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Constructed wetlands (CWs) are well-proven ecologically engineered systems that remove nutrients, pathogens, and other contaminants from wastewater. The inherent role of CWs as wastewater polishing systems makes them hotspots for microplastic accumulation. To investigate the transport and characteristics of microplastic pollution in full-scale surface flow municipal CWs, environmental microplastic samples were collected from the Se7en/Seven Wetlands in Lakeland (Florida), one of the largest wastewater CWs in the United States (650 hectares). Both water and sediment samples were collected at eight control stations in each of the seven wetland cells and at six locations in the influent distribution channel to investigate the linkage between water and sediments in microplastic fate and transport. This study found that the Se7en Wetlands has a near complete retention of microplastics greater than 300 μm. Concentrations at each sampling site in the CW ranged from 0 to 17 particles/m3 in water and 0–1217 particles/kg dry weight in sediment. The highest concentrations of particles were found in sediment samples, especially those found in locations of reduced flow, signaling settling occurring as water velocities decrease. Microplastics were also analyzed for size, shape indicators, and polymer type to inform how their properties change as they travel through the system. Particles were extracted visually and analyzed using ImageJ and Raman spectroscopy. Polyethylene and polypropylene were the most abundant polymer types with the highest proportion of particles being fragments between 1 and 5 mm in size. Shape indicators (particle area, circularity, and solidity) in water decreased through the treatment stream, whereas sediment samples saw no clear trend. Overall, this study finds that large CWs retain a vast amount of microplastics. It sheds light on how the dynamics of natural processes affect the fate and transport of microplastics as well as the importance of evaluating multimedia concentrations in CWs. [ABSTRACT FROM AUTHOR]

Partially Saturated Vertical Constructed Wetlands (PSV-CWs) are novel wastewater treatment systems that work through aerobic and anaerobic conditions that favor the removal of pollutants found in high concentrations, such as rivers contaminated with domestic wastewater and landfill leachate. The objective of the study was to evaluate the efficiency of PSV-CWs using monocultures and polycultures of Typha latifolia and Heliconia psittacorum to treat river waters contaminated with leachates from open dumps and domestic wastewater. Six experimental units of PSV-CWs were used; two were planted with Typha latifolia monoculture, two with Heliconia psittacorum monoculture and two with polycultures of both plants. The results indicated better organic matter and nitrogen removal efficiencies (p < 0.05) in systems with polycultures (TSS:95%, BOD5:83%, COD:89%, TN:82% and NH4+:99%). In general, the whole system showed high average removal efficiencies (TSS:93%, BOD5:79%, COD:85%, TN:79%, NH4+:98% and TP:85%). Regarding vegetation, both species developed better in units with monocultures, being Typha latifolia the one that reached a more remarkable development. However, both species showed high resistance to the contaminated environment. These results showed higher removals than those reported in the literature with conventional Free Flow Vertical Constructed Wetlands (FFV-CWs), so PSV-CWs could be a suitable option to treat this type of effluent. NOVELTY STATEMENT: The research addresses the contamination of water resources in developing countries by landfill leachate and domestic wastewater discharges. It proposes treatment through Partially Saturated Vertical Constructed Wetlands (PSV-CWs), which, despite the limited information available, have been shown to be effective in removing pollutants in effluents with high concentrations. In addition to evaluating PSV-CWs, the study examines the impact of different types of vegetation on pollutant removal efficiency, concluding that PSV-CWs are a promising and viable option for the treatment of these effluents. [ABSTRACT FROM AUTHOR]

Natural water resources often contain fluorides and chlorides due to wastewater discharge; however, excessive exposure to fluorides can pose health risks to humans. Elevated chloride levels can negatively affect aquatic fauna and disrupt the reproductive rates of plants. This study assessed constructed wetlands (CWs) featuring monocultures (including Canna hybrid, Alpinia purpurata, and Hedychium coronarium) and polycultures (combinations of species from the monoculture systems) of ornamental plants (OPs) to evaluate their efficiency in removing fluorides and chlorides. The results revealed that the ornamental plants flourished in the CW conditions without sustaining any physical damage. C. hybrid demonstrated the longest roots and the highest volume, as well as greater height compared to other species. However, this did not affect the ion removal efficiency. In polyculture systems, 42.2 ± 8.8% of fluoride was removed, a result that was not significantly different (p > 0.05) from the removal rates observed in monocultures of C. hybrid (42.5 ± 7.5%), H. coronarium (36.8 ± 7.0%), or A. purpurata (30.7 ± 7.9%). For chloride, a similar pattern emerged, with 32.4 ± 4.8% removed in constructed wetlands (CWs) using a polyculture of ornamental plants, a figure that was also not significantly different (p > 0.05) from the removal percentages in monocultures of C. hybrid (29.1 ± 5.3%), H. coronarium (28.1 ± 5.0%), or A. purpurata (32.0 ± 5.7%). Our results indicate that CWs with polyculture species contribute to pollutant removal at levels comparable to those found in monoculture systems. However, polyculture systems offer enhanced aesthetic appeal and biodiversity, incorporating various ornamental flowering plants. The use of this eco-technology for removing fluoride and chloride pollutants helps prevent river contamination and associated health issues. [ABSTRACT FROM AUTHOR]

The pig farming industry in Mexico is an important economic activity that is growing significantly, generating large volumes of wastewater that negatively affect water bodies and human health. The lack of adequate treatment systems exacerbates this problem. Hybrid constructed wetlands that combine Vertical Flow Constructed Wetlands (VF-CWs) and Horizontal Flow Constructed Wetlands (HF-CWs) offer an economical and effective treatment using natural processes. The objective was to evaluate the removal of contaminants from pig farm wastewater using two configurations of hybrid systems with ornamental plants. Two configurations were established: System I: VF-CWs + HF-CWs and System II: HF-CWs + VF-CWs. The VF-CWs were planted with Canna hybrids and the HF-CWs with Heliconia latispatha. The results indicated higher removal efficiencies of organic matter, nitrogen, and phosphorus in System I (BOD5: 72.99 %, COD: 71.41 %, TN: 79 %, NH4+: 84.31 %, NO3-: 74.29 %, TP: 59.54 %, FC: 99.88 %) compared to System II (BOD5: 66.80 %, COD: 67.01 %, TN: 77.90 %, NH4+: 82.31 %, NO3-: 70.48 %, TP: 55.81 %, FC: 99.89 %), regarding FC, the same results were obtained in both systems. Both plant species showed vigorous development, although the growth of Heliconia latispatha was more notable. In conclusion, the results suggest that the VF-CWs + HF-CWs configuration in hybrid wetlands could be a suitable option for treating this type of effluent.

This study investigated the use of nature‐based solutions for treating real pharmaceutical industry wastewater in Jordan. A pilot‐scale hybrid treatment wetland (TW) equipped with local zeolite was employed, comprising a tidal flow TW and a horizontal subsurface flow TW. This system was efficient in treating pharmaceutical wastewater with removal efficiencies of 61.4%, 52.6%, 60.1%, and 61.9% for chemical oxygen demand, total phosphorus, total nitrogen, and NH4+‐N, respectively. The final effluent met Jordanian standards for the reuse of treated wastewater in irrigation (Class B). Five pharmaceuticals, namely, enrofloxacin, ciprofloxacin, ofloxacin, lincomycin, and trimethoprim, demonstrated nearly completed removal (93.6–99.9%). Moderated removal performances (59.2–68.2%) were observed for two compounds, flumequine and sulfaquinoxaline. However, three pharmaceuticals, namely, carbamazepine, diclofenac, and sulfadimidine, showed limited removal performances (1.1–20.5%). This study supported the feasibility of using nature‐based solutions for treating pharmaceutical wastewater and highlighted that future studies are required to optimize this strategy for removing a broader range of pharmaceuticals. Highlights: Treatment wetland (TW) as a nature‐based solution can treat pharmaceutical wastewater.Tidal flow TW with a better aerobic condition was favourable for pollutant removal.Jordanian zeolite was a promising wetland media to enhance the treatment performance.The final effluent complied with Jordanian standards for wastewater reuse in irrigation.Some pharmaceuticals could achieve completed removal by the hybrid TW system. [ABSTRACT FROM AUTHOR]

Treatment wetlands are recognized as an effective technology for mitigating the impacts of urban runoff. However, there is no consensus on the design guidelines, and the effects of some design features, such as the underdrain system, remain unexplored. A simple analog model has been developed to mimic the underdrain network (when operating at saturation) and to evaluate the spatial heterogeneity of the flow entering it. The model has been applied to a treatment wetland in the Paris area and shows that the underdrain network was largely undersized, likely causing an uneven distribution of infiltrating flow along the length of the treatment wetland. It was also shown that this analog model can be used for optimization purposes and that it is important to use conservative values of the rugosity coefficient when designing an underdrain network. HIGHLIGHTS A brand-new analog model has been developed to mimic the hydraulic functioning of the underdrain.; Inflows into the underdrain decrease with the distance to the outlet.; Undersized underdrains can create uneven distribution of the percolating flow along the length of a treatment wetland (TW).; The analog model allows optimizing the design of underdrains for TWs with a saturated layer at the bottom.;

Natural water resources often contain fluorides and chlorides due to wastewater discharge; however, excessive exposure to fluorides can pose health risks to humans. Elevated chloride levels can negatively affect aquatic fauna and disrupt the reproductive rates of plants. This study assessed constructed wetlands (CWs) featuring monocultures (including Canna hybrid, Alpinia purpurata, and Hedychium coronarium) and polycultures (combinations of species from the monoculture systems) of ornamental plants (OPs) to evaluate their efficiency in removing fluorides and chlorides. The results revealed that the ornamental plants flourished in the CW conditions without sustaining any physical damage. C. hybrid demonstrated the longest roots and the highest volume, as well as greater height compared to other species. However, this did not affect the ion removal efficiency. In polyculture systems, 42.2 ± 8.8% of fluoride was removed, a result that was not significantly different (p > 0.05) from the removal rates observed in monocultures of C. hybrid (42.5 ± 7.5%), H. coronarium (36.8 ± 7.0%), or A. purpurata (30.7 ± 7.9%). For chloride, a similar pattern emerged, with 32.4 ± 4.8% removed in constructed wetlands (CWs) using a polyculture of ornamental plants, a figure that was also not significantly different (p > 0.05) from the removal percentages in monocultures of C. hybrid (29.1 ± 5.3%), H. coronarium (28.1 ± 5.0%), or A. purpurata (32.0 ± 5.7%). Our results indicate that CWs with polyculture species contribute to pollutant removal at levels comparable to those found in monoculture systems. However, polyculture systems offer enhanced aesthetic appeal and biodiversity, incorporating various ornamental flowering plants. The use of this eco-technology for removing fluoride and chloride pollutants helps prevent river contamination and associated health issues.

Nature-based solutions are increasingly used in domestic wastewater treatment, because of their potential to remove contaminants and pathogens from water (e.g., stormwater, river water, wastewater) as well as their provided co-benefits, such as mitigation of the heat island effect or enhanced biodiversity. The transition from traditional grey technologies towards nature-based solutions in domestic wastewater treatment might yield multiple benefits for local communities while enhancing biodiversity. Although some nature-based solutions such as treatment wetlands have been used for decades in domestic wastewater treatment, this is not the case for others such as green walls or roofs, which lack implementation guidelines and design criteria. Aiming to support implementation of nature-based solutions in domestic wastewater treatment, we have developed an online decision-support system for the pre-selection of the best nature-based solution to use in each socio-environmental context and adapted to the needs, as well as an estimate of the required area. Our decision-support system's recommendations are based on an expert knowledge-driven approach, building on two complementary expert knowledge elicitation workshops. We hope the developed online decision-support system will support the transition towards integrating nature-based solutions into urban water and wastewater treatment systems. HIGHLIGHTS We lack implementation guidelines and design criteria for nature-based solutions (NBS) in water sanitation.; We have developed an online decision-support system to facilitate NBS implementation.; NBS implementation in domestic wastewater treatment will support SDG6 achievement.;

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. HIGHLIGHTS VF-TWs with the proposed modifications (bed depth, feeding/resting period; footprint reduction; zeolite as medium) had effective removal of total solids, organic matter, and pathogens.; VF-TWs with the proposed modifications were shown to be robust and able to cope with flow variations in tourist facilities of rural areas.; Further work should be conducted for consistent nitrogen removal in VF-TWs with the proposed modifications.;

Distillery wastewater is a difficult type of wastewater to treat because of its low pH (pH = 3.3), high chloride and sulfate content, high organic matter concentrations (3.2 gTSS/L, 6.8 gBOD5/L and 14.6 gCOD/L). Moreover, the rum production is intermittent over the season (5 months per year). The acidity of this type of wastewater, combined with the relatively underbalanced nitrogen concentrations, requires the addition of specific chemicals such as soda solution and urea, when a biological treatment technology is envisioned. In this full scale experiment, located in a tropical zone (Martinique island), the objective was to demonstrate the ability of treatment chain composed of a sequencing batch reactor (SBR) followed by vertical flow treatment wetlands (VFTWs). The objective was to use VFTWs for treatment polishing as well as sludge/water separation and sludge treatment over years. The VFTWs are planted with Heliconia psittacorum and Cyperus papyrus. The monitoring occurred during three rum production seasons. The treatment chain allows an overall average removal of TSS of 92% and 96% for organic matter (COD and BOD5). The average annual load applied to the filter in operation was 32 kgTSS/m²/y, which is equivalent to 78 kgTSS/m²/y over the distillation period. The applied load was too high for the plants tested and lead to plant death and surface clogging of the filters. Nevertheless, this experiment allowed specifying the way to operate the whole treatment plant as well as acceptable daily loads that should be applied on the VFTWs. Even if the operation of the filters and the selection of plants in a tropical climate still need to be optimized, this combination of intensive and extensive processes is an effective and sustainable nature-based solution for rum distillery wastewater treatment.

In recent decades, previously unobserved trace compounds have become more widely detected in wastewater treatment effluents and freshwater ecosystems. Emanating from various sources and presenting potential human health and ecological risks at much lesser concentrations than traditional contaminants, detection of "emerging contaminants" has increased with improvements in analytical techniques. The behavior of emerging contaminants in wetlands is a topic of increasing interest, as natural wetlands are known to transform and sequester pollutants and constructed or treatment wetlands are widely utilized to address elevated concentrations of constituents of concern. Both natural and constructed wetlands are complex biogeochemical systems with interrelated abiotic and biotic mechanisms leading to the removal of emerging contaminants. A literature review was performed to assess the current state of knowledge of various wetland mechanisms involved in removing these contaminants from surface waters and effluents. The primary mechanisms discussed in the literature are sorption, photodegradation, microbial biodegradation and phytoremediation. The most influential mechanisms are dependent on the properties of the contaminants and wetland systems studied. Common trends exist for different constructed wetland designs to leverage various mechanisms based on hydrology, substrate and vegetation plantings. Much remains to be understood about the various processes occurring in wetlands as they relate to emerging contaminant removal. Improving the understanding of the potential role of wetland mechanisms can help manage this environmental challenge more effectively. [ABSTRACT FROM AUTHOR]

Free water surface (FWS) wetlands can be used to treat agricultural runoff, thereby reducing diffuse pollution. However, as these are highly dynamic systems, their design is still challenging. Complex models tend to require detailed information for calibration, which can only be obtained when the wetland is constructed. Hence simplified models are widely used for FWS wetlands design. The limitations of these models in full-scale FWS wetlands is that these systems often cope with stochastic events with different input concentrations. In our study, we compared different simple transport and degradation models for total nitrogen under steady- and unsteady-state conditions using information collected from a tracer experiment and data from two precipitation events from a full-scale FWS wetland. The tanks-in-series model proved to be robust for simulating solute transport, and the first-order degradation model with non-zero background concentration performed best for total nitrogen concentrations. However, the optimal background concentration changed from event to event. Thus, to use the model as a design tool, it is advisable to include an upper and lower background concentration to determine a range of wetland performance under different events. Models under steady- and unsteady-state conditions with simulated data showed good performance, demonstrating their potential for wetland design. HIGHLIGHTS The most robust model combination: the tanks-in-series model under steady conditions.; First-order kinetics with non-zero background concentration was the best for degradation.; The optimal background concentration changed from event to event.; Potential use of TIS model in unsteady conditions when infiltration and evapotranspiration occur.;

[Display omitted] • Coupling of anaerobic process with constructed wetlands. • Full-scale sub-mesophilic sewage treatment with high-purity CH 4 recovery. • Anaerobic reactor COD utilization correlation with temperature. • >94 % BOD 5 and > 97 % TSS removal from the integrated system. • Nutrient-rich reclaimed water suitable for fertigation. This work investigated the long-term (>1000 days) performance of an integrated process consisting of an upflow anaerobic sludge blanket (UASB) coupled to a two-stage (saturated and unsaturated) vertical subsurface flow constructed wetland (VSSF-CW) for the treatment of up to 91.3 ± 10.3 m3/d domestic wastewater. The UASB reactor operated under ambient conditions during both the winter (temperature of 13.5 ± 0.7 °C) and the summer (temperature of 26.4 ± 0.8 °C). The two-stage CW treated the UASB effluent to maximize the total suspended solids (TSS) and chemical oxygen demand (COD) removal of the integrated process and oxidize ammonium to nitrate. The UASB reactor was able to remove 50 % ± 17 % to 83 % ± 9 % of TSS and 43 % ± 18 % to 76 % ± 3 % of COD, producing on average 0.36 Nm3 CH 4 kg COD rem –1 of biogas, which varied significantly with season. The two-stage CW contributed to the further removal of the pollutants achieving overall removal of TSS ranging from 97 % ± 3 % to 99 % ± 0 % and COD from 91 % ± 2 % to 96 % ± 1 %. The influent ammonium nitrogen removal ranged between 87 % ± 4 % and 99 % ± 0 % via nitrification. This operation scheme allowed nutrient retention in the final effluent as the total nitrogen and total phosphorus removal was only partial (no more than 41 % ± 7 % and 44 % ± 13 %, respectively). The results suggest that the UASB – CW integration is a very promising solution to produce energy and Class A reclaimed water (EU Regulation 2020/741). The robustness and effectiveness of the treatment process against loading and temperature fluctuations can prevent the quality compromise of the final effluent. [ABSTRACT FROM AUTHOR]

Constructed Wetlands (CW) have gained popularity over the last decades due to their cost-effectiveness, easy and simple operation and environmental compatibility in wastewater treatment. This ecological engineering technology appears particularly ideal for low-income regions. In this study, three widely used CW types (horizontal flow, vertical flow, and hybrid CW) were constructed and evaluated for their effectiveness in removing various pollution parameters (BOD 5 , COD, TSS, NH 4 -N, NO 3 -N, and TP) from an industrial effluent. Different configurations were tested such as CW type, hydraulic residence time, plants presence, and artificial aeration. Results showed that the hybrid CW configuration (i.e., vertical flow CW followed by horizontal subsurface flow CW) achieved the highest removal rates of all pollutants, i.e., more than 90% of BOD 5 , COD, TSS, and NH 4 -N. The single horizontal flow and vertical flow CW designs showed variations in the removal of NO 3 -N and TP (less than 30%), which were significantly improved (50% and 70%, respectively) by using the hybrid CW system. Artificial aeration significantly improves the performance of the CW system, especially for ammonia nitrogen and organic matter removal, while plants presence is also beneficial in the treatment performance. An 8-days HRT seems to be adequate for high removal rates in passive CW designs, though in aerated wetlands a lower HRT of 4 days seems sufficient. These findings suggest that the hybrid CW system could be a promising option for efficient wastewater treatment in developing regions. [Display omitted] • High effect of artificial aeration on BOD 5 and NH 4 -N removal compared to other variables. • The presence of plants in all designs enhances the system performance. • The hybrid system (VF combined with HF) provides the highest pollutant removal rates. • Increasing the retention time significantly increases the nutrient removal efficiency. • An efficiency of over 95% in BOD 5 , COD, TSS and NH 4 -N removal was achieved. [ABSTRACT FROM AUTHOR]

Treatment wetlands have the potential to treat a range of water and wastewater pollutants while using less energy and chemicals than conventional treatment processes, making them a viable option for improving the sustainability of water treatment systems. However, water treatment systems used for water reuse must also be protective of human health. To date, the human health protection benefits of treatment wetlands have not been rigorously quantified in the context of current human health risk frameworks. This study presents a comprehensive review of the ability of treatment wetlands to provide reliable pathogen reduction to meet risk-based treatment targets for water reuse. Following an existing protocol for establishing log reduction credits, we systematically reviewed the documented pathogen reduction performance of major treatment wetland types in terms of core components of that protocol, including pathogen removal mechanisms, identification of target pathogens, and influencing factors. Results of the review point to design and operational conditions under which treatment wetlands could likely be credited with a log reduction value of approximately 0.5 or greater for virus, protozoa and bacteria. These conditions are specified in terms of preliminary operating envelopes, or design and operational parameter windows associated with optimal performance. Important caveats are noted, as are specific and tractable recommendations for future research and data collection efforts that would help refine operating envelopes and define log reduction credits for these promising water treatment technologies. As a resource to other practitioners, we have also included the detailed performance characterization database as Supplemental Information. This database includes a detailed tracking of log reduction values as well as design and operational parameters reported in the literature., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier B.V.)

Wastewater treatment using constructed wetlands (CWs) based on natural wetlands constitute a viable alternative with excellent cost and benefit, presenting themselves as efficient technologies in the secondary and tertiary treatment of wastewaters with low implementation, operation, and maintenance costs. The present study aims to evaluate the use of bamboo species, as an alternative to macrophytes, frequently used in CWs, through bibliometric analysis, besides to a review based on case studies. The maps generated by the VOSviewer software and by the analyses of the Web of Science and Scopus databases allowed for a review of typical concepts of CWs, in addition to revealing potential benefits of using bamboos in CWs, such as their hyperaccumulation capacity and bioproduct generation. Other promising aspects were identified, for example the use of bamboo charcoal as a substrate used in subsurface wetlands and the application of ornamental bamboo species for landscape improvements, among other observations. The efficiencies found in six case studies showed values between 89–99.7%, 47.6–99.7%, 58.3–99.9%, and 85.5–99.8% for BOD5, COD, total nitrogen (TN), and total phosphorus (TP), respectively. Despite the promising results, the lack of studies using bamboos in CWs for the treatment of wastewaters limits an assertive statement about the use of this technology, requiring further research, focusing on the morphological functions of bamboos in this treatment with landscape integration and resources recovery. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the removal efficiency and the hydraulic behavior of the 10-year-old hybrid treatment wetland (TW) system treating effluents of the IKEA® store of Catania (Eastern Sicily, Italy), under Mediterranean semi-arid climate conditions. The system is placed downstream to the conventional wastewater (WW) treatment of the store, that includes a sequential batch reactor (SBR) followed by a horizontal subsurface treatment wetland (HF) unit and two vertical subsurface flow treatment wetlands (VF1 and VF2) units. The assessment of chemical, physical, and microbiological parameters in treated WW was carried out through regular monitoring activities, occurring approximately on a monthly basis, over a 8-year period spanning from 2016 to 2023. Up to 72 samples were collected for the following parameters measurements: total suspended solids (TSS), BOD 5 , COD, total phosphorus (TP), ammonia (as NH 4), nitrate (as NO 3 -N), nitrite (as NO 2 -N), total nitrogen (TN) and E. coli. Hydraulic conductivity at saturation (K s) measurements and tracer tests were conducted to evaluate the extent of clogging and to characterize the hydraulic behavior within the HF unit. Results obtained during the entire monitoring period show the following mean and standard errors (±) removal efficiency ranges (%): TN 21(±11)-80(±9); TSS 18(±42)-95(±3); COD 28(±23)-93(±2); BOD 5 31(±10)-85(±44); TP 14(±6)-49(±19); NH 4 50(±50)-95(±3); E. coli was abated with a mean range of 3.3(±0.2)-4.8(±0.4) Ulog reduction, reaching not detectable values in most samples analyzed since 2018. The efficacy of the treatment system is assessed in the context of both national and European regulatory frameworks governing effluent discharge and water reuse standards. K s values and tracer test results agree in showing the progressive clogging of the HF unit influencing the hydraulic behavior of the unit giving useful on the management of TWs in Mediterranean area. Finally, the performance results also indicate that the overall treatment is not affected by the HF unit clogging. • Clogging evolution may eventually result in ponding phenomena and sanitation risks. • In spite of the clogging occurrence TW effluent quality meets standard requirements. • A correct TW management allows safe toilet flushing and green areas irrigation reuse. [ABSTRACT FROM AUTHOR]

• Mass balance shows that wetland plants and microbes are crucial for PFAS removal in TWs. • Wetland plants adsorb and transfer long-chain PFAS better than terrestrial plants. • Wetland microbes can degrade PFAS by head group transformation and defluorination. • Wetland plants and microbes are pivotal in the sustainable removal of PFAS. Poly- and perfluoroalkyl substances (PFAS) are widespread emerging contaminants in aquatic environments, raising serious concerns due to their persistence and potential toxicity to both human health and ecosystems. Treatment wetlands (TWs) provide a sustainable, low-carbon solution for PFAS removal by harnessing the combined actions of substrates, plants, and microorganisms. This review evaluates the effectiveness of TWs in PFAS treatment, emphasizing their role as a post-treatment option for conventional wastewater treatment plants. Mass balance analysis reveals that substrate adsorption was the primary pathway for PFAS removal from TWs, while plant uptake and subsequent harvesting treatments, as well as microbial degradation, contribute substantially to long-term PFAS removal. Comparisons of bioaccumulation factor (BCF) and translocation factors (TF) between wetland and terrestrial plants demonstrate that wetland plants are particularly effective at adsorbing long-chain PFAS and transferring them from roots to aboveground tissues. The diverse environmental conditions within TWs support varied microbial communities, facilitating the evolution of PFAS-degrading microorganisms. Wetland microorganisms demonstrate the capacity to break down PFAS through processes such as head group transformations (e.g., decarboxylation, desulfonation) and defluorination (e.g., elimination, reductive defluorination, hydrolysis, dealkylation). This review emphasizes the crucial role of wetland plants and microorganisms in the sustainable removal of PFAS in TWs, providing insights for the ecological remediation of PFAS-contaminated wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

Upgrading treated wastewater systems can provide reclaimed water for different uses. In this paper, the potential for wetland creation and maintenance is evaluated. The upgrading treatment consists of intensified vertical flow constructed wetlands (VFCWs), where the physicochemical and microbiological water quality is improved, followed by free-water surface constructed wetlands (FWSCWs), where biodiversity is enhanced. This renaturalization system has been implemented in two wastewater treatment plants (WWTPs): Monasterios, where one VFCW 60 m2 and two FWSCWs (50 m2 each) have been built, and Carricola, where two VFCWs in series (20 m2 each) have been constructed. The VFCWs were filled with drinking water treatment sludge (DWTS), a waste produced in drinking water treatment plants, hence the circularity of the project. Data obtained during the first year of operation is presented. The mean hydraulic loading rates in the VFCWs were 0.79 and 0.62 m/d in Monasterios and Carricola, respectively. In FWSCWs, the HLRs were 0.35 and 0.32 m/d in FWSCW1, which receives the effluent of the VFCW, and FWSCW2, which receives the secondary treatment effluent, respectively. In the VFCWs, an important reduction of total phosphorus was achieved, 77% in Monasterios and 70% in Carricola, and other pollutants were fairly reduced as well. In FWSCWs, some pollutants, such as total nitrogen or phosphorus, were reduced, but other, such as total suspended solids or organic matter, increased due to algae growth and external inputs. The critical point is that biodiversity is increased thanks to these systems, aquatic invertebrate presented better diversity indexes in the FWSCW receiving the upgraded water from the intensified VFCW. Birds, amphibians, and reptiles have also colonised the created habitats. • Treated wastewater can be upgraded by intensified vertical flow constructed wetlands. • Drinking water treatment sludge is an appropriate adsorbent material. • Valorisation of drinking water treatment sludge integrates circularity in urban water cycle. • Upgraded water benefits the receiving water bodies, enhancing biodiversity. • Birds use the created wetlands to feed, rest and nest. [ABSTRACT FROM AUTHOR]

In response to the global loss and degradation of wetland ecosystems, extensive efforts have been made to reestablish wetland habitat and function in landscapes where they once existed. The reintroduction of wetland ecosystem services has largely occurred in two categories: constructed wetlands (CW) for wastewater treatment, and restored wetlands (RW) for the renewal or creation of multiple ecosystem services. This is the first review to compare the objectives, design, performance, and management of CW and RW, and to assess the status of efforts to combine CW and RW as Integrated Constructed Wetlands (ICW). These wetland systems are assessed for their ecological attributes and their relative contribution to ecosystem services. CW are designed to process a wide variety of wastewaters using surface, subsurface, or hybrid treatment systems. Designed and maintained within narrow hydrologic parameters, CW can be highly effective at contaminant transformation, remediation, and sequestration. The ecosystem services provided by CW are limited by their status as high-stress, successionally arrested systems with low landscape connectivity and an effective lifespan. RW are typically situated and designed for a greater degree of connection with regional ecosystems. After construction, revegetation, and early successional management, RW are intended as self-maintaining ecosystems. This affords RW a broader range of ecosystem services than CW, though RW system performance can be highly variable and subject to invasive species and landscape-level stressors. Where the spatial and biogeochemical contexts are favorable, ICW present the opportunity to couple CW and RW functions, thereby enhancing the replacement of wetland services on the landscape. [ABSTRACT FROM AUTHOR]

Passive treatment wetlands are conventionally designed with the primary objective of purifying contaminated mine water; any benefit of enhanced biodiversity is ancillary. We propose a new approach that incorporates enhanced biodiversity as an explicit objective. In this approach, treatment units are selected based on water flows and chemistry and the ecological requirements of key species are identified. Elements of the wetland design that meet these distinct requirements are selected and sized, then merged within the constraints imposed by site geomorphology and hydrology. This concept is illustrated with the wetland design for the Los Bronces Mine in Chile, where aspects of treatment, biodiversity, and water management were developed separately, and then integrated into a holistic design. The treatment wetlands are integrated within the local ecology. This approach adheres more closely to the objective of designing wetlands that offer ecosystem services and also meets the requirements for long-term water treatment. [ABSTRACT FROM AUTHOR]

Drinking water treatment sludge (DWTS) is the main waste produced in drinking water treatment plants (DWTPs). Its valorisation as substrate for constructed wetlands (CWs) aimed at upgrading treated urban wastewater is presented. Keeping a holistic approach in mind, this study looks for nutrient and organic matter removal but also contaminants of emerging concern (CECs) and pathogens. Three pilot subsurface flow CWs (1 m2) were installed under outdoor conditions in real WWTPs. Different operation modes (sequential: S-CW and continuous saturated flow: C-CW, CC-CW), different nutrient influent concentrations (S-CW and C-CW: 0.6 mg TP/l, 12.7 mg TN/l; CC-CW: 6.5 mg TP/l, 48 mg TN/l) and high hydraulic loading rates (HLRs, 0.9-5.1 m3/m2/d) were tested. C-CW presented higher removal efficiencies than S-CW for TP (C-CW: 56-86%; S-CW: 32-66%), total nitrogen (C-CW: 23-38%; S-CW: -3 to 6%) and E. coli (C-CW: 94%; S-CW: 84%), while S-CW performed better for ammonium (C-CW: 29-45%; S-CW: 72-86%) and CECs removal. Among fifteen CECs monitored, most pharmaceuticals, four were significantly reduced in C-CW and nine in S-CW, which had more aerobic conditions. CC-CW reduced nutrients and organic matter by 62% (TP), 8% (TN), 23% and 40% (chemical and biochemical oxygen demands, respectively). The potential release of aluminium was negligible. Novel values for the first-order reaction coefficient of P-k-C* model are provided for the TP removal process using DWTS (0.6-1.0 h-1). The main conclusion is that DWTS is a suitable substrate to significantly upgrade WWTP effluents, even at high HLRs. A hybrid system combining sequential and continuous flow modes could optimize the upgrading treatment. A proposal for the full valorisation of the sludge produced in one DWTP is presented. [ABSTRACT FROM AUTHOR]

This study deals with the dairy wastewater treatment using laboratory scale vertical flow (VF) constructed wetlands with the Canna indica plantation over wetland beds due to phytoremediation capabilities. Three laboratory scale VF CWs (CW-A, CW-B and CW-C) each with an area of 0.135 m2 filled with gravel (CW-A: 20 mm; CW-B:10 mm gravel) and sand (CW-C) receiving 0.04 m³ d-1 dairy wastewater were operated for the wastewater purification. Each unit was operated at three hydraulic retention times (HRTs) i.e. 12 h, 24 h and 48 h for assessing its effect on wastewater purification. Among all units, removal rates fluctuated as: total suspended solids (TSS): 64.2-74.5%; biochemical oxygen demand (BOD): 45.3 - 63.1%; ammonium nitrogen (NH4-N): 29.6 - 56.5% and phosphate phosphorous (PO4-P): 20.5 - 57.8% at different HRTs. Increase in HRT showed better removal of pollutants in all CWs. Moreover, maximum removal of pollutants excluding TSS and NH4-N was achieved in CW-B at 48 h HRT. CW-B with similar HRT provided maximum removal of PO4-P (57.8%), BOD (63.1%) and chemical oxygen demand (COD): 67.4%. Increase in the size of filter media, from sand (0.25 mm) to 20 mm gravel resulted in higher removal of NH4 -N from wastewater. [ABSTRACT FROM AUTHOR]

Chromium (Cr), Nickel (Ni), and zinc (Zn) removal from landfill leachate using mesocosm-scale vertical flow wetlands, the effect of recirculation, and the ability of macrophytes to retain metals were evaluated. Wetlands were filled with coarse sand and light expanded clay aggregates and planted with Typha domingensis or Canna indica. Wetlands were operated using intermittent loading, with and without recirculation. Raw leachate was diluted and spiked with metals to reach the following concentrations: 0.2 mg L−1 Cr , 0.2 mg L−1 Ni, and0.2 mg L−1 Zn and 1.0 mg L−1 Cr, 1.0 mg L−1 Ni, and 1.0 mg L−1 Zn. Wetlands planted with T. domingensis presented higher metal removal than those planted with C. indica. Recirculation enhanced metal removal efficiencies significantly, being for T. domingensis/C. indica: 60/54, 49/47, 61/47% for Cr, Ni, and Zn at 0.2 mg L−1, and 80/71, 76/62, 73/59% for Cr, Ni, and Zn at 1.0 mg L−1, respectively. Metals were efficiently retained by macrophytes. Plant biomass and metal concentrations in roots were significantly higher than in shoots. Scanning electron microscopy and X-ray microanalysis showed that metals were absorbed by internal root tissues. A hybrid wetland planted with T. domingensis may be implemented to improve not only metal but also chemical oxygen demand and total nitrogen removals. Landfills generate leachate that contains a wide range of contaminants in concentrations that vary over time. Even when a landfill ceases to receive solid waste, the leachate will continue to be generated for years. To avoid environmental impact, such leachate should be treated. This work evaluated chromium (III), nickel (II), and zinc (II) removal from landfill leachate using vertical flow wetlands (VFWs) at mesocosm-scale. The performance of wetlands planted with Typha domingensis or Canna indica, and with and without recirculation were compared. VFWs have demonstrated to be efficient for landfill leachate treatment. At a global scale, studies on metal removal using this type of wetlands are scarce. Despite the advantages of treatment wetlands in Argentina (easy operation and maintenance and usual large availability of land inside factories), they are scarcely implemented. [ABSTRACT FROM AUTHOR]

In recent decades, previously unobserved trace compounds have become more widely detected in wastewater treatment effluents and freshwater ecosystems. Emanating from various sources and presenting potential human health and ecological risks at much lesser concentrations than traditional contaminants, detection of “emerging contaminants” has increased with improvements in analytical techniques. The behavior of emerging contaminants in wetlands is a topic of increasing interest, as natural wetlands are known to transform and sequester pollutants and constructed or treatment wetlands are widely utilized to address elevated concentrations of constituents of concern. Both natural and constructed wetlands are complex biogeochemical systems with interrelated abiotic and biotic mechanisms leading to the removal of emerging contaminants. A literature review was performed to assess the current state of knowledge of various wetland mechanisms involved in removing these contaminants from surface waters and effluents. The primary mechanisms discussed in the literature are sorption, photodegradation, microbial biodegradation and phytoremediation. The most influential mechanisms are dependent on the properties of the contaminants and wetland systems studied. Common trends exist for different constructed wetland designs to leverage various mechanisms based on hydrology, substrate and vegetation plantings. Much remains to be understood about the various processes occurring in wetlands as they relate to emerging contaminant removal. Improving the understanding of the potential role of wetland mechanisms can help manage this environmental challenge more effectively.

The Everglades Stormwater Treatment Areas (STAs) are a complex of large constructed wetlands that are an integral component of the State and Federal efforts to restore the Everglades ecosystem. The overall objective of this study was to determine the accumulation rates of macro‐elements including carbon (C), nitrogen (N), phosphorus (P), sulfur (S), and associated secondary elements including calcium (Ca), magnesium (Mg), aluminum (Al), and iron (Fe) in two Everglades STAs over their periods of operation. The study was conducted in STA‐2 with parallel flow‐ways consisting of emergent aquatic vegetation (EAV) and submerged aquatic vegetation (SAV) and the Western flow‐way of STA‐3/4 with EAV and SAV cells operated in series. Elemental accumulation rates were determined in the unconsolidated surficial sediments (floc) and recently accreted soil (RAS) that have accumulated on top of the antecedent soil over the 14‐ and 10‐yr periods of operation for STA‐2 and STA‐3/4, respectively. Flow‐ways with SAV were more efficient than EAV in accreting mineral matter, resulting in increased bulk density and higher accumulation rates of elements. Average C accumulation in the floc and RAS of SAV flow‐ways was 320 g·m−2·yr−1 with approximately equal proportions of inorganic and organic C, while in the EAV flow‐ways accumulation rates of C ranged from 116 to 147 g·m−2·yr−1 with mostly organic C. Phosphorus accumulation rates were approximately 2–3 times higher in SAV than in EAV flow‐ways. Differences in accumulation of elements between SAV and EAV were largest for Ca with 17–42 times more Ca in SAV than EAV systems. This suggests that in the SAV systems, possible occlusion of macro‐elements and metals during CaCO3 precipitation facilitated accretion of material with high mineral content. In EAV, biomass turnover and associated biotic processes regulated organic matter accumulation rates. The spatial accumulation patterns of P, C, and N in the EAV areas of STA‐2 and STA‐3/4 were similar to those observed in the EAV areas of the natural wetlands in Water Conservation Areas, suggesting that constructed wetland systems function similarly to natural wetlands dominated by EAV areas in retaining and storing macro‐ and secondary elements. [ABSTRACT FROM AUTHOR]

In order to know the behaviour and performance of a vertical flow constructed wetland (VF-CW) operating with earthworm, this study evaluated the earthworm presence linked to hydraulic loading rates applied for domestic wastewater treatment. Two VF-CW units (710 cm², 0.75 m deep, with sand as filter media and planted with Heliconia rostrata) operated with a variable hydraulic and organic loadings rates (200 mm d−1/123 g COD m−2 d−1; 280 mm d−1/186 g COD m−2 d−1; 160 mm d−1/94 g COD m−2 d−1). Although the efficiency of COD load removal was similar (around 70%) for both CWs, the efficiency of total nitrogen load removal was around 95% throughout the evaluated period. The nitrification–denitrification process was identified with and without the presence of earthworm. VF-CW with earthworms showed higher hydraulic conductivity values (from 0.11 to 0.14 m h−1) compared with the VF-CW wetland without earthworms (0.07–0.09 m h−1). This study showed that the use of earthworms in CWs can be associated mainly with a preventive measure of clogging, which requires measures to maintain earthworms inside the bed media. Additionally, the earthworm presence has an ingestion mechanism of organic and inorganic solid particles in wastewater which excretes them as finer particles. [ABSTRACT FROM AUTHOR]

Managed treatment wetlands technology is now used around the world to treat wastewater and stormwater by removing nutrients and other contaminants to obtain a desired water quality. In this paper we present a brief review of a large-scale application of the nature-based technology known as stormwater treatment areas (STAs). These STAs were constructed to treat agricultural and urban runoff to reduce outflow total phosphorus (TP) concentrations to <20 μg P L−1, which is required to protect downstream water quality and preserve the remaining Everglades ecosystem. Five STAs with a total area of approximately 25,000 ha were built at strategic locations to reduce TP loads to the Everglades Protection Area. For the past three decades, these Everglades STAs have done remarkable job by 70 to 85% TP load reduction, with an average outflow TP concentrations of 15-40 μg P L−1. In this Everglades STAs special issue, we present research findings on the influence of both external and internal drivers influencing STA performance and potential adaptive management strategies to enhance treatment efficiency to further reduce outflow TP concentrations. • Introduction of the Everglades STAs – largest constructed treatment wetland network in the world. • Everglades STAs serve as 'kidneys' of the Everglades ecosystem by reducing phosphorus loads to downstream waterbodies. • Phosphorus loading is one of the key drivers regulating treatment efficiency STAs. [ABSTRACT FROM AUTHOR]

Abstract Background Evaluation of carbon (C), nitrogen (N), and phosphorus (P) ratios in aquatic and terrestrial ecosystems can advance our understanding of biological processes, nutrient cycling, and the fate of organic matter (OM) in these ecosystems. Eutrophication of aquatic ecosystems can change the accumulation and decomposition of OM which can alter biogeochemical cycling and alter the base of the aquatic food web. This study investigated nutrient stoichiometry within and among wetland ecosystem compartments (i.e., water column, flocculent, soil, and aboveground vegetation biomass) of two subtropical treatment wetlands with distinct vegetation communities. Two flow-ways (FWs) within the network of Everglades Stormwater Treatment Areas in south Florida (USA) were selected for this study. We evaluated nutrient stoichiometry of these to understand biogeochemical cycling and controls of nutrient removal in a treatment wetland within an ecological stoichiometry context. Results This study demonstrates that C, N, and P stoichiometry can be highly variable among ecosystem compartments and between FWs. Power law slopes of C, N, and P within surface water floc, soil, and vegetation were significantly different between and along FWs. Conclusions Assessment of wetland nutrient stoichiometry between and within ecosystem compartments suggests unconstrained stoichiometry related to P that conforms with the notion of P limitation in the ecosystem. Differences in N:P ratios between floc and soil suggest different pathways of organic nutrient accumulation and retention between FWs. Surface nutrient stoichiometry was highly variable and decoupled (or close to decoupled as indicated by

Conventional wastewater treatment technologies are costly and energy demanding; such issues are especially remarkable when small communities have to clean up their pollutants. In response to these requirements, a new variety of nature-based solution, so-called METland®, has been recently develop by using concepts from Microbial Electrochemical Technologies (MET) to outperform classical constructed wetland regarding wastewater treatment. Thus, the current study evaluates two operation modes (aerobic and aerobic–anoxic) of a full-scale METland®, including a Life Cycle Assessment (LCA) conducted under a Net Environmental Balance perspective. Moreover, a combined technical and environmental analysis using a Net Eutrophication Balance (NEuB) focus concluded that the downflow (aerobic) mode achieved the highest removal rates for both organic pollutant and nitrogen, and it was revealed as the most environmentally friendly design. Actually, aerobic configuration outperformed anaero/aero-mixed mode in a fold-range from 9 to 30%. LCA was indeed recalculated under diverse Functional Units (FU) to determine the influence of each FU in the impacts. Furthermore, in comparison with constructed wetland, METland® showed a remarkable increase in wastewater treatment capacity per surface area (0.6 m2/pe) without using external energy. Specifically, these results suggest that aerobic–anoxic configuration could be more environmentally friendly under specific situations where high N removal is required. The removal rates achieved demonstrated a robust adaptation to influent variations, revealing a removal average of 92% of Biology Oxygen Demand (BOD), 90% of Total Suspended Solids (TSS), 40% of total nitrogen (TN), and 30% of total phosphorus (TP). Moreover, regarding the global warming category, the overall impact was 75% lower compared to other conventional treatments like activated sludge. In conclusion, the LCA revealed that METland® appears as ideal solution for rural areas, considering the low energy requirements and high efficiency to remove organic pollutants, nitrogen, and phosphates from urban wastewater.

Conventional wastewater treatment technologies are costly and energy demanding; such issues are especially remarkable when small communities have to clean up their pollutants. In response to these requirements, a new variety of nature-based solution, so-called METland®, has been recently develop by using concepts from Microbial Electrochemical Technologies (MET) to outperform classical constructed wetland regarding wastewater treatment. Thus, the current study evaluates two operation modes (aerobic and aerobic–anoxic) of a full-scale METland®, including a Life Cycle Assessment (LCA) conducted under a Net Environmental Balance perspective. Moreover, a combined technical and environmental analysis using a Net Eutrophication Balance (NEuB) focus concluded that the downflow (aerobic) mode achieved the highest removal rates for both organic pollutant and nitrogen, and it was revealed as the most environmentally friendly design. Actually, aerobic configuration outperformed anaero/aero-mixed mode in a fold-range from 9 to 30%. LCA was indeed recalculated under diverse Functional Units (FU) to determine the influence of each FU in the impacts. Furthermore, in comparison with constructed wetland, METland® showed a remarkable increase in wastewater treatment capacity per surface area (0.6 m2/pe) without using external energy. Specifically, these results suggest that aerobic–anoxic configuration could be more environmentally friendly under specific situations where high N removal is required. The removal rates achieved demonstrated a robust adaptation to influent variations, revealing a removal average of 92% of Biology Oxygen Demand (BOD), 90% of Total Suspended Solids (TSS), 40% of total nitrogen (TN), and 30% of total phosphorus (TP). Moreover, regarding the global warming category, the overall impact was 75% lower compared to other conventional treatments like activated sludge. In conclusion, the LCA revealed that METland® appears as ideal solution for rural areas, considering the low energy requirements and high efficiency to remove organic pollutants, nitrogen, and phosphates from urban wastewater. [ABSTRACT FROM AUTHOR]

In response to the global loss and degradation of wetland ecosystems, extensive efforts have been made to reestablish wetland habitat and function in landscapes where they once existed. The reintroduction of wetland ecosystem services has largely occurred in two categories: constructed wetlands (CW) for wastewater treatment, and restored wetlands (RW) for the renewal or creation of multiple ecosystem services. This is the first review to compare the objectives, design, performance, and management of CW and RW, and to assess the status of efforts to combine CW and RW as Integrated Constructed Wetlands (ICW). These wetland systems are assessed for their ecological attributes and their relative contribution to ecosystem services. CW are designed to process a wide variety of wastewaters using surface, subsurface, or hybrid treatment systems. Designed and maintained within narrow hydrologic parameters, CW can be highly effective at contaminant transformation, remediation, and sequestration. The ecosystem services provided by CW are limited by their status as high-stress, successionally arrested systems with low landscape connectivity and an effective lifespan. RW are typically situated and designed for a greater degree of connection with regional ecosystems. After construction, revegetation, and early successional management, RW are intended as self-maintaining ecosystems. This affords RW a broader range of ecosystem services than CW, though RW system performance can be highly variable and subject to invasive species and landscape-level stressors. Where the spatial and biogeochemical contexts are favorable, ICW present the opportunity to couple CW and RW functions, thereby enhancing the replacement of wetland services on the landscape.

Objective: This research aimed to assay the dehydration and stabilization of surplus biosolids from a wastewater activated sludge treatment plant, with sludge-treatment wetlands, at the Iguazú National Park (Misiones, Argentina). Materials and Methods: A 12-cell sludge-treatment reed beds (STRB) system was built and operated for four years. Afterwards, the accumulated sediments were analyzed for total solids (TS) concentration, volatile solids (VS) reduction, specific oxygen-uptake rate (SOUR), and heavy metals and pathogens concentrations. Results and Discussion: TS concentration increased from 0.55 % to 14.3 %, VS were reduced by 33.3 %, and SOUR lowered to 1.09 mg O2gTS-1 h-1. These figures and the final concentrations of heavy metals and pathogenic microorganisms (102 MPN E.coli.gTS-1) indicated a degree of stabilization and sanitation that allowed classifying these biosolids as Class A, according to the Argentine guidelines, National Resolution 410/18, and enabled their reuse for soil amendment in landscapes and other agronomic purposes. Conclusion: The technology tested showed good results applied under a tropical climate, with annual temperatures between 17 and 27 °C, rainfall of 1870 mm y-1, and planted with autochthonous vegetation. Furthermore, it allowed the reuse of 221 t (144 m3 ) of a harmless product in an environmentally sustainable way. [ABSTRACT FROM AUTHOR]

In this study, the simulation results of four vertical flow wetland systems using the HYDRUS Wetland Module are presented. The four wetland systems comprise three single-stage pilot scale systems and one full-scale two-stage system. The main difference between these systems is the filter media used, referred to as fine media, i.e., sand with a grain size distribution 0.063–4 mm, or coarse media, i.e., sand with grain size distributions between 1–4 mm, respectively. The water-flow simulation of each system is carried out using the single porosity van Genuchten-Mualem model. A good match between measured and simulated volumetric effluent flow rates could be achieved for all wetland systems. For reactive transport simulations, the CW2D biokinetic model was applied. First, simulations were run using the standard CW2D parameter set. For some systems, adjustments of the parameter set were needed in order to avoid unlimited bacteria growth. To better fit measured COD, NH4-N, and NO3-N effluent concentrations, adjustments of few parameters of the standard parameter set were required. The results show that for the VF wetlands with fine sand, no adjustments of the CW2D standard parameter set were needed, while for systems with coarser filter media as the main layer, the standard parameter set had to be adjusted to match simulated and measured effluent concentrations.

Plant species selection is an important criterion for improving treatment wetland performance. The aim of this work was to evaluate removal efficiency and potential uses of woody species in treatment wetlands during the establishment year. Plant development, removal efficiency and evapotranspiration rate of five woody species (Salix interior, Salix miyabeana, Sambucus canadensis, Myrica gale, Acer saccharinum) and four herbaceous taxa typically used in treatment wetlands (Typha angustifolia, Phragmites australis australis, Phragmites australis americanus, Phalaris arundinacea) were compared in a mesocosm-scale study during one growing season. Woody species showed significantly slower growth, but displayed several characteristics of interest for treatment wetland applications: good adaptation to wetlands conditions; high organic matter removal (76–88%); high nutrient accumulation in tissues and high evapotranspiration capacity. During the establishment year, herbaceous species showed greater biomass development (above- and belowground parts), higher evapotranspiration rate (>3.84 L m−2 d−1 compared to <3.23 L m−2 d−1 for woody species) and overall pollutant removal efficiency. These characteristics confirm the high efficiency of treatment wetlands planted with herbaceous species even in the first growing season. However, given their greater potential biomass development, woody species could represent an excellent alternative for improving treatment wetlands long-term performance. [ABSTRACT FROM AUTHOR]

The objective of this study was to implement a pilot system of treatment wetlands, using phytoremediation as an alternative technology to remove arsenic from the concentrate of a reverse osmosis system. The pilot system was composed of two subsurface flow constructed wetlands, planted with Eleocharis macrostachya and Shoenoplectus americanus. The wetlands were fed concentrate from a reverse osmosis system for seven months, with an average flow of 962 Ld-1 and an average arsenic concentration of 0.241 mgL-1. Removal rates between 43 % and 86 % were obtained for wetland 1 and between 35 % and 79 % for wetland 2 throughout the experiment. The two plant species developed normally despite the high levels of electrical conductivity in the range of 3584 to 5455 µscm-1 in wetland intake waters. The pilot wetland system removed significant levels of arsenic from the reverse osmosis concentrate, resulting in arsenic levels in the output waters that meet Mexican standard for using water in agricultural irrigation. [ABSTRACT FROM AUTHOR]

• Constructed wetlands provide an optimal environment for cyanotoxin biodegradation. • First report of cylindrospermopsin degradation in constructed wetlands. • Cyanotoxins induced a shift in the constructed wetland prokaryotic community. • The enzymatic gene known to be responsible for microcystin-LR was not observed. • Removal seem to be more associated with the microbial community than the plants. Cyanobacterial blooms releasing harmful cyanotoxins, such as microcystin (MC) and cylindrospermopsin (CYN), are prominent threats to human and animal health. Constructed wetlands (CW) may be a nature-based solution for bioremediation of lake surface water containing cyanotoxins, due to its low-cost requirement of infrastructure and environmentally friendly operation. There is recent evidence that microcystin-LR (MC-LR) can efficiently be removed in CW microcosms where CYN degradation in CW is unknown. Likewise, the mechanistic background regarding cyanotoxins transformation in CW is not yet elucidated. In the present study, the objective was to compare MC-LR and CYN degradation efficiencies by two similar microbial communities obtained from CW mesocosms, by two different experiments setup: 1) in vitro batch experiment in serum bottles with an introduced CW community, and 2) degradation in CW mesocosms. In experiment 1) MC-LR and CYN were spiked at 100 µg L−1 and in experiment 2) 200 µg L−1 were spiked. Results showed that MC-LR was degraded to ≤1 µg L−1 within seven days in both experiments. However, with a markedly higher degradation rate constant in the CW mesocosms (0.18 day−1 and 0.75 day−1, respectively). No CYN removal was detected in the in vitro incubations, whereas around 50 % of the spiked CYN was removed in the CW mesocosms. The microbial community responded markedly to the cyanotoxin treatment, with the most prominent increase of bacteria affiliated with Methylophilaceae (order: Methylophilales , phylum: Proteobacteria). The results strongly indicate that CWs can develop an active microbial community capable of efficient removal of MC-LR and CYN. However, the CW operational conditions need to be optimized to achieve a full CYN degradation. To the best of our knowledge, this study is the first to report the ability of CW mesocosms to degrade CYN. [Display omitted] [ABSTRACT FROM AUTHOR]

The Everglades Stormwater Treatment Areas (STAs) are a 25,000 ha (61,000 acre) complex of constructed wetlands built to remove phosphorus (P) from agricultural and urban runoff in support of Everglades restoration. These STAs treat inflow waters that contain P in concentrations from 100 to 200 μg L−1, average calcium (Ca) concentrations of 60–90 mg L−1, and alkalinity (Alk) in the range of 150–350 mg L−1 as calcium carbonate (CaCO 3). Photosynthesis, primarily from submerged aquatic vegetation (SAV) within these STAs, increases water pH resulting in CaCO 3 formation, which is thought to contribute to P removal through coprecipitation and other processes. Since 2002, the STA complex has removed over 3000 MT of P and over 400,000 MT of Ca. Because the STAs at times treat Lake Okeechobee waters that are lower in Ca and Alk (35–50 mg L−1 and 95–125 mg L−1 as CaCO 3 , respectively), we conducted two experiments to explore the role of Ca and Alk on wetland P removal. First, in outdoor flow-through microcosms (0.18 m2) containing Najas guadalupensis and treating artificial inflow solutions, Ca/Alk at typical STA inflow concentrations (77 mg Ca L−1/316 mg L−1 as CaCO 3) resulted in significantly lower outflow P concentrations compared to lower Ca/Alk treatments (28 mg Ca L−1/67 mg L−1 as CaCO 3). Based on sediment organic carbon to total P (TP) ratios, organic matter production and sedimentation was the P removal mechanism under low Ca/Alk levels, where CaCO 3 precipitation did not occur, and also under high Ca/Alk, low P (31 μg L−1) conditions, despite CaCO 3 formation. High Ca/Alk increased organic matter sedimentation and associated P burial at low and high (168 μg L−1) water P concentrations. Additional P removal associated with CaCO 3 precipitation occurred only under high Ca/Alk, high P concentrations, and accounted for about 47% of P sedimentation in those microcosms. Second, in flow-through mesocosms (4.75 m2) containing STA muck soil and common STA SAV species, elevated Ca/Alk (94 mg Ca L−1/185 mg L−1 as CaCO 3) produced significantly lower outflow TP concentrations than treatments receiving unamended Lake Okeechobee inflow water with lower Ca/Alk concentrations (44 mg Ca L−1/112 mg L−1 as CaCO 3). In the same experiment, Ca/Alk levels had no effect on P removal in mesocosms containing Typha domingensis , a common STA emergent macrophyte species. SAV mesocosms produced lower outflow TP concentrations than Typha , regardless of Ca/Alk levels. In a follow-on laboratory incubation, low Ca/Alk concentrations in incubation waters did not increase P release from sediments formed under prior low or high inflow Ca/Alk concentrations in the SAV mesocosms, but anoxia sharply increased P release from both. These experiments suggest that coprecipitation with CaCO 3 is a meaningful P removal process in hardwater wetlands where high P concentrations and SAV coincide. Conversely, in STA outflow regions, where surface water P has already been treated to a low level, coprecipitation with CaCO 3 probably does not contribute to further P reductions. However, Ca/Alk also may contribute to inorganic-C availability which influences submerged aquatic productivity, so the role of inorganic C limitation on STA vegetation communities and P removal merits further study. • CaCO 3 precipitates in wetlands with SAV treating P for Everglades restoration. • Ca/Alk increased P removal in SAV systems via greater organic matter production. • Additional P coprecipitated with CaCO 3 only under high water P and Ca/Alk levels. • SAV outperformed Typha for P removal at both high and low Ca/Alk concentrations. • Low Ca/Alk inflow waters should not destabilize P in calcareous soils. [ABSTRACT FROM AUTHOR]

The potential of using the biomass of four wetland plant species (Iris pseudacorus, Juncus effusus, Phragmites australis and Typha latifolia) grown in treatment wetland systems and under natural conditions were tested to produce high-value materials using hydro-thermal liquefaction (HTL). The results show that the wetland plants biomass is suitable for biocrude and biochar production regardless of the origin. The hydrothermal liquefaction products’ (biocrude, biochar, aqueous and gaseous phase) yields vary according with the specific biomass composition of the species. Furthermore, the results show that the biomass composition can be affected by the growing condition (treatment wetland or natural unpolluted conditions) of the plants. None of the single components seems to have a determinant effect on the biocrude yields, which reached around 30% for all the analyzed plants. On the contrary, the biochar yields seem to be affected by the composition of the biomass, obtaining different yields for the different plant species, with biochar yields values from around 12% to 22%, being that Phragmites australis is the one with the highest average yield. The obtained aqueous phase from the different plant species produces homogeneous compounds for each plant species and each growing environment. The study shows that biomass from treatment wetlands is suitable for biocrude production. The environmental value of this biomass lies on the fact that it is considered a residual product with no aggregated value. The treatment wetland biomass is a potential sustainable source for biofuel production since these plants do not need extra land or nutrients for growing, and the biomass does not compete with other uses, offering new sources for enhancing the bioeconomy concepts.

• Caffeine and ibuprofen were removed efficiently (>80) in the CWs. • Caffeine removal (%) > than ibuprofen in the FFM-CW and VF-CW. • E. crassipe s (FFM-CW) presented similar performance to VF-CW with filter media. • Correlation between ibuprofen/caffeine removal vs. °C/TP/TN/NH 4 +/COD/BOD loading. • Earthworms did not show significant variation in emerging contaminants removal. Emerging pollutants appear more frequently in the environment and adverse effects affects not only human health but also the environment. This study evaluated the efficiency of two types of constructed wetlands (CWs) and a 12-unit mesocosm-scale system to remove ibuprofen and caffeine compounds: (i) vertical flow constructed wetland (VF-CW) planted with Heliconia rostrata using sand as filter media with and without earthworms; (ii) free-floating surface horizontal flow constructed wetland with Eichhornia crassipes macrophyte (FFM-CW); and (iii) mesocosm-scale 12 unit system using Eichhornia crassipes with clean water (opposed to wastewater), where the intention was to evaluate the removal of the added compounds without effects from wastewater or biofilm. The systems were efficient in removing the pollutants and demonstrated a limit for the applied COD and BOD rates, where the adequate application rate was 120 g COD.m−2.d−1 and 70 g BOD.m−2.d−1 to obtain maximum removal efficiency. TP varied independent of the applied load, while TN and NH4+ showed removals (99%) close to the applied rates (9 g TN.m−2.d−1 and 7 g NH 4 +.m−2.d−1 for the VF-CW and 8.5 g TN.m−2.d−1 and 5 g NH 4 +.m−2.d−1 for the FFM-CW). The emerging contaminants removal efficiency in the VF-CW was 97 and 89% for caffeine and ibuprofen, respectively. Inserting earthworms did not show a significant variation in relation to compound removal. The FFM-CW system removed 94 and 89% of the caffeine and ibuprofen, respectively. The VF-CW system with filter media presented better removal for caffeine and ibuprofen when compared to the FFM-CW. The performance between the macrophyte E. crassipes systems in the mesocosm units showed potential to remove emerging compounds even though clean water was used, with a 70% removal efficiency for caffeine and ibuprofen. [ABSTRACT FROM AUTHOR]

Utilization of the French system of vertical wetlands for treating raw sewage keeps increasing, but there is still limited consolidated information on their long term use in tropical countries. Under these conditions, there are indications that surface area requirements can decrease, whilst still keeping a satisfactory performance. However, variations in the operational mode and the role of the surface organic deposit layer under warm climatic conditions have not been fully investigated. The goal of this work was to evaluate the performance of a system comprised of only the first stage of the French system, with a further reduction of 1/3 of the area (utilization of only two units in parallel, instead of three) in terms of organic matter removal and nitrogen conversion, with one unit with a deposit layer accumulated over 9 years of operation, and the other unit without sludge layer, under Brazilian tropical conditions. The system was originally designed according to Cemagref/Irstea recommendations for the first-stage of the French system for the treatment of raw sewage generated by an equivalent population of 100 inhabitants. However, it was later on changed, and operated with only two units, using only 0.6 m²⋅pe-1. Feeding and resting periods were of 7 days each. In order to evaluate the influence of the sludge layer, the top sludge from one of the units was removed, and the performance of both units was compared by the Mann-Whitney test. The database comprises the wetland performance values in terms of dissolved oxygen (DO), redox potential (Eh), chemical oxygen demand (COD), biochemical oxygen demand (BOD), total suspended solids (TSS), total Kjeldahl nitrogen (TKN), NH4+-N and NO3+-N, covering a monitoring period of 15 months. The effluent DO concentrations were significantly lower in the unit with top sludge, but still sufficiently high in both units. Although there were some variations between both units, effluent concentrations of the major pollutants were not significantly different in the units with and without sludge, and removal efficiencies based on mean values were considered good, given the reduced area of the system: BOD (80% and 79%), TSS (85% and 82%), TKN (60% and 63%) for the units with and without sludge, respectively. Under Brazilian climatic conditions, with the reduced area and employing longer feeding cycles (7 days), the sludge accumulation rate (less than 1 cm⋅year-1) was lower compared to the French mean values. [ABSTRACT FROM AUTHOR]

Abstract 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 BOD 5 , 90% for COD, 46% for NH 4 -N, and 86% for PO 4 -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 PO 4 -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. Graphical abstract Unlabelled Image Highlights • EABB-CWs show organic matter removal rates comparable with conventional wetlands • High organic matter removal even at inlet loading rates 10× higher than HFCW • COD removal rates could be related to electron flux in electro-conductive systems • Removal rate constants (K) of EABB-CWs are higher than reported for HF and VFCWs • Electro-conductive materials with iron traces ease PO 4 -P removal [ABSTRACT FROM AUTHOR]

The objective of this work is to evaluate the performance of two horizontal subsurface flow constructed wetlands, one planted with cattail (Typha latifolia) and the other unplanted. The distinguishing feature of this study is that it spans a period of more than 10 years, from start-up to a final operation with heavy clogging and full overland flow. For most of the time, starting in June 2007, the system received municipal sewage previously treated in an upflow anaerobic sludge blanket (UASB) reactor, but for one specific period, the pre-treatment was comprised of the UASB reactor and a trickling filter in series. The two constructed wetlands worked in parallel, each serving approximately 50 p.e. and continuously receiving a flow around 7.5 m³ d-1 for most of the time. The beds had a length of 25 m and a width of 3 m and were filled with blast furnace slag. For most of this long operational period, performance was very good in terms of biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total suspended solids (TSS), with median effluent concentrations of 19/18, 46/52 and 12/8, respectively (planted/unplanted units). Clogging was noticeable in the first years of operation, soon leading to overland flow. However, treatment performance was still successful, even when the system's hydraulics were strongly deteriorated. The type of pre-treatment and the applied loads influenced more the performance of the units than the period of operation itself, evidencing the robustness of the system. [ABSTRACT FROM AUTHOR]