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16 pages, 2516 KiB

Open AccessArticle

Modelling PAHs Transfer from Polluted Soil to Herbaceous Species in Phytoremediation Attempts

by Pulchérie Matsodoum Nguemté, Ives Magloire Kengne Noumsi, Guy Valérie Djumyom Wafo, Pierre François Djocgoue and Adrien Wanko

Water 2020, 12(6), 1759; https://doi.org/10.3390/w12061759 - 20 Jun 2020

Cited by 3 | Viewed by 3030

Abstract

To address the soil–plant transfer modelling of 13 US-EPA Polycyclic Aromatic Hydrocarbons (PAHs), a mechanistic model—MM_19—has been developed based on the fugacity concept. For that, the Mackay_97 model has been improved in terms of reconsidering the losses related to the transport and transformation [...] Read more.

To address the soil–plant transfer modelling of 13 US-EPA Polycyclic Aromatic Hydrocarbons (PAHs), a mechanistic model—MM_19—has been developed based on the fugacity concept. For that, the Mackay_97 model has been improved in terms of reconsidering the losses related to the transport and transformation mechanisms taking place in the compartments—roots and aboveground shoots—of the three short-life species (Eleusine indica, Cynodon dactylon and Alternanthera sessilis). Model input parameters consist of both experimental and literature data, including the initial soil and air PAHs content, flowrates, PAHs physico-chemical properties, retention times and transport half-lives of PAHs inside plant species. Using in situ weather data and Penman’s law, xylem flows were estimated as the evapotranspiration for each plant. Model calibration was performed using a Generalized Reduced Gradient (GRG) nonlinear optimization solver method. Sensitivity analysis showed that the phloem flow was the most sensitive among all tested parameters. According to the Nash–Sutcliffe efficiency (NSE), the MM_19 model is more efficient than the Mackay_97 model for all three plant species. Finally, the impact of PAHs physico-chemical parameters on their sol-plant transfer was discussed in terms of slight, intermediate and high molecules weight. The NSE values showed that the MM_19 model is more efficient than the Mackay_97 model. Indeed, comparisons between experimental and simulated results in the MM_19 model showed similarities for each compartment of the plant species. Thus, the MM_19 model can be used to predict the soil–plant transfer of organic pollutants. Full article

(This article belongs to the Special Issue Wetlands in Action: Sustainable Water Management and Resource Recovery)

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21 pages, 15594 KiB

Open AccessArticle

Recent Advances in the Application, Design, and Operations & Maintenance of Aerated Treatment Wetlands

by Jaime Nivala, Clodagh Murphy and Andrew Freeman

Water 2020, 12(4), 1188; https://doi.org/10.3390/w12041188 - 21 Apr 2020

Cited by 35 | Viewed by 6508

Abstract

This paper outlines recent advances in the design, application, and operations and maintenance (O&M) of aerated treatment wetland systems as well as current research trends. We provide the first-ever comprehensive estimate of the number and geographical distribution of aerated treatment wetlands worldwide and [...] Read more.

This paper outlines recent advances in the design, application, and operations and maintenance (O&M) of aerated treatment wetland systems as well as current research trends. We provide the first-ever comprehensive estimate of the number and geographical distribution of aerated treatment wetlands worldwide and review new developments in aerated wetland design and application. This paper also presents and discusses first-hand experiences and challenges with the O&M of full-scale aerated treatment wetland systems, which is an important aspect that is currently not well reported in the literature. Knowledge gaps and suggestions for future research on aerated treatment wetlands are provided. Full article

(This article belongs to the Special Issue Wetlands in Action: Sustainable Water Management and Resource Recovery)

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15 pages, 1195 KiB

Open AccessEditor’s ChoiceArticle

Potential Application of Chilean Natural Zeolite as a Support Medium in Treatment Wetlands for Removing Ammonium and Phosphate from Wastewater

by Ismael Vera-Puerto, Matias Saravia, Jorge Olave, Carlos Arias, Erica Alarcon and Hugo Valdes

Water 2020, 12(4), 1156; https://doi.org/10.3390/w12041156 - 18 Apr 2020

Cited by 13 | Viewed by 4509

Abstract

This study aims to evaluate the sorption characteristics of

{NH}_{4}^{+}

-N and

{PO}_{4}^{3 -}

-P onto the surface of natural zeolites coming from Chile and their potential application in the subsurface-flow treatment wetlands for wastewater treatment in rural areas. [...] Read more.

This study aims to evaluate the sorption characteristics of

{NH}_{4}^{+}

-N and

{PO}_{4}^{3 -}

-P onto the surface of natural zeolites coming from Chile and their potential application in the subsurface-flow treatment wetlands for wastewater treatment in rural areas. For this purpose, adsorption experiments onto the zeolite were developed in batch assays. The effects of the adsorbent quantity (20 g and 50 g) and particle size (0.2–1.0 mm; 1.5–3.0 mm, and 5.0–8.0 mm) were evaluated in terms of adsorption capacity at different NH₄⁺-N and PO₄⁻³-P concentrations. Then, the obtained laboratory results were adjusted to theoretical models: Saturation-growth-rate and Langmuir. The saturation adsorption of NH₄⁺-N on the zeolite increases at the same time that the initial concentration increases for the same zeolite quantity; however, the saturation values were similar between the different zeolite sizes tested. For PO₄⁻³-P, the adsorption did not have a direct relationship with the initial concentration nor zeolite quantity and better results were only achieved for zeolite sizes of 1.5–3.0 mm. Regarding the Langmuir model, sizes of 1.5–3.0 mm had the best adsorption characteristics, with the maximum adsorption capacity of up to 1.58 mg/g for NH₄⁺-N and up to 0.08 mg/g for PO₄⁻³-P. Therefore, a new material—a natural zeolite from the Maule Region of Chile—is described as a potential support medium for treatment wetlands. Full article

(This article belongs to the Special Issue Wetlands in Action: Sustainable Water Management and Resource Recovery)

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21 pages, 2528 KiB

Open AccessFeature PaperArticle

Catchment-Scale Analysis Reveals High Cost-Effectiveness of Wetland Buffer Zones as a Remedy to Non-Point Nutrient Pollution in North-Eastern Poland

by Ewa Jabłońska, Marta Wiśniewska, Paweł Marcinkowski, Mateusz Grygoruk, Craig R. Walton, Dominik Zak, Carl C. Hoffmann, Søren E. Larsen, Michael Trepel and Wiktor Kotowski

Water 2020, 12(3), 629; https://doi.org/10.3390/w12030629 - 26 Feb 2020

Cited by 28 | Viewed by 6792

Abstract

Large-scale re-establishment of wetland buffer zones (WBZ) along rivers is regarded as an effective measure in order to reduce non-point source nitrogen (N) and phosphorus (P) pollution in agricultural catchments. We estimated efficiency and costs of a hypothetical establishment of WBZs along all [...] Read more.

Large-scale re-establishment of wetland buffer zones (WBZ) along rivers is regarded as an effective measure in order to reduce non-point source nitrogen (N) and phosphorus (P) pollution in agricultural catchments. We estimated efficiency and costs of a hypothetical establishment of WBZs along all watercourses in an agricultural landscape of the lower Narew River catchment (north-eastern Poland, 16,444 km², amounting to 5% of Poland) by upscaling results obtained in five sub-catchments (1087 km²). Two scenarios were analysed, with either rewetting selected wetland polygons that collect water from larger areas (polygonal WBZs) or reshaping and rewetting banks of rivers (linear WBZs), both considered in all ecologically suitable locations along rivers. Cost calculation included engineering works necessary in order to establish WBZs, costs of land purchase where relevant, and compensation costs of income forgone to farmers (needed only for polygonal WBZs). Polygonal WBZs were estimated in order to remove 11%–30% N and 14%–42% P load from the catchment, whereas linear WBZs were even higher with 33%–82% N and 41%–87% P. Upscaled costs of WBZ establishment for the study area were found to be 8.9 M EUR plus 26.4 M EUR per year (polygonal WBZ scenario) or 170.8 M EUR (linear WBZ scenario). The latter value compares to costs of building about 20 km of an express road. Implementation of buffer zones on a larger scale is thus a question of setting policy priorities rather than financial impossibility. Full article

(This article belongs to the Special Issue Wetlands in Action: Sustainable Water Management and Resource Recovery)

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15 pages, 3147 KiB

Open AccessArticle

Enhancing Nitrate Removal from Waters with Low Organic Carbon Concentration Using a Bioelectrochemical System—A Pilot-Scale Study

by Rauno Lust, Jaak Nerut, Kuno Kasak and Ülo Mander

Water 2020, 12(2), 516; https://doi.org/10.3390/w12020516 - 13 Feb 2020

Cited by 8 | Viewed by 3286

Abstract

Assessments of groundwater aquifers made around the world show that in many cases, nitrate concentrations exceed the safe drinking water threshold. This study assessed how bioelectrochemical systems could be used to enhance nitrate removal from waters with low organic carbon concentrations. A two-chamber [...] Read more.

Assessments of groundwater aquifers made around the world show that in many cases, nitrate concentrations exceed the safe drinking water threshold. This study assessed how bioelectrochemical systems could be used to enhance nitrate removal from waters with low organic carbon concentrations. A two-chamber microbial electrosynthesis cell (MES) was constructed and operated for 45 days with inoculum that was taken from a municipal wastewater treatment plant. A study showed that MES can be used to enhance nitrate removal efficiency from 3.66% day⁻¹ in a control reactor to 8.54% day⁻¹ in the MES reactor, if a cathode is able to act as an electron donor for autotrophic denitrifying bacteria or there is reducing oxygen in a cathodic chamber to favor denitrification. In the MES, greenhouse gas emissions were also lower compared to the control. Nitrous oxide average fluxes were −639.59 and −9.15 µg N m⁻² h⁻¹ for the MES and control, respectively, and the average carbon dioxide fluxes were −5.28 and 43.80 mg C m⁻² h⁻¹, respectively. The current density correlated significantly with the dissolved oxygen concentration, indicating that it is essential to keep the dissolved oxygen concentration in the cathode chamber as low as possible, not only to suppress oxygen’s inhibiting effect on denitrification but also to achieve better power efficiency. Full article

(This article belongs to the Special Issue Wetlands in Action: Sustainable Water Management and Resource Recovery)

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14 pages, 2360 KiB

Open AccessEditor’s ChoiceArticle

Heavy Metals Distribution, Sources, and Ecological Risk Assessment in Huixian Wetland, South China

by Liangliang Huang, Saeed Rad, Li Xu, Liangying Gui, Xiaohong Song, Yanhong Li, Zhiqiang Wu and Zhongbing Chen

Water 2020, 12(2), 431; https://doi.org/10.3390/w12020431 - 6 Feb 2020

Cited by 104 | Viewed by 6096

Abstract

This research has focused on the source identification, concentration, and ecological risk assessment of eight heavy metals in the largest karst wetland (Huixian) of south China. Numerous samples from superficial soil and sediment within ten representative landuse types were collected and examined, and [...] Read more.

This research has focused on the source identification, concentration, and ecological risk assessment of eight heavy metals in the largest karst wetland (Huixian) of south China. Numerous samples from superficial soil and sediment within ten representative landuse types were collected and examined, and the results were analyzed using multiple methods. Single pollution index (Pi) results were underpinned by the Geoaccumulation index (I_geo) method, in which Cd was observed as the priority pollutant with the highest contamination degree in this area. As for the most polluted landuse type, via applying Nemerow’s synthetical contamination index (P_N) and Potential ecological risk index (RI), the river and rape field posed the highest ecological risks, while moderate for the rest. To quantify the drivers of the contaminants, a principal component analysis (PCA) was carried out and weathering of the watershed’s parent carbonate rocks was found to be the main possible origin, followed by anthropogenic sources induced by agricultural fertilizer. Considering the impacts of these potentially toxic elements on public health, the results of this study are essential to take preventive actions for environmental protection and sustainable development in the region. Full article

(This article belongs to the Special Issue Wetlands in Action: Sustainable Water Management and Resource Recovery)

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12 pages, 1947 KiB

Open AccessArticle

Natural Nitrogen Isotope Ratios as a Potential Indicator of N₂O Production Pathways in a Floodplain Fen

by Mohit Masta, Holar Sepp, Jaan Pärn, Kalle Kirsimäe and Ülo Mander

Water 2020, 12(2), 409; https://doi.org/10.3390/w12020409 - 4 Feb 2020

Cited by 5 | Viewed by 3827

Abstract

Nitrous oxide (N₂O), a major greenhouse gas and ozone depleter, is emitted from drained organic soils typically developed in floodplains. We investigated the effect of the water table depth and soil oxygen (O₂) content on N₂O fluxes [...] Read more.

Nitrous oxide (N₂O), a major greenhouse gas and ozone depleter, is emitted from drained organic soils typically developed in floodplains. We investigated the effect of the water table depth and soil oxygen (O₂) content on N₂O fluxes and their nitrogen isotope composition in a drained floodplain fen in Estonia. Measurements were done at natural water table depth, and we created a temporary anoxic environment by experimental flooding. From the suboxic peat (0.5–6 mg O₂/L) N₂O emissions peaked at 6 mg O₂/L and afterwards decreased with decreasing O₂. From the anoxic and oxic peat (0 and >6 mg O₂/L, respectively) N₂O emissions were low. Under anoxic conditions the δ¹⁵N/δ¹⁴N ratio of the top 10 cm peat layer was low, gradually decreasing to 30 cm. In the suboxic peat, δ¹⁵N/δ¹⁴N ratios increased with depth. In samples of peat fluctuating between suboxic and anoxic, the elevated ¹⁵N/¹⁴N ratios (δ¹⁵N = 7–9‰ ambient N₂) indicated intensive microbial processing of nitrogen. Low values of site preference (SP; difference between the central and peripheral ¹⁵N atoms) and δ¹⁸O-N₂O in the captured gas samples indicate nitrifier denitrification in the floodplain fen. Full article

(This article belongs to the Special Issue Wetlands in Action: Sustainable Water Management and Resource Recovery)

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15 pages, 8786 KiB

Open AccessArticle

Water Level Fluctuation Requirements of Emergent Macrophyte Typha angustifolia L.

by Zhen-Dong Yang, Sai-Bo Yuan, Xue-Qin Liu and Hong-Zhu Wang

Water 2020, 12(1), 127; https://doi.org/10.3390/w12010127 - 30 Dec 2019

Cited by 7 | Viewed by 3681

Abstract

The management of water levels in wetlands is of great importance for the wetland ecosystem, including the conservation and revitalization of plants. However, the water level requirements (WLRs) of wetland plants have not been well investigated. In this study, Typha angustifolia was selected [...] Read more.

The management of water levels in wetlands is of great importance for the wetland ecosystem, including the conservation and revitalization of plants. However, the water level requirements (WLRs) of wetland plants have not been well investigated. In this study, Typha angustifolia was selected as an experimental plant species. Combining field investigation and simulation experiments, the relationship between the development status of this species and water level fluctuations (WLFs) in different life-history stages were analyzed. The results show that populations in the Yangtze floodplain, China, had two phenotypic forms ‘tall’ and ‘short’, and that these were distributed in lakes with intermittent or quasi-natural fluctuations and reservoir-like fluctuations, respectively. Lakes with high amplitude (>3.2 m) water fluctuations did not contain T. angustifolia. We investigated the distribution and growth of T. angustifolia in lakes of varying hydrology across the Yangtze floodplain, seeking to define its tolerance of water-level fluctuations and submergence at different stages in its life cycle. The upper tolerance limit of static submerged water depth was bounded by 1.5 times the height of plants in the seedling stage, and the upper tolerance limit of the submergence rate in the seedling stage was the average growth rate of seedling, 1.5 cm/d. The plant height had a positive linear correlation with amplitude and water depth from June to July. The autumn biomass was significantly negatively correlated with amplitude and water depth from January to May. This paper is perhaps the first case study on water level fluctuation requirements (WLFRs) of emergent macrophytes. It systematically assessed the WLFRs of T. angustifolia in each life-history stage, and established a comprehensive WLFR conceptual model. The results of this study could provide a quantitative operational basis for the protection and restoration of this species in Yangtze floodplain lakes. Full article

(This article belongs to the Special Issue Wetlands in Action: Sustainable Water Management and Resource Recovery)

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16 pages, 909 KiB

Open AccessArticle

Assessment of Constructed Wetlands’ Potential for the Removal of Cyanobacteria and Microcystins (MC-LR)

by Guna Bavithra, Joana Azevedo, Flávio Oliveira, João Morais, Edgar Pinto, Isabel M.P.L.V.O. Ferreira, Vitor Vasconcelos, Alexandre Campos and C. Marisa R. Almeida

Water 2020, 12(1), 10; https://doi.org/10.3390/w12010010 - 18 Dec 2019

Cited by 22 | Viewed by 4437

Abstract

Microcystis blooms and the subsequent release of hepatotoxic microcystins (MCs) pose a serious threat to the safety of water for human and livestock consumption, agriculture irrigation, and aquaculture worldwide. Microcystin-LR (MC-LR), the most toxic variant of MCs, has been widely detected in a [...] Read more.

Microcystis blooms and the subsequent release of hepatotoxic microcystins (MCs) pose a serious threat to the safety of water for human and livestock consumption, agriculture irrigation, and aquaculture worldwide. Microcystin-LR (MC-LR), the most toxic variant of MCs, has been widely detected in a variety of environments such as water, sediments, plants, and many aquatic organisms. Conventional solutions of water treatment are costly, requiring specific infrastructure, as well as specialized personnel and equipment. Therefore, these solutions are not feasible in many rural areas or in the treatment of large reservoirs. In this regard, low-cost and low-technology solutions, such as constructed wetlands (CWs), are attractive solutions to treat surface waters contaminated with toxic cyanobacteria blooms from lakes, ponds, reservoirs, and irrigation systems. In line with this, the main aim of this work was to evaluate the potential of CWs for the treatment of water contaminated with MC-LR produced by Microcystis aeruginosa—LEGE 91094. For that, microcosms (0.4 × 0.3 × 0.3 m) simulating CWs were assembled with Phragmites australis to treat lake water contaminated with Microcystis aeruginosa cells and MCs. Results showed removal percentages of M. aeruginosa cells above 94% and about 99% removal of MC-LR during 1 week treatment cycles. CWs maintained their functions, regardless the presence of MC-LR in the system, and also showed significant removal of nutrients (ammonium ion removal up to 86%) and organic matter (removal reaching 98%). The present work indicates that CWs have the potential for removal of cyanobacterial cells and cyanotoxins, which can be useful for the treatment of eutrophic waters and provide water of sufficient quality to be used, for instance, in agriculture. Full article

(This article belongs to the Special Issue Wetlands in Action: Sustainable Water Management and Resource Recovery)

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10 pages, 846 KiB

Open AccessArticle

Effects of Water Depth and Phosphorus Availability on Nitrogen Removal in Agricultural Wetlands

by Xiaojun Song, Per Magnus Ehde and Stefan E. B. Weisner

Water 2019, 11(12), 2626; https://doi.org/10.3390/w11122626 - 13 Dec 2019

Cited by 11 | Viewed by 3655

Abstract

Excess nitrogen (N) from agricultural runoff is a cause of pollution in aquatic ecosystems. Created free water surface (FWS) wetlands can be used as buffering systems to lower the impacts of nutrients from agricultural runoff. The purpose of this paper was to evaluate [...] Read more.

Excess nitrogen (N) from agricultural runoff is a cause of pollution in aquatic ecosystems. Created free water surface (FWS) wetlands can be used as buffering systems to lower the impacts of nutrients from agricultural runoff. The purpose of this paper was to evaluate critical factors for N removal in FWS wetlands receiving high nitrate (NO₃⁻) loads from agriculture. The study was performed in 12 experimental FWS wetlands in southern Sweden, receiving drainage water from an agricultural field area. The effects of water depth (mean depth of 0.4 m and 0.6 m, respectively) and phosphorus (P) availability (with or without additional P load) were investigated from July to October. The experiment was performed in a two-way design, with three wetlands of each combination of depth and P availability. The effects of P availability on the removal of NO₃⁻ and total N were strongly significant, with higher absolute N removal rates per wetland area (g m⁻² day⁻¹) as well as temperature-adjusted first-order area-based removal rate coefficients (K_at) in wetlands with external P addition compared to wetlands with no addition. Further, higher N removal in deep compared to shallow wetlands was indicated by statistically significant differences in K_at. The results show that low P availability may limit N removal in wetlands receiving agricultural drainage water. Furthermore, the results support that not only wetland area but also wetland volume may be important for N removal. The results have implications for the planning, location, and design of created wetlands in agricultural areas. Full article

(This article belongs to the Special Issue Wetlands in Action: Sustainable Water Management and Resource Recovery)

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16 pages, 5176 KiB

Open AccessArticle

Addition of Corn Cob in the Free Drainage Zone of Partially Saturated Vertical Wetlands Planted with I. sibirica for Total Nitrogen Removal—A Pilot-Scale Study

by Aarón Del Toro, Allan Tejeda and Florentina Zurita

Water 2019, 11(10), 2151; https://doi.org/10.3390/w11102151 - 16 Oct 2019

Cited by 15 | Viewed by 2975

Abstract

The aim of this 15-month study was to evaluate and compare two partially saturated (PS) vertical flow (VF) wetlands for total nitrogen (TN) removal. The PS VF wetlands, evaluated in duplicate, were added with corncob (CC) in two different heights of the free-drainage [...] Read more.

The aim of this 15-month study was to evaluate and compare two partially saturated (PS) vertical flow (VF) wetlands for total nitrogen (TN) removal. The PS VF wetlands, evaluated in duplicate, were added with corncob (CC) in two different heights of the free-drainage zone (FDZ). The FDZ had a height of 40 cm and the saturated zone (SZ) had a height of 30 cm. The configuration of the system I (SI) was a 20 cm-corncob bed above the SZ followed by a 20 cm-tezontle bed; in system II (SII) the order of the beds were inverted. The SZ was added with tezontle with a size of 1−2 cm. Weekly measurements of water quality parameters including oxygen demand (BOD₅), chemical oxygen demand (COD), color, total suspended solids (TSS), organic nitrogen (Org-N), ammonium (NH₄⁺), nitrate (NO₃⁻) and nitrite (NO₂⁻), were taken in the influent and effluents, and interfaces (nitrate and nitrite). Measurements of pH, dissolved oxygen (DO) and oxidation-reduction potential (ORP) were taken in the SZ. The addition of CC in the FDZ did not interfere with the capacity of the PS VF wetlands for BOD₅, COD, TSS and true color removal, reaching mass removal efficiencies of 91.9% and 92.2%, 66.6% and 75%, 89.8% and 92%, 63.3% and 66.0%, for SI and SII, respectively; without significant difference between the systems (p > 0.05). The CC in the FDZ neither interfered with the PS VF wetlands nitrification capacity. The removal of TN was similar in SI and SII (p > 0.05), attaining average mass removal efficiencies of 68.2% and 66.0%, respectively. These efficiencies were not sufficiently high due to the limited denitrification process in the SZ as a result of the absence of biodegradable carbon, generated and consumed in the FDZ. Full article

(This article belongs to the Special Issue Wetlands in Action: Sustainable Water Management and Resource Recovery)

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21 pages, 3116 KiB

Open AccessArticle

Assessment of Potential Toxic Metals in a Ramsar Wetland, Central Mexico and its Self-Depuration through Eichhornia crassipes

by J. Tabla-Hernandez, P. F. Rodriguez-Espinosa, J. A. Mendoza-Pérez, E. Sánchez-Ortíz, E. Martinez-Tavera and A. G. Hernandez-Ramirez

Water 2019, 11(6), 1248; https://doi.org/10.3390/w11061248 - 14 Jun 2019

Cited by 8 | Viewed by 4442

Abstract

The Valsequillo reservoir is a Ramsar wetland due to its importance as a point of convergence of migratory waterfowl. It is located in Central Mexico and is currently endangered by the constant spill of municipal and industrial discharges from Puebla city. On this [...] Read more.

The Valsequillo reservoir is a Ramsar wetland due to its importance as a point of convergence of migratory waterfowl. It is located in Central Mexico and is currently endangered by the constant spill of municipal and industrial discharges from Puebla city. On this context, we evaluated thirteen potential toxic metals (PTMs) in water, Water hyacinth (E. crassipes) plants and sediments at this site. A combined number of 31 samples were collected from the study area. The degree/extent of metal contamination in sediments was assessed through different geochemical indexes, namely: Geoaccumulation index (I_geo), Enrichment Factor (EF) and Potential Ecological Risk Index (PERI). The ability of Water hyacinth plants residues as a phytodepurator in the Ramsar site was tested in terms of the bioaccumulation factor (BF) and the translocation factor (TF). The results concerning sediments showed that Pb, Cu and Hg pose a threat to the aquatic environment since I_geo and EF indicate sediments ranging from moderately contaminated to contaminated. Moreover, PERI pointed out Hg as the main contributor to the ecological risk in sediments, especially in the part of the reservoir covered by E. crassipes. Water hyacinth plants displayed good capacity to absorb PTMs from the water, since the content of Co, Zn, As, Ni, Cu, Pb, Ti, Cr, Ba, Mo and V in the total plant was (all values in mg/kg of dry weight) 21 ± 9, 408 ± 300, 12 ± 6, 93 ± 21, 93 ± 69, 53 ± 29, 1067 ± 643, 78 ± 55, 362 ± 39, 14 ± 0.6 and 96 ± 35, respectively. Metal content in sediments resembles to that of E. crassipes; especially in the roots, suggesting a constant deposition of plants at the bottom of the reservoir, which contributes to the eutrophication of the water. The present work encourages the need for a sustainable management of Water hyacinth plants in the Ramsar site, since they represent a plague and a natural phyto-depurator at the same time. Full article

(This article belongs to the Special Issue Wetlands in Action: Sustainable Water Management and Resource Recovery)

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Review

Jump to: Research

31 pages, 1505 KiB

Open AccessReview

Constructed Wetlands in Latin America and the Caribbean: A Review of Experiences during the Last Decade

by Marco A. Rodriguez-Dominguez, Dennis Konnerup, Hans Brix and Carlos A. Arias

Water 2020, 12(6), 1744; https://doi.org/10.3390/w12061744 - 18 Jun 2020

Cited by 37 | Viewed by 9262

Abstract

The review aims to report the state-of-the-art constructed wetlands (CW) in the Latin America and Caribbean (LAC) region not limited to national and local conditions. The aim is with a broader view, to bring updated and sufficient information, to facilitate the use of [...] Read more.

The review aims to report the state-of-the-art constructed wetlands (CW) in the Latin America and Caribbean (LAC) region not limited to national and local conditions. The aim is with a broader view, to bring updated and sufficient information, to facilitate the use of the CW technology in the different countries of LAC. Thus, 520 experiences extracted from the 169 reviewed documents in 20 countries were analyzed. According to the data, horizontal subsurface flow wetlands are the most reported CW in the region (62%), the second most common CW technology in the region is free water surface CW (17%), then vertical flow systems (9%), followed by intensified constructed wetlands (8%), and finally French systems (4%). The performance for nutrient removal is analyzed, finding that the mean of Chemical Oxygen Demand (COD), Total Nitrogen (TN), and Total Phosphorous (TP) removal efficiencies varies from 65% to 83%, 55% to 72%, and 30% to 84%, respectively. The results suggest a generally good performance for COD and TN removal, but a low performance for TP removal. Regarding plant species used for CWs, 114 different plant species were reported, being until now the most extensive report about plant species used in CWs in the LAC region. Full article

(This article belongs to the Special Issue Wetlands in Action: Sustainable Water Management and Resource Recovery)

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24 pages, 6651 KiB

Open AccessEditor’s ChoiceReview

Constructed Wetlands for Sustainable Wastewater Treatment in Hot and Arid Climates: Opportunities, Challenges and Case Studies in the Middle East

by Alexandros I. Stefanakis

Water 2020, 12(6), 1665; https://doi.org/10.3390/w12061665 - 10 Jun 2020

Cited by 96 | Viewed by 16128

Abstract

Many countries and regions around the world are facing a continuously growing pressure on their limited freshwater resources, particularly those under hot and arid climates. Higher water demand than availability led to over-abstraction and deterioration of the available freshwater resources’ quality. In this [...] Read more.

Many countries and regions around the world are facing a continuously growing pressure on their limited freshwater resources, particularly those under hot and arid climates. Higher water demand than availability led to over-abstraction and deterioration of the available freshwater resources’ quality. In this context, wastewater, if properly treated, can represent a new water source added in the local water balance, particularly in regions of Colorado, California, Australia, China and in the wide region of the Middle East, which is characterized as one of most water-stressed regions in the world. This article summarizes the status of wastewater treatment and management in the Middle East and discusses the challenges, the various barriers and also the opportunities that arise by introducing the sustainable technology of Constructed Wetlands in the region. Furthermore, the aim of the article is to provide a better insight into the possibility and feasibility of a wider implementation of this green technology under the hot and arid climate of Middle East by presenting several successful case studies of operating Constructed Wetlands facilities in the region for the treatment of various wastewater sources. Full article

(This article belongs to the Special Issue Wetlands in Action: Sustainable Water Management and Resource Recovery)

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