Predicting Antibiotic Resistance and Assessing the Risk Burden from Antibiotics: A Holistic Modeling Framework in a Tropical Reservoir.

Predicting the hotspots of antimicrobial resistance (AMR) in aquatics is crucial for managing associated risks. We developed an integrated modeling framework toward predicting the spatiotemporal abundance of antibiotics, indicator bacteria, and their corresponding antibiotic-resistant bacteria (ARB), as well as assessing the potential AMR risks to the aquatic ecosystem in a tropical reservoir. Our focus was on two antibiotics, sulfamethoxazole (SMX) and trimethoprim (TMP), and on Escherichia coli (E. coli) and its variant resistant to sulfamethoxazole-trimethoprim (EC_SXT). We validated the predictive model using withheld data, with all Nash-Sutcliffe efficiency (NSE) values above 0.79, absolute relative difference (ARD) less than 25%, and coefficient of determination (R2) greater than 0.800 for the modeled targets. Predictions indicated concentrations of 1-15 ng/L for SMX, 0.5-5 ng/L for TMP, and 0 to 5 (log10 MPN/100 mL) for E. coli and -1.1 to 3.5 (log10 CFU/100 mL) for EC_SXT. Risk assessment suggested that the predicted TMP could pose a higher risk of AMR development than SMX, but SMX could possess a higher ecological risk. The study lays down a hybrid modeling framework for integrating a statistic model with a process-based model to predict AMR in a holistic manner, thus facilitating the development of a better risk management framework.

Removal efficiency of antibiotic residues, antibiotic resistant bacteria, and genes across parallel secondary settling tank and membrane bioreactor treatment trains in a water reclamation plant.

Antimicrobial resistance is recognized as a potent threat to human health. Wastewater treatment facilities are viewed as hotspots for the spread of antimicrobial resistance. This study provides comprehensive data on the occurrences of 3 different antibiotic resistant opportunistic pathogens (with resistance to up to 5 antibiotics), 13 antibiotic resistant genes and intI1, and 22 different antimicrobial residues in a large water reclamation plant (176 million gallons per day) that runs a conventional Modified Ludzack-Ettinger (MLE) reactor followed by a secondary settling tank (SST) and membrane bioreactor (MBR) in parallel. All the antibiotic resistant bacteria and most of the antibiotic resistance genes were present in the raw influent, ranging from 2.5 × 102-3.7 × 106 CFU/mL and 1.2× 10-1-6.5 × 1010 GCN/mL, respectively. MBR outperformed the SST system in terms of ARB removal as the ARB targets were largely undetected in MBR effluent, with log removals ranging from 2.7 to 6.8, while SST only had log removals ranging from 0.27 to 4.6. Most of the ARG concentrations were found to have significantly higher in SST effluent than MBR permeate, and MBR had significantly higher removal efficiency for most targets (p < 0.05) except for sul1, sul2, blaOXA48, intI1 and 16S rRNA genes (p > 0.05). As for the antibiotic residues (AR), there was no significant removal from the start to the end of the treatment process, although MBR had higher removal efficiencies for azithromycin, chloramphenicol, erythromycin, erythromycin-H2O, lincomycin, sulfamethoxazole and triclosan, compared to the SST system. In conclusion, MBR outperformed SST in terms of ARB and ARGs removal. However low removal efficiencies of most AR targets were apparent.

Quaternary ammonium compounds of emerging concern: Classification, occurrence, fate, toxicity and antimicrobial resistance.

Amplified hygiene and precautionary measures are of utmost importance to control the spread of COVID-19 and future infection; however, these changes in practice are projected to trigger a rise in the purchase, utilisation and hence, discharge of many disinfectants into the environment. While alcohol-based, hydrogen peroxide-based, and chlorine-based compounds have been used widely, quaternary ammonium compounds (QACs) based disinfectants are of significant concern due to their overuse during this pandemic. This review presents the classification of disinfectants and their mechanism of action, focusing on QACs. Most importantly, the occurrence, fate, toxicity and antimicrobial resistance due to QACs are covered in this paper. Here we collated evidence from multiple studies and found rising trends of concern, including an increase in the mass load of QACs at a wastewater treatment plant (WWTP) by 331% compared to before the COVID-19 pandemic, as well as an increases in the concentration of 62% in residential dust, resulting in high concentrations of QACs in human blood and breast milk and suggesting that these could be potential sources of persistent QACs in infants. In addition to increased toxicity to human and aquatic life, increased use of QACs and accelerated use of antibiotics and antimicrobials during the COVID-19 pandemic could multiply the threat to antimicrobial resistance.

Source, fate, transport and modelling of selected emerging contaminants in the aquatic environment: Current status and future perspectives.

The occurrence of emerging contaminants (ECs), such as pharmaceuticals and personal care products (PPCPs), perfluoroalkyl and polyfluoroalkyl substances (PFASs) and endocrine-disrupting chemicals (EDCs) in aquatic environments represent a major threat to water resources due to their potential risks to the ecosystem and humans even at trace levels. Mathematical modelling can be a useful tool as a comprehensive approach to study their fate and transport in natural waters. However, modelling studies of the occurrence, fate and transport of ECs in aquatic environments have generally received far less attention than the more widespread field and laboratory studies. In this study, we reviewed the current status of modelling ECs based on selected representative ECs, including their sources, fate and various mechanisms as well as their interactions with the surrounding environments in aquatic ecosystems, and explore future development and perspectives in this area. Most importantly, the principles, mathematical derivations, ongoing development and applications of various ECs models in different geographical regions are critically reviewed and discussed. The recommendations for improving data quality, monitoring planning, model development and applications were also suggested. The outcomes of this review can lay down a future framework in developing a comprehensive ECs modelling approach to help researchers and policymakers effectively manage water resources impacted by rising levels of ECs.

Multi-class secondary metabolites in cyanobacterial blooms from a tropical water body: Distribution patterns and real-time prediction.

Cyanobacterial blooms that produce toxins occur in freshwaters worldwide and yet, the occurrence and distribution patterns of many cyanobacterial secondary metabolites particularly in tropical regions are still not fully understood. Moreover, predictive models for these metabolites by using easily accessible water quality indicators are rarely discussed. In this study, we investigated the co-occurrence and spatiotemporal trends of 18 well-known and less-studied cyanobacterial metabolites (including [D-Asp3] microcystin-LR (DM-LR), [D-Asp3] microcystin-RR (DM-RR), microcystin-HilR (MC-HilR), microcystin-HtyR (MC-HtyR), microcystin-LA (MC-LA), microcystin-LF (MC-LF), microcystin-LR (MC-LR), microcystin-LW (MC-LW), microcystin-LY (MC-LY), microcystin-RR (MC-RR) and microcystin-WR (MC-WR), Anatoxin-a (ATX-a), homoanatoxin-a (HATX-a), cylindrospermospin (CYN), nodularin (NOD), anabaenopeptin A (AptA) and anabaenopeptin B (AptB)) in a tropical freshwater lake often plagued with blooms. Random forest (RF) models were developed to predict MCs and CYN and assess the relative importance of 22 potential predictors that determined their concentrations. The results showed that 11 MCs, CYN, ATX-a, HATX-a, AptA and AptB were found at least once in the studied water body, with MC-RR and CYN being the most frequently occurring, intracellularly and extracellularly. AptA and AptB were detected for the first time in tropical freshwaters at low concentrations. The metabolite profiles were highly variable at both temporal and spatial scales, in line with spatially different phytoplankton assemblages. Notably, MCs decreased with the increase of CYN, possibly revealing interspecific competition of cyanobacteria. The rapid RF prediction models for MCs and CYN were successfully developed using 4 identified drivers (i.e., chlorophyll-a, total carbon, rainfall and ammonium for MCs prediction; and chloride, total carbon, rainfall and nitrate for CYN prediction). The established models can help to better understand the potential relationships between cyanotoxins and environmental variables as well as provide useful information for making policy decisions.

The characteristics of coalbed water and coal in a coal seam situated in the Red River Basin, Vietnam.

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.

The stress-sensing domain of activated IRE1α forms helical filaments in narrow ER membrane tubes.

The signaling network of the unfolded protein response (UPR) adjusts the protein-folding capacity of the endoplasmic reticulum (ER) according to need. The most conserved UPR sensor, IRE1α, spans the ER membrane and activates through oligomerization. IRE1α oligomers accumulate in dynamic foci. We determined the in situ structure of IRE1α foci by cryogenic correlated light and electron microscopy combined with electron cryo-tomography and complementary immuno­electron microscopy in mammalian cell lines. IRE1α foci localized to a network of narrow anastomosing ER tubes (diameter, ~28 nm) with complex branching. The lumen of the tubes contained protein filaments, which were likely composed of arrays of IRE1α lumenal domain dimers that were arranged in two intertwined, left-handed helices. This specialized ER subdomain may play a role in modulating IRE1α signaling.

The WAVE complex associates with sites of saddle membrane curvature.

How local interactions of actin regulators yield large-scale organization of cell shape and movement is not well understood. Here we investigate how the WAVE complex organizes sheet-like lamellipodia. Using super-resolution microscopy, we find that the WAVE complex forms actin-independent 230-nm-wide rings that localize to regions of saddle membrane curvature. This pattern of enrichment could explain several emergent cell behaviors, such as expanding and self-straightening lamellipodia and the ability of endothelial cells to recognize and seal transcellular holes. The WAVE complex recruits IRSp53 to sites of saddle curvature but does not depend on IRSp53 for its own localization. Although the WAVE complex stimulates actin nucleation via the Arp2/3 complex, sheet-like protrusions are still observed in ARP2-null, but not WAVE complex-null, cells. Therefore, the WAVE complex has additional roles in cell morphogenesis beyond Arp2/3 complex activation. Our work defines organizing principles of the WAVE complex lamellipodial template and suggests how feedback between cell shape and actin regulators instructs cell morphogenesis.

Developing Surrogate Markers for Predicting Antibiotic Resistance "Hot Spots" in Rivers Where Limited Data Are Available.

Pinpointing environmental antibiotic resistance (AR) hot spots in low-and middle-income countries (LMICs) is hindered by a lack of available and comparable AR monitoring data relevant to such settings. Addressing this problem, we performed a comprehensive spatial and seasonal assessment of water quality and AR conditions in a Malaysian river catchment to identify potential "simple" surrogates that mirror elevated AR. We screened for resistant coliforms, 22 antibiotics, 287 AR genes and integrons, and routine water quality parameters, covering absolute concentrations and mass loadings. To understand relationships, we introduced standardized "effect sizes" (Cohen's D) for AR monitoring to improve comparability of field studies. Overall, water quality generally declined and environmental AR levels increased as one moved down the catchment without major seasonal variations, except total antibiotic concentrations that were higher in the dry season (Cohen's D > 0.8, P < 0.05). Among simple surrogates, dissolved oxygen (DO) most strongly correlated (inversely) with total AR gene concentrations (Spearman's ρ 0.81, P < 0.05). We suspect this results from minimally treated sewage inputs, which also contain AR bacteria and genes, depleting DO in the most impacted reaches. Thus, although DO is not a measure of AR, lower DO levels reflect wastewater inputs, flagging possible AR hot spots. DO measurement is inexpensive, already monitored in many catchments, and exists in many numerical water quality models (e.g., oxygen sag curves). Therefore, we propose combining DO data and prospective modeling to guide local interventions, especially in LMIC rivers with limited data.

Novel cyanotoxin-producing Synechococcus in tropical lakes.

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 sensitive and accurate method for simultaneous analysis of algal toxins in freshwater using UPLC-MS/MS and 15N-microcystins as isotopically labelled internal standards.

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 <2.0 ng/L that is sensitive enough to quantify extremely low levels of target toxins in freshwater samples.

Quantification of cylindrospermopsin, anatoxin-a and homoanatoxin-a in cyanobacterial bloom freshwater using direct injection/SPE coupled with UPLC-MS/MS.

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. 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.

Ribosome-associated vesicles: A dynamic subcompartment of the endoplasmic reticulum in secretory cells.

The endoplasmic reticulum (ER) is a highly dynamic network of membranes. Here, we combine live-cell microscopy with in situ cryo-electron tomography to directly visualize ER dynamics in several secretory cell types including pancreatic ß-cells and neurons under near-native conditions. Using these imaging approaches, we identify a novel, mobile form of ER, ribosome-associated vesicles (RAVs), found primarily in the cell periphery, which is conserved across different cell types and species. We show that RAVs exist as distinct, highly dynamic structures separate from the intact ER reticular architecture that interact with mitochondria via direct intermembrane contacts. These findings describe a new ER subcompartment within cells.

Determination of 19 anthelmintics in environmental water and sediment using an optimized PLE and SPE method coupled with UHPLC-MS/MS.

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.

Quantitative microscopy reveals dynamics and fate of clustered IRE1α.

The endoplasmic reticulum (ER) membrane-resident stress sensor inositol-requiring enzyme 1 (IRE1) governs the most evolutionarily conserved branch of the unfolded protein response. Upon sensing an accumulation of unfolded proteins in the ER lumen, IRE1 activates its cytoplasmic kinase and ribonuclease domains to transduce the signal. IRE1 activity correlates with its assembly into large clusters, yet the biophysical characteristics of IRE1 clusters remain poorly characterized. We combined superresolution microscopy, single-particle tracking, fluorescence recovery, and photoconversion to examine IRE1 clustering quantitatively in living human and mouse cells. Our results revealed that: 1) In contrast to qualitative impressions gleaned from microscopic images, IRE1 clusters comprise only a small fraction (∼5%) of the total IRE1 in the cell; 2) IRE1 clusters have complex topologies that display features of higher-order organization; 3) IRE1 clusters contain a diffusionally constrained core, indicating that they are not phase-separated liquid condensates; 4) IRE1 molecules in clusters remain diffusionally accessible to the free pool of IRE1 molecules in the general ER network; 5) when IRE1 clusters disappear at later time points of ER stress as IRE1 signaling attenuates, their constituent molecules are released back into the ER network and not degraded; 6) IRE1 cluster assembly and disassembly are mechanistically distinct; and 7) IRE1 clusters' mobility is nearly independent of cluster size. Taken together, these insights define the clusters as dynamic assemblies with unique properties. The analysis tools developed for this study will be widely applicable to investigations of clustering behaviors in other signaling proteins.

Synergistic Effect of High-Frequency Ultrasound with Cupric Oxide Catalyst Resulting in a Selectivity Switch in Glucose Oxidation under Argon.

We report here, and rationalize, a synergistic effect between a non-noble metal oxide catalyst (CuO) and high-frequency ultrasound (HFUS) on glucose oxidation. While CuO and HFUS are able to independently oxidize glucose to gluconic acid, the combination of CuO with HFUS led to a dramatic change of the reaction selectivity, with glucuronic acid being formed as the major product. By means of density functional theory (DFT) calculations, we show that, under ultrasonic irradiation of water at 550 kHz, the surface lattice oxygen of a CuO catalyst traps H· radicals stemming from the sonolysis of water, making the ring-opening of glucose energetically unfavorable and leaving a high coverage of ·OH radical on the CuO surface, which selectively oxidizes glucose to glucuronic acid. This work also points toward a path to optimize the size of the catalyst particle for an ultrasonic frequency that minimizes the damage to the catalyst, resulting in its successful reuse.

Occurrence and risk assessment of multiple classes of antibiotics in urban canals and lakes in Hanoi, Vietnam.

Very little information on the occurrence and risk assessment of antibiotics in the aquatic environment is reported for Vietnam, where antibiotics are assumed to be omnipresent in urban canals and lakes at high concentrations due to the easy accessibility of antibiotics without doctor prescription. This study provides comprehensive analysis of the occurrence of 23 antibiotics in urban canals (To Lich and Kim Nguu) and lakes (West Lake, Hoan Kiem, and Yen So) in Hanoi, Vietnam. Of these 23 antibiotics, 18 were detected in urban canals at above 67.9% detection frequency (DF). The concentrations of detected antibiotics were in the range from below quantification limit (MQL) to almost 50,000 ng/L, depending on the compound and sampling site. In urban canals, median concentration of amoxicillin, erythromycin, and sulfamethoxazole was >1000 ng/L while other antibiotics such as ampicillin, chloramphenicol, clindamycin, sulfamethazine, tetracycline, tylosin and vancomycin were detected at median concentrations of <100 ng/L. Similarly, 16 target antibiotics were also detected in urban lakes. Macrolides (azithromycin, clarithromycin, and erythromycin-H2O), fluoroquinolones (enrofloxacin and ofloxacin), lincosamides (clindamycin and lincomycin), and trimethoprim were ubiquitously detected in urban lakes (DF = 100%). In this study, potential risks of antibiotics in the investigated urban canals and lakes were assessed based on the predicted no-effect concentration (PNEC) from the existing literature for antibiotic resistance selection (PNECARM) and ecological toxicity to aquatic organisms (PNECEcotox). Ampicillin, amoxicillin, azithromycin, ciprofloxacin, clarithromycin, enrofloxacin, erythromycin, ofloxacin, tetracycline, and trimethoprim were found in the investigated urban canals at concentrations exceeding their PNECARM and PNECEcotox. Similarly, most of the target antibiotics (i.e. amoxicillin, ciprofloxacin, clarithromycin, clindamycin, enrofloxacin, erythromycin, lincomycin, ofloxacin, sulfamethoxazole, tetracycline, trimethoprim and tylosin) were detected in the investigated urban lakes at concentrations close to or exceeding PNECEcotox for aquatic organisms. Further investigations on the occurrence and fate of antibiotic residues and antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in surface waters are recommended.

Biotransformation of polyfluoroalkyl substances by microbial consortia from constructed wetlands under aerobic and anoxic conditions.

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.

Insights into biofilm carriers for biological wastewater treatment processes: Current state-of-the-art, challenges, and opportunities.

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.

Emerging contaminants in wastewater, stormwater runoff, and surface water: Application as chemical markers for diffuse sources.

Diffuse sources of pollution such as sewer leakages, sewer overflows, illicit discharges and stormwater runoff affect the urban surface water quality but often remain unknown. Therefore, the development of chemical markers for identifying and characterizing the origin of diffuse sources of pollution in urban surface waters is a requisite for protecting and managing urban water resources. In this study, the occurrence of 31 emerging contaminants (ECs) in untreated wastewater, treated wastewater, urban stormwater runoff, agricultural stormwater runoff, and freshwater bodies was investigated. Artificial sweeteners (ASs), pharmaceuticals and personal care products (PPCPs) were more frequently detected in the collected water samples. In raw wastewater, 21 target ECs were detected 100% in the collected samples with median concentrations ranging from 49.6 to 77,721 ng/L, while in freshwater bodies, only 13 compounds were found with detection frequency >50%. The median concentration of the majority of detected ECs in freshwater samples was below 100 ng/L. The suitability of ECs as chemical markers of diffuse sources in an urban watershed was assessed using a suite of criteria, including the detection frequency (DF), detection ratio (DR) (i.e. the ratio between median concentration and method quantification limit of a compound) and attenuation rates (i.e., biodegradation, sorption and abiotic degradation) in wastewater treatment processes. In addition, we propose a new key criterion, the concentration ratio (CR) of labile to conservative compounds, to evaluate the applicability of suitable chemical markers for source tracking. Using this new set of criteria (i.e. CR, DF, DR and attenuation rates), our analysis showed that among the investigated ECs, only acesulfame (ACE), acetaminophen (ACT), cyclamate (CYC), saccharin (SAC) were suitable as chemical markers of diffuse sources in surface waters. For caffeine (CF), N,N-diethyl-meta-toluamide (DEET), crotamiton (CTMT), triclocarban (TCC) and triclosan (TCS), their median concentration ratio to sucralose (SUC) in water bodies was consistently higher than that in raw wastewater, suggesting that these compounds might be unsuitable as chemical markers of sewage leakage in surface waters for this study area.