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Understanding how per- and poly-fluoroalkyl substances (PFAS) are transported is critical to site characterization, monitoring, risk assessment, and remediation planning. This includes an understanding of PFAS retention and release at air-water interfaces. These interfaces exist throughout the vadose zone, but can also exist as trapped air bubbles created by water table fluctuations, recharge, and biogenic gas production. In addition to being directly applicable to transport through trapped gas zones at PFAS-impacted sites, laboratory experiments using emplaced trapped gas (quasi-saturated conditions) provide a controlled method to investigate PFAS behavior, including the effects of different PFAS, concentrations, and mixtures. In this study, a series of laboratory experiments was conducted using one-dimensional sand-packed columns (20 cm × 7 cm dia.). Trapped air was emplaced by sequential drainage and imbibition to create quasi-saturated conditions. Each experiment included separate injections of non-reactive tracer (NaCl) and PFAS solutions through both water-saturated and quasi-saturated columns. A clean, low organic carbon sand was used to eliminate solid-phase sorption (verified through comparison of non-reactive tracer and PFAS breakthrough in the water-saturated columns) and to isolate the effect of air-water interfaces. Experiments were conducted using single-component solutions of PFOA, PFOS and 6:2 FTS, as well as mixtures of those PFAS, at concentrations of 0.1-1 mg/L. Experiments were also conducted using diluted aqueous film-forming foam (AFFF) solutions. Measured retardation factors in triplicate experiments were used to estimate air-water partitioning coefficients.The results showed that PFAS breakthrough was significantly delayed in the presence of trapped air bubbles. Breakthrough delay was greater for PFOS than for PFOA or 6:2 FTS, and was greater for lower PFAS concentrations, for the range of concentrations used in these experiments. For PFAS mixtures, differences in retention were sufficient to completely separate breakthrough (i.e., PFOA and 6:2 FTS achieved complete breakthrough prior to any PFOS arrival) even over short (20 cm) distances. However, the behavior of each PFAS tested was altered by the presence of other PFAS, with PFOA and 6:2 FTS experiencing earlier breakthrough at higher concentrations (concentration overshoot) in the presence of PFOS. Mixture effects were also observed for branched and linear PFOS isomers, and for AFFF solutions, which was further complicated by the presence of hydrocarbon surfactants. The experimental results will be presented along with numerical simulations of PFAS transport subject to air-water partitioning, both to interpret the behavior of PFAS mixtures in experimental systems and to explore the implications of mixture transport in more complex field scenarios.

Per- and polyfluoroalkyl substances (PFAS) are a diverse group of manmade, fluorinated organic chemicals that gained notoriety for their diverse application, widespread distribution in the environment and toxicity. One of the main sources of PFAS to the environment is through aqueous film forming foam (AFFF), intended for use on fuel fires. AFFF may enter the environment through system testing, training activities, emergency use or accidental release. When AFFF enters the environment PFAS readily adsorb to porous media through hydrophobic and electrostatic interactions. As a result, PFAS impacted porous media may act as a long-term source of contamination to groundwater, potentially influencing water resources and human health. There is a demand for effective treatment of PFAS impacted porous media. Ball milling has emerged as a potential treatment option for PFAS, however, the viability of treating AFFF impacted porous media has been seldom explored. In this work four AFFF formulations were amended onto silica sand and milled without and with the use of potassium hydroxide (KOH) as a co-milling reagent. Six hour milling trials were conducted using a planetary ball mill with stainless steel grinding media. Significant destruction of perfluorosulfonic acids, perfluorocarboxylic acids (PFCAs), fluorotelomer sulfonates, fluorotelomer betaines and fluorotelomer sulfonamido betaines was observed. With the use of KOH as a co-milling reagent the total PFAS destruction percentage in all four AFFFs exceeded 90%. Greater destruction of PFAS was observed in fluorotelomer dominant AFFFs when compared to perfluoroalkyl acid dominant AFFFs. PFCAs and soluble fluoride were identified as destruction byproducts. KOH as a co-milling reagent had the effect of reducing PFCA byproduct formation and increasing fluoride recovery in three of four AFFFs. Fluoride recoveries indicate PFAS molecule defluorination occurs by ball milling. When PFAS in AFFF is compared to PFAS destruction in single analyte trials, less destruction is observed, displaying the necessity of evaluating realistic AFFF contamination events over single or multi analyte mixtures.

The transport of per- and polyfluoroalkyl substances (PFAS) in soil and groundwater is important for site investigation, risk characterization, and remediation planning. The adsorption of PFAS at air-water interfaces has been shown to significantly contribute to PFAS retention, with subsequent effects on concentrations and the time scales of transport. In this study, column experiments were conducted to investigate the transport of perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and 6:2 fluorotelomer sulfonate (6:2 FTS) individually and in binary mixtures in the presence of a trapped gas phase, using clean sands to isolate adsorption to air-water interfaces. Consistent with previous studies, the transport of PFOS, PFOA, and 6:2 FTS was retarded by adsorption at the air-water interface, with greater retention of PFOS due to its higher affinity for the air-water interface. Chromatographic separation occurred in the experiments using binary mixtures of PFOS and PFOA, with greater retention at lower influent concentrations. The mixture experiments also showed enhanced breakthrough of PFOA in the presence of PFOS, where effluent concentrations of PFOA were temporarily greater than the influent concentration prior to the breakthrough of PFOS. This enhanced breakthrough was attributed to competition between PFOS and PFOA for adsorption to the air-water interface.

There is a need for destructive technologies for per- and polyfluoroalkyl substances (PFAS) in soil. While planetary ball mill have been shown successful degradation of PFAS, there are issues surrounding scale up (maximum size is typically 0.5 L cylinders). While having lower energy outputs, horizontal ball mills, for which scale up is not a limiting factor, already exist at commercial/industrial sizes from the mining, metallurgic and agricultural industries, which could be re-purposed. This study evaluated the effectiveness of horizontal ball mills in degrading perfluorooctanesulfonate (PFOS), 6:2 fluorotelomer sulfonate (6:2 FTSA), and aqueous film forming foam (AFFF) spiked on nepheline syenite sand. Horizontal ball milling was also applied to two different soil types (sand dominant and clay dominant) collected from a firefighting training area (FFTA). Liquid chromatography tandem mass spectrometry was used to track 21 target PFAS throughout the milling process. High-resolution accurate mass spectrometry was also used to identify the presence and degradation of 19 non-target fluorotelomer substances, including 6:2 fluorotelomer sulfonamido betaine (FtSaB), 7:3 fluorotelomer betaine (FtB), and 6:2 fluorotelomer thioether amido sulfonate (FtTAoS). In the presence of potassium hydroxide (KOH), used as a co-milling reagent, PFOS, 6:2 FTSA, and the non-target fluorotelomer substances in the AFFF were found to undergo upwards of 81%, 97%, and 100% degradation, respectively. Despite the inherent added complexity associated with field soils, better PFAS degradation was observed on the FFTA soils over the spiked NSS, and more specifically, on the FFTA clay over the FFTA sand. These results held through scale-up, going from the 1 L to the 25 L cylinders. The results of this study support further scale-up in preparation for on-site pilot tests.

For irradiation experiments (e.g., of per- and polyfluoroalkyl substances), values of nuclear particle flux and absorbed dose rates were obtained for the Safe LOW-POwer Kritical Experiment-2 (SLOWP...

Biofilms serve to house diverse microbial communities, which are responsible for the majority of wastewater constituent degradation and transformation in treatment wetlands (TWs). TW biofilm has been generally conceptualized as a relatively uniform film covering available surfaces. However, no studies attaining direct visual 3D representations of biofilm morphology have been conducted. This study focuses on imaging the morphology of detached, gravel-associated, and rhizospheric (Phalaris arundinacea) biofilms from subsurface TW mesocosms. Images obtained through both traditional light microscopy, environmental scanning electron microscopy (E-SEM) and Wet-SEM revealed that TW biofilms are structurally heterogeneous ranging from corrugated films to clusters of aggregates. Features such as water channels and pores were observed suggesting that pollutant transport inside biofilms is complex, and that the interfacial surface area between water and biofilm is much larger than previously understood. Biofilm thickness generally ranged between 170 and 240 μm, with internal biofilm porosities estimated as 34 ± 10 %, reaching a maximum of 50 %. Internal biofilm matrix pore diameters ranged from 1 to 205.2 μm, with a distribution that favored pores and channels smaller than 10 μm, and a mean equivalent spherical diameter of 8.6 μm. Based on the large variation in pore and channel sizes it is expected that a variety of flow regimes and therefore pollutant dynamics are likely to occur inside TW biofilm matrices. Based on the visual evidence and analysis, a new conceptual model was created to reflect the microscale TW biofilm dynamics and morphology. This new conceptual model will serve to inform future biokinetic modelling, microscale hydrology, microbial community assessment, and pollutant treatment studies.

Silver nanomaterials (Ag NMs) have been used in a variety of commercial products to take advantage of their antimicrobial properties. However, there are concerns that these AgNMs can be released during/after use and enter wastewater streams, potentially impacting aquatic systems or accumulating in wastewater biosolids. Biosolids, which are a residual of wastewater treatment processes, have been found to contain AgNMs and are frequently used as agricultural fertilizer. Since the function of soil microbial communities is imperative to nutrient cycling and agricultural productivity, it is important to characterize and assess the effects that silver nanomaterials could have in agricultural soils. In this study agricultural soil was amended with pristine engineered (PVP-coated or uncoated AgNMs), aged silver (sulphidized or released from textiles) nanomaterials, and ionic silver to determine the fate and toxicity over the course of three months. Exposures were carried out at various environmentally relevant concentrations (1 and 10 mg Ag/kg soil) representing between 30 to over 800 years of equivalent biosolid loadings. Over thirteen different methodologies and measures were used throughout this study to assess for potential effects of the silver nanomaterials on soil, including microbial community composition, average well colour development (AWCD) and enzymatic activity. Overall, the AgNM exposures did not exhibit significant toxic effects to the soil microbial communities in terms of density, activity, function and diversity. However, the positive ionic silver treatment (100 mg Ag/kg soil) resulted in suppression to microbial activity while also resulting in significantly higher populations of Frankia alni (nitrogen-fixer) and Arenimonas malthae (phytopathogen) as compared to the negative control (p < 0.05, Tukey HSD) which warrants further investigation.

Per- and polyfluoroalkyl substances (PFAS) are presently essential ingredients in aqueous film forming foam (AFFF) used for fire-fighting, but are also pervasive environmental contaminants. The use and subsequent release and transport of AFFF in the ocean environment from marine vessels has not been studied to date. A numerical model (Delft3D) was rigorously calibrated and validated for the hydrodynamics, and used to predict the transport of PFAS released instantaneously into a large harbour (Halifax Harbour, Nova Scotia) that is representative of coastal environments in eastern Canada and other parts of the world. The numerical model results indicate that PFAS released in the presence of strong winds and waves during a storm will travel up to 31 km in 2 days, approximately 40% farther than PFAS release during a time period dominated by tidal currents with light winds and small waves (1 m). After a 10 day simulation, PFAS levels from release sites in the Inner Harbour were higher (40-60 μg/L) compared to PFAS levels from the Outer Harbour release site which had decreased to low levels (1 μg/L) during a non-storm period. Along shorelines within the Harbour, PFAS concentrations remained elevated after 12 h (40-500 μg/L) and 48 h (2-300 μg/L). These concentrations are within the range of PFAS guidance values for recreational water use. The methods described here are relevant to studies of PFAS dispersion and transport in other coastal areas, and could be used to determine best practices for applications of AFFF in the coastal environment.

The discharge from food production greenhouses (greenhouse effluent) contains high nutrient and salt concentrations, which, if directly released, can have adverse effects on the environment. Wood-chip bioreactors are increasingly popular passive water treatment systems favoured for their economical denitrification in treating agricultural field tile drainage. Microbial communities are central to denitrification; however little is known about the maturation of microbial communities in wood-chip bioreactors treating greenhouse effluents. In this study, multiple subsurface flow wood-chip bioreactors, each vegetated with a different plant species, together with an unplanted unit, received synthetic greenhouse effluent with elevated nitrate concentrations. The hybrid bioreactors were operated for over 2 years, during which time water samples were collected from the inlet, outlet and within the reactors. The increasing denitrification rate in the bioreactor planted with Typha angustifolia (narrowleaf cattail) correlated with increasing microbial activity and metabolic richness, measured by the carbon utilization patterns in Biolog® EcoPlates. Increased denitrifying gene (nirS) copies (determined by quantitative polymerase chain reaction, qPCR), and near-complete nitrate removal were observed in the T. angustifolia and unplanted reactors after 16 and 23 months of operation respectively. The findings suggested that an acclimation period of at least one year can be expected in unseeded bioreactors planted with T. angustifolia, while bioreactors without vegetation may require a longer time to maximize their denitrification capacity. These results are important for the design and operation of wood-chip bioreactors, which are expected to be more commonly applied in the future.

The recent commercialisation of antimicrobial textiles has resulted in concern regarding the incidental release of silver nanomaterials (Ag-NMs) to the environment. To date, studies have measured Ag-NMs released from unworn textiles under simulated conditions, but little is known of Ag-NMs released under actual wearing conditions. Our experiments were conducted for three cycles of wearing and washing, where the textiles (socks) were worn for a similar distance under walking or running scenarios. The effect of wearing was assessed through characterization of both the fibres and the Ag-NMs released into the wash water. Ag released into the wash water was ∼2–3× higher for the running and walking trial respectively compared to the unworn control during the 1st cycle. Silver releases in the 2nd and 3rd cycles were similar for the walking trial and the unworn control, but lower for the running trial. A 29% decrease in silver content was observed on the socks used for walking after the 3rd cycle. Silver in the wash water was mainly particulates (≥92%; particles >1–2 nm) and wearing created a higher number of smaller sized particles (∼50 to 100 nm). Imaging of the Ag-NMs revealed that 54% of the particles surveyed were micrometer size silver sheet-like structures, but with an estimated thickness of only 67 ± 56 nm. This data set can serve as a reference for the development of artificial wearing methodologies into the future. The Ag-NM sheet-like structures identified here require further study as their fate, transport and toxicological properties will be different to those of their pristine and/or spherical counterparts.

Nanotoxicology research commonly utilizes pristine nanomaterials for toxicity assessment, which may not be perfectly representative of what is released into environmental systems. The goal of the present study was to develop a method to simulate human weathering of silver-containing textiles. To achieve this goal the roles of physical and chemical stress on X-Static® containing athletic textiles were investigated and compared to data collected from human weathering experiments and literature. Chemical weathering methods (artificial sweat) were used independently and alongside physical weathering methods (3D printed stretching and abrasion instruments). Non-weathered control textiles were found to release 29 ± 11 mg Ag/kg of textile into wash water effluent (ICP-MS), with 16% being released as ionic silver (ICP-MS) and the rest as metallic nanomaterials, nanosheets, and particulates of varying size (SEM/XANES). Real and simulated human weathered textiles released similar amounts of total silver (67 ± 11 mg Ag/kg, 84 ± 13 mg Ag/kg respectively) with the silver released being composed of ionic (1.5%, 2%) and a mixture of metallic and chlorinated nanomaterials, nanosheets, and particulates. The method was shown to effectively detach environmentally representative silver materials from silver-containing textiles and can provide such materials for future studies on the assessment of their fate, transport, and toxicity.

This study explored smoldering combustion for remediating polyfluoroalkyl substance (PFAS)-impacted granular activated carbon (GAC) and PFAS-contaminated soil. GAC, both fresh and PFAS-loaded, was employed as the supplemental fuel supporting smoldering in mixtures with sand (≈175 mg PFAS/kg GAC-sand), with PFAS-spiked, laboratory-constructed soil (≈4 mg PFAS/kg soil), and with a PFAS-impacted field soil (≈0.2 mg PFAS/kg soil). The fate of PFAS and fluorine was quantified with soil and emission analyses, including targeted PFAS and suspect screening as well as hydrogen fluoride and total fluorine. Results demonstrated that exceeding 35 g GAC/kg soil resulted in self-sustained smoldering with temperatures exceeding 900 °C. Post-treatment PFAS concentrations of the treated soil were near (2 experiments) or below (7 experiments) detection limits (0.0004 mg/kg). Further, 44% of the initial PFAS on GAC underwent full destruction, compared to 16% of the PFAS on soil. Less than 1% of the initial PFAS contamination on GAC or soil was emitted as PFAS in the quantifiable analytical suite. Results suggest that the rest were emitted as altered, shorter-chain PFAS and volatile fluorinated compounds, which were scrubbed effectively with GAC. Total organic fluorine analysis proved useful for PFAS-loaded GAC in sand; however, analyzing soils suffered from interference from non-PFAS. Overall, this study demonstrated that smoldering has significant potential as an effective remediation technique for PFAS-impacted soils and PFAS-laden GAC.

The factors controlling per- and polyfluoroalkyl substances (PFAS) environmental fate remains the subject of considerable debate and study. As surfactants, PFAS readily partition to interfaces, a property that controls their transport and fate. A group contribution model is developed to predict the extent to which PFAS partitions to the air-water interface. Langmuir adsorption and Szyszkowski equation parameters were fitted to literature air-water surface tension data for a range of PFAS and conventional hydrocarbon surfactants. This approach enabled the prediction of the impact of the hydrophilic head group, and other molecular components, on PFAS interfacial partitioning in instances when PFAS data are unavailable but analogous hydrocarbon surfactant data are available. The model was extended to predict a range of parameters (i.e., solubility, critical micelle concentration (CMC), KD, Koc and Kow) that are used to predict PFAS environmental fate, including long-range PFAS transport and in multimedia models. Model predictions were consistent with laboratory and field derived parameters reported in the literature. Additionally, the proposed model can predict the impact of pH and speciation on the extent of PFAS interfacial partitioning, a potentially important feature for understanding the behaviors of some ionizable PFAS, such as fluorinated carboxylic acids. The proposed model provides a conceptually straightforward method to predict a wide range of environmental fate parameters for a wide range of PFAS. As such, the model is a powerful tool that can be used to determine parameters needed to predict PFAS environmental fate.

Per- and polyfluoroalkyl substances (PFAS) are manmade, fluorinated organic chemicals which have been identified as persistent organic pollutants. PFAS have surface active properties that have made them suitable for applications in oil- and water-resistant products, as well as many firefighting foams. No on-site remediation strategies exist to treat PFAS impacted soils. Mechanochemical remediation of PFOS- and PFOA-amended sand via a planetary ball mill was studied. The effect of sand mass, KOH as a co-milling reagent, and water saturation on the degradation of PFOA and PFOS was evaluated. By 4 h of milling concentrations were reduced by up to 98% for PFOS-amended dry sand and 99% for PFOA-amended dry sand without the addition of a co-milling reagent. Water saturation was determined to be a significant hindrance on the mechanochemical destruction of PFOS and PFOA. A maximum of 89% of fluoride was recovered from PFOS-amended sand when KOH was used as a co-milling reagent. It is hypothesized that reactive particles generated from the fracture of sand grains react with PFAS molecules to initiate destruction, which can result in full defluorination. Milling experiments were also conducted on soils from a Canadian firefighting training area (FFTA), demonstrating that PFOS concentrations can be reduced by up to 96% in site soils. For the first time, ball milling for the remediation of PFAS in environmental media has been demonstrated using amended sand and legacy soils from a FFTA.

Assessing the extent to which emerging contaminants (ECs) such as perfluoroalkyl and polyfluoroalkyl substances (PFAS) have been released into the environment is one of the foundations for developing effective management and remediation strategies for impacted sites. PFAS are known to have caused the contamination of soil, groundwater, and surface water as a result of aqueous film forming foam (AFFF) being accidentally or intentionally released into the environment. To date, the scope of the issue has not been evaluated in Canada. In this study we developed a framework, in the form of a decision tree, to estimate the number of potentially PFAS impacted airport sites in Canada as a result of AFFF releases. The screening process was completed using publicly available resources including airport websites, the Canadian Owners and Pilots Association website, Sky Vector, Transport Safety Board of Canada aviation investigation reports, the Aviation Safety Network website, and Google maps. The methodology presented in this study could be used to identify additional PFAS impacted sites in Canada or other jurisdictions worldwide. 2071 airport/heliport sites in Canada were investigated with indications that 152 (7%) of these sites likely have PFAS contamination as a result of the use of AFFF at firefighter training areas (FFTAs) and/or accidents where fires occurred. In addition, another 268 sites (13%) were identified as possibly impacted with PFASs primarily as a result of the location having the ability to store and dispense petroleum products, and therefore having AFFF systems onsite. Surficial geology was also identified for all sites determined to likely have PFAS contamination. An estimated 42.8% had surficial geology composed of sand, 27% had clay, 19.7% organic-based, with the remaining sites found on cryosols or rock. Methodological validation was also completed. The procedure used in this study successfully predicted occurrences of PFAS contamination at 25 sites where contamination, as a result of AFFF use, was confirmed by Canadian governmental departments. For these 25 sites, the distance from potential release areas to the nearest surface water was calculated. Five of the sites were within 200 meters of surface water, 19 were within one kilometer, and all 25 were within 2.5 kilometers. This suggests that surface water may have been historically impacted by PFAS at as many as 152 to 420 different airport locations in Canada.

Analysis of water table fluctuations can provide important insight into the hydraulic properties and structure of a coastal aquifer system including the connectivity between the aquifer and ocean. This study presents an improved approach for characterizing a permeable heterogeneous coastal aquifer system through analysis of the propagation of the tidal signal, as well as offshore storm pulse signals through a coastal aquifer. Offshore storms produce high wave activity, but are not necessarily linked to significant onshore precipitation. In this study, we focused on offshore storm events during which no onshore precipitation occurred. Extensive groundwater level data collected on a sand barrier island (Sable Island, NS, Canada) show nonuniform discontinuous propagation of the tide and offshore storm pulse signals through the aquifer with isolated inland areas showing enhanced response to both oceanic forcing signals. Propagation analysis suggests that isolated inland water table fluctuations may be caused by localized leakage from a confined aquifer that is connected to the ocean offshore but within the wave setup zone. Two-dimensional groundwater flow simulations were conducted to test the leaky confined-unconfined aquifer conceptualization and to identify the effect of key parameters on tidal signal propagation in leaky confined-unconfined coastal aquifers. This study illustrates that analysis of offshore storm signal propagation, in addition to tidal signal propagation, provides a valuable and low resource approach for large-scale characterization of permeable heterogeneous coastal aquifers. Such an approach is needed for the effective management of coastal environments where water resources are threatened by human activities and the changing climate.

Bioremediation through the injection of electron donors and bacterial cultures is effective at treating chlorinated solvent contamination. However, it has had limited application in low permeability zones where amendments cannot be delivered successfully. This field-scale study investigated the application of electrokinetics to enhance the delivery of lactate at a clay site contaminated with chlorinated solvents. Groundwater and soil samples were collected before, during and for 1 year after the 71-day field test and analyzed for a wide suite of chemical and biological parameters. Lactate was successfully delivered to all monitoring locations. Lactate emplacement resulted in the stimulation of bacterial populations, specifically within the phylum Firmicutes, which contains fermenters and strict anaerobes. This likely led to biodegradation, as the field trial resulted in significant decreases in both soil and aqueous phase chlorinated solvent concentrations. Contaminant decreases were also partially attributable to dilution, given evidence of some advective lactate flux. This research provides evidence that electrokinetically-enhanced bioremediation has potential as a treatment strategy for contaminated low permeability strata.

The objective of this research was to study the differences in microbial community metabolic function in planted and unplanted saturated constructed wetland mesocosm systems with five different wetland plant species, Typha latifolia, Phragmites australis, Iris pseudacorus, Berula erecta and Juncus effusus treating the pesticides imazalil and tebuconazole. Community level physiological profiling (CLPP) was used to determine the microbial community metabolic function from each mesocosm. Microbial activity and metabolic richness were in general not differentiated by pesticides presence. Significantly lower values in comparison with a non-pesticide control were only found in the Iris mesocosms exposed to imazalil and tebuconazole and in the Berula mesocosms exposed to tebuconazole during winter. Planted mesocosms had different microbial community carbon source utilization patterns in comparison to the unplanted mesocosms. In comparison to pesticide presence, plant species had a larger effect on differentiating the microbial community carbon source utilization patterns. Seasonal effects on carbon source utilization patterns were observed for both planted and unplanted mesocosms. In summer, microbial activity and metabolic richness were negatively correlated with TN, NH4+-N, TP concentration and pH in the control group, but not in the pesticide treatment groups, again suggesting a microbial community functional shift in the presence of pesticides. The main factors driving microbial community activity and functional diversity were plant species and season, while carbon source utilization revealed some pesticide adaptation in the summer period.

Combined sewer overflows are contaminated with various micropollutants which pose risk to both environmental and human health. Some micropollutants, such as carbamazepine and sulfamethoxazole, are very persistent and difficult to remove from wastewater. Event loaded vertical-flow constructed wetlands (retention soil filters; RSFs) have proven to be effective in the treatment of combined sewer overflows for a wide range of pollutants. However, little is known about how microbial communities contribute to the treatment efficiency, specifically to the reduction of micropollutants. To the best of our knowledge, this is the first study attempting to close this gap. Microbial communities in pilot-scale RSFs were investigated, which showed explicit grouping of metabolic activity at different filter depths with some differential abundance of identified genera. The highest microbial activity was found in the top layer of 0.75 m deep filters, whereas homogeneous activity dominated in a 0.50 m deep filter, indicating oxygen availability to be a limiting factor of the metabolic activity in RSFs. The removal efficiencies of all investigated organic trace substances were correlated to the utilization of specific carbon sources. Most notable is the correlation between the carbon source glucose-1-phosphate and the removal of metoprolol. The strongest correlations for other substances were the removal of diclofenac to the utilization of the carbohydrate i-erythritole; bisphenol A to carbohydrate α- d -lactose, and 1-H-benzotriazole to carbonic acid D-galacturonic acid. Those results are supported by positive correlations of specific microbial genera with both the utilization of the above mentioned carbon sources and the removal efficiency for the respective micropollutants. Most notable is correlation of Tetrasphaera and the removal of benzotriazole and diclofenac.

Silver nanoparticles (AgNPs) are increasingly used as an antimicrobial agent in various consumer products. Silver release from these products occurs during use, washing and disposal at varying rates, into the wastewater system and eventually into aquatic ecosystems. Constructed wetlands (wetlands designed for water pollution control) represent a unique type of water treatment system which are beginning to receive growing amounts of influent AgNP loadings. In order to examine potential impacts to the health and ongoing utility of constructed wetlands we evaluated the susceptibility and the developed resistence of constructed wetland microbial communities to two types of AgNPs (citrate and polyvinylpyrrolidone (PVP)-coated), and ionic Ag (Ag+). Microcosms representing an unplanted batch-fed subsurface flow constructed wetland were exposed to an AgNP contaminated (100 mu g/l) simulated wastewater for 28 days. Experiments were triplicated and included unexposed controls. Analysis of total Ag in the interstitial water and biofilm matrix via inductively coupled plasma mass-spectrometry (ICP-MS) revealed the majority (>98%) of AgNPs partitioned from the interstitial water and accumulated in the biofilm and presumably the sediment matrix. No significant alteration to the microbial community function (assessed via community-level physiological profiling, CLPP) or structure (using denaturing gradient gel electrophoresis, DGGE) was observed following the initial 28 day exposure. Subsequent ex-situ dose-response testing over a wide concentration range (0-5 mu g/l) provided some evidence for increased resistance to Ag toxicity in the previously exposed microbial communities when compared to the controls. The ex-situ evaluated susceptibility of the microbial communities to AgNPs varied between treatments with significant reductions in catabolic activity observed at 0.5 mg/l for ionic Ag, 1 mg/l for citrate coated AgNPs and 5 mg/l for PVP coated AgNPs. These findings suggest that wetland microbial communities can tolerate and develop resistance to lower levels of in-situ AgNP exposure in a relatively short time, however ex-situ toxicity is observed past certain threshold concentrations and this threshold varies depending on the original form of the AgNP. (C) 2016 Elsevier B.V. All rights reserved. This work was financially supported by the Erasmus Mundus programme IMETE (Ghent University, Belgium) and COST action ES1205. The authors thank Nico Boon for access to the Laboratory of Microbial Ecology and Technology (LabMET) and for fruitful discussions. Support from NSERC in the form of a Discovery and an SPG grant to KPW is gratefully acknowledged. We would also like to thank Tim Lacoere for his help with the molecular techniques, Xiao Yi for help with CLPP and Quenten Denon for the assistance with the PCS analysis.

Both the presence and diversity of plants are integral to the development and functional abilities of microbial communities within constructed wetlands (CWs). The aim of this study was to assess the impacts of different individual and paired plant species combinations on microbial community function in HSSF mesocosm CWs. Experimental systems were quadruplicated and operated as two mesocosms in series planted with Phragmites australis (X) or Phalaris arundinacea (O), giving four possible sequential combinations (XX, XO, OX, OO). Wastewater was loaded each day into position 1 mesocosm with the outflow entering position 2 mesocosm, and the corresponding position 2 mesocosm outflow representing an overall experimental system effluent. The metabolic function of the interstitial-based microbial communities within each of the 16 mesocosm pairs was assessed at a single time point in the spring (May) based on community-level physiological profiles (CLPPs) gathered using Biolog ® EcoPlates. Microbial activity and metabolic richness (number of carbon sources utilised) were found to be higher in position 1 mesocosms compared to position two. Microbial community carbon source utilisation patterns (CSUPs), overall activity and metabolic richness were similar between all mesocosms from position 1—irrespective of plant species. When assessing microbial communities in position 2 of each pairing a greater variety of CSUPs, activities and metabolic richness' could be found suggesting the sequence and choice of plant can alter the microbial community function in the HSSF mesocosms. Of particular interest were the mesocosm/plant species combinations containing Phalaris in the position 2 which led to higher overall microbial activity and richness, distinct carbon source utilisation patterns (CSUPs) and an increased utilisation of specific carbon sources further from the inlet. More specifically the XO pairings ( Phragmites-Phalaris ) seemed to offer the most promising overall microbial function throughout both positions 1 and 2 in series suggesting plant diversity may help enhance microbial community function, and therefore microbial based water treatment capacity. The findings also suggest that the microbial communities associated with each plant species respond differently to factors such as nutrient availability, and although not yet clearly defined, further highlights the potential for improved or tailored water treatment in CWs through selection of specific plant species and combinations. Broader microbial community function or greater activity did not correlate with improved water treatment efficiency in this study. This may have been due to the relatively low contaminant loads utilised, or the limited amount of data collected. Further study across several seasons or with higher contaminant loads is recommended.

We collected over 40 groundwater samples from a per- and polyfluoroalkyl substances (PFAS) impacted legacy fire fighting training area in Canada to develop an in-depth assessment of the relationship between PFAS and in situ microbial communities. Results suggest differential transport of PFAS of differing chain-length and head group. There is also evidence of PFAS degradation, in particular 6:2 FTS degradation. Although PFAS constituents were not major drivers of microbial community structure, the relative abundance of over one hundred individual genera were significantly associated with PFAS chemistry. For example, lineages within the Oxalobacteraceae family had strong negative correlations with PFAS, whilst the Desulfococcus genus has strong positive correlations. Results also suggest a range of genera may have been stimulated at low to mid-range concentrations (e.g., Gordonia and Acidimicrobium), with some genera potentially inhibited at high PFAS concentrations. Any correlations identified need to be further investigated to determine the underlying reasons for observed associations as this is an open field site with the potential for many confounding factors. Positive correlations may ultimately provide important insights related to development of biodegradation technologies for PFAS impacted sites, while negative correlations further improve our understanding of the potential negative effects of PFAS on ecosystem health.

The impacts to microbial function, overall performance and eventual fate were assessed for triclosan (TCL) and sulfamethoxazole (SMX) in intensified (re-circulating) vertical subsurface flow (VSSF) constructed wetlands (CWs). The potential toxicity of each pharmaceutical to the intrinsic microbial communities was first assessed over a wide exposure range (0–1000 μg/l) via an ex-situ dose-response assay to estimate the concentration at which adverse effects were likely to occur. Based on these results an acute (7 day) in-situ exposures (500 μg/l) were then performed and impacts to the mesocosm systems monitored for 1 month via community-level physiological profiling (CLPP) alongside chemical oxygen demand (COD) removal rates and a range of water quality, and hydrological parameters. Despite the clear potential for negative impacts to microbial function from both compounds observed at 100 μg/l in the ex-situ dose-response test, no impacts were observed for the 500 μg/l in-situ exposure in the VSSF mesocosms. COD removal, water chemistry, plant health, and hydrological parameters did not significantly change in response to the in-situ exposure. In terms of fate, the removal efficiency for both TCL and SMX was high (>80%) after 1 h and complete removal (>99.7%) was observed after 168 h. Following the in-situ exposure, and subsequent one month effects-monitoring period, the mesocosms were decommissioned with the media biofilm spatially assessed for organic content as well as TCL and SMX concentrations. TCL and SMX were found to have persisted in the media and demonstrated spatial variation with an overall 2–20% and 5–6% recovered respectively. This suggests that biofilm bound TCL and SMX were biologically degraded in VSSF CWs, however may also accumulate in the biofilm if TCL and SMX are maintained in the influent. These results reinforce the robustness and potential of constructed wetlands for the treatment of pharmaceutical and personal care product (PPCP) contaminated wastewater.

Community-level physiological profiling (CLPP) using BIOLOG® EcoPlates™ has become a popular method for characterizing and comparing the functional diversity, functional potential, and metabolic activity of heterotrophic microbial communities. The method was originally developed for profiling soil communities; however, its usage has expanded into the fields of ecotoxicology, agronomy, and the monitoring and profiling of microbial communities in various wastewater treatment systems, including constructed wetlands for water pollution control. When performing CLPP on aqueous samples from constructed wetlands, a wide variety of sample characteristics can be encountered and challenges may arise due to excessive solids, color, or turbidity. The aim of this study was to investigate the impacts of different sample preparation methods on CLPP performed on a variety of aqueous samples covering a broad range of physical and chemical characteristics. The results show that using filter paper, centrifugation, or settling helped clarify samples for subsequent CLPP analysis, however did not do so as effectively as dilution for the darkest samples. Dilution was able to provide suitable clarity for the darkest samples; however, 100-fold dilution significantly affected the carbon source utilization patterns (CSUPs), particularly with samples that were already partially or fully clear. Ten-fold dilution also had some effect on the CSUPs of samples which were originally clear; however, the effect was minimal. Based on these findings, for this specific set of samples, a 10-fold dilution provided a good balance between ease of use, sufficient clarity (for dark samples), and limited effect on CSUPs. The process and findings outlined here can hopefully serve future studies looking to utilize CLPP for functional analysis of microbial communities and also assist in comparing data from studies where different sample preparation methods were utilized.

Microorganisms are central to the biogeochemical processes in constructed treatment wetlands. In this study we explored the spatial dynamics of microbial community metabolic function in several different constructed treatment wetland designs at the pilot-scale constructed wetlands of the UFZ Ecotechnology Research Facility in Langenreichenbach, Germany. The constructed wetland designs differed in terms of flow direction, degree of saturation, depth, and intensification. Internal sampling was conducted in April 2013 at different locations along the flow path of each system. The microbial community metabolic function was characterized via community level physiological profiling (CLPP). Microbial community activity (substrate utilization rate) and metabolic richness (number of carbon sources utilize) decreased dramatically with increasing distance along the flow path for most systems. Variation in the metabolic function of microbial communities was observed based on carbon source utilization patterns (CSUPs) and was found to be strongly influenced by system design and sample location within the wetland but not by the presence of plants or depth of media. Analysis of specific carbon source guilds highlighted increased utilization of polymers and carbohydrates in the early stages of all systems, pointing to the establishment of microbial communities optimized to best utilize more easily degradable compounds close to the inlet. Correlations between measures of microbial functionality (activity, richness, and diversity) and turbidity, total organic carbon (TOC), total nitrogen (TN) were observed in horizontal-flow systems but less so in vertical-flow systems. The results presented provide useful insight into the spatial dynamics of microbial community function in constructed wetlands. Potential opportunities for system optimization, based on the results of this study, are provided.

A robust computational fluid dynamics (CFD) model accounting for both spatial and temporal dynamics of a subsurface vertical flow treatment wetland system was developed by combining fluid transport, solute transport, biokinetics, biofilm development, and biofilm detachment/sloughing using COMSOL Multiphysics™. The local porosity of the porous media was calculated based on the estimated biofilm development over time. The biofilm development sub-model considered both organic pollutant metabolism/degradation as a mechanism for microbial growth and the effect of fluid shear stress on the local biofilm detachment. The influence of biofilm accumulation on the permeability of the porous media was considered using the Kozeney–Carman relation. The permeability of the porous media was estimated by calibrating the model against experimental tracer data that had been collected in a full water-recirculation batch operation. As the biofilm developed from start-up, removal efficiency of readily biodegradable organic matter improved during the first 10 weeks of operation while no significant change was predicted after 10 weeks. A dead-zone region was predicted near the bottom of the system opposite to the outflow port after 100 days of operation attributed to exponential biofilm growth and low biofilm detachment rates. A decrease of 95% in the advective transport of organic matter in the dead-zone region occurred after 280 days of operation. No appreciable biofilm accumulation was predicted in the region near the outlet due to the high fluid shear stress acting on the biofilm surface. The averaged porosity of the mesocosm decreased by 6.6% after 365 days of operation while the local porosity in the dead-zone region decreased by 71%. Good agreement was found between the averaged porosity of the entire system and experimental data. This is the first model to integrate hydrodynamics, solute transport, biokinetics relating to pollutant removal, biofilm development, and biofilm detachment into a comprehensive model. Although computationally intensive, this is the first model to predict bio-clogging processes in a spatial manner similar to what would be realistically expected.

Microbial degradation is an important pathway during the removal of pharmaceuticals in constructed wetlands (CWs). However, the effects of CW design, plant presence, and different plant species on the microbial community in CWs have not been fully explored. This study aims to investigate the microbial community metabolic function of different types of CWs used to treat ibuprofen via community-level physiological profiling (CLPP) analysis. We studied the interactions between three CW designs (unsaturated, saturated and aerated) and six types of mesocosms (one unplanted and five planted, with Juncus, Typha, Berula, Phragmites and Iris) treating synthetic wastewater. Results show that the microbial activity and metabolic richness found in the interstitial water and biofilm of the unsaturated designs were lower than those of the saturated and aerated designs. Compared to other CW designs, the aerated mesocosms had the highest microbial activity and metabolic richness in the interstitial water, but similar levels of biofilm microbial activity and metabolic richness to the saturated mesocosms. In all three designs, biofilm microbial metabolic richness was significantly higher (p

This chapter summarizes the methods used within the MODUM project for monitoring chemical munition dumpsites. It includes general introduction to monitoring process, listing the requirements that are a basis for the establishment of full scale monitoring programme. It describes survey procedures, for locating dumped munitions, Sampling and analytical procedures for the detection of Chemical Warfare Agents, as well as the usage of fish as bioindicators are described. Modelling of pollutants originating from dumped munitions is presented and discussed. Only methods, which were proven to be most effective within the MODUM projects were selected, also data interpretation methods providing coherent information regarding the environmental risk are explained in details.

The objective of this study was to investigate if the catabolic capabilities (the overall ability to utilize a wide range of carbon sources) and catabolic profiles (the overall pattern of carbon source usage based on the carbon source types and relative usage extent) of microbial communities in free-floating plant treatment wetlands differ based on the presence or combination of different plant species. Free Floating-plant treatment wetland mesocosms were established using four different plant species: Limnobium laevigatum (L), Salvinia molesta (S), Eichhornia crassipes (E), and Pistia stratiotes (P). Mesocosms were either arranged as a monoculture (one plant species), biculture (two different plant species; all possible pairings), or quadricultures (one of each plant species). Mesocosms were fed twice weekly with 20 L of reconstituted wastewater using diluted fish farm sludge effluent. The microbial communities in each mesocosm were assessed after a 4 month operational period using the community level physiological profiling (CLPP) method. It was observed that monoculture wetland systems had different catabolic activities and catabolic richness’ (number of carbon sources utilized) with the following respective trends: (L) > (P) = (S) > (E) and (L) > (E) = (P) > (S). It was also found that the carbon source utilization patterns of the microbial communities from the monoculture mesocosms were distinctly different from each other, and that the polyculture communities were different from the respective monoculture counterparts. These findings further support the hypothesis that plant type and combination plays a critical role in the development of the microbial communities present in treatment wetlands. It was also found that increasing the number of plant species did not, on average, promote the development of microbial communities with a more active and diverse catabolic capability, but rather specific plant selection and plant/plant interactions were important. In comparison to the other plant species E. crassipes had the largest amount of root mass available for microbial community attachment. Observations suggested that this larger root mass translated into E. crassipes having a dominating effect on defining the carbon source utilization patterns of microbial communities from polyculture mesocosms. Although microbial communities from the monoculture mesocosms containing E. crassipes had the lowest activities (on a per unit volume basis), E. crassipes mesocosms generally had the best COD removal rates in either monoculture or polyculture systems, potentially because of the greater amount of root mass available.

Nanoscale zerovalent iron (nZVI) particles were injected into a contaminated sandy subsurface area in Sarnia, Ontario. The nZVI was synthesized on site, creating a slurry of 1 g/L nanoparticles using the chemical precipitation method with sodium borohydride (NaBH4) as the reductant in the presence of 0.8% wt. sodium carboxymethylcellulose (CMC) polymer to form a stable suspension. Individual nZVI particles formed during synthesis had a transmission electron microscopy (TEM) quantified particle size of 86.0 nm and dynamic light scattering (DLS) quantified hydrodynamic diameter for the CMC and nZVI of 624.8 nm. The nZVI was delivered to the subsurface via gravity injection. Peak normalized total Fe breakthrough of 71% was observed 1m from the injection well and remained above 50% for the 24 h injection period. Samples collected from a monitoring well 1 m from the injection contained nanoparticles with TEM-measured particle diameter of 80.2 nm and hydrodynamic diameter of 562.9 nm. No morphological changes were discernible between the injected nanoparticles and nanoparticles recovered from the monitoring well. Energy dispersive X-ray spectroscopy (EDS) was used to confirm the elemental composition of the iron nanoparticles sampled from the downstream monitoring well, verifying the successful transport of nZVI particles. This study suggests that CMC stabilized nZVI can be transported at least 1 m to the contaminated source zone at significant Fe(0) concentrations for reaction with target contaminants.

The effect of gold nanoparticles (AuNPs) and ciprofloxacin on the catabolism of microbial communities was assessed. This was accomplished through an ex situ methodology designed to give a priori knowledge on the potential for nanoparticles, or other emerging contaminants, to affect the catabolic capabilities of microbial communities in the environment. Microbial communities from a variety of sources were incubated with 31 prespecified carbon sources and either National Institute of Standards and Technology reference material 10-nm AuNPs or ciprofloxacin on 96-well microtiter plates. From the ciprofloxacin study, dose−response curves were generated and exemplified how this method can be used to assess the effect of a toxicant on overall catabolic capabilities of microbial communities. With 10-nm AuNPs at concentrations ranging from 0.01 µg/mL to 0.5 µg/mL, rhizosphere communities from Typha roots were only slightly catabolically inhibited at a single concentration (0.05 µg/mL); no effects were seen on wetland water communities, and a minor positive (i.e., enhanced catabolic capabilities) effect was observed for loamy soil communities. This positive effect might have been because of a thin layer of citrate found on these AuNPs that initiated cometabolism with some of the carbon sources studied. Under the conditions considered, the possible adverse effects of AuNPs on the catabolic capabilities of microbial communities appears to be minimal. Environ Toxicol Chem 2013;33:44–51. © 2013 SETAC

Microbial communities play a vital role in maintaining soil health. A multiphasic approach to assess the effect of pulp and paper mill effluent on both the structure and function of microbial soil communities is taken. Bacterial communities from agricultural soils irrigated with pulp and paper mill effluent were compared to communities form soils irrigated with well water. Samples were taken from fields in the state of Uttarakhand, India, where pulp and paper mill effluent has been used for irrigation for over 25 years. Comparisons of bacterial community structure were conducted using sequencing of the 16S rRNA gene from both isolates and clone libraries attained from the soil. Community-level physiological profiling was used to characterize the functional diversity and catabolic profile of the bacterial communities. The multiphasic approach using both physiological and molecular techniques proved to be a powerful tool in evaluating the soil bacterial community population and population differences therein. A significant and consistent difference in the population structure and function was found for the bacterial communities from soil irrigated with effluent in comparison to fields irrigated with well water. The diversity index parameters indicated that the microbial community in pulp and paper mill effluent irrigated fields were more diverse in both structure and function. This suggests that the pulp and paper mill effluent is not having a negative effect on the soil microbial community, but in fact may have a positive influence. In terms of soil health, this finding supports the continued use of pulp and paper mill effluent for irrigation. This is however only one aspect of soil health which was evaluated. Further studies on soil resistance and robustness could be undertaken to holistically evaluate soil health in this situation.

Microbial communities play a critical role in degrading organic contaminants in treatment wetlands; however, an understanding of the different roles played by rhizospheric, gravel-associated and interstitial microbial communities is deficient due to a lack of data directly comparing these microbial communities. Community level physiological profiling (CLPP) was used to compare the catabolic capabilities of rhizospheric, gravel-associated and interstitial microbial communities in vertical-flow planted and unplanted wetland mesocosms. Wetland mesocosms were decommissioned to gather microbial community samples associated with the roots and gravel bed media taken from the top (10 cm depth), middle (30 cm depth) and bottom (60 cm depth). The catabolic capabilities of the rhizospheric microbial communities were seen to be much greater than those of the gravel-associated communities. A decrease in catabolic capability was seen with increasing depth, suggesting that communities near the surface play a larger role in the degradation of carbon-based compounds. A general difference in catabolic profiles based on plant presence/absence was observed for the interstitial water and all gravel-associated samples at all depths, suggesting that the presence of roots within part of the mesocosm not only has a localized effect on the attached microbial population, but also on gravel-associated microbial communities throughout the mesocosms.

Nanoscale zerovalent iron (nZVI) is an emerging technology for the remediation of contaminated sites. However, there are concerns related to the impact of nZVI on in situ microbial communities. In this study, the microbial community composition at a contaminated site was monitored over two years following the injection of nZVI stabilized with carboxymethyl cellulose (nZVI-CMC). Enhanced dechlorination of chlorinated ethenes to nontoxic ethene was observed long after the expected nZVI oxidation. The abundance of Dehalococcoides (Dhc) and vinyl chloride reductase (vcrA) genes, monitored using qPCR, increased by over an order of magnitude in nZVI-CMC-impacted wells. The entire microbial community was tracked using 16S rRNA gene amplicon pyrosequencing. Following nZVI-CMC injection, a clear shift in microbial community was observed, with most notable increases in the dechlorinating genera Dehalococcoides and Dehalogenimonas. This study suggests that coupled abiotic degradation (i.e., from reaction with nZVI) and biotic degradation fueled by CMC led to the long-term degradation of chlorinated ethenes at this field site. Furthermore, nZVI-CMC addition stimulated dehalogenator growth (e.g., Dehalococcoides) and biotic degradation of chlorinated ethenes.

In this study, the effect of the antibiotic ciprofloxacin on the presentation and potential development of antibiotic resistance among selected faecal indicators (Escherichia coli and Enterococcus spp.) and the intrinsic bacterial community for a freshwater model ecosystem was investigated. Four parallel mesocosm wetlands planted with Phragmites australis were initially seeded with an activated sludge inoculum from a wastewater treatment plant and monitored over the course of 63 days. Two of the four mesocosms (CIP1 and CIP2) were initially exposed to a ciprofloxacin concentration of 2 μg mL−1 for a 5 day period, and two were considered controls (CON1 and CON2). Minimum inhibitory concentrations were determined for the culturable interstitial microbial community using ciprofloxacin concentrations ranging from 0.5 to 16 μg mL−1 and compared with total heterotrophic plate counts (HPCs). E. coli and Enterococcus spp. were enumerated and screened for antimicrobial resistance to twelve different antibiotics both before and after mesocosm ciprofloxacin exposure. Concentrations for total heterotrophs within the interstitial water were in the order of 106–108 CFU 100 mL−1, while E. coli and Enterococcus spp. were present in lower concentrations, at 102–103 CFU 100 mL−1. All four mesocosms had the same minimum inhibitory concentrations (MICs) of 2 μg mL−1 for total heterotrophic community during the first week of start-up (before ciprofloxacin exposure), followed by a sharp increase in ciprofloxacin exposed mesocosms on day 14 (after ciprofloxacin exposure), reaching a maximum MIC of 16 μg mL−1. The resistance levels of interstitial heterotrophic counts determined by the agar dilution method peaked 7 days following the ciprofloxacin exposure, and decreased thereafter. A significant increase (p < 0.05) to the following antibiotics was observed among E. coli following ciprofloxacin exposure within mesocosm CIP2: ciprofloxacin (CIP), chloramphenicol (C), cefotaxime (CTX), ceftriaxone (CRO), and doxycycline (D). These results illustrate the potential for a single antibiotic exposure event to create a noticeable increase in the antibiotic resistance profile, not only to the imposed antibiotic, but to other classes of antibiotics. The initial background levels of resistance among Enterococcus spp. were significantly higher than those observed among E. coli, exhibiting a combined average of 96%, 96%, and 100% resistance to ciprofloxacin (CIP), linezolid (LZD), and streptomycin (S), respectively. Following the addition of ciprofloxacin, Enterococcus spp. retained high levels of resistance to ciprofloxacin, linezolid, and streptomycin, with a significant increase (p < 0.05) to vancomycin (VA), reaching 100% on Day 63. The findings of this study suggest that the transient presence of an isolated exposure event of ciprofloxacin can impact the antibiotic resistance profiles among faecal indicators in lab-scale constructed mesocosms and has the potential to impact constructed wetland treatment systems.

The objective of this work was to study the effect of plant presence ( Phragmites australis ) and inoculant origin on wetland mesocosm start-up dynamics. Eight mesocosms were studied based on a duplicated 2 2 factorial design tracking bacterial community and hydrological changes during an 8 month start-up period. The mesocosms were characterized in terms of their hydrological character based on evapotranspiration (ET), porosity, and a dispersion coefficient. The microbiological regime was characterized using a microbial activity measure and community-level physiological profiling (CLPP) employing BIOLOG™ ECO plates. CLPP-related indices such as substrate richness, substrate diversity, over-all community profile, and community divergence are also presented. It was found that mesocosm porosities decreased over time as a result of media-related biofilm development. This biofilm development also contributed to a substantial increase in the dispersion coefficient in the mesocosms over the start-up period. Dispersion coefficients in planted systems reached values of ∼50–55 cm 2 /min whereas in the unplanted systems values of ∼30–35 cm 2 /min were observed. Bacterial community divergence in the mesocosms was quantified using a Euclidean-based divergence metric. All mesocosms showed a sharp increase in community divergence until day 75, at which point a steady state was reached. The interstitial communities were also characterized in terms of similarity based on the experimental design treatments. Four stages of mesocosm development were identified that can be described by an initial community state based on the origins of the initial inoculum [days 0–6]; a dynamic period where adjustments and shifts in the bacterial community occurred in all mesocosms [days 7–26]; a period where all interstitial CLPPs were quite similar [days 27–73]; and finally a shift towards unplanted and planted mesocosm CLPP groupings [days 74–232].

The study of bacterial communities in microbially-mediated water treatment systems is becoming increasingly popular. Aquatic bacterial communities are often found in fixed-film environments, residing within a matrix of extracellular polymeric substances commonly referred to as a biofilm. A method for detaching the biofilm is required to either enumerate or characterize these bacterial communities. There are a variety of detachment methods including scraping, swabbing, shaking, sonication, blending, and digestion. The objective of this work was to develop an agitation-based protocol for detachment of culturable bacterial communities from the biofilm surrounding pea gravel from constructed wetland mesocosms. Three different protocol factors were systematically investigated using a triplicated 2(3) factorial design to determine the most effective detachment protocol. Factors studied included: the use of either tap water or phosphate buffer as the shaking/detachment solution; the use of either manual-shaking at room temperature or mechanical shaking at 30 degrees C; and the presence or absence of an enzyme cocktail consisting of lipase, beta-galactosidase and alpha-glucosidase. The resulting suspensions were evaluated for organics, inorganics, culturable bacteria, community level physiological profile (CLPP) and several BIOLOG ECO plate substrate related diversity indices. Using these metrics, the most effective shaking/detachment protocol was identified as mechanical shaking for 3h at 30 degrees C using a phosphate buffer with an enzyme cocktail.

Microbial communities certainly have an influence on the treatment performance of constructed wetlands (CWs); however, microbial community structure or microbial activity (MA) is rarely concurrently or comparatively quantified in relation to treatment performance. The objective of this study was to better understand the influence of the resident CW microbial community on water treatment performance in CWs. Using laboratory-scale mesocosm wetlands, several CW design variables and water chemistry variables were quantitatively and comparatively determined to assess their role in Fe(II) removal from simulated acid mine drainage (AMD). Initial AMD pH, initial AMD Fe(II) concentration, and overall wetland MA had a significant effect on an apparent first-order iron removal rate constant. Under the aerobic conditions used in this study, the presence of Phragmites australis did not have a significant effect on treatment performance. Of all the factors studied, the MA associated with the fixed microbial co...

BIOLOG® EcoPlates™ provide one method for determination of functional diversity indices and community-level physiological profiling of microbial populations based on carbon substrate utilization. In this study, the effect of data transformation on BIOLOG EcoPlate data derived from wetland mesocosms and biofiltration systems was examined. Homoscedasticity, normality, and the number of linear correlations between variables were quantified and evaluated for data that had been transformed using either Taylor or logarithmic transforms. Subsequent multivariate analysis was implemented using the untransformed, Taylor transformed and logarithmic transformed data sets. The effect of data transformation and its effect on principle component analysis are presented. The transforms are shown to help increase homogeneity of variance, increase normality of the data, and increase the number of significant linear correlations for the data. Separate principle component analyses and ordinations of the data showed the transforms to be well suited to this type of data and in particular illustrate the ability of the logarithmic transform to reduce the influence of high leverage or outlying observations on the overall analysis and its robustness in terms of treating data from different ecological systems. Although BIOLOG EcoPlates were used in this study to illustrate the use of transformations on multivariate data, the techniques described may be employed on similar microplate data. In addition, if homoscedasticity, normality and the number of linear correlations within a data set are not evaluated and the possibility of transforming the data, using the Taylor, logarithmic or another transform, is not considered, erroneous analysis and misleading conclusions may be attained when performing multivariate analysis on microplate data.

In aerated treatment wetlands, oxygen availability is not a limiting factor in sustaining a high level of nitrification in wastewater treatment. In the case of an air blower failure, nitrification would cease, potentially causing adverse effects to the nitrifying bacteria. A field trial was completed investigating nitrification loss when aeration is switched off, and the system recovery rate after the aeration is switched back on. Loss of dissolved oxygen was observed to be more rapid than loss of nitrification. Nitrate was observed in the effluent long after the aeration was switched off (48 h+). A complementary modeling study predicted nitrate diffusion out of biofilm over a 48 h period. After two weeks of no aeration in the established system, nitrification recovered within two days, whereas nitrification establishment in a new system was previously observed to require 20–45 days. These results suggest that once established resident nitrifying microbial communities are quite robust.

A pilot scale injection of nanoscale zerovalent iron (nZVI) stabilized with carboxymethyl cellulose (CMC) was performed at an active field site contaminated with a range of chlorinated volatile organic compounds (cVOC). The cVOC concentrations and microbial populations were monitored at the site before and after nZVI injection. The remedial injection successfully reduced parent compound concentrations on site. A period of abiotic degradation was followed by a period of enhanced biotic degradation. Results suggest that the nZVI/CMC injection created conditions that stimulated the native populations of organohalide-respiring microorganisms. The abundance of Dehalococcoides spp. immediately following the nZVI/CMC injection increased by 1 order of magnitude throughout the nZVI/CMC affected area relative to preinjection abundance. Distinctly higher cVOC degradation occurred as a result of the nZVI/CMC injection over a 3 week evaluation period when compared to control wells. This suggests that both abiotic and biotic degradation occurred following injection.

Nano-scale zero valent iron (nZVI) has been used at a number of contaminated sites over the last decade. At most of these sites, significant decreases in contaminant concentrations have resulted from the application of nZVI. However, limited work has been completed investigating nZVI field-scale mobility. In this study, a field test was combined with numerical modeling to examine nZVI reactivity along with transport properties in variably saturated soils. The field test consisted of 142L of carboxymethyle cellulose (CMC) stabilized monometallic nZVI synthesized onsite and injected into a variably saturated zone. Periodic groundwater samples were collected from the injection well, as well as, from two monitoring wells to analyze for chlorinated solvents and other geochemistry indicators. This study showed that CMC stabilized monometallic nZVI was able to decrease tricholorethene (TCE) concentrations in groundwater by more than 99% from the historical TCE concentrations. A three dimensional, three phase, finite difference numerical simulator, (CompSim) was used to further investigate nZVI and polymer transport at the variably saturated site. The model was able to accurately predict the field observed head data without parameter fitting. In addition, the numerical simulator estimated the mass of nZVI delivered to the saturated and unsaturated zones and distinguished the nZVI phase (i.e. aqueous or attached). The simulation results showed that the injected slurry migrated radially outward from the injection well, and therefore nZVI transport was governed by injection velocity and viscosity of the injected solution. A suite of sensitivity analyses was performed to investigate the impact of different injection scenarios (e.g. different volume and injection rate) on nZVI migration. Simulation results showed that injection of a higher nZVI volume delivered more iron particles at a given distance; however, the travel distance was not proportional to the increase in volume. Moreover, simulation results showed that using a 1D transport equation to simulate nZVI migration in the subsurface may overestimate the travel distance. This is because the 1D transport equation assumes a constant velocity while pore water velocity radially decreases from the well during injection. This study suggests that on-site synthesized nZVI particles are mobile in the subsurface and that a numerical simulator can be a valuable tool for optimal design of nZVI field applications.

The field of treatment wetlands (TWs) is rapidly expanding and, arguably, is tasked with studying and understanding one of the most complex water treatment systems available. Microbial communities are generally considered to be responsible for the majority of wastewater constituent degradation in TWs. However, they are also known to be spatially heterogeneous, temporally dynamic, as well as structurally and functionally diverse. Presented here is a meta-analysis of all peer reviewed TW journal articles which utilized a microbial community assessment methodology over the period of 1988 to July 2016. A total of 1101 papers were reviewed, 512 from 1988 to 2012, 215 of which included a microbial community assessment aspect and were subsequently classified as representing past research, and 589 from 2013 to July 2016, 196 of which were classified as representing current TW microbial community research. In general, TW microbial community research has increased over time, with a marked surge in the past four years. Microbial community structure is currently the most commonly used methodological type followed by activity, enumeration and function, respectively. Areas of research focus included nitrogen transformations (156), organic degradation (33), and emerging contaminants (32), with general characterization studies also accounting for a significant proportion (243). Microbial communities from a range of TW systems have been investigated over the last four years with meso-scale (10–1000 L) being the most commonly studied system size followed by large-scale (>100,000 L), micro-scale (

An understanding of how antibiotics and other "emerging contaminants" affect both water treatment systems and natural environments is of growing interest. Ciprofloxacin is a broad-spectrum antibiotic active against both Gram-positive and Gram-negative bacteria and has been extensively used over the past 20 years. The objective of this research was to study the effect of an antibiotic such as ciprofloxacin on the development, function and stability of bacterial communities in wetland systems. Four mesocosm wetlands planted with Phragmites australis were initially seeded with activated sludge from a waste water treatment plant and allowed to develop for a 1 week period, after which 2 of the 4 mesocosms were exposed to a ciprofloxacin concentration of 2 μg/mL for a 5 day period. The 4 mesocosms were then monitored for several microbiological and hydrological parameters over the course of 22 weeks. The bacterial community species distribution and catabolic capabilities were assessed via denaturing gradient gel electrophoresis (DGGE) and community level physiological profiling (CLPP), based on carbon utilization. DGGE results indicated that the ciprofloxacin decreased the total number of PCR-amplifiable DNA (bacteria) and the overall diversity of bacterial operational taxonomic units (OTUs). Through CLPP it was shown that the interstitial microbiological community was initially adversely affected by the ciprofloxacin, creating a temporary decrease in the activity and overall catabolic capabilities of the inherent wetland bacterial communities. However, after a 2-5 week recovery period the activities and catabolic capabilities of the bacterial communities exposed to ciprofloxacin returned to levels comparable to those found for bacterial communities not exposed to the ciprofloxacin. These findings suggest that ciprofloxacin exposure may have an adverse effect on the inherent bacterial communities in wetland systems initially reducing their ability to assimilate anthropogenic carbon-based compounds; however, normal functionality may resume after a 2-5 week period. It was also observed that plants in the ciprofloxacin-treated mesocosms did not adapt to the antibiotic presence, instead showing initial browning of above ground parts and eventual die-off. Reduced porosity, evapotranspiration, and overall hydrological mixing in the ciprofloxacin-treated mesocosms was observed.

Community-level physiological profiling (CLPP) is a technique which offers an easily applied protocol yielding information regarding mixed microbial community function and functional adaptations over space and time. Different communities can be compared and classified based on sole carbon source utilization patterns (CSUPs) gathered using BIOLOG microplates. One of the most challenging aspects associated with the CLPP method is in the data analysis. This chapter describes the relatively simple CLPP laboratory protocol and provides a detailed description of different data analysis techniques.

Community-level physiological profiling (CLPP) is a technique which offers an easily applied protocol yielding information regarding mixed microbial community function and functional adaptations over space and time. Different communities can be compared and classified based on sole carbon source utilization patterns (CSUPs) gathered using BIOLOG microplates. One of the most challenging aspects associated with the CLPP method is in the data analysis. This chapter describes the relatively simple CLPP laboratory protocol and provides a detailed description of different data analysis techniques.

Community level physiological profiling (CLPP) has become a popular method to characterize and track changes in heterotrophic bacterial communities. Although the CLPP method is a straight forward laboratory protocol which yields large amounts of functional information, the amount of data obtained can become overwhelming and often requires some type of multivariate analysis method for ordination and interpretation. Multivariate analysis can be challenging and requires a significant statistics background along with an understanding of the inferences and biases each multivariate analysis method incurs. This paper presents and evaluates a new approach to analyzing sole carbon source utilization data. A method is described which provides a one-dimensional metric derived from standard CLPP data (BIOLOG™ EcoPlate data). The one-dimensional community metric was derived using normalized Euclidean distances and shifts in the carbon source utilization patterns. The one-dimensional community metric did not provide all of the information of classical approaches such as principle component analysis (PCA) or guild grouping analysis; however, it was found to be more easily implemented and interpreted when analyzing the plate data. Validation of this approach is demonstrated using data acquired to track the divergence of bacterial communities in wetland mesocosm systems after an experimentally controlled disturbance. If the objective is to investigate community shifts over time the one-dimensional community divergence metric can be a useful tool.

Changes in the bacterial community in the interstitial water of 5 different constructed wetland mesocosms were studied over a 22-day period following exposure to simulated acid mine drainage (AMD). The community-level physiological profile (CLPP) of each mesocosm was assessed using substrate utilization patterns gathered via BIOLOG™ ECO plates. Principal component analysis (PCA) of the BIOLOG™ ECO plate data proved feasible and useful in characterizing the interstitial bacterial community in the constructed wetland mesocosms based on mesocosm characteristics such as fixed biological regime development and plant presence, and was also used to successfully track changes in the interstitial bacterial community in response to AMD exposure. Clustering analysis of the BIOLOG™ ECO plate data was used to characterize the interstitial bacterial community and to validate the mesocosm groupings observed through PCA ordination. The calculation of substrate-based diversity indices from the BIOLOG™ ECO plate data was used to assess the robustness and the degree of change shown by the metabolic fingerprint of the interstitial bacterial community within the mesocosms. The interstitial bacterial community in the constructed mesocosms was shown to be significantly affected after exposure to AMD. Exposure to AMD caused similar bacterial species to detach from the fixed biotic regime of the mesocosms. It was also shown that mesocosms planted with Phragmites australis did not experience as great an ecological shift in the microbial ecology of the interstitial water after exposure to AMD as did the unplanted mesocosms. The substrate-based diversity indices for the planted mesocosms were also found to be more stable, after exposure to AMD, than those for the unplanted mesocosms. It is possible that the interaction between the plant root system and the substrate biological regime, collectively called the rhizosphere, may create a more ecologically robust and stable treatment system.