anti-inflammatory drugs in the environment: Where were we and how far we have come?

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most well-known pharmaceuticals with a broad scope of properties that are widely used in human and veterinary medicine. Because of their extensive utilization, NSAIDs are commonly identified in the environment as trace emerging contaminants. Regardless of vast experience with these drugs, NSAIDs are full of contradictions that trigger major concerns for environmental researchers. A limited understanding on NSAID's occurrence, distribution and eco-toxicological effects have led to an escalated dilemma in the last decade. Thus, a broad-spectrum study covering all aspects of occurrence, detection and removal is required to meet the fundamental levels of knowledge on the effects of NSAIDs in all exposed environmental aspects. Therefore, this paper focuses on classifying the sources and entry points of residual NSAIDs. Further, detecting and regulating their concentrations in both input streams and receiving environments, along with the removal processes of this specific class of emerging compounds, in the direction of developing a management policy is comprehensively reviewed.

Biodegradation of aflatoxin B1 with cell-free extracts of Trametes versicolor and Bacillus subtilis.

Aflatoxin B1 (AFB1) is one of the most common contaminants of poultry feed and has been linked to adverse effects on animal health and productivity. In this study, the degradation of AFB1 was studied with cell-free extracts (CFE) of Trametes versicolor and Bacillus subtilis using High-Performance Liquid chromatography (HPLC). CFE from B. subtilis and T. versicolor gave 60% and 34% of AFB1 degradation respectively, while heat-inactivated extracts showed no degradation. By-products obtained at the end of AFB1 degradation were analyzed by Liquid Chromatography with tandem mass spectrometry (LC-MS/MS). After 96 h of incubation, by-products with lower m/z values were obtained with CFE from B. subtilis as compared to that from T. versicolor, indicating a higher degradation efficiency of the former. Additionally, the detection of a by-product which could correspond to AFB1-8,9 dihydrodiol - a less toxic derivative of AFB1 - after 72 and 96 h of incubation with CFE from B. subtilis, could indicate the simultaneous detoxification along with degradation of AFB1 by B. subtilis CFE.

Acute Impact of Chlortetracycline on Nitrifying and Denitrifying Processes.

In the current study, sequential nitrification and anoxic experiments in synthetic municipal wastewater were exposed to 0.5 to 100 mg/L of chlortetracycline for 24 h to evaluate acute impact on the nitrification, and denitrification processes of biological treatment. Both processes were significantly (p < 0.05) inhibited at >50 mg/L of chlortetracycline, and the results revealed that nitrification was adversely affected by chlortetracycline compared with the anoxic process. In nitrification, chemical oxygen removal (COD) and ammonia oxidation kinetics were 50% inhibited at 10 mg chlortetracycline/L, and nitrite oxidation kinetics at 0.5 mg chlortetracycline/L. Likewise, in the anoxic process, 14 and 10 mg/L of chlortetracycline inhibited 50% of COD removal and nitrate reduction kinetics, respectively. In nitrification and denitrification, 90% of chlortetracycline was removed by adsorbing onto sludge suspended solids. In addition, a higher chlortetracycline concentration in anoxic effluent, compared with aerobic effluents, indicated a dissimilarity in the composition of sludge solids, pH, and biomass production for both processes.

Activation of persulfate by homogeneous and heterogeneous iron catalyst to degrade chlortetracycline in aqueous solution.

This study investigates the removal of chlortetracycline (CTC) antibiotic using sulfate radical-based oxidation process. Sodium persulfate (PS) was used as a source to generate sulfate radicals by homogeneous (Fe2+) and heterogeneous (zero valent iron, ZVI) iron as a catalyst. Increased EDTA concentration was used to break the CTC-Fe metal complexes during CTC estimation. The influence of various parameters, such as PS concentration, iron (Fe2+ and ZVI) concentration, PS/iron molar ratio, and pH were studied and optimum conditions were reported. CTC removal was increased with increasing concentration of PS and iron at an equal molar ratio of PS/Fe2+ and PS/ZVI processes. PS/Fe2+ and PS/ZVI oxidation processes at 1:2 (500 µM PS and 1000 µM) molar ratio showed 76% and 94% of 1 µM CTC removal in 2 h. Further increased molar ratio 1:2 onwards, PS/Fe2+ process showed a slight increase in CTC degradation whereas in PS/ZVI process showed similar degradation to 1:2 (PS/Fe) ratio at constant PS 500 µM concentration. Slower activation of persulfate which indirectly indicates the slower generation of sulfate radicals in PS/ZVI process showed higher degradation efficiency of CTC. The detected transformation products and their estrogenicity results stated that sulfate radicals seem to be efficient in forming stable and non-toxic end products.

Ciprofloxacin-metal complexes -stability and toxicity tests in the presence of humic substances.

The co-contamination of ciprofloxacin (CIP) with metal ions results in alteration of CIP mobility, antimicrobial activity and distribution/development of the antibiotic-resistance genes. In this study, the stability of five CIP-Me complexes [Me = Al(III), Co(II), Cu(II), Fe(III), Mg] was investigated in the presence of humic substances (HS) at two temperatures 18 ±â€¯2 °C and 4 ±â€¯1 °C for seven days period. The most stable complexes were CIP-Al, CIP-Cu, and CIP-Co with the stability constants (K) at 18 °C 35.5 ±â€¯1.4 11.5 ±â€¯1.5 and 11.7 ±â€¯1.5 respectively. At lower temperature (4 °C), the stability constants decreased: 1-fold for CIP-Al, 14-fold for CIP-Co and 2-fold for CIP-Cu. The presence of humic substances decreased the stability of complexes. The chemical reactions of Fe3+ in water at circumneutral pH resulted in stability alteration. The formation of CIP-Mg complexes at lower temperatures and in the presence of HS was limited. In ultrapure water, CIP-Me complexes exhibit higher toxicity towards Gram-negative Enterobacter aeruginosa (ranged between 0.125 and 0.5 µg/ml). However, the presence of HS reduced the antimicrobial activity of CIP-Me complexes by at least 2-fold. Gram-positive representative, Bacillus subtilis was not affected by the presence of metal ions and/or HS. The toxicity toward B. subtilis for the complexes was equal to toxicity of CIP alone (MIC = 0.25 µg/ml). This suggested the different susceptibility to CIP and its complexes.

Filter feeders increase sedimentation of titanium dioxide: The case of zebra mussels.

Titanium dioxide particles (TiO2) are widely used to produce whitens (titanium white) and different class of nanomaterials (semiconductors, photo catalysts and nanotubes). Nanomaterials are excellent adsorbents and catalysts with a wide range of applications. However, these are reported to induce biological and genetic alterations among several invertebrate groups. Invasive species such as zebra mussels can be used as model organisms to study the behavior of particles and nanoparticles (NPs) due to their wide distribution; mussels have been extensively used for monitoring water pollution. In the present study, TiO2 particles were dispersed and added to a Chlorella culture to emulate a natural scenario. To study the reaction of zebra mussels to different TiO2 concentrations, they were fed with 0.35, 0.7 and 3.5 mgTiO2/L of the suspension for 3days and the titanium was measured in the water column, mussels and sediments with ICP-AES. Zebra mussels obtained from the Port of Quebec had up 61.62mgTi/kg wet tissue at the time of capture. After 10days of depuration, they had from 0.23 to 16.28mgTi/kg wet tissue. Mussels accumulated TiO2 after 36h of exposition as a function of TiO2 concentration, but mussels did not present significant mortality due to TiO2 toxicity until concentrations higher than 0.7ppm. A second set of experiments was run to understand the TiO2 pathway attached to microalgae vs free TiO2. Results indicated that mussels accumulated slightly more Ti when it was mixed with microalgae. However, the statistical difference was non- significant. A 100 times higher accumulation of Ti in sediments was identified when mussels are present. Thus, it was concluded that the sedimentation of TiO2 is enhanced by the zebra mussels' filtration activity.

Acid mediated chemical treatment to remove sugar from waste acid stream from nano-crystalline cellulose manufacturing process.

Nano-crystalline cellulose (NCC) is a nano-scale biomaterial derived from highly abundant natural polymer cellulose. It is industrially produced by concentrated acid hydrolysis of cellulosic materials. However, presences of as high as 5-10% of sugar monomers in spent sulphuric acid during the manufacturing process, makes it unsuitable for such recycling or reuse of sulphuric acid. Currently, the industry has been using membrane and ion exchange technology to remove such sugars, however, such technologies cannot achieve the target of 80-90% removal. In the current investigation, thermal treatment and acid mediated thermal treatment have been evaluated for sugar removal from the spent sulphuric acid. Almost complete removal of sugar has been achieved by this approach. Maximum sugar removal efficiency (99.9%) observed during this study was at 120±1°C for 60min using 0.8 ratio (sample: acid) or at 100±1°C for 40min using 1.5 ratio.

Tetracyclines metal complexation: Significance and fate of mutual existence in the environment.

Concern over tetracyclines (TCs) complexation with metals in the environment is growing as a new class of emerging contaminants. TCs exist as a different net charged species depending on their dissociation constants, pH and the surrounding environment. One of the key concerns about TCs is its strong tendency to interact with various metal ions and form metal complexes. Moreover, co-existence of TCs and metals in the environment and their interactions has shown increased antibiotic resistance. Despite extensive research on TCs complexation, investigations on their antibiotic efficiency and pharmacological profile in bacteria have been limited. In addition, the current knowledge on TCs metal complexation, their fate and risk assessment in the environment are inadequate to obtain a clear understanding of their consequences on living systems. This indicates that vital and comprehensive studies on TCs-metal complexation, especially towards growing antibiotic resistance trends are required. This review summarizes the role of TCs metal complexation on the development of antibiotic resistance. Furthermore, impact of metal complexation on degradation, toxicity and the fate of TCs in the environment are discussed and future recommendations have been made.

Degradation of chlortetracycline in wastewater sludge by ultrasonication, Fenton oxidation, and ferro-sonication.

Residual emerging contaminants in wastewater sludge remain an obstacle for its wide and safe applications such as landfilling and bio-fertilizer. In this study, the feasibility of individual ultrasonication (UlS) and Fenton oxidation (FO) and combined, Ferro-sonication processes (FO) on the degradation of chlortetracycline (CTC) in wastewater sludge was investigated. UlS parameters such as amplitude and sonication time were optimized by response surface methodology (RSM) for further optimization of FS process. Generation of highly reactive hydroxyl radicals in FO and FS processes were compared to evaluate the degradation efficiency of CTC. Increasing in the ratio of hydrogen peroxide and iron concentration showed increased CTC degradation in FO process; whereas in FS, an increase in iron concentration did not show any significant effect (p>0.05) on CTC degradation in sludge. The estimated iron concentration in sludge (115mg/kg) was enough to degrade CTC without the addition of external iron. The only adjustment of sludge pH to 3 was enough to generate in-situ hydroxyl radicals by utilizing iron which is already present in the sludge. This observation was further supported by hydroxyl radical estimation with adjustment of water pH to 3 and with and without the addition of iron. The optimum operating UlS conditions were found to be 60% amplitude for 106min by using RSM. Compared to standalone UlS and FO at 1:1 ratio, FS showed 15% and 8% increased CTC degradation respectively. In addition, UlS of sludge increased estrogenic activity 1.5 times higher compared to FO. FS treated samples did not show any estrogenic activity.

Encapsulation and release studies of strawberry polyphenols in biodegradable chitosan nanoformulation.

Polyphenols (negative groups) of strawberry extract interacts with positively protonated amino groups of chitosan which helps in maximum encapsulation. This approach can improve the bioavailability and sustained release of phytochemicals having lower bioavailability. The optimum mass ratio of chitosan-tripolyphosphate and polyphenols (PPs) loading was investigated to be 3:1 and 0.5mg/ml of strawberry extract, respectively. Prepared nanoformulation were characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy. The formed particles size ranged between 300 and 600nm and polydispersity index (PDI) of≈0.5. The optimized formulation showed encapsulation efficiency of 58.09% at 36.47% of polyphenols loading. Initial burst and continuous release of PPs was observed at pH 7.4 of in vitro release studies. PPs release profile at this pH was found to be non-Fickian analomous diffusion and the release was followed first order kinetics. And at pH 1.4, diffusion-controlled Fickian release of PPs was observed.