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The wide application of 6:2 fluorotelomer sulfonate (6:2 FTS) and its precursors results in their ubiquitous occurrence in the environment. This study investigated the biotransformation of 6:2 FTS using fresh slurries collected from constructed wetland under aerobic and anoxic conditions. Biotransformation rates of 6:2 FTS was extremely slow under both aerobic and anoxic conditions. The analysis of transformation products showed that less than 0.7 mol% of initial concentration of 6:2 FTS was biotransformed under anoxic conditions. Effects of 6:2 FTS on the shifts in microbial community in wetland slurry during aerobic and anoxic transformation were evaluated using 16S rRNA gene amplicon sequencing. Under aerobic conditions, 6:2 FTS altered the microbial community structure, in which Methylocaldum (Gamma-proteobacteria) became the predominant genus after being exposed to 6:2 FTS. This means that Methylocaldum appears to have higher tolerance to 6:2 FTS and seems to be potential 6:2 FTS-degrading bacteria. Under anoxic transformation, only the genus Methanomethylovorans (Euryarchaeota) was increased remarkably in wetland slurry exposed to 6:2 FTS.

Antibiotic residues, antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are considered new classes of water contaminants due to their potential adverse effects on aquatic ecosystems and human health. This paper provides comprehensive data on the occurrences of 19 antibiotics, bacteria resistant to 10 antibiotics, and 15 ARGs in raw influent and different treatment stages of conventional activated sludge (CAS) and membrane bioreactor (MBR) systems. Seventeen out of the 19 target antibiotics were detected in raw influent with concentrations of up to ten micrograms per liter. Concentrations of antibiotics measured in the secondary effluent were much lower compared to those in the raw influent. Among the antibiotics, amoxicillin, azithromycin, ciprofloxacin, chloramphenicol, meropenem, minocycline, oxytetracycline, sulfamethazine and vancomycin had highest removal by CAS or MBR systems with median removal efficiency (RE) 70%, while trimethoprim and lincomycin were recalcitrant in the CAS system with median RE50%. Similarly, the target ARB and ARGs were omnipresent in the raw influent samples with average concentrations as high as 2.6 × 10

An in-depth understanding of the hydrogeochemical characteristics of coal mines is helpful in establishing an effective and successful exploration program of coalbed methane (CBM). This study provides a comprehensive analysis of hydrogeological characteristics, characteristics of coalbed water, and characteristics of the coal sample from a coal seam located in the Red River Basin (RRB). These physicochemical characteristics along with the microbial composition of coalbed water were critically analyzed. A high concentration of chloride and sodium was found in the coalbed water, presumably due to the coal mine's stratigraphic association with marine or marine-transitional beds. A correlation between the occurrence of microbes and the chemical components in the coalbed water was established. The characteristics of the coal were systematically analyzed, including proximate, ultimate, and petrographic analyses. Based on the coal macerals, coal rank is classified as low-rank (sub-bituminous) with a vitrinite reflectance (Ro, max) of 0.36%, suggesting that this type of low-rank coal is favorable for biogenic methane generation. Pore structures and pore types were characterized using different methods, including low-temperature nitrogen adsorption/desorption (LTNA), mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM). Coal from the study area has microporous and macroporous features. Pore types of the coal were also characterized using SEM. The primary genetic pore types of the Red River coal include plant tissue holes and blowholes.

This study provided the first comprehensive data on the occurrence and removal of twenty-five target emerging contaminants (ECs) in a full-scale water reclamation plant (WRP) in the Southeast Asian region. Nineteen out of the twenty-five ECs were ubiquitously detected in raw influent samples. Concentrations of the detected ECs in raw influent samples ranged substantially from 44.3 to 124,966ng/L, depending upon the compound and sampling date. The elimination of ECs in full-scale conventional activated sludge (CAS) and membrane bioreactor (MBR) systems at a local WRP was evaluated and compared. Several ECs, such as acetaminophen, atenolol, fenoprofen, indomethacin, ibuprofen, and oxybenzone, exhibited excellent removal efficiencies (>90%) in biological wastewater treatment processes, while some of the investigated compounds (carbamazepine, crotamiton, diclofenac, and iopamidol) appeared to be persistent in the both CAS and MBR systems. Field-based monitoring results showed that MBR outperformed CAS in the elimination of most target ECs. The relationship between molecular characteristics of ECs (i.e. physicochemical properties and structural features) and their removal efficiencies during biological wastewater treatment was also elucidated. Excellent removal efficiencies (>90%) were often noted for ECs with the sole presence of electron donating groups (i.e. phenolic [OH], amine [NH2], methoxy [OCH3], phenoxy [OC6H5], or alkyl groups). Conversely, ECs with the absence of electron donating groups or the predominance of strong electron withdrawing groups (e.g. halogenated, carbonyl, carboxyl, and sulfonamide) tended to show poor removal efficiencies (

Landfill leachate could be a significant source of emerging contaminants (ECs) and antibiotic resistance genes (ARGs) into the environment. This study provides the first information on the occurrence of selected ECs and ARGs in raw leachate from 16-year old closed landfill site in Singapore. Among the investigated ECs, acetaminophen (ACT), bisphenol A (BPA), clofibric acid (CA), caffeine (CF), crotamiton (CTMT), diclofenac (DCF), N,N-diethyl-m-toluamide (DEET), gemfibrozil (GFZ), lincomycin (LIN), salicylic acid (SA), and sulfamethazine (SMZ) were the most frequently detected compounds in raw landfill leachate. The concentrations of detected ECs in raw landfill leachate varied significantly, from below quantification limit to 473,977 ng/L, depending on the compound. In this study, Class I integron (intl1) gene and ten ARGs were detected in raw landfill leachate. Sulfonamide resistance (sul1, sul2, and dfrA), aminoglycoside resistance (aac6), tetracycline resistance (tetO), quinolone resistance (qnrA), and intl1 were ubiquitously present in raw landfill leachate. Other resistance genes, such as beta-lactam resistance (blaNMD1, blaKPC, and blaCTX) and macrolide-lincosamide resistance (ermB) were also detected, detection frequency of50%. The removal of target ECs and ARGs by a full-scale hybrid constructed wetland (CW) was also evaluated. The vast majority of ECs exhibited excellent removal efficiencies (90%) in the investigated hybrid CW system. This hybrid CW system was also found to be effective in the reduction of several ARGs (intl1, sul1, sul2, and qnrA). Aeration lagoons and reed beds appeared to be the most important treatment units of the hybrid CW for removing the majority of ECs from the leachate.

Very little information on the occurrence and fate of multiple classes of antimicrobials in the aquatic environment is reported for the Southeast Asian region. This study provides the first and comprehensive data on the occurrence of ten different classes of antimicrobials in wastewater samples for Singapore. Among the investigated antimicrobials, 19 out of 21 target compounds were detected in 100% of the collected raw influent samples. Concentrations of the detected antimicrobials in raw influent varied from 23.8 to 43,740 ng/L. Removal of antimicrobials by conventional activated sludge (CAS) and membrane bioreactor (MBR) systems at a local wastewater treatment plant was evaluated. MBR exhibited better performance over CAS for most target antimicrobials. Beta-lactam, glycopeptide, and fluoroquinolone classes were largely eliminated by biological wastewater treatment processes, whereas trimethoprim and lincosamides appeared to be persistent. Effects of physicochemical properties and chemical structures of target antimicrobials on their removal efficiencies/mechanisms during wastewater treatment process were also discussed.

Picocyanobacteria are small cyanobacteria, being about 0.8–1.5 µm in size. They are present in freshwater environments all over the world and are known to cause harmful algal blooms, although their effects are not well understood. Algal blooms are important to manage because they threaten freshwater resources, with potentially severe effects on ecological and human health. There is also increased urgency due to urbanization and climate change trends which are expected to exacerbate these bloom dynamics. These changes are expected to especially favour picocyanobacteria groups, emphasizing the need for better characterization of their effects in the environment. In this study, we report the discovery that Synechococcus sp. could produce cylindrospermopsin (CYN) and anatoxin-a (ATX). This ability had never been previously reported for this species. Their toxin genes were also partial compared to other major producers such as Raphidiopsis sp. and Anabaena sp., demonstrating potentially unique synthesis pathways that provides insight into the various mechanisms of genetic variation that drives toxin synthesis. The Synechococcus sp. strains were found to produce about 9.0 × 10−5–6.8 × 10−4 fg CYN cell−1 and 4.7 × 10−4–1.5 × 10−2 fg ATX cell−1. The potential for Synechococcus sp. to be toxic highlights a global concern due to its widespread distribution, and through environmental trends that increasingly favour its productivity within freshwater systems around the world.

A robust and sensitive analytical method was developed for the simultaneous analysis of 21 target antimicrobials in different environmental water samples. Both single SPE and tandem SPE cartridge systems were investigated to simultaneously extract multiple classes of antimicrobials. Experimental results showed that good extraction efficiencies (84.5–105.6%) were observed for the vast majority of the target analytes when extraction was performed using the tandem SPE cartridge (SB+HR-X) system under an extraction pH of 3.0. HPLC-MS/MS parameters were optimized for simultaneous analysis of all the target analytes in a single injection. Quantification of target antimicrobials in water samples was accomplished using 15 isotopically labeled internal standards (ILISs), which allowed the efficient compensation of the losses of target analytes during sample preparation and correction of matrix effects during UHPLC-MS/MS as well as instrument fluctuations in MS/MS signal intensity. Method quantification limit (MQL) for most target analytes based on SPE was below 5 ng/L for surface waters, 10 ng/L for treated wastewater effluents, and 15 ng/L for raw wastewater. The method was successfully applied to detect and quantify the occurrence of the target analytes in raw influent, treated effluent and surface water samples.

The quality of surface waters/groundwater of a geographical region can be affected by anthropogenic activities, land use patterns and fecal pollution sources from humans and animals. Therefore, the development of an efficient fecal pollution source tracking toolbox for identifying the origin of the fecal pollution sources in surface waters/groundwater is especially helpful for improving management efforts and remediation actions of water resources in a more cost-effective and efficient manner. This review summarizes the updated knowledge on the use of fecal pollution source tracking markers for detecting, evaluating and characterizing fecal pollution sources in receiving surface waters and groundwater. The suitability of using chemical markers (i.e. fecal sterols, fluorescent whitening agents, pharmaceuticals and personal care products, and artificial sweeteners) and/or microbial markers (e.g. F+RNA coliphages, enteric viruses, and host-specific anaerobic bacterial 16S rDNA genetic markers) for tracking fecal pollution sources in receiving water bodies is discussed. In addition, this review also provides a comprehensive approach, which is based on the detection ratios (DR), detection frequencies (DF), and fate of potential microbial and chemical markers. DR and DF are considered as the key criteria for selecting appropriate markers for identifying and evaluating the impacts of fecal contamination in surface waters/groundwater.

There is limited information on the occurrence and removal of artificial sweeteners (ASs) in biological wastewater treatment plants, and in particular, the contribution of sorption and biodegradation to their removal. This study investigated the fate of ASs in both the aqueous and solid phases in a water reclamation plant (WRP). All the four targeted ASs, i.e. acesulfame (ACE), sucralose (SUC), cyclamate (CYC) and saccharine (SAC), were detected in both the aqueous and solid phases of raw influent and primary effluent samples. The concentrations of CYC and SAC in secondary effluent or MBR permeate were below their method detection limits. ACE and SUC were persistent throughout the WRP, whereas CYC and SAC were completely removed in biological treatment (>99%). Experimental results showed that sorption played a minor role in the elimination of the ASs due to the relatively low sorption coefficients (Kd), where Kd

The development of analytical methods for the detection and accurate quantification of algal toxins is of importance to assess the health risk of exposure to algal toxins in freshwater sources. This study established a sensitive and accurate analytical method for the quantification of 13 algal toxins (microcystins and nodularin) based on solid phase extraction (SPE) coupled with UPLC-MS/MS, in which 15N-microcystins were used as surrogate/internal standards. SPE method was optimized to extract the target algal toxins in freshwater samples. Good SPE efficiencies (84–96%) were achieved for the overwhelming majority of the investigated algal toxins when SPE was performed using HLB (500 mg, 6 mL) under alkaline conditions (pH 11). An accurate quantitative analysis of the algal toxins in real freshwater samples was performed by using 15N-labelled microcystins as isotopically labelled internal standards (ILISs), which compensated for the loss of target toxins during the whole analytical process. In addition, ILISs also helped to correct the effects of environmental matrices and instrument fluctuation in UPLC-MS/MS analysis. The limit of method quantification (MQL) for the algal toxins was

Analytical methods based on direct injection (DI) and solid phase extraction (SPE) coupled with ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC- MS/MS) were developed for the determination of anatoxin-a (ATX-a), cylindrospermopsin (CYN), and homoanatoxin-a (HATX-a) in freshwater samples impacted with cyanobacterial blooms. The presence of CYN in freshwater samples was detected and quantified based on direct injection method, while ATX-a and HATX-a could be determined by both DI and SPE-based methods. Matrix effects (ME) on the signal intensity of the cyanotoxins were systematically evaluated for both direct injection and SPE extract samples. CYN, ATX-a, and HATX-a suffered a significant suppression during UPLC-MS/MS. The selection of internal standards (ISs) for compensating/correcting the losses of target cyanotoxins during sample preparation and matrix effects in UPLC-MS/MS analyses were systematically evaluated. Acetaminophen-d4 (an isotopically labelled acetaminophen) is a suitable internal standard for correcting the ME on the signal intensity of ATX-a and HATX-a, while the use of L-phenylalanine-d5 or caffeine-d9 as IS for correcting ME of these toxins was not efficient, as expected. The method detection limit (MDL) for the target cyanotoxins ranged from 0.6 to 15 ng/L, which is sensitive enough to detect the presence of these toxins in cyanobacterial bloom freshwater. The developed methods were successfully applied for routine monitoring of the occurrence of these cyanotoxins in a local water body in Singapore. Monitoring results depicted that ATX-a, CYN and HATX-a were ubiquitously detected in water samples, at concentrations ranging from 70 to 24,600 ng/L.

A sensitive quantification method using pressurized liquid extraction (PLE) and solid phase extraction (SPE) coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed for determination of 19 anthelmintic drugs (ADs) belonging to seven structural groups (Benzimidazoles, Diphenylsulfides, Imidazothiazoles, Hexahydropyrazines, Macrocylic lactones, Salicylanilides, Tetrahydropyrimidines) in environmental water and sediment samples. Eleven SPE cartridges, sample pH, elution solvents were tested to determine the optimal conditions for extraction. Among these investigated SPE types, the best recoveries for 19 target ADs were obtained from Oasis HLB cartridge with 37-102%, 45-103%, 37-88%, 28-82% and 31-90% for spiked river water, tap water, rainwater, wastewater, and sediment respectively (with RSD 15%), except for closantel. The 19 ADs were separated within 10 min by a BEH C18 column and monitored in both positive and negative ions modes with switching electrospray ionization source. The cross-talk interferences were solved by identification of secondary mass spectrum of substances through MRM-IDA-EPI scanning using Qtrap. These interference peaks could be efficiently eliminated by setting MRM segments or using Qtrap to obtain tertiary fragmented information. The developed methods were satisfactory in terms of linearity, accuracy, and precision, and used eight isotopically labeled compounds as internal standards to correct matrix effects. Method quantification limit (MQL) for 19 ADs was below 1.1 ng/L, 0.4 ng/L, 5.4 ng/L and 2.3 ng/g for river water, tap water, wastewater, and sediment, respectively. The validated method was successfully used to investigate the occurrence of anthelmintics in water and sediment samples from Chengdu, China. All ADs were detected in environment with the concentrations at ng/L level.

The ubiquitous occurrence of nutrients (e.g. phosphorus) and micropollutants (e.g. pharmaceuticals and endocrine disrupting chemicals) in wastewater and urban stormwater runoff sources may cause adverse effects on aquatic ecosystems and human health. Therefore, the removal of these pollutants from wastewater, treated effluent, and urban stormwater runoff is critically needed. In this study, a novel modified red mud with polypyrrole (RM-PPy) was successfully synthesized with improved functional groups (–OH, –N=, –NH–, N+), specific area (SBET 102.24 m2/g), and mesopore structure (i.e. average pore diameter of 3.29 nm), which are assumed to enhance the adsorptive removal of diclofenac (DCF) and phosphorus (P) in aqueous solution. The measured maximum adsorption capacity of RM-PPy towards diclofenac (195 mg/g) in single adsorbate system was higher than that (115.7 mg/g) in the binary adsorbates system (i.e. in the presence of P), indicating that the presence of pollutants such as P in water hampered the adsorptive removal of DCF. The adsorption of DCF and P was largely dependent on solution pH values. Higher adsorptive removals of DCF and P were observed at acidic conditions (pH 2–5). Adsorption isotherm of DCF and P was better fitted to Freundlich model compared to Langmuir isotherm model, suggesting multilayer coverage. Adsorption of DCF onto RM-PPy might take place via anion exchange and electrostatic interactions. For P adsorption, apart from anion exchange and electrostatic interactions, the chemical precipitation via ligand exchange between P and hydroxyl (–OH) in RM-PPy can be considered as one of the main adsorption mechanisms. Further studies on the competitive adsorption of other anionic micropollutants at environmentally relevant concentrations (ng/L–μg/L) in water samples by RM-PPy are needed to evaluate the potential application of RM-PPy for the removal of other anionic micropollutants (i.e. antibiotics) in treated wastewater and stormwater runoff.

Seaweeds are found abundance in most seashores. They contain relatively high lipid contents and are exhibiting medicinal properties. The present work focused on the use of seaweed species Ulva linza, U. tubulosa, U. fasciata, U. rigida, and U. reticulate to synthesize Mn2ZnO4 composite nanoparticles. The later was utilized for biodiesel production and its antibacterial potential was also assessed. Heterogeneous mixed metal oxides are suitable catalysts for biodiesel production due to ease of separation, reusability and environmental friendliness. The employment of multi-resistant organisms (MROS) is of major importance in modern medicines. Thus there is an extreme need for potential antibacterial alternatives such as metal oxides. Mn2ZnO4 nanoparticles were synthesized by using a co-precipitation method. The crystalline behavior and morphological characterizations were carried out through XRD, FE-SEM, Raman Spectra and FT-IR respectively. The particle size was found to be 42 nm. Fatty Acid Methyl Ester (FAME) produced from Ulva species was analyzed by gas chromatography and physical parameters were also determined. The yields were as follows: U. linza 72.3%, U. tubulosa 72%, U. fasciata 70.6%, U. rigida 70.4%, and U. reticulate 71.5%. The antibacterial potential of synthesized Mn2ZnO4 nanoparticles after transesterification, showed strong antibacterial activity against both gram positive and gram negative bacteria and were found to be comparable to commercially available antibiotics. To assess their antibacterial efficiency, the minimum inhibition concentration was measured. The used catalysts exhibit high efficient catalytic activity on degrading methylene blue under UV irradiation.

Two efficient and practical approaches are reported for the synthesis of β- and γ-carboline derivatives from 3,4-dibromopyridine as a common starting material. The β-carbolines were prepared by site-selective Pd-catalyzed C–C coupling with o-bromophenylboronic acid and subsequent cyclization by double C–N coupling with amines. γ-Carbolines were prepared from the same starting material by C–N coupling with anilines and subsequent annulation by domino C–C/C–N coupling with o-bromophenylboronic acid.

Biofilm carriers play an important role in attached growth systems for wastewater treatment processes. This study systematically summarizes the traditional and novel biofilm carriers utilized in biofilm-based wastewater treatment technology. The advantages and disadvantages of traditional biofilm carriers are evaluated and discussed in light of basic property, biocompatibility and applicability. The characteristics, applications performance, and mechanism of novel carriers (including slow-release carriers, hydrophilic/electrophilic modified carriers, magnetic carriers and redox mediator carriers) in wastewater biological treatment were deeply analyzed. Slow release biofilm carriers are used to provide a solid substrate and electron donor for the growth of microorganisms and denitrification for anoxic and/or anaerobic bioreactors. Carriers with hydrophilic/electrophilic modified surface are applied for promoting biofilm formation. Magnetic materials-based carriers are employed to shorten the start-up time of bioreactor. Biofilm carriers acting as redox mediators are used to accelerate biotransformation of recalcitrant pollutants in industrial wastewater.

The biodegradation of 10 selected pharmaceuticals by enriched nitrifier cultures with ammonia oxidizing activity of 30 mg NH4-N/g MLVSS h was investigated under various initial operating conditions such as in the presence of different growth substrates and inhibitors. The enriched nitrifier culture showed higher degradation of the target pharmaceuticals than the conventional activated sludge. The degradation efficiency of persistent pharmaceuticals such as clofibric acid (CA), diclofenac (DCF), carbamazepine (CBZ), and propyphenazone (PPZ) was increased with the increase in the ammonium concentration. A higher removal efficiency of CA, DCF, CBZ and PPZ was obtained when organic substrates were added. The contribution of autotrophs and heterotrophs in the biotransformation of the pharmaceuticals by the enriched nitrifier culture was successfully estimated by the addition of inhibitors. Experimental results showed that the high degradation of IBP and partial degradation of other selected pharmaceuticals were observed in the presence of allylthiourea (ATU), an ammonia monooxygenase inhibitor, reflecting the activity of heterotrophic bacteria, while the results with and without ATU addition showed that the contribution of the nitrification in the degradation of most pharmaceuticals was also dominant. The results suggest that nitrification can enhance the biotransformation of pharmaceutical substances.