Cyanobacterial blooms in surface waters - Nature-based solutions, cyanotoxins and their biotransformation products

Cyanobacterial blooms are expected to become more frequent and severe in surface water reservoirs due to climate change and ecosystem degradation. It is an emerging challenge that especially countries relying on surface water supplies will face. Nature-based solutions (NBS) like constructed wetlands and biofilters can be used for cyanotoxin remediation. Both technologies are reviewed and critically assessed for different types of water resources. The available information on cyanotoxins (bio)transformation products (TPs) is reviewed to point out the potential research gaps and to disclose the most reliable enzymatic degradation pathways. Knowledge gaps were found, such as information on the performance of the revised NBS in pilot and full scales, the removal processes covering different cyanotoxins (besides the most widely studied microcystin-LR), and the difficulties for real-world implementation of technologies proposed in the literature. Also, most studies focus on bacterial degradation processes while fungi have been completely overlooked. This review also presents an up-to-date overview of the transformation of cyanotoxins, where degradation product data was compiled in a unified library of 22 metabolites for microcystins (MCs), 7 for cylindrospermopsin (CYN) and 10 for nodularin (NOD), most of them reported only in a single study. Major gaps are the lack of environmentally relevant studies with TPs in pilot and full- scale treatment systems, information on TP's toxicity, as well as limited knowledge of environmentally relevant degradation pathways. NBS have the potential to mitigate cyanotoxins in recreational and irrigation waters, enabling the water-energy-food nexus and avoiding the degradability of the ecosystems.

Combination of advanced biological systems and photocatalysis for the treatment of real hospital wastewater spiked with carbamazepine: A pilot-scale study

Over the past few decades, the increase in dependency on healthcare facilities has led to the generation of large quantities of hospital wastewater (HWW) rich in chemical oxygen demand (COD), total suspended solids (TSS), ammonia, recalcitrant pharmaceutically active compounds (PhACs), and other disease-causing microorganisms. Conventional treatment methods often cannot effectively remove the PhACs present in wastewater. Hence, hybrid processes comprising of biological treatment and advanced oxidation processes have been used recently to treat complex wastewater. The current study explores the performance of pilot-scale treatment of real HWW (3000 L/d) spiked with carbamazepine (CBZ) using combinations of moving and stationary bed bio-reactor-sedimentation tank (MBSST), aerated horizontal flow constructed wetland (AHFCW), and photocatalysis. The combination of MBSST and AHFCW could remove 85% COD, 93% TSS, 99% ammonia, and 30% CBZ. However, when the effluent of the AHFCW was subjected to photocatalysis, an enhanced CBZ removal of around 85% was observed. Furthermore, the intermediate products (IPs) formed after the photocatalysis was also less toxic than the IPs formed during the biological processes. The results of this study indicated that the developed pilot-scale treatment unit supplemented with photocatalysis could be used effectively to treat HWW.

Horizontal flow aerated constructed wetlands for municipal wastewater treatment: The influence of bed depth

The influence of bed depth on the performance of aerated horizontal constructed wetlands was investigated at the pilot plant scale. Two horizontal flow subsurface constructed wetlands (HF) intensified units of different bed depth (HF1: 0.90 m and HF2: 0.55 m, 0.8 m and 0.5 m water level, respectively) were fitted with forced aeration, while a third one (HFc, 0.55 m bed depth, 0.5 m water level) was used as control and not aerated. The three HF units were operated in parallel, receiving the same municipal wastewater pre-treated in a hydrolytic up-flow sludge blanket anaerobic digester. Applied surface loading rates (SLR) ranged from 20 to 80 g biochemical oxygen demand (BOD5)/m2·d and from 3.7 to 6.7 g total nitrogen (TN)/m2·d, while it ranges from 6 to 23 g BOD5/m2·d and from 1.1 to 1.7 g TN/m2·d in the control unit. Removal of total suspended solids (TSS) and BOD5 was usually close to a 100 % in all units, whilst chemical oxygen demand (COD) removal was higher for the HF1 unit (97 % on average, range of 96-99 %) than for HF2 (92 %, 82-98 %) and HFc (94 %, 86-99 %). TN removal reached on average 33 % (16-43 %) in HFc, 37 % (10-76 %) in HF2 and 51 % (21-79 %) in HF1. High TN removal required a longer aeration time for nitrification and higher effluent recirculation ratio to enhance denitrification. The results indicate that artificial aeration and a high bed depth allows to increase the SLR by a factor of 4 in HF1 but only by a factor of 2 in HF2.

Variation of the feeding/resting period in modified vertical treatment wetlands (depth, zeolite as medium) employed for treating rural domestic wastewater in tourist areas

This work aimed to evaluate the performance of modified vertical flow treatment wetlands (VF-TWs) in terms of depth and medium to assess the effect of the feeding/resting periods and footprint (FP). The modifications were proposed for treating domestic wastewater in rural areas with flow variations such as tourist sites. The experimental setup included six laboratory-scale VF-TWs: (a) normal (VF-N), bed depth 1.0 m, filled with sand and (b) modified (VF-M), bed depth 0.5 m, filled with sand (upper) and zeolite (bottom, saturated). The operation was divided into three phases (3 months each), varying the feeding/resting period and FP: phase I, 5 d/10 d, 2.6 m2/person-equivalent (PE); phase II, 3.5 d/3.5 d, 1.7 m2/PE; and phase III, only feeding no resting, 0.85 m2/PE. Influent and effluent grab samples were taken every 2 weeks. The results showed effective removal (above 60%) of total solids, organic matter, and pathogens for both VF-N and VF-M. Regarding nutrients, VF-M showed a phosphate removal below 60%, but no consistent removal (15-60%) of total nitrogen. Thus, the results suggest that proposed modifications can be an option to be established in tourist sites, but further work should be conducted to improve and optimize total nitrogen removal.

Effects of electroconductive materials on treatment performance and microbial community structure in biofilter systems with silicone tubings

Biofilter systems coupling with microbial electrochemical technology can enhance the removal performance of pollutants. In this study, two types of coke (PK-A and PK-LSN) were used as electroconductive substrates in biofilter systems with silicone tubings. The results showed that the silicone tubings were beneficial for removing NH₄⁺-N. The PK-A systems reached removal efficiencies up to 83.5-85.3% for NH₄⁺-N without aeration. Compared to gravel systems, significantly higher removal efficiencies of NO₃^--N (84.8-95.4%) were obtained in coke systems, and better removal of PO₄^3--P (91.9-95.7%) was also simultaneously achieved in PK-A systems. Redundancy analysis (RDA) indicated that the better performances of coke systems rely on the functions of both electroactive (Trichococcus and Sulfurovum) and non-electroactive bacteria (Clostridium_sensu_stricto_1, Propionicicella, and Acinetobacter). These findings highlight the important contribution of silicone tubings to oxygen supply and provide useful guidance for the application of coke in composite matrix systems.

The use of treatment wetlands plants for protein and cellulose valorization in biorefinery platform

Different wetland plants were evaluated regarding their potential to be used in further green biorefining platforms to produce soluble protein and cellulose-textile fibers. The results show a higher protein content in the plants grown in treatment wetland conditions, compared with the same species grown in natural conditions, and diverse effect on the content of cellulose, hemicellulose, and lignin, depending on the plant species, more than the growing environment. The TW biomass did not represent a risk regarding accumulation of heavy metals, named Pb, Cd, and Cr, since the studied plants did not present it in their tissues, neither in the roots nor in the leaves. The results regarding cellulose quality of the TW plants showed positive results, having values of molar mass distributions and degrees of polymerization that suggest a suitability to be considered for cellulose-fiber textiles studies. This is one of the first approaches, in the TW field, to establish a new criterion for selecting plant species to be planted in the system, aiming at recovering resources and use them as inputs for biorefineries and sustainable biobased products.

Effect of intermittent induced aeration on nitrogen removal and denitrifying-bacterial community structure in Cork and gravel vertical flow pilot-scale treatment wetlands

In this work, we have evaluated the impact of intermittent induced aeration in total nitrogen (TN), ammonia (NH₄-N) and nitrate-nitrogen (NO₃-N) removal in four pilot-scale vertical flow constructed wetlands (VFCW) (two aerated two non-aerated) using cork by-product or gravel as the filter material and planted with Phragmites australis. Both aerated and non-aerated systems achieved high COD and BOD₅ elimination rates (≥ 90%) at the end of the 5-month test period. However, the aerated systems presented maximal COD and BOD₅ removal from the third month of operation onwards since air supply favored the oxidative bioprocesses occurring within the wetlands. Cork and gravel aerated VFCW also proved to be more efficient (p < 0.05) in NO₃-N removal than the non-aerated systems and this upgraded performance was correlated with a significant higher relative abundance of the nirS gene. The aerated systems also showed a slightly improved NH₄-N removal. Noticeably, cork VFCW showed higher TN removal mean values (∼35%) than gravel wetlands (27-28%) regardless aeration. Moreover, cork VFCW showed higher relative abundance of the nosZ gene. Our results demonstrated a better nitrogen elimination for the aerated cork pilot-scale VFCW, and this behavior was correlated with a higher abundance of both nirS and nosZ, two of the key functional genes involved in nitrogen metabolism.

Video-Assisted Thoracoscopy For Penetrating Cardiac Box Injury in Stable Patients

INTRODUCTION

In high-volume trauma centers, especially in developing countries, penetrating cardiac box injuries are frequent. Although many aspects of penetrating chest injuries have been well established, video-assisted thoracoscopy is still finding its place in cardiac box trauma and algorithmic approaches are still lacking. The purpose of this manuscript is to provide a streamlined recommendation for penetrating cardiac box injury in stable patients.

METHODS

Literature review was carried out using PubMed/ MEDLINE and Google Scholar databases to identify articles describing the characteristics and concepts of penetrating cardiac box trauma, including the characteristics of tamponade, cardiac ultrasound, indications and techniques of pericardial windows and, especially, the role of video-assisted thoracoscopy in stable patients.

RESULTS

Penetrating cardiac box injuries, whether by stab or gunshot wounds, require rapid surgical consultation. Unstable patients require immediate open surgery, however, determining which stable patients should be taken to thoracoscopic surgery is still controversial. Here, the classification of penetrating cardiac box injury used in Colombia is detailed, as well as the algorithmic approach to these types of trauma.

CONCLUSION

Although open surgery is mandatory in unstable patients with penetrating cardiac box injuries, a more conservative and minimally invasive approach may be undertaken in stable patients. As rapid decision-making is critical in the trauma bay, surgeons working in high-volume trauma centers should expose themselves to thoracoscopy and always consider this possibility in the setting of penetrating cardiac box injuries in stable patients, always in the context of an experienced trauma team.

Novel bioelectrochemical strategies for domesticating the electron flow in constructed wetlands

Constructed wetlands are an effective biofilter-based technology for treating wastewater in a sustainable way; however, their main disadvantage is a large area footprint. To cope with this limitation a new generation of constructed wetlands, the METlands®, have been recently reported. METlands® replace gravel with a granular electrically conductive material to enhance the oxidative metabolisms of electroactive bacteria by facilitating the flux of electron through the material and, consequently, increase bioremediation rates. In this work we evaluated the performance of a new electron sink (e-sink) device with the purpose of controlling and enhancing the electrochemical consumption of electrons from microbial metabolism without energy consumption. The e-sink device was integrated inside the biofilter bed and was tested using different electron acceptors with high redox potentials, like oxygen and hypochlorite. Interestingly, the presence of the e-sink allowed novel redox gradients to form inside the METland® and, consequently, a new electron flow was demonstrated by measuring both the electric potential and current density profiles of the bed. Three independent biofilters were constructed and operated under flooded conditions. Ec-coke and electroconductive biochar (ec-biochar) were used as electrically conductive bed materials, while gravel was used as an inert control. Furthermore, e-sink integration inside the electrically conductive bed outperformed METlands® for removing pollutants, already much more efficient than standard gravel biofilters. COD removal was increased from 90% in METland® to 95% in the e-sink METland® as compared to 75% for the control, while total nitrogen removal was enhanced from 64% in METland® to 71% in e-sink METland® as compared to 55% for the control. Our results indicate that increasing the electrochemical availability of electron acceptors by using the e-sink will be a suitable method for controlling the electron flow inside the filter bed and can be integrated in full scale METlands® for achieving high removal rates.

Community level physiological profiling of microbial electrochemical-based constructed wetlands

The performance of constructed wetlands (CW) can be enhanced through the use of microbial electrochemical technologies like METland systems. Given its novelty, uncertainties exist regarding processes responsible for the pollutant removal and microbial activity within the systems. Genetic characterization of microbial communities of METlands is desirable, but it is a time and resource consuming. An alternative, is the functional analysis based on community-level physiological profile (CLPP), which allows to evaluate the diversity of microbial communities based on the carbon consumption patterns and derived indexes (average well color development - AWCD -, richness, and diversity). This study aimed to characterize the microbial community function of laboratory-scale METlands using the CLPP method. It encompassed the analysis of planted and non-planted set-ups of two carbon-based electroconductive materials (Coke-A and Coke-LSN) colonized with electroactive biofilms, and compared to Sand-filled columns. Variations in the microbial metabolic activity were found to depend on the characteristics of the material rather than to the presence of plants. Coke-A systems showed lower values of AWCD, richness, and diversity than Sand and Coke-LSN systems. This suggests that Coke-A systems provided more favorable conditions for the development of relatively homogeneous microbial biofilms. Additionally, typical parameters of water quality were measured and correlations between utilization of carbon sources and removal of pollutants were established. The results provide useful insight into the spatial dynamics of the microbial activity of METland systems.

Electroactive biofilm-based constructed wetland (EABB-CW): A mesocosm-scale test of an innovative setup for wastewater treatment

Constructed wetlands (CWs) performance enhancement can be done with intensification strategies. A recent strategy still in study is the coupling with Microbial Electrochemical Technologies (MET). An alternative system using electro-conductive biofilters instead of electrodes and circuits used in MET, resulted in the development of a Microbial Electrochemical-based CW (METland). This system relies on electroactive bacteria (EAB) metabolism to transfer electrons to an electro-conductive material, thus boosting substrate consumption, and diminishing electron availability for biomass build-up and methane generation. In previous studies this biofilters have shown an improvement in biodegradation rates in comparison with subsurface flow CW. However, this set-up is still in development, hence there are uncertainties regarding the dynamics involve in the removal of pollutants. Considering that, this work aimed at establishing the capacity and removal kinetics of organic matter and nutrients in an Electroactive Biofilm-Based CW (EABB-CW). Two electro-conductive materials were tested (PK-A and PK-LSN) in planted and non-planted mesocosms and compared with sand. The systems were operated in a continuous upflow mode for 32 weeks and fed with real wastewater. The electro-conductive systems reached removal efficiencies up to 88% for BOD₅, 90% for COD, 46% for NH₄-N, and 86% for PO₄-P. Organic matter removal in electro-conductive systems was possible even at loading rates 10-fold higher than recommended for horizontal flow CWs. First-order area-based removal constants (k), calculated for organic matter and nutrients are higher than values typically reported for saturated CW and in certain cases comparable with vertical flow CW. The organic removal was correlated with electron current densities measures, as indicator of the presence of EAB. The tested EABB-CW profiles as a promising CW type for the removal of organic matter and PO₄-P with margin for modifications to improve nitrogen removal. Future studies with pilot/real scale systems are proposed to validate the findings of this study.

Characterization of Hydrocarbon-Degrading Bacteria in Constructed Wetland Microcosms Used to Treat Crude Oil Polluted Water

Ten plant species were grown in constructed wetlands (CWs) to remediate water containing 2% (w/v) crude oil. The plant species with better growth and biomass production were Typha latifolia and Cyperus laevigatus, and they were significantly correlated (R² = 0.91) with hydrocarbon degradation. From T. latifolia and C. laevigatus, 33 hydrocarbon-degrading bacterial strains were isolated from the rhizosphere, and root and shoot interiors. More diversified bacteria were found in the rhizosphere and endosphere of C. laevigatus than those of T. latifolia. The predominant cultural hydrocarbon-degrading bacteria were shown to belong to the genera Pseudomonas, Acinetobacter and Bacillus. In addition to genes involved in hydrocarbon degradation, most of the bacteria displayed multiple plant growth promoting (PGP) activities. This study suggests the importance of selecting suitable bacterial strains with hydrocarbon degradation and PGP activities for improving the efficacy of CWs used in remediating water contaminated with crude oil.

Microbial nitrate removal efficiency in groundwater polluted from agricultural activities with hybrid cork treatment wetlands

Agricultural practices have raised the level of nutrients reaching aquifers. In Europe, nitrate pollution is considered as one of the main threats for the quality of groundwater in agricultural areas. Treatment wetlands (TWs), also known as Constructed Wetlands, are used for groundwater treatment in areas with an important concentration of nitrogen compounds; total nitrogen removal depends on the type and operation scheme. Cork by-product from the industry has shown clear adsorbent properties to remove organic pollutants. The work is focused on the characterization of microbial communities involved in the nitrate‑nitrogen removal process in groundwater polluted from agricultural activities. The experimental design allowed the comparison of nitrate removal efficiency depending on the filter media material, cork by-product or gravel, used in two hybrid TWs (a vertical flow cell followed by a horizontal subsurface flow cell), installed in areas close to two irrigated agricultural plots at the Lleida plain area (Spain). Both physicochemical and microbial results were consistent and confirm the nitrate removal efficiency using cork as a filter media. A significant (p = 0.0025) higher removal in Bellvís TW using cork compared with the Vilanova de la Barca gravel system was observed, achieving a removal rate from 80 to 99% compared to the 5-46%, respectively. Regarding the community composition of the two different TWs, microorganisms were mainly related to the phylum Proteobacteria, and included members found to be key players in the nitrogen cycle, such as ammonia and nitrite oxidizers, as well as denitrifiers. Also, the group Bacteroidetes turns to be another abundant phylum from our bacterial dataset, whose members are suggested to be strongly involved in denitrification processes. Some groups showed to prevail depending on the type of media (cork or gravel); Firmicutes and Delta and Epsilonproteobacteria had a significant higher abundance in the TW with cork, while Acidobacteria and Planctomyces were prevalent in gravel. Therefore, cork could be an alternative material used by treatment wetlands to minimize the impact in the environment caused by nitrogen pollution in groundwater bodies.

Microbial community metabolic profiles in saturated constructed wetlands treating iohexol and ibuprofen

The aim of the present study was to elucidate the microbial community metabolic profiles in saturated constructed wetland (CW) mesocosms planted with five different wetland plant species fed with water individually spiked with 100 μg L^-1 ibuprofen or iohexol. Community-level physiological profiling (CLPP) using Biolog Ecoplates was performed and coupled with the assessment of water quality parameters (water temperature, pH, DO and TOC, TN, NH₄-N, PO₄-P removal efficiency). The microbial community metabolic profiles (microbial activity, richness, and carbon source utilization), as well as the water quality parameters revealed similar trends among the control mesocosms and the mesocosms fed with water spiked with iohexol and ibuprofen. Significant differences were observed between the planted and unplanted mesocosms and between seasons (summer and winter) within each of the feeding lines (control, iohexol or ibuprofen). The microbial community metabolic profiles in the saturated CW were shaped by plant presence and plant species, while no negative impact of iohexol and ibuprofen presence was noticed at the 100 μg L^-1. In addition, the microbial activity and richness were generally higher in planted mesocosms than in the unplanted systems in the summer. For the first time, a positive correlation between iohexol removal and the microbial community metabolic profiles (activity, richness and amines and amides utilization in summer, and carbohydrates utilization in winter) in the saturated mesocosms was observed. Putrescine utilization in the summer and d-cellobiose, d,l-alpha-glycerol phosphate in winter were linked with the metabolic processing of iohexol, while glycogen in summer and l-phenylalanine, Glycyl-l-glutamic acid in winter were linked with ibuprofen removal efficiency in the saturated CW.

Cork as a sustainable carbon source for nature-based solutions treating hydroponic wastewaters - Preliminary batch studies

Reusing by-products is an important strategy to ensure the preservation of natural capital and climate change mitigation. This study aimed at evaluating the potential of cork granulates, a by-product of winery industry, as an organic carbon (OC) source for the treatment of hydroponic wastewaters. First, chemical characterization was performed and discussed. Secondly, batch studies were performed using synthetic hydroponic wastewater to understand the role of particle size (PS), pH and contact time (CT) on the release of OC. The suberin is the major compound, representing >50%. It was noticed that a variance on the content of suberin across species, within the same species and depending on the extraction part (belly, cork and back) could be expected. >60% of the sample is composed by carbon while <1% was nitrogen (high C:N ratio), indicating a low risk of releasing organic nitrogen. The statistical results suggested that the main effect of PS on the release of OC is greater than both, CT and pH. The chemical release of OC gets slower with time, being this effect greater as the PS increase. Moreover, estimations showed that using the 4 mm PS, the amount of water treated would be twice the amount if the 8 mm PS had been used. The PS seems to play an important role at design nature-based solutions (NBS) focused on denitrification. The surface response methodology indicates a significant negative interaction between CT and PS suggesting that the mathematical model could be used for further optimization studies. The reuse of organic by-products as filter media seems to be an economic and environmentally friendly alternative to enhance denitrification in NBS, while preserving natural capital. However, further real scale and long-term experiments are needed to validate cork's potential as an "internal" OC source for NBS.

New insights into the effects of support matrix on the removal of organic micro-pollutants and the microbial community in constructed wetlands

Constructed wetlands (CWs) are an eco-friendly and cost-effective technology to remove organic micro-pollutants (OMPs) from wastewater. The support matrix is an important component in CWs as it has a primary role in the growth and development of plants and microbes. However, the roles of the support matrix in CWs in removing OMPs have not been systematically studied. Therefore, in this study, six common materials (sand, zeolite, blast iron slag, petcoke, polonite and crushed autoclaved aerated concrete (CAAC)) as support matrixes were firstly investigated by batch tests to explore their adsorption capacities to selected OMPs (ibuprofen, iohexol, tebuconazole and imazalil). Results showed that the adsorption capacities of the materials were low (at the level of μg/g) compared to well-known sorbents (at the level of mg/g), such as activated carbon and carbon nanotubes. Columns packed with the six materials, respectively, were then built up to study the effects of different materials on microbial community. In the medium-term study (66 days), the removal of four OMPs in all the columns increased by 2-58% from day 25 to day 66, and was mainly attributed to microbial degradation. Furthermore, Community-level physiological profiling (CLPP) analysis indicates that material presence shaped the microbial community metabolic function not only in the interstitial water but also in the biofilm. Overall, all the findings demonstrate that although the adsorption capacities of the common materials are low, they may be a driver to improve the removal of OMPs by altering microbial community function in CWs.

Hydraulic and hydrological aspects of an evapotranspiration-constructed wetland combined system for household greywater treatment

Constructed wetlands systems demand preliminary and primary treatment to remove solids present in greywater (GW) to avoid or reduce clogging processes. The current paper aims to assess hydraulic and hydrological behavior in an improved constructed wetland system, which has a built-in anaerobic digestion chamber (AnC), GW is distributed to the evapotranspiration and treatment tank (CEvaT), combined with a subsurface horizontal flow constructed wetland (SSHF-CW). The results show that both the plants present in the units and the AnC improve hydraulic and volumetric efficiency, decrease short-circuiting and improve mixing conditions in the system. Moreover, the hydraulic conductivity measured on-site indicates that the presence of plants in the system and the flow distribution pattern provided by the AnC might reduce clogging in the SSHF-CW. It is observed that rainfall enables salt elimination, thus increasing evapotranspiration (ET), which promotes effluent reduction and enables the system to have zero discharge when reuse is unfeasible.

Impacts of design configuration and plants on the functionality of the microbial community of mesocosm-scale constructed wetlands treating ibuprofen

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 < .05) than that of interstitial water. Both the interstitial water and biofilm microbial community metabolic function were influenced by CW design, plant presence and species, but design had a greater influence than plants. Moreover, canonical correlation analysis indicated that biofilm microbial communities in the three designs played a key role in ibuprofen degradation. The important factors identified as influencing ibuprofen removal were microbial AWCD (average well color development), microbial metabolic richness, and the utilization of amino acids and amine/amides. The enzymes associated with co-metabolism of l-arginine, l-phenyloalanine and putrescine may be linked to ibuprofen transformations. These results provide useful information for optimizing the operational parameters of CWs to improve ibuprofen removal.

Removal of the pesticide tebuconazole in constructed wetlands: Design comparison, influencing factors and modelling

Constructed wetlands (CWs) are a promising technology to treat pesticide contaminated water, but its implementation is impeded by lack of data to optimize designs and operating factors. Unsaturated and saturated CW designs were used to compare the removal of triazole pesticide, tebuconazole, in unplanted mesocosms and mesocosms planted with five different plant species: Typha latifolia, Phragmites australis, Iris pseudacorus, Juncus effusus and Berula erecta. Tebuconazole removal efficiencies were significantly higher in unsaturated CWs than saturated CWs, showing for the first time the potential of unsaturated CWs to treat tebuconazole contaminated water. An artificial neural network model was demonstrated to provide more accurate predictions of tebuconazole removal than the traditional linear regression model. Also, tebuconazole removal could be fitted an area-based first order kinetics model in both CW designs. The removal rate constants were consistently higher in unsaturated CWs (range of 2.6-10.9 cm d^-1) than in saturated CWs (range of 1.7-7.9 cm d^-1) and higher in planted CWs (range of 3.1-10.9 cm d^-1) than in unplanted CWs (range of 1.7-2.6 cm d^-1) for both designs. The low levels of sorption of tebuconazole to the substrate (0.7-2.1%) and plant phytoaccumulation (2.5-12.1%) indicate that the major removal pathways were biodegradation and metabolization inside the plants after plant uptake. The main factors influencing tebuconazole removal in the studied systems were system design, hydraulic loading rate and plant presence. Moreover, tebuconazole removal was positively correlated to dissolved oxygen and all nutrients removal.

Effects of constructed wetland design on ibuprofen removal - A mesocosm scale study

This study aimed to investigate the effects of constructed wetland design (unsaturated, saturated and aerated saturated) and plant species (Juncus, Typha, Berula, Phragmites and Iris) on the mass removal and removal kinetics of the pharmaceutical ibuprofen. Planted systems had higher ibuprofen removal rates (29%-99%) than in the unplanted ones (15%-85%) in all designs. The use of forced aeration improved ibuprofen removal only in the unplanted mesocosms. In general, ibuprofen removal followed an area-based first-order removal kinetics model with removal rate coefficients (k_A) varying between 3 and 35cm/d. The ibuprofen removal was mainly attributed to microbial degradation by the fixed bed biofilm, but plant uptake and degradation within plant tissues also occurred. The ibuprofen removal was positively correlated with the oxygen concentration in the water and the removal of nutrients, indicating that degradation may be due to co-metabolisation processes.

Enantioselective uptake, translocation and degradation of the chiral pesticides tebuconazole and imazalil by Phragmites australis

Phytoremediation of realistic environmental concentrations (10 μg L^-1) of the chiral pesticides tebuconazole and imazalil by Phragmites australis was investigated. This study focussed on removal dynamics, enantioselective mechanisms and transformation products (TPs) in both hydroponic growth solutions and plant tissues. For the first time, we documented uptake, translocation and metabolisation of these pesticides inside wetland plants, using enantioselective analysis. Tebuconazole and imazalil removal efficiencies from water reached 96.1% and 99.8%, respectively, by the end of the experiment (day 24). Removal from the solutions could be described by first-order removal kinetics with removal rate constants of 0.14 d^-1 for tebuconazole and 0.31 d^-1 for imazalil. Removal of the pesticides from the hydroponic solution, plant uptake, within plant translocation and degradation occurred simultaneously. Tebuconazole and imazalil concentrations inside Phragmites peaked at day 10 and 5d, respectively, and decreased thereafter. TPs of tebuconazole i.e., (5-(4-Chlorophenyl)-2,2-dimethyl-3-(1H-1,2,4-triazol-1-ylmethyl)-1,3-pentanediol and 5-(3-((1H-1,2,4-Triazol-1-yl)methyl)-3-hydroxy-4,4-dimethylpentyl)-2-chlorophenol) were quantified in solution, while the imazalil TPs (α-(2,4-Dichlorophenyl)-1H-imidazole-1-ethanol and 3-[1-(2,4-Dichlorophenyl)-2-(1H-imidazol-1-yl)ethoxy]-1,2-propanediol) were quantified in both solution and plant tissue. Pesticide uptake by Phragmites was positively correlated with evapotranspiration. Pesticide removal from the hydroponic solution was not enantioselective. However, tebuconazole was degraded enantioselectively both in the roots and shoots. Imazalil translocation and degradation inside Phragmites were also enantioselective: R-imazalil translocated faster than S-imazalil.

Constructed wetlands and solar-driven disinfection technologies for sustainable wastewater treatment and reclamation in rural India: SWINGS project

SWINGS was a cooperation project between the European Union and India, aiming at implementing state of the art low-cost technologies for the treatment and reuse of domestic wastewater in rural areas of India. The largest wastewater treatment plant consists of a high-rate anaerobic system, followed by vertical and horizontal subsurface flow constructed wetlands with a treatment area of around 1,900 m² and a final step consisting of solar-driven anodic oxidation (AO) and ultraviolet (UV) disinfection units allowing direct reuse of the treated water. The implementation and operation of two pilot plants in north (Aligarh Muslim University, AMU) and central India (Indira Gandhi National Tribal University, IGNTU) are shown in this study. The overall performance of AMU pilot plant during the first 7 months of operation showed organic matter removal efficiencies of 87% total suspended solids, 95% 5-day biological oxygen demand (BOD₅) and 90% chemical oxygen demand, while Kjeldahl nitrogen removal reached 89%. The UV disinfection unit produces water for irrigation and toilet flushing with pathogenic indicator bacteria well below WHO guidelines. On the other hand, the AO disinfection unit implemented at IGNTU and operated for almost a year has been shown to produce an effluent of sufficient quality to be reused by the local population for agriculture and irrigation.

Impact of High-Level Daptomycin Resistance in the Streptococcus mitis Group on Virulence and Survivability during Daptomycin Treatment in Experimental Infective Endocarditis

Among the viridans group streptococci, the Streptococcus mitis group is the most common cause of infective endocarditis. These bacteria have a propensity to be β-lactam resistant, as well as to rapidly develop high-level and durable resistance to daptomycin (DAP). We compared a parental, daptomycin-susceptible (DAPs) S. mitis/S. oralis strain and its daptomycin-resistant (DAPr) variant in a model of experimental endocarditis in terms of (i) their relative fitness in multiple target organs in this model (vegetations, kidneys, spleen) when animals were challenged individually and in a coinfection strategy and (ii) their survivability during therapy with daptomycin-gentamicin (an in vitro combination synergistic against the parental strain). The DAPr variant was initially isolated from the cardiac vegetations of animals with experimental endocarditis caused by the parental DAPs strain following treatment with daptomycin. The parental strain and the DAPr variant were comparably virulent when animals were individually challenged. In contrast, in the coinfection model without daptomycin therapy, at both the 106- and 107-CFU/ml challenge inocula, the parental strain outcompeted the DAPr variant in all target organs, especially the kidneys and spleen. When the animals in the coinfection model of endocarditis were treated with DAP-gentamicin, the DAPs strain was completely eliminated, while the DAPr variant persisted in all target tissues. These data underscore that the acquisition of DAPr in S. mitis/S. oralis does come at an intrinsic fitness cost, although this resistance phenotype is completely protective against therapy with a potentially synergistic DAP regimen.

Functionality of microbial communities in constructed wetlands used for pesticide remediation: Influence of system design and sampling strategy

The objective of this study was to compare the microbial community metabolic function from both unsaturated and saturated constructed wetland mesocosms (CWs) when treating the pesticide tebuconazole. The comparison was performed for both interstitial water and substrate biofilm by community level physiological profiling (CLPP) via BIOLOG™ EcoPlates. For each CW design (saturated or unsaturated), six mesocosms were established including one unplanted and five planted individually with either Juncus effusus, Typha latifolia, Berula erecta, Phragmites australis or Iris pseudacorus. Microbial activity and metabolic richness of interstitial water from unsaturated CWs were significantly lower than that from saturated CWs. However, in general, the opposite result was observed for biofilm samples. Wetland plants promoted significantly higher biofilm microbial activity and metabolic richness than unplanted CWs in both CW designs. Differences in the microbial community functional profiles between plant species were only found for saturated CWs. Biofilm microbial metabolic richness was generally statistically higher than that of interstitial water in both unsaturated (1.4-24 times higher) and saturated (1.2-1.7 times higher) CWs. Carbon source (guild) utilization patterns were generally different between interstitial water and biofilm samples. Functionality of the biofilm microbial community was positively correlated to the removal of all pollutants (TN, NH₄⁺-N, TP, TOC and tebuconazole) for both unsaturated and saturated CWs, suggesting the biofilm plays a more important role in pollutant removal than the interstitial water microbial community. Thus, merely observing the interstitial water microbial communities may underestimate the role of the microbial community in CW performance. Interestingly, the ability for the biofilm microbial community to utilize amino acids and amines/amides was positively correlated with tebuconazole removal in all system types.

Hydrolytic anaerobic reactor and aerated constructed wetland systems for municipal wastewater treatment - HIGHWET project

The HIGHWET project combines the hydrolytic up-flow sludge bed (HUSB) anaerobic digester and constructed wetlands (CWs) with forced aeration for decreasing the footprint and improving effluent quality. The HIGHWET plant in A Coruña (NW of Spain) treating municipal wastewater consists of a HUSB and four parallel subsurface horizontal flow (HF) CWs. HF1, HF2 and HF3 units are fitted with forced aeration, while the control HF4 is not aerated. All the HF units are provided with effluent recirculation, but different heights of gravel bed (0.8 m in HF1 and HF2, and 0.5 m in HF3 and HF4) are implemented. Besides, a tobermorite-enriched material was added in the HF2 unit in order to improve phosphorus removal. The HUSB 76-89% of total suspended solids (TSS) and about 40% of chemical oxygen demand (COD) and biological oxygen demand (BOD). Aerated HF units reached above 96% of TSS, COD and BOD at a surface loading rate of 29-47 g BOD₅/m²·d. An aeration regime ranging from 5 h on/3 h off to 3 h on/5 h off was found to be adequate to optimize nitrogen removal, which ranged from 53% to 81%. Average removal rates of 3.4 ± 0.4 g total nitrogen (TN)/m²·d and 12.8 ± 3.7 g TN/m³·d were found in the aerated units, being 5.5 and 4.1 times higher than those of the non-aerated system. The tobermorite-enriched HF2 unit showed a distinct higher phosphate (60-67%) and total phosphorus (54%) removal.

Phytoremediation of imazalil and tebuconazole by four emergent wetland plant species in hydroponic medium

Pollution from pesticide residues in aquatic environments is of increasing concern. Imazalil and tebuconazole, two commonly used systemic pesticides, are water contaminants that can be removed by constructed wetlands. However, the phytoremediation capability of emergent wetland plants for imazalil and tebuconazole, especially the removal mechanisms involved, is poorly understood. This study compared the removal of both pesticides by four commonly used wetland plants, Typha latifolia, Phragmites australis, Iris pseudacorus and Juncus effusus, and aimed to understand the removal mechanisms involved. The plants were individually exposed to an initial concentration of 10 mg/L in hydroponic solution. At the end of the 24-day study period, the tebuconazole removal efficiencies were relatively lower (25%-41%) than those for imazalil (46%-96%) for all plant species studied. The removal of imazalil and tebuconazole fit a first-order kinetics model, with the exception of tebuconazole removal in solutions with I. pseudacorus. Changes in the enantiomeric fraction for imazalil and tebuconazole were detected in plant tissue but not in the hydroponic solutions; thus, the translocation and degradation processes were enantioselective in the plants. At the end of the study period, the accumulation of imazalil and tebuconazole in plant tissue was relatively low and constituted 2.8-14.4% of the total spiked pesticide in each vessel. Therefore, the studied plants were able to not only take up the pesticides but also metabolise them.

Removal of the pesticides imazalil and tebuconazole in saturated constructed wetland mesocosms

The aim of this study was to investigate the removal of the pesticides imazalil and tebuconazole at realistic concentration levels (10 and 100 μg L(-1)) in saturated constructed wetland (CW) mesocosms planted with five wetland plant species (Typha latifolia, Phragmites australis, Iris pseudacorus, Juncus effusus and Berula erecta) at different hydraulic loading rates during summer and winter. The removal of imazalil and tebuconazole was not influenced by the influent concentration, but the removal efficiency for both compounds was lower in winter than in summer. Planted mesocosms had significantly higher removal efficiencies than the unplanted controls only in summer. The first-order kinetics model fitted the tebuconazole removal in all mesocosms, and the reaction rate constants varied by plant species and season (0.1-0.7 d(-1) in winter and 0.6-2.9 d(-1) in summer). For imazalil, the first-order kinetics model fitted the removal only in mesocosms planted with Phragmites australis (k = 1.2 ± 0.4 d(-1)) and in the unplanted control (k = 1.2 ± 0.5 d(-1) in both summer and winter). The removal of imazalil and tebuconazole by sorption to the bed substrate and plant uptake were low, suggesting a high rate of metabolization in the saturated CW mesocosms. The removal of imazalil and tebuconazole correlated with the rate of evapotranspiration and the removal of nutrients (N and P) during summer and with the DO/oxygen saturation during winter. This reveals two possible metabolization pathways: degradation inside the plant tissue after uptake and plant-stimulated microbial degradation in the bed substrate. Furthermore, the results indicate that nitrifying bacteria may play an active role in the biodegradation of these pesticides.

Removal of the pharmaceuticals ibuprofen and iohexol by four wetland plant species in hydroponic culture: plant uptake and microbial degradation

We aimed at assessing the effects of four wetland plant species commonly used in constructed wetland systems: Typha, Phragmites, Iris and Juncus for removing ibuprofen (IBU) and iohexol (IOH) from spiked culture solution and exploring the mechanisms responsible for the removal. IBU was nearly completely removed by all plant species during the 24-day experiment, whereas the IOH removal varied between 13 and 80 %. Typha and Phragmites were the most efficient in removing IBU and IOH, respectively, with first-order removal rate constants of 0.38 and 0.06 day(-1), respectively. The pharmaceuticals were taken up by the roots and translocated to the aerial tissues. However, at the end of the experiment, plant accumulation constituted only up to 1.1 and 5.7 % of the amount of IBU and IOH spiked initially. The data suggest that the plants mainly function by facilitating pharmaceutical degradation in the rhizosphere through release of root exudates.

Microbial communities from different types of natural wastewater treatment systems: vertical and horizontal flow constructed wetlands and biofilters

The prokaryotic microbial communities (Bacteria and Archaea) of three different systems operating in Denmark for the treatment of domestic wastewater (horizontal flow constructed wetlands (HFCW), vertical flow constructed wetlands (VFCW) and biofilters (BF)) was analysed using endpoint PCR followed by Denaturing Gradient Gel Electrophoresis (DGGE). Further sequencing of the most representative bacterial bands revealed that diverse and distinct bacterial communities were found in each system unit, being γ-Proteobacteria and Bacteroidetes present mainly in all of them, while Firmicutes was observed in HFCW and BF. Members of the Actinobacteria group, although found in HFCW and VFCW, seemed to be more abundant in BF units. Finally, some representatives of α, β and δ-Proteobacteria, Acidobacteria and Chloroflexi were also retrieved from some samples. On the other hand, a lower archaeal diversity was found in comparison with the bacterial population. Cluster analysis of the DGGE bacterial band patterns showed that community structure was related to the design of the treatment system and the organic matter load, while no clear relation was established between the microbial assemblage and the wastewater influent.

Evaluation of aquatic plants for removing polar microcontaminants: a microcosm experiment

Microcosm wetland systems (5 L containers) planted with Salvinia molesta, Lemna minor, Ceratophyllum demersum, and Elodea canadensis were investigated for the removal of diclofenac, triclosan, naproxen, ibuprofen, caffeine, clofibric acid and MCPA. After 38 days of incubation, 40-99% of triclosan, diclofenac, and naproxen were removed from the planted and unplanted reactors. In covered control reactors no removal was observed. Caffeine and ibuprofen were removed from 40% to 80% in planted reactors whereas removals in control reactors were much lower (2-30%). Removal of clofibric acid and MCPA were negligible in both planted and unplanted reactors. The findings suggested that triclosan, diclofenac, and naproxen were removed predominantly by photodegradation, whereas caffeine and naproxen were removed by biodegradation and/or plant uptake. Pseudo-first-order removal rate constants estimated from nonlinear regressions of time series concentration data were used to describe the contaminant removals. Removal rate constants ranged from 0.003 to 0.299 d(-1), with half-lives from 2 to 248 days. The formation of two major degradation products from ibuprofen, carboxy-ibuprofen and hydroxy-ibuprofen, and a photodegradation product from diclofenac, 1-(8-Chlorocarbazolyl)acetic acid, were followed as a function of time. This study emphasizes that plants contribute to the elimination capacity of microcontaminants in wetlands systems through biodegradation and uptake processes.

Musk fragrances, DEHP and heavy metals in a 20 years old sludge treatment reed bed system

The Sludge Treatment Reed Bed (STRB) technology is a cost-efficient and environmentally friendly technology to dewater and mineralize surplus sludge from conventional wastewater treatment systems. Primary and secondary liquid sludge is loaded onto the surface of the bed over several years, where it is dewatered, mineralized and turned into a biosolid with a high dry matter content for use as an organic fertilizer on agricultural land. We analysed the concentrations of five organic micropollutants (galaxolide, tonalide, cashmeran, celestolide and DEHP) and six heavy metals (Pb, Ni, Cu, Cd, Zn and Cr) in the accumulated sludge in a 20-year old STRB in Denmark in order to assess the degradation and fate of these contaminants in a STRB and the relation to sludge composition. The results showed that the deposited sludge was dewatered to reach a dry matter content of 29%, and that up to a third of the organic content of the sludge was mineralized. The concentrations of heavy metals generally increased with depth in the vertical sludge profile due to the dewatering and mineralization of organic matter, but in all cases the concentrations were below the European Union legal limits for agricultural land disposal. The concentrations of fragrances and DEHP ranged from 10 to 9000 ng g(-1) dry mass. The attenuation of hydrophobic micropollutants from the top to the bottom layer of the reed bed ranged from 40 to 98%, except for tonalide which increased significantly with sludge depth, and consequently showed an unusual depth distribution of the galaxolide/tonalide ratio. This unexpected pattern may reflect changes imposed by a long storage time and/or different composition of the fresh sludge in the past. The lack of a significant decreasing DEHP concentration with sludge age might indicate that this compound is very persistent in STRBs. In conclusion the STRB was a feasible technology for sludge treatment before its land disposal.

Occurrence and behavior of emerging contaminants in surface water and a restored wetland

Pollution mitigation is an important target for restored wetlands, and although there is much information in relation to nutrient removal, little attention has been paid to emerging contaminants. This paper reports on the occurrence and attenuation capacity of 17 emerging contaminants in a restored wetland and two rivers in North-East Denmark. The compounds belong to the groups of pharmaceuticals, fragrances, antiseptics, fire retardants, pesticides, and plasticizers. Concentrations in surface waters ranged from 2 to 1476 ng L(-1). The compounds with the highest concentrations were diclofenac, 2-methyl-4-chlorophenoxyacetic acid (MCPA), caffeine, and tris(2-chloroethyl) phosphate (TCEP). The herbicide concentrations increased after a rain-fall event, demonstrating the agricultural run-off origin of these compounds, whereas the concentration of the other emerging contaminants was rather conservative. The mitigation capacity of the restored wetland for the compounds ranged from no attenuation to 84% attenuation (19% on average). Hence, restored wetlands may be considered as a feasible alternative for mitigating emerging contaminants from river waters.

Improved urban stormwater treatment and pollutant removal pathways in amended wet detention ponds

Dissolved and colloidal bound pollutants are generally poorly removed from stormwater in wet detention ponds. These fractions are, however, the most bio-available, and therefore three wet detention ponds were amended with planted sand filters, sorption filters and addition of precipitation chemicals to enhance the removal of dissolved pollutants and pollutants associated with fine particles and colloids. The three systems treated runoff from industrial, residential and combined (residential and highway) catchments and had permanent volumes of 1,990, 6,900 and 2,680 m(3), respectively. The treatment performance of the ponds for elimination of total suspended solids (TSS), total nitrogen (Tot-N), total phosphorous (Tot-P), PO(4)-P, Pb, Zn, Cd, Ni, Cr, Cu, Hg were within the range typically reported for wet detention ponds, but the concentrations of most of the pollutants were efficiently reduced by the planted sand filters at the outlets. The sorption filters contributed to further decrease the concentration of PO(4)-P from 0.04 ± 0.05 to 0.01 ± 0.01 mg L(-1) and were also efficient in removing heavy metals. Dosing of iron sulphate to enrich the bottom sediment with iron and dosing of aluminium salts to the inlet water resulted in less growth of phytoplankton, but treatment performance was not significantly affected. Heavy metals (Pb, Zn, Cd, Ni, Cr and Cu) accumulated in the sediment of the ponds. The concentrations of Zn, Ni, Cu and Pb in the roots of the wetland plants were generally correlated to the concentrations in the sediments. Among 13 plant species investigated, Rumex hydrolapathum accumulated the highest concentrations of heavy metals in the roots (Concentration Factor (CF) of 4.5 and 5.9 for Zn and Ni, respectively) and Iris pseudacorus the lowest (CF < 1). The translocation of heavy metals from roots to the aboveground tissues of plants was low. Therefore the potential transfer of heavy metals from the metal-enriched sediment to the surrounding ecosystem via plant uptake and translocation is negligible.

Management of multidrug-resistant enterococcal infections

Enterococci are organisms with a remarkable ability to adapt to the environment and acquire antibiotic resistance determinants. The evolution of antimicrobial resistance in these organisms poses enormous challenges for clinicians when faced with patients affected with severe infections. The increased prevalence and dissemination of multidrug-resistant Enterococcus faecium worldwide has resulted in a major decrease in therapeutic options because the majority of E. faecium isolates are now resistant to ampicillin and vancomycin, and exhibit high-level resistance to aminoglycosides, which are three of the traditionally most useful anti-enterococcal antibiotics. Newer antibiotics such as linezolid, daptomycin and tigecycline have good in vitro activity against enterococcal isolates, although their clinical use may be limited in certain clinical scenarios as a result of reduced rates of success, possible underdosing for enterococci and low serum levels, respectively, and also by the emergence of resistance. The experimental agent oritavancin may offer some hope for the treatment of vancomycin-resistant enterococci but clinical data are still lacking. Thus, optimal therapies for the treatment of multidrug-resistant enterococcal infections continue to be based on empirical observations and extrapolations from in vitro and animal data. Clinical studies evaluating new strategies, including combination therapies, to treat severe vancomycin-resistant E. faecium infections are urgently needed.

Elimination and accumulation of polycyclic aromatic hydrocarbons in urban stormwater wet detention ponds

The concentrations of polycyclic aromatic hydrocarbons (PAHS) in water and sediments of seven wet detention ponds receiving urban stormwater were investigated. The ponds comprised traditional wet detention ponds with a permanent wet volume and a storage volume as well as ponds that were expanded with sand filters and other means to improve the removal of micropollutants. The concentrations of sigmaPAH in the sediments varied between 6 +/- 5 and 2,222 +/- 603 ng g(-1) dry weight (mean +/- standard deviation), and were highest in the ponds with lower pond volume per catchment area and did not clearly reflect different activities in the catchments. In general, the concentrations of PAHS in the sediments decreased from inlet to outlet, especially in the systems with good conditions for sedimentation such as systems with flow perpendicular sand dikes and extensive submerged vegetation. High molecular weight PAHs were predominant in the sediments indicating the pyrogenic origin of the PAHS. There was no correlation between PAH species concentrations in water or sediments and their hydrophobicity (log K(ow)). PAH concentrations in water fluctuated in response to intensity and frequency of rain events, whereas concentrations in the sediments integrated the pollutant load over time. Pond systems expanded with sand filters and other technologies to enhance removal of micropollutants consistently had concentrations of PAHS in the effluents below the detection level.

Nosocomial outbreak of Enteroccocus gallinarum: untaming of rare species of enterococci

An unusual increase in infections caused by vancomycin-resistant Enterococcus gallinarum (VREG) was identified in May 2004, in a Colombian tertiary care teaching hospital. A case-control study was subsequently designed to identify risk factors associated with the development of infections due to these organisms. All VREG isolates were subjected to antimicrobial susceptibility testing, vancomycin resistance gene detection and pulsed-field gel electrophoresis (PFGE) typing. Additionally, the presence of genes associated with an acquired pathogenicity island of E. faecalis and a hyl-like gene of E. faecium was assessed by hybridisation assays. Eleven cases of VREG were identified between May through June 2004. VREG was isolated from blood (N=4), surgical secretions (N=4), paranasal sinus secretion (N=1), lung abscess (N=1) and urine (N=1). Infections with VREG were associated with mucositis, hospitalisation in the haematology ward and surgical unit, length of hospital stay prior to culture and invasive procedures within 30 days prior to the culture. Logistic regression found that female sex and hospitalisation in the surgical unit were independent factors for VREG infection. All isolates were identified as E. gallinarum, harboured the vanC1 gene and exhibited indistinguishable restriction patterns by PFGE. Virulence-associated genes were not detected. This is the first documented hospital-wide outbreak of VREG and highlights the fact that uncommon species of enterococci are capable of nosocomial dissemination.

Twenty years experience with constructed wetland systems in Denmark--what did we learn?

Full scale constructed wetland systems for wastewater treatment have been in operation in Denmark since 1983, mainly for the treatment of domestic sewage from small villages. The systems are constructed as soil-based horizontal subsurface flow systems but, because of low soil hydraulic conductivity, surface runoff is evident in most of the systems. Two decades of experience show that soil-based systems are generally efficient in removing suspended solids and BOD, but the removal of nitrogen and phosphorus is lower (typically 30-50%) and the systems do not nitrify ammonium. Contrary to earlier claims, the reeds do not increase the hydraulic conductivity of cohesive soils as much as necessary to secure sub-surface flow. Operation needs of soil-based reed beds are low and normally restricted to emptying of the sedimentation tank, cleaning of the distribution system and mowing of the grass around the system. The dead plant material and accumulated litter on the surface of the systems improve performance after the initial years. A significant number of systems have been shut down or extended with other technologies in order to meet new effluent standards, particularly demands for nitrification. New constructed wetland systems are either compact vertical flow systems which provide good nitrification, willow systems with no discharge or restored wetland systems for nitrate removal. If efficient removal of phosphorus is required, this is achieved by chemical precipitation in the sedimentation tank.

Recycling of treated effluents enhances removal of total nitrogen in vertical flow constructed wetlands

It is widely documented that vertical flow constructed wetlands are efficient for producing well nitrified effluent. However, because the treated effluent is oxygen saturated and has a low availability of carbon, the removal of total nitrogen is limited. We hypothesize that by recycling the fully nitrified effluent to the pretreatment unit and the sedimentation tank (where conditions are favorable for denitrification) the removal of total nitrogen from the wastewater can be enhanced. In order to assess the effects of recycling volumes, we monitored the nitrogen removal in an experimental vertical flow constructed wetland, consisting of a 2 m3 sedimentation tank, two vertical flow beds of 10 and 5 m2, and the necessary pumping equipment and controllers to manage the loading and recycling volumes. The system was loaded with approximately 0.5 m3 d(-1), and the recycling volumes evaluated were equal to the loading rate (100% recycling), as well as twice (200%) and three times (300%) the loading. The system produced a fully nitrified effluent independent of recycling rate. However, recycling increased removal of total-N in the system from ca. 1% removal when there was no recycling to 52%, 66%, and 68% removal with 100, 200, and 300% recycling, respectively. The optimal recycling rate seems to be 100-200%. At lower recycling rates, the removal of total-N was poor, and at higher recycling rates, the system became hydraulically overloaded, compromising both the denitrification capacity of the sedimentation tank and the nitrification capacity of the vertical bed.

Danish guidelines for small-scale constructed wetland systems for onsite treatment of domestic sewage

The Danish Ministry of Environment and Energy has passed new legislation that requires the wastewater from single houses and dwellings in rural areas to be treated adequately before discharge into the aquatic environment. Therefore official guidelines for a number of onsite treatment solutions have been produced. These include guidelines for soakaways, biological sand filters, technical systems as well as different types of constructed wetland systems. This paper summarises briefly the guidelines for horizontal flow constructed wetlands, vertical flow constructed wetlands, and willow systems with no outflow and with soil infiltration. There is still a lack of a compact onsite solution that will fulfil the treatment classes demanding 90% removal of phosphorus. Therefore work is presently being carried out to identify simpler and robust P-removal solutions.

Phosphorus removal in constructed wetlands: can suitable alternative media be identified?

Removal of phosphorous in constructed wetlands is limited by the capacity of the media to adsorb, bind or precipitate the incoming P. To enhance P removal and the life span of constructed wetlands the approach might be to use natural sands rich in calcium or iron, to use an alternative 'artificial' medium with high P-binding capacity, or to establish external P-binding filters after the wetland. Our studies focused on the evaluation of calcium-rich materials potentially useful as P-binding media. The materials tested included calcite products, natural sands and seashells. Tests included assessment of physical and chemical properties of the materials, extractions in P-spiked water at different P concentrations to determine P-binding equilibrium isotherms, and column experiments. In addition, full-scale tests were performed with calcite in an external filter. The result showed that equilibrium isotherm is an indicator of the potential P-sorption capacity of the media, although the value is of limited application for the determination of the binding capacity in full-scale systems. The columns showed that the materials do bind phosphorus. However, the binding capacities are still insufficient for the establishment of external P-removal filter; the volumes of the filters would be too large to be of practical use.

Phosphorus adsorption maximum of sands for use as media in subsurface flow constructed reed beds as measured by the Langmuir isotherm

The P-adsorption capacities of 13 Danish sands were studied by short-term isotherm batch experiments and related to the physico-chemical characteristics of the sands. The maximum P-adsorption capacities (Q) and P-binding energy constants (b) were calculated using the Langmuir-isotherm model. The Freundlich model was also used, but it was not useful for the description of adsorption phenomena per se since it fitted well P-removal data even if precipitation of P-salts occurred simultaneously. The Langmuir model described the data well (R(2)=0.90-0.99) when precipitation of phosphates did not occur and seems therefore to be useful for describing the adsorption processes per se. The relationships between maximum sorption capacities and physico-chemical characteristics of the sands were investigated using classical univariate and partial least squares regression analyses. Among the physico-chemical properties of the sands, Ca and Mg content, grain size, porosity, bulk density and hydraulic conductivity were significantly related (P<0.1) to the maximum adsorption capacity as estimated by the Langmuir model. Using the maximum P-adsorption capacities, it was estimated how long the P-removal can be sustained with the different sands in subsurface flow constructed reed beds. If the most efficient sand for P-adsorption was used, the adsorption capacity would be used up after about 1 year, while, for the less efficient sands, the P-retention would go on for about 2 months. This suggests that, in order to sustain a long-term P-removal in subsurface flow constructed reed beds, precipitation reactions of insoluble P-salts should be promoted. P-binding energy constants were not significantly related to the physico-chemical properties of the sands, except the Ca content, which showed, however, a low correlation coefficient.

Role of the transmembrane domain of the VanT serine racemase in resistance to vancomycin in Enterococcus gallinarum BM4174

Enterococcus gallinarum BM4175 (a vancomycin-susceptible derivative of BM4174 obtained by insertional inactivation of vanC-1) was transformed with plasmid constructs pCA10 (containing the genes necessary for resistance, vanC-1-XYc-T), pJP1 (with a fragment lacking the DNA encoding the transmembrane region of VanT, -vanC-1-XYc-T((Delta))(2-322)-) and with plasmids containing fragments encoding either the transmembrane (mvanT(1-322)) or racemase (svanT(323-698)) domains of VanT under the control of a constitutive promoter. Accumulated peptidoglycan precursors were measured in all strains in the presence of L-Ser, D-Ser (50 mM) or in the absence of any growth supplement. Uptake of 0.1 mM L-[(14)C]serine was also determined in BM4174, BM4175 and BM4175/pCA10. Vancomycin resistance was restored in BM4175 transformed with pCA10(C-1-XYc-T), and the profile of peptidoglycan precursors was similar to wild-type E. gallinarum BM4174. Transformation of E. gallinarum BM4175 with plasmid pJP1(vanC-1-XYc-T((Delta))(2-322)) resulted in: (i) vancomycin MICs remaining within susceptible levels (< or =4 mg/L) in the absence of any growth supplement, but increasing to 8 mg/L when either L-Ser or D-Ser was added to the medium; and (ii) the relative amounts of accumulated UDP-MurNAc-pentapeptide[D-Ser] and tetrapeptide precursors decreasing substantially compared with BM4175/pCA10 and BM4174. The effect on the appearance of tetrapeptide appeared to be host dependent, since a substantial amount was present when the same plasmid construct pJP1(vanC-1-XYc-T((Delta))(2-322)) was electroporated into Enterococcus faecalis JH2-2. The uptake of L-[(14)C]Ser at 240 s was decreased by approximately 40% in BM4175 compared with BM4174. Plasmid pCA10(C-1-XY(C)-T) restored uptake of L-[(14)C]Ser at 180 and 240 s in BM4175. The results suggest that the transmembrane domain of VanT is likely to be involved in the transport of L-Ser, and that in its absence the resistance phenotype is compromised.

Multicentre surveillance of antimicrobial resistance in enterococci and staphylococci from Colombian hospitals, 2001-2002

Invasive isolates of staphylococci and enterococci were collected from 15 tertiary care centres in five Colombian cities from 2001 to 2002. A total of 597 isolates were available for analysis. Identification was confirmed by both automated methods and multiplex PCR assays in a central laboratory. Staphylococcus aureus and coagulase-negative staphylococci (CoNS) corresponded to 49.6% and 29.6% of isolates, respectively, and 20.8% were identified as enterococci. MICs of ampicillin, ciprofloxacin, chloramphenicol, erythromycin, gentamicin, linezolid, oxacillin, rifampicin, teicoplanin, tetracycline, trimethoprim/sulfamethoxazole (SXT) and vancomycin were determined using an agar dilution method as appropriate. Screening for vancomycin-resistant S. aureus was also carried out on brain-heart infusion agar plates supplemented with vancomycin. The presence of mecA and van genes was investigated in methicillin-resistant staphylococci and glycopeptide-resistant enterococci (GRE), respectively. All staphylococci were susceptible to vancomycin, teicoplanin and linezolid. No VISA isolates were found. In S. aureus and CoNS, the lowest rates of resistance were found for SXT (7.4%) and chloramphenicol (10.7%), respectively. Resistance to oxacillin in S. aureus and CoNS was 52% and 73%, respectively. The mecA gene was detected in 97.5% of methicillin-resistant S. aureus isolates. In enterococci, resistance to glycopeptides was 9.7%: vanA (58.3%) and vanB (41.7%) genes were found. Pulsed-field gel electrophoresis indicated that the GRE isolates were closely related. Rates of resistance to ampicillin, ciprofloxacin, chloramphenicol, rifampicin and high levels of gentamicin and streptomycin were 9.7%, 27.4%, 8.9%, 43%, 17% and 28.2%, respectively. All enterococci were susceptible to linezolid.

Removal of indicator bacteria from municipal wastewater in an experimental two-stage vertical flow constructed wetland system

The removal of sanitary indicator bacteria (total coliforms, faecal coliforms, and faecal streptococci) was studied in an experimental constructed wetland system consisting of (1) a 2-m3 three-chamber sedimentation tank, (2) a 5 m2 vertical flow constructed wetland, (3) a filter-unit with calcite aimed at removing phosphorus, and (4) a 10 m2 vertical flow constructed wetland. The indicator bacteria were enumerated before and after each unit of the wetland system during four monitoring episodes with different loading conditions. At a hydraulic loading rate of 520-1,370 mm/d, the first-stage vertical flow beds removed about 1.5 log-units of total coliforms, 1.7 log-units of faecal coliforms and 0.8 log-units of faecal streptococci. In the second stage bed receiving lower loadings both in term of concentration and quantity (260-690 mm/day), the eliminations were lower. It was not possible in the present study to identify any seasonal effects, but no measurements were done during summer. Recycling of treated effluent back to the sedimentation tank did not affect elimination. Area-based rate constants for the vertical flow wetland receiving effluent from the sedimentation tank averaged 3.2 m/d for total coliforms, 3.3 m/d for faecal coliforms and 2.1 m/d for faecal streptococci. The rate constants depended on loading rates. It is suggested that filtration is a major removal mechanism for bacterial indicator organisms in vertical flow constructed wetland systems.

Phosphorus removal from municipal wastewater in an experimental two-stage vertical flow constructed wetland system equipped with a calcite filter

Laboratory studies have indicated that calcite may be used in separate, exchangeable filter units in constructed wetland systems to remove phosphorus. Based on these studies we built a full-scale experimental constructed wetland with a calcite-based filter unit to study its performance, under real-life conditions. The system consists of a 2-m3 sedimentation tank and two vertical flow constructed wetlands. The system has three 0.09 m3 calcite filter-units to study phosphorus removal. The hydraulic loading rate varied between 1.7 and 6.2 m3/d. The residence time in filters ranged from 28 to 99 minutes. Overall the system removed 62 +/- 18% of phosphorus. The removal in the calcite filter was initially good, but after three months all P-filters were saturated. The calcite increased pH by approximately half a unit and released calcium. A total of about 2.2 kg P/m3 calcite was removed by the filter. The first-stage bed receiving effluent from the sedimentation tank consistently removed phosphorus, whereas the second bed sometimes released phosphorus. The first order area-based removal rate constant for total-P in the vertical bed averaged 0.24 +/- 0.20 m/d and was highly dependent on the loading rate. This shows that first order removal kinetics do not satisfactorily describe removal of phosphorus in vertical flow constructed wetland systems with unsaturated flow.

Phosphorus removal by sands for use as media in subsurface flow constructed reed beds

Sorption of P to the bed sand medium is a major removal mechanism for P in subsurface flow constructed reed beds. Selecting a sand medium with a high P-sorption capacity is therefore important to obtain a sustained P-removal. The objective of this study was to evaluate the P-removal capacities of 13 Danish sands and to relate the removal to their physico-chemical characteristics. The P-removal properties were evaluated in short-term isotherm batch-experiments as well as in 12-week percolation experiments mimicking the P-loading conditions in constructed reed bed systems. The P-removal properties of sands of different geographical origin varied considerably and the suitability of the sands for use as media in constructed reed beds thus differs. The P-removal capacity of some sands would be used up after only a few months in full-scale systems, whereas that of others would persist for a much longer time. The most important characteristic of the sands determining their P-removal capacity was their Ca-content. A high Ca content favours precipitation with P as sparingly soluble calcium phosphates particularly at the slightly alkaline conditions typical of domestic sewage. In situations where the wastewater to be treated is more acid, the contents of Fe and Al may be more important as the precipitation reactions with these ions are favoured at lower pH levels. The maximum P-sorption capacities estimated using the Langmuir-isotherm plots did not correspond to or correlate with the actual amount of P removed in the percolation columns. Hence, the Langmuir-isotherm does not estimate the P-removal capacities of sands. It is suggested that a suitable quick method of screening a selection of potential media for P-removal potential is to perform simple removal isotherm studies using water with a similar chemical composition as the wastewater to be treated. This method will not provide a direct estimate of the P-removal capacity that can be obtained in full-scale systems, but it is a means of comparing the relative performance of potential media.

Urocortin II: a member of the corticotropin-releasing factor (CRF) neuropeptide family that is selectively bound by type 2 CRF receptors

Here we describe the cloning and initial characterization of a previously unidentified CRF-related neuropeptide, urocortin II (Ucn II). Searches of the public human genome database identified a region with significant sequence homology to the CRF neuropeptide family. By using homologous primers deduced from the human sequence, a mouse cDNA was isolated from whole brain poly(A)(+) RNA that encodes a predicted 38-aa peptide, structurally related to the other known mammalian family members, CRF and Ucn. Ucn II binds selectively to the type 2 CRF receptor (CRF-R2), with no appreciable activity on CRF-R1. Transcripts encoding Ucn II are expressed in discrete regions of the rodent central nervous system, including stress-related cell groups in the hypothalamus (paraventricular and arcuate nuclei) and brainstem (locus coeruleus). Central administration of 1-10 microg of peptide elicits activational responses (Fos induction) preferentially within a core circuitry subserving autonomic and neuroendocrine regulation, but whose overall pattern does not broadly mimic the CRF-R2 distribution. Behaviorally, central Ucn II attenuates nighttime feeding, with a time course distinct from that seen in response to CRF. In contrast to CRF, however, central Ucn II failed to increase gross motor activity. These findings identify Ucn II as a new member of the CRF family of neuropeptides, which is expressed centrally and binds selectively to CRF-R2. Initial functional studies are consistent with Ucn II involvement in central autonomic and appetitive control, but not in generalized behavioral activation.

Media selection for sustainable phosphorus removal in subsurface flow constructed wetlands

Sorption of phosphorus (P) to the bed sand medium is a major removal mechanism for P in subsurface flow constructed wetlands. Selecting a sand medium with a high P-sorption capacity is therefore important to obtain a sustained P-removal. The P-removal capacities of 13 Danish sands were evaluated and related to their physico-chemical characteristics. The P-removal properties of sands of different geographical origin varied considerably and the suitability of the sands for use as media in constructed reed beds thus differs. The P-sorption capacity of some sands would be used up after only a few months in full-scale systems, whereas that of others would subsist for a much longer time. The most important characteristic of the sands determining their P-sorption capacity was their Ca-content. Also the P-binding capacities of various artificial media were tested (light-expanded-clay-aggregates (LECA), crushed marble, diatomaceous earth, vermiculite and calcite). Particularly calcite and crushed marble were found to have high P-binding capacities. It is suggested that mixing one of these materials into the sand or gravel medium can significantly enhance the P-sorption capacity of the bed medium in a subsurface-flow constructed wetland system. It is also possible to construct a separate unit containing one of these artificial media. The media may then be replaced when the P-binding capacity is used up.