Search

Understanding nutrient cycling patterns in plants deployed within constructed floating wetlands (CFWs) is critical for improving CFWs’ design and management practices. This study evaluated phosphorus (P) uptake and release patterns during fall/winter plant senescence and spring regrowth. Two mesocosm-scale CFW experiments were conducted characterizing plant growth, plant tissue P levels, and water quality (nutrients and phytoplankton). Experiment 1 quantified P uptake during spring regrowth after overwintering, and experiment 2 quantified P release during fall senescence. Plant treatments (CFWs with Pontederia cordata or Juncus effusus) were compared to an open-water control. In spring, J. effusus removed 0.056 g P m−2 d−1 (19.4% of the load), P. cordata removed 0.034 g P m−2 d−1 (10%), and the open-water control removed 0.03 g P m−2 d−1 (10%). In fall, J. effusus fixed 0.008 g P m−2 d−1 (2.1% of the load), P. cordata released 0.014 g P m−2 d−1 (−2.1%), and controls fixed 0.023 g P m−2 d−1 (6.3%). P was consistently released during the fall experiment and occasionally released in the spring experiment, likely from senescing plant tissues (fall) and from roots sloughing after new root growth (spring). Results demonstrate the potential for multi-season deployment of CFWs using J. effusus for reducing P loads year-round. HIGHLIGHTS Seasonal nutrient cycling should inform constructed floating wetland (CFW) design and management.; Juncus effusus fixed phosphorus (P) both in the fall and spring.; Pontederia cordata released P in the fall and slowly absorbed P in late spring.; Semi-evergreen species may be ideal plants for year-round CFW deployment.;

Nature-based solutions (NBS) imitate natural processes and serve to generate multi-benefit values and services to the local communities. Sustainable solutions are multi-purpose measures implemented at the site, and offer communities targeted environmental water-related solutions in wastewater treatment, water retention, and pollution mitigation that result in a climate-resilient landscape. Numerous good cases combine NBS for environmental pollution mitigation, prevention, and management. They can be implemented and managed locally, and are stimulated as zero-emission and climate-resilient technology. The main areas of intervention where NBS is best applied are agricultural run-off mitigation (constructed ecosystems), wastewater and leachate treatment (constructed wetlands), revitalisation of standing water bodies (floating wetlands), stormwater retention measures (rain gardens), and nutrient reuse (sludge drying reed beds). A new report by the Sustainable sanitation Task Force (active in Global Water Partnership Central and Eastern Europe) on NBS in wastewater treatment indicates a moderate improvement in NBS application, but also relevant progress in engineering knowledge and innovation. It also estimates the application of several NBS treatment technologies for rural sanitation improvement and water reuse potentials.

Floating treatment wetlands (FTWs) are artificial ecosystems designed to mimic the nutrient removal capabilities of natural wetlands through the hydroponic cultivation of plants on floating rafts, thereby utilizing the process of phytoremediation. This approach provides plants with protection against submersion, creating an optimal environment for the growth of valuable hydroponic crops. To ensure the removal of nutrients absorbed and incorporated into plant biomass from aquatic systems, the implementation of routine plant harvesting serves as an effective management strategy. This practice prevents the decomposition and subsequent release of nutrients back into the water. Furthermore, the cultivation of crops for commercial purposes can serve as an incentive to enhance biomass harvesting and replanting efforts, which may be financially impractical otherwise. This study aimed to assess the growth success and nutrient remediation capacities of five cut-flower species on FTWs in controlled mesocosm systems at Florida International University in Miami, Florida. The surviving species were evaluated based on growth metrics, bloom count, and nutrient removal abilities, specifically for total phosphorus (TP) and total nitrogen (TN). Among the five species tested, only marigold (Tagetes erecta) survived throughout the 12-week trial on the FTWs. The marigold-planted treatment exhibited a significant enhancement in nutrient reduction efficiencies compared to the control treatment, removing 52% more TP and 33% more TN mass from the mesocosm system. This resulted in a nutrient removal rate of 0.062 g of TP ‧ m2 ‧ day−1 and 0.321 g of TN ‧ m2 ‧ day−1 in the marigold-treated mesocosm. Additionally, the marigold treatment yielded an average of 65 market-quality blooms per m2, with mean widths of 6.4±1.8 cm and lengths of 27.6±7.3 cm. Given the substantial nutrient removal and the production of marketable blooms, marigold (Tagetes erecta) shows promising potential as a commercially viable remediating crop cultivated on FTWs in South Florida. Statement of Significance: This study demonstrated that marigolds grew successfully on an FTW, removed a comparable amount of nutrients from the water as other wetland plants tested on FTWs in previous studies, and produced a high number of blooms for market. This species is worth testing at a field scale to see how well they thrive in application. Future studies should increase the thickness of the FTW for roots to anchor better and help stabilize the growth of additional cut-flower species. Specifically, the production of cut-flowers on FTWs in South Florida could take advantage of the floral industry infrastructure in Miami, FL while also helping to address increasing water quality issues in the region.

Floating treatment wetlands (FTWs), also called constructed floating wetlands or floating islands, are a recent innovation in constructed wetlands (CWs) inspired by natural wetlands. In FTWs, emergent plants grown hydroponically on buoyant mats are used for wastewater treatment, which makes them far more economical than other CWs. The objective of this study was to evaluate the performance of FTWs for the treatment of municipal wastewater from an urban drain using native plant species Canna indica and Phragmites australis. A pilot-scale experiment was carried out using four FTW treatment cells with different plant coverages for pollutant removal: C1 (Canna indica, 100% coverage), C2 (Phragmites australis, 100% coverage), C3 (Phragmites australis, 50% coverage), and C4 (control). Overall, treatment cells with Canna indica and Phragmites australis showed reductions in BOD5, COD, EC, TDS, NO3−, and PO43− compared with the control. Maximum BOD5 and COD removal was 53% and 50%, respectively, at 50% coverage of Phragmites australis (C3). The maximum reduction in NO3− (61%) was achieved using Canna indica at 100% coverage (C1). Conversely, moderate removal of PO43− (27%) was obtained in the control (C4) with a visibly high amount of algal growth, indicating the influence of algae on pollutant removal. This study highlights the significance of Phragmites australis for organic matter removal and Canna indica for nutrient removal, mainly NO3− from municipal wastewater. Furthermore, this study suggests that FTWs perform well for BOD5 and COD removal at 50% plant coverage (Phragmites australis) and NO3− removal at 100% coverage (Canna indica). [ABSTRACT FROM AUTHOR]

Nature-based solutions (NBS) imitate natural processes and serve to generate multi-benefit values and services to the local communities. Sustainable solutions are multi-purpose measures implemented at the site, and offer communities targeted environmental water-related solutions in wastewater treatment, water retention, and pollution mitigation that result in a climate- resilient landscape. Numerous good cases combine NBS for environmental pollution mitigation, prevention, and management. They can be implemented and managed locally, and are stimulated as zero-emission and climate-resilient technology. The main areas of intervention where NBS is best applied are agricultural run-off mitigation (constructed ecosystems), wastewater and leachate treatment (constructed wetlands), revitalisation of standing water bodies (floating wetlands), stormwater retention measures (rain gardens), and nutrient reuse (sludge drying reed beds). A new report by the Sustainable sanitation Task Force (active in Global Water Partnership Central and Eastern Europe) on NBS in wastewater treatment indicates a moderate improvement in NBS application, but also relevant progress in engineering knowledge and innovation. It also estimates the application of several NBS treatment technologies for rural sanitation improvement and water reuse potentials. [ABSTRACT FROM AUTHOR]

One of the most significant techniques for saline wastewater treatment is bioremediation. Halophytes are known as the plants that can tolerate the high concentration of salts, in such salinity common plants cannot be often able to survive. In this research, the feasibility of desalination by using halophyte (Chenopodium quinoa Willd.) was studied. Quinoa plants were grown in the hydroponic system in 12 containers including 9 containers with plants and 3 containers without plants as control. Fifteen plants were planted in each container and three salinity levels including 2, 8, and 14 ds/m for two different periods (15 and 30 days) were studied in a multi-factors completely randomized design. Three replications of each salinity level were conducted and the Electrical Conductivity (EC) parameters, including Calcium, Magnesium, Sodium, and Chloride ions were determined before and after treatment by Quinoa plants. The results showed that the Quinoa plants reduced 5.33%, 8.12%, and 9.35% of the EC at EC~2 dS/m (Marginal Water), EC~8 dS/m (Brackish Water), and EC~14 dS/m (Saline Water), respectively. Moreover, Calcium, Magnesium, Sodium, and Chloride ions decreased up to 10%, 7.62%, 5.60%, and 7.01%, respectively depending on the salinity levels. Therefore, the Quinoa plant has a relatively low potential in unconventional water treatment especially saline wastewater.

The textile industry is one of the largest consumers of water and chemicals, so that each kilogram of textile product requires 100-200 liters of water.Therefore, due to the limited water resources available, having the most pollution among industrial activities and the need to comply with wastewater disposal standards in the environment necessitates wastewater treatment. This study was conducted by review-descriptive method using existing studies. In this article, a review of floating treatment wetland and its application in the wastewater treatment of the textile industry, the key factors affecting the treatment and the combined role of plants and bacteria for maximum purification of contaminated water are presented. Plant tissue in water, roots and rhizomes in sediments play a major role in pollutant treatment. Examining the results of the advantages and disadvantages of different methods in wastewater treatment of the textile industry shows that floating wetland technology is an alternative to traditional and expensive wastewater treatment methods. According to the researches, Phragmites australis is widely used in this technology. Phragmites australis, along with Acinetobacter, Pseudomonas and Rhodococcus, can reduce COD by 92%, BOD by 91%, dye by 86% and heavy metals by 87%.

Penatu adalah usaha yang bergerak di bidang pencucian atau penyetrikaan pakaian. Selain banyak keuntungan, bisnis penatu ternyata berdampak buruk bagi lingkungan. Biasanya air limbah deterjen dibuang langsung ke saluran drainase tanpa melalui proses pengolahan terlebih dahulu. Jika hal ini dibiarkan terus menerus akan menimbulkan masalah pencemaran air. Penelitian ini bertujuan untuk mengetahui pengaruh kadar air dan waktu detensi pada pengolahan air limbah laundry dengan metode floating treatment wetland dengan tumbuhan Vetiveria zizanioides. Kualitas hasil pengolahan diukur dengan parameter pH, TSS, COD. Variasi tinggi muka air dan waktu detensi pada penelitian ini adalah 10 cm, 15 cm, 20 cm dan 5, 10, 15 hari. Berdasarkan uji anova dua arah dapat disimpulkan bahwa waktu detensi berpengaruh terhadap penurunan kadar pH, TSS, dan COD. Hasil penelitian menunjukkan penurunan pH 19,35%, TSS 83,33%, COD sebesar 62,96 %. Hal ini menunjukkan bahwa floating treatment wetland dapat digunakan untuk mengolah limbah laundry.

Floating treatment wetlands (FTW) are an emerging Nature Based Solution that have exhibited promising nitrogen removal under different range of effluents pollutant concentrations. Despite the notable increase in the number of FTW studies in the last years, nitrogen (N) removal mechanisms within FTW have not been fully assessed. The present study aims to understand N removal in FTW and investigate their microbial biofilm activity through a pilot scale experiment for agri-food tertiary wastewater treatment. A conventional and a modified (with added cellular concrete (CC)) FTW were monitored over 7 months with respect to two control lagoons (conventional lagoons with or without CC hanging in the water column). Experimental results revealed that the best TN removal was achieved by the lagoon equipped with the modified FTW (20% mean removal increase compared to the conventional lagoon). Biofilm denitrification activity potential was up to 6.7–9.0 times higher within pilot lagoons equipped with FTW than that in control lagoon (LC without FTW), while nitrification activity potential was prominent in biofilms within the control pilot lagoons (exhibiting high dissolved oxygen (DO) concentration). Biofilms from plant roots exhibited the highest overall dissolved inorganic nitrogen treatment followed by the biofilms from sediments and CC material. Plant root biofilms exhibited both significant nitrification and denitrification activity potentials despite the overall low DO and COD concentrations within FTW pilot lagoons' water column. This suggests the existence of micro sites in the roots network which provide adequate aerobic conditions and access to organic carbon most probably through root exudates. Overall, N accumulation in the sediment was a minor removal mechanism for all pilot lagoons. Plant accumulation (accounting for one third of TN removal), nitrification and enhanced denitrification appeared to be the main removal mechanisms in pilot lagoons equipped with FTWs (with or without CC) while nitrification, algal assimilation and NH 4 -N volatilization may have been the major processes driving TN removal in the control pilot lagoons. Hence, FTW could be an interesting retrofit of existing lagoons to promote nitrogen removal through denitrification and plant assimilation, especially in the case of receiving bodies highly sensitive to nitrate input. Further research should address optimizing FTW design to guarantee stable N removal under changing water temperature and mitigate seasonal variations as well as investigate biofilm species for in-depth understanding of N cycle within FTWs. [ABSTRACT FROM AUTHOR]

One of the most significant techniques for saline wastewater treatment is bioremediation. Halophytes are known as the plants that can tolerate the high concentration of salts, in such salinity common plants cannot be often able to survive. In this research, the feasibility of desalination by using halophyte (Chenopodium quinoa Willd.) was studied. Quinoa plants were grown in the hydroponic system in 12 containers including 9 containers with plants and 3 containers without plants as control. Fifteen plants were planted in each container and three salinity levels including 2, 8, and 14 ds/m for two different periods (15 and 30 days) were studied in a multi-factors completely randomized design. Three replications of each salinity level were conducted and the Electrical Conductivity (EC) parameters, including Calcium, Magnesium, Sodium, and Chloride ions were determined before and after treatment by Quinoa plants. The results showed that the Quinoa plants reduced 5.33%, 8.12%, and 9.35% of the EC at EC~2 dS/m (Marginal Water), EC~8 dS/m (Brackish Water), and EC~14 dS/m (Saline Water), respectively. Moreover, Calcium, Magnesium, Sodium, and Chloride ions decreased up to 10%, 7.62%, 5.60%, and 7.01%, respectively depending on the salinity levels. Therefore, the Quinoa plant has a relatively low potential in unconventional water treatment especially saline wastewater. [ABSTRACT FROM AUTHOR]

The city of Sialkot in Pakistan is a hub of leather tanneries, with approximately 260 tanneries in operation and, while producing millions of leather products per day, the city discharges millions of gallons of untreated effluent into drains each day. In order to devise a cost-effective system for the treatment of tannery wastewater, a floating treatment wetland (FTW) was established to treat the effluent using local plant species through phytoremediation. The efficiency of the FTW was tested with three different plant species, each grown separately and operating for three months in the FTW tank. Two of the plant species introduced, water hyacinth and water lettuce, were floating and vascular; the third plant species Typha latifolia was vegetated on a floating mat of styrofoam while the roots extended down to the contaminated water. Wastewater from a tannery drain was pumped into the FTW tank with a flow of 0.5 L per minute and was given a retention time of six days. The influent and effluent from the FTW were periodically tested to determine the percentage removal of contaminants, primarily the total suspended solids, biochemical oxygen demand, chemical oxygen demand, and chromium. After two months with each species, a significant change in the quality of wastewater was measured: chromium was removed by up to 95 percent by the water hyacinth and water lettuce and 33 percent by the Typha latifolia. The pilot model indicates that FTWs are an effective system to treat effluent from tanneries in a cost-effective way as an alternative to establishing an expensive treatment system with high associated operational costs. It can help in achieving the circular economy concept of conventional wastewater schemes towards more sustainable ones. Moreover, to achieve the principles of circular economy and environmentally friendly development, it is crucial that the substances used for a wetland foundation have the capacity to be recycled, are available at a cheap price, and are locally available. [ABSTRACT FROM AUTHOR]

Most water bodies around the world suffer from pollution to varying degrees. Floating treatment wetlands (FTWs) are a simple and efficient ecological treatment technology and have been widely studied and applied as a sustainable solution for different source waters. Based on the analysis of abundant literature in the last ten years, this paper systematically reviews the history and the latest development of FTWs. Meanwhile, the treatment performance and pollutant removal mechanisms of FTWs on the natural water, stormwater, domestic wastewater, industrial wastewater, and agricultural runoff are analyzed. In particular, very interesting information is provided, such as water depth, water surface coverage, the ratio of dissolved to total phosphorous (DRP/TP), the ratio of nitrogen to phosphorous (N/P), BOD/COD ratio, and its effects on the efficiency and removal mechanisms of FTWs. This information will provide useful references and guidance for optimizing the design of FTW and pollutant treatment efficiency of different source waters. This paper also provides an objective review of the limitations of FTWs. Subsequently, the enhancements of FTW technology which are recognized to be effective, including aeration, adding functional fillers or obligate degrading bacteria, and construction of hybrid FTWs, are summarized and recommendations are made for further research. [ABSTRACT FROM AUTHOR]

The presence of non-reactive phosphorus (NRP) in environmental waters presents a potential risk of eutrophication and poses challenges for the removal of all phosphorus (P) fractions. This study presents the first investigation on the removal performance and mechanism of three model NRP compounds, sodium tripolyphosphate (STPP), adenosine 5′-monophosphate (AMP) and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), in the sediment microbial fuel cell-floating treatment wetland (SMFC-FTW). Coupling SMFC with plants proved to be effective at removing NRP via electrochemical oxidation and plant uptake, particularly the challenging-to-degrade phosphonates that contain C–P bonds. Compared with the control group, the removal efficiencies of the model NRP in SMFC were observed to increase by 11.9%–20.8%. SMFC promoted the conversion of NRP to soluble reactive phosphorus (sRP) and the transfer of P to sediment. Furthermore, the electrochemical process enhanced both plant growth and P uptake, and increased P assimilation by 72.6%. The presence of plants in the bioelectrochemical system influenced the occurrence and fate of P by efficiently assimilating sRP and supporting microbial transformation of NRP. Consequently, plants enhanced the removal efficiencies of all P fractions in the overlying water. This study demonstrated that SMFC-FTW is a promising technology to remove various NRP species in environmental waters. [Display omitted] • Coupling SMFC with plants can effectively degrade various NRP species. • SMFC facilitated the NRP conversion to RP in the overlying water and sediments. • Electrochemical treatment enhanced plant growth and P uptake. • Plants improved the removal efficiencies of all P fractions. [ABSTRACT FROM AUTHOR]

Though having an economic and ecological impact on Marriott Lake management in Egypt, water hyacinth (Eichhornia crassipes) is an aquatic floating macrophyte with a known phytoremediation potential. In order to assess its remediation potential, pilot floating treatment wetlands (FTWs) with E. crassipes were built in duplicates to evaluate the removal of nutrients and heavy metals from the polluted lake water. The experimental design included units with different water depths (15, 25, and 35 cm; D15, D25, and D35, respectively) and plant coverage (90, 70, 50, and 0%; P90, P70, P50, and P0, respectively). The pilot FTWs were monitored over a 7-day operation cycle to identify the optimum combination of design (plant coverage, water depth) and operation (hydraulic retention time; HRT) parameters needed for maximum BOD5, TN, NH4-N, and TP removal. NH4-N removal reached 97.4% in the D25P50 unit after 3 days, BOD5 75% in the D15P90 after 3 days, TN 82% in the D25P70 after 4 days, and TP 84.2% in the D35P70 after 4 days. The open-water evaporation rate was higher than the evapotranspiration rate in the planted units, probably due to the warm climate of the study area. Metals were also sufficiently removed through bioaccumulation in plant tissues in the order of Fe > Pb > Cu > Ni (62.5%, 88.9%, 81.7%, and 80.4% for D25P50, D25P70, D25P50, and D25P90, respectively), while most of the assimilated metal mass was translocated to the plant roots. The biochemical composition of the plant tissue was significantly different between the shoot and root parts. Overall, the FTW with 70% E. crassipes coverage, 25-cm water depth, and an HRT of 3–5 days was identified as the optimum design for effective remediation of the polluted Marriott Lake in Egypt. [ABSTRACT FROM AUTHOR]

Floating treatment wetland (FTW) in restoration of low C/N ratio wastewater was deemed to a frequently used method. However, the nitrate removal performance in floating beds was limited due to insufficient organic carbon sources. Iron scraps as a potential electron donor was beneficial to the NO3--N reduction. To research the removal performance and mechanism of denitrification in FTW with iron scraps, FTW with Iris pseudacorus was built, and iron scraps were added as an electron donor to improve nitrogen removal efficiency. The batch experimental results demonstrated that the proper mass ratio of iron scraps to NO3--N was 500:1. With iron scraps, the NO3--N removal efficiency of FTW and control system increased significantly to 98.04% and 44.42% respectively in 2 weeks, while there was no obvious influence on the removal of NH4+-N. After adding iron scraps, the proportion of bacteria in the systems related to iron cycle and the relative abundance of nitrifying and denitrifying bacteria have increased obviously. By calculating the nitrogen balance, nitrogen reduction via plant uptake accounted for 8.79%, and the microbial denitrification was the main nitrogen removal pathway in FTW. [ABSTRACT FROM AUTHOR]

Surface water bodies worldwide may be contaminated with various organic contaminants. In many cases, the actual toxicity thresholds to nontarget organisms are unknown, thus presenting unknown risks. This study evaluated the potential use of floating treatment wetlands (FTWs) planted with Canna flaccida (common name: Canna) for removing two pharmaceuticals (acetaminophen and carbamazepine) and one herbicide (atrazine) from contaminated water. Triplicate FTWs with varying plant densities were established in 378 L mesocosms. After dosing the mesocosms with the contaminants, water samples were collected over a 12-week period for analysis. The planted FTWs showed differing abilities for removing acetaminophen, atrazine, and carbamazepine. Plant densities on the FTWs did not affect dissipation of acetaminophen or atrazine, but did carbamazepine. All acetaminophen residues were removed from the water within 2 weeks, while all atrazine residues were removed within 12 weeks. Approximately, 79−92% of these residues removed were associated with the FTWs. In contrast, all of the carbamazepine was not removed after 12 weeks, at which time only 29–36.7% of the total removed was associated with the FTWs. Overall results suggest that FTWs established with C. flaccida are promising for removing trace concentrations of acetaminophen, atrazine, and carbamazepine from surface water. [ABSTRACT FROM AUTHOR]

With the wide application of floating treatment wetland (FTW), the limited performance of FTWs should be improved. A comprehensive review is accordingly necessary to summarize the state-of-the-art on FTWs for performance improvement. An attempt has been made to gain information from literature about technologies to enhance the performance of FTWs. These technologies have been classified into three categories according to their mechanisms: 1) increasing the amount and activity of bacteria; 2) enhancing the growth of plant; and 3) configurable innovations. The design and application of each enhanced FTW have been discussed in detail. Thereafter, all the technologies have been compared and analyzed according to their improvement in pollutant removal and ecological effects. In summary, FTW with additional bio-carriers has a higher potential for future applications with the benefits of wide application conditions, scale-up potential, and the easy combination with other methods to further improve the removal efficiency. The stability and sustainability of these technologies should be further investigated. [Display omitted] • The state-of-the-art of intensified FTW was summarized. • Bio-carriers were found to be the most attractive intensified technology. • The appropriate technological combination should base on the wastewater conditions. • The resilience and sustainability of intensified FTW should be further evaluated. [ABSTRACT FROM AUTHOR]

Excessive nitrogen accumulated from wastewater with low C/N ratio is a new threat to water ecosystem. In this study, surface flow constructed wetland (SFCW) and floating treatment wetland (FTW) planted with Iris pseudacorus were set in parallel for nitrogen removal. The nitrogen removal efficiencies and pathways, as well as the abundance and functional diversities of the microbial community, were investigated. The results demonstrated that SFCW generally had better nitrogen removal performance than FTW did over four seasons. The average total nitrogen removal efficiency was 66.0% and 43.8% in SFCW and FTW, respectively. The plant uptake played a vital role in nitrogen reduction, which accounted for 29.3% and 7.7% of the total removed nitrogen in SFCW and FTW, respectively. A combination of high-throughput sequencing and quantitative polymerase chain reaction analysis revealed that the two wetland systems had complete nitrogen cycling, and the narG gene was the dominant nitrogen-transformation functional gene in both systems. More abundant denitrifying genes in SFCW than in FTW were also responsible for higher removal capacity of nitrogen. The results suggest that the planting pattern of wetland vegetation has an important impact on nitrogen removal efficiency by influencing the plant absorption and the development of microbial communities. [ABSTRACT FROM AUTHOR]

Artificial substrates (ASs) and floating treatment wetlands (FTWs) have been widely used in the treatment of polluted surface water. In fact, periphyton on ASs functions in nutrient removal, while the plant-periphyton complex functions in FTWs. However, the nutrient removal performance of the periphyton on ASs and the plant-periphyton complex in FTWs has not been systematically compared. Thus, ASs and FTWs were established in a mesocosm experiment to compare nitrogen and phosphorus removal between the two ecological treatment techniques. The results showed that the total nitrogen removal efficiency was 60.4% in the AS treatments and 65.3% in the FTWs, while the total phosphorus removal efficiency was 83.7% in the AS treatments and 39.45% in the FTWs. Periphyton on the ASs absorbed 2.5 g N m−2 and 0.85 g P m−2, accounting for 20.8% of the N removal and 18.7% of the P removal. Sedimentation contributed to 71.3% of the N removal and 56.1% of the P removal in the AS treatments. For the plant-periphyton complex in the FTWs, 25.1% of the N and 53.0% of the P accumulated in plant tissue. Most of the reduced N (47.1%) was removed by other pathways, which was likely the effect of periphyton attached on plant roots and floating rafts. The nutrient removal efficiencies and pathways of AS and FTW treatments showed different characteristics, providing a reference for the selection of treatment measures for polluted surface water remediation. [ABSTRACT FROM AUTHOR]

Treatment wetlands are ecological systems that are engineered to improve polluted water quality through macrophyte, soil, and microbial remediation and are used commonly for urban and agricultural runoff treatment. However, constructed wetlands used for marine aquaculture effluent treatments are understudied when compared to their freshwater counterpart. We compared the nutrient retention and the microbial communities of two types of constructed wetland mesocosms, a vertical-flow treatment wetland (VFTW) and floating treatment wetland (FTW) in subtropical south Florida. To enhance nutrient retention efficiency, we implemented biodegradable plastic (polycaprolactone), as an external carbon source and monitored the performance of VFTW and FTW for the treatment of marine aquaculture effluent. Polycaprolactone surface were covered by various cyanobacterial genera including Oscillatoria , Leptolyngbya , Brasilonema , and Trichormus and some plastic-degrading bacteria such as Pseudomonas. The presence of a biodegradable plastic in FTW improved the overall performance of nitrogen removal (nitrite plus nitrate) by 14% through denitrification. The pattern of nutrient removal between two treatment wetland mesocosms were significantly different (p < 0.01), with over 87–91% retention of total nitrogen in VFTW and no retention in FTW, the latter due to poor retention of nitrite plus nitrate and production of organic nitrogen from the system not present in inflow waters. Total phosphorus was retained in both mesocosm types, with higher retention (74–81%) in the VFTW than in the FTW (17–40%). The nutrient retention in VFTW was higher overall compared with FTW mesocosms regardless of biodegradable plastic presence. [ABSTRACT FROM AUTHOR]

The potential growth of buffalo grass (Stenotaphrum secundatum) and couch grass (Cynodon dactylon) on artificial floating islands (AFIs) and their ability to remove total nitrogen (TN) and total phosphorus (TP) from a simulated paper mill wastewater was studied. This was done to assess the potential of AFIs for removal of nutrients from aerated stabilization basins (ASBs) that had occasional growth of blue-green algae (BGA) to bloom levels. Small scale AFIs were prepared using polyethylene foam and planted with the grasses in 30 L of tested water. Trials were conducted in a plastic covered greenhouse over a three-month period where temperatures ranged from 15 to 44 °C. The results showed that both buffalo and couch grasses can adapt to planting in AFIs showing increases of 125% and 148% in wet weight, respectively. Nutrient uptake by buffalo grass and couch grass were found to be similar. Percentage uptakes of TP and TN from the synthetic water by the buffalo grass were 82% and 47%, whereas by couch grass, uptakes were 83% and 45%, respectively. [ABSTRACT FROM AUTHOR]

Eutrophic conditions occur when waterbodies accumulate excessive nutrients, which leads to algae growth, depleted dissolved oxygen, and increased turbidity. To improve water quality, a biological-chemical treatment was implemented using floating treatment wetlands (FTWs) and slow-release lanthanum delivered through airlift pumps. FTWs remove nutrients via plant uptake and denitrification while lanthanum binds and precipitates phosphate from the water column. The study sites, Densmore and Wilderness Ridge Ponds, had two FTWs and two lanthanum airlift pumps installed in 2020 and 2021. Our hypothesis was that if the biological-chemical treatment reduced nitrate and phosphate, algae growth would be limited, water clarity would improve, and benthic vegetation would increase. Chlorophyll- a , the photosynthetic pigment found in plants and algae, was analyzed to create a direct correlation to algae content within waterbodies. Chlorophyll- a samples were collected twice a month at strategically selected, georeferenced locations in both ponds between May and October in 2022. Water samples were collected when the European Union's Sentinel-2 multispectral satellite passed over the study sites. To estimate chlorophyll- a concentrations prior to the biological-chemical treatment, a correlation was developed between the collected chlorophyll- a concentrations and Sentinel-2 band algorithms. Sentinel-2 imagery provided a means to analyze how chlorophyll- a fluctuated before and during treatment. We found the novel band algorithm, 3BR1, had the best correlation (R2 = 0.72). Applying this band ratio for Sentinel-2 images from 2019 to 2022, a Tukey's HSD test analyzed monthly differences between years. The FTW and lanthanum treatment reduced chlorophyll- a concentrations in Densmore Pond, but not in Wilderness Ridge Pond. One likely reason was Wilderness Ridge Pond had a complex irrigation system and was continuously replenished with nitrate-rich groundwater. Our results show Sentinel-2 can be used to predict historical chlorophyll- a concentrations by using the novel 3BR1 band algorithm and that FTWs and lanthanum can effectively reduce algal growth. [ABSTRACT FROM AUTHOR]

The present study had as objective to evaluate the influence of different operation conditions on two treatment systems composed of anerobic biofilter (AF) and hybrid constructed wetlands (CWs). Both treatment lines had as the first treatment stages an 1450 L AF unit and a CW designed as a Floating Treatment Wetland. Then, a pump directed half of the wastewater flow for each of the treatment lines. One of the lines was composed of a Vertical Flow CW incorporated with microbial fuel cells (CW-MFC), called Configuration 1 (C1), whereas the other line consisted of a Vertical Flow CW (VFCW) and a Horizontal Flow CW (HFCW), named Configuration 2 (C2). The treatment system was fed with wastewater generated in a university campus and monitored for 13 months, with three operation conditions tested: 3 pulses per day with 50 L each (20.5 L/m2day); 4 pulses with 75 L each (41 L/m2day) and 6 pulses with 75 L each (61.6 L/m2day). In addition, the potential bioenergy generated was monitored. For the last operation condition, C1 efficiently reduced BOD 5 (88.7%) and turbidity (84.4%). On the other hand, for the nutrients the treatment efficiencies were lower, with 40.3% (TP) and 46.6% (N−NH 3). Overall, similar results were obtained with the C2, with mean removal efficiencies of BOD 5 (87.3%), turbidity (93.1%), and lower TP (10.4%) reduction. The treatment performance presented similar tendencies even with the changes in loading rates and in hydraulic retention times. Regarding the voltage monitoring, a peak of 687 mV was obtained considering a mean loading rate of 15.6 gCOD/m2day, whereas the maximum power density was 0.25 mW/m. Future research should focus on reducing the internal resistance of the CW system, thus increasing the bioelectricity generated and in treating wastewater with higher organic matter content. [Display omitted] [ABSTRACT FROM AUTHOR]

Floating Treatment Wetland (FTW) merupakan salah satu jenis constructed wetland yang ditanam dalam media yang dapat mengapung dipermukaan air. Dalam FTW tanaman tidak ditanam di tanah melainkan pada media apung yang kemudian diletakkan di permukaan air. Akar tanaman menggantung di badan air sebagai tempat tumbuhnya biofilm dan juga menyaring partikulat tersuspensi. FTW telah diaplikasikan di berbagai negara di dunia namun belum di Indonesia. Studi literatur ini bertujuan untuk meninjau dan menginterpretasikan informasi yang relevan untuk pengembangan dan penerapan FTW di negara tropis. Yaitu dengan merangkum berbagai percobaan yang telah dilakukan untuk lebih memahami kemampuan FTW dalam mereduksi kontaminan dan mengidentifikasi kriteria desain perencanaan FTW. FTW terdiri dari tanaman emergent plant, media tanam, media apung (bouyant material dan bouyant frame), dan anchor. Pemilihan tanaman adalah berdasarkan ketersediaan tanaman (tanaman lokal) yang mampu tumbuh secara optimal dengan kondisi lingkungan dan iklim Indonesia. FTW menggunakan sistem apung sehingga dapat secara langsung diaplikasikan di badan air. Sistem anchoring berfungsi untuk menahan FTW dari pengaruh arus, angin, gelombang, dan fluktuasi ketinggian air. Kriteria desain perencanaan FTW adalah kedalaman air >0,8 m, HRT

Floating treatment wetlands (FTWs) are an innovative type of phytoremediation technique being used to reduce the impact of excess nutrient loading. Plants hydroponically grown on FTWs take up nutrients from water through their roots. In general microbial communities in the rhizosphere are important for healthy growth and nutrient uptake by plants. Despite most of previous studies focused on the nutrient removal processes, very little is known about microbial communities associated with FTW plant roots. The purpose of this study was to characterize the microbiomes revolving around the submerged roots of FTW in a manmade stormwater pond and to elucidate the source of FTW plant root microbiomes. The microbial communities collected from the plant roots Canna flaccida (golden canna) and Juncus effusus (soft rush), biofilms of plant pot (polyethylene) and floating mat foam (closed-cell urethane), and surrounding water were studied using 16S rRNA gene amplicon sequencing. The FTW plant root microbiomes were dominated by Alphaproteobacteria and Cyanobacteria at the class level, and Anabaena , Rhizobium and Rhodobacter at the genus level. Microbial communities of the FTW plant roots showed unique compositions resembling most closely the surrounding water samples while being quite different from the biofilm samples, leading the conclusion that the major source of microbial populations was the surrounding water. However, the dominance of Rhizobium species was only observed in the two plant roots and not recognized in the surrounding water samples, indicating that the FTW roots may selectively shape root microbiomes. Unexpectedly, quite a few groups of microbes were associated with the sulfur cycle. This finding indicates that the oxic-anoxic gradient is formed in the FTW rhizosphere, and this environmental gradient assists to extend the phylogenetic and functional diversities of microorganisms. We anticipate the presence of intrinsic rhizosphere microbiomes and the importance of complex biogeochemical processes that include carbon, sulfur and nitrogen driven by physical activity and chemical releases of FTW plant roots. [ABSTRACT FROM AUTHOR]

This work evaluated depuration performance and macrophyte plants growth in a full-scale hybrid-constructed wetland (H-CW) (1000 population equivalent) treating municipal wastewater. The plant was activated in June 2010 after a restoration of an existent H-CW composed of a horizontal subsurface flow (HSSF) bed vegetated with evergreen xerophile species ( Prunus laurocerasus , Pittosporum spp., Elaeagnus angustifolia ), connected with a sedimentation pond vegetated with Lemna spp. To enhance the depuration performances, in both sections of the plant the original vegetation was removed and the HSSF bed was vegetated with Phragmites australis , whereas in the pond, a floating treatment wetland vegetated with Iris pseudacorus was installed. The depuration performance in treating total nitrogen (TN), nitrate nitrogen (NO 3 -N), ammonia nitrogen (NH 4 -N), total phosphorus (TP), orthophosphate (PO 4 -P) and chemical oxygen demand (COD) was weekly monitored between August 2010 and August 2011. Results indicated median concentration abatements for the entire system of 74.3% for TN, 62.1% for NH 4 -N, 77.7% for NO 3 -N, 29.6% for TP, 37.4% for PO 4 -P, and 46.7% for COD. In addition, at the end of the first growing season (June 2010–November 2010), good adaption to the system was detected for both P. australis and I. pseudacorus , which produced respectively 3.9 ± 2.2 kg m −2 and 3.7 ± 1.0 kg m −2 of above-ground dry biomass, with average above-ground N uptakes of 62.4 ± 35.6 g m −2 and 69.8 ± 19.0 g m −2 and average above-ground P uptakes of 4.6 ± 2.6 g m −2 and 7.8 ± 2.1 g m −2 . The results indicate that a H-CW composed of a sequence of HSSF bed and FTW represents an effective application for abating TN, NH 4 -N, NO 3 -N and COD concentrations from municipal wastewater. [ABSTRACT FROM AUTHOR]

Two different chemical recipes comprising various pollutants were selected to create high (HC) and low (LC) levels of contaminated synthetic greywaters (SGW). Remediation in macrocosm–scale floating treatment wetlands (FTW) vegetated with Phragmites australis (Cav.) Trin. ex Steud. (common reed) was investigated under natural weather conditions. The presence or absence of vegetation, short or long contact time of treatment, and low or high contamination loads are the main operational variables in the experimental set-up design of the FTW. The focus on removal processes (other than sedimentation) such as the role of macrophytes in phytoremediation was achieved by agitation of the treated outflow before sampling. To assess the impact of interactions between the experimental operational variables on removal performances of FTW, different approaches of statistical analysis were applied. The results revealed that total suspended solids (TSS) and turbidity values dropped significantly ( p < 0.05) in the presence of vegetation compared with those values from unvegetated wetlands. The presence of vegetation can significantly ( p < 0.05) improve the biodegradation possibility of greywater by increasing the five-day biochemical oxygen demand (BOD) and decreasing the chemical oxygen demand (COD) concentrations. In vegetated FTW, higher removal rates of COD can be achieved when treating HC-SGS compared to LC-SGW. However, no significant differences ( p > 0.05) in the removal of BOD was noted. Significant increases ( p < 0.05) in BOD concentrations have been recorded with increasing contact time of treatment, while high removals of COD have been recorded. The presence of vegetation in wetlands affected significantly ( p < 0.05) the decrease of dissolved oxygen (DO) concentrations in outflow of both types of greywater. If limited sources of organic matter are available, vegetation has significantly ( p < 0.05) enhanced the nutrient balance with increasing nitrate-nitrogen (NO 3 -N) and decreasing ortho-phosphate-phosphorus (PO 4 -P) concentrations in the outflow. Furthermore, significant increases ( p < 0.05) in ammonia-nitrogen (NH 4 -N) and DO were observed with increasing contact time, while TSS, turbidity, and NO 3 -N concentrations significantly decreased ( p < 0.05). In addition, yellow leaves and considerably lower growth rates were observed for the hydroponic plant rhizomes of P. australis , which might be an effect of light-induced fluorescein degradation due to the relatively open water surfaces of the wetlands. [ABSTRACT FROM AUTHOR]

The selection of emergent plants is of primary importance during the construction of floating treatment wetlands (FTWs). Focusing on the comparison of the nitrogen removal, pot-culture experiments were carried out in floating treatment wetlands constructed with Phragmites australis and Acorus calamus in northeast China, a cold temperate zone. Nitrogen removal and transformation processes were investigated to explore the pathways and factors that influence the nitrogen removal. FTWs showed a high capacity for nitrogen removal. In water with TN concentrations of 9.63 and 4.58 mg L, the average TN removal efficiencies of the FTWs constructed with P. australis were 91.5 and 84.2%, respectively, and those of FTWs constructed with A. calamus were 84.2 and 82.8%, respectively. Plant uptake accounted for 36.4 to 77.1% of total N removal. The average TN removal rates of P. australis systems in the first 2 days were 4.20 and 1.77 mg L day for treatments with TN concentrations of 9.36 and 4.58 mg L, respectively, significantly higher than those of the A. calamus system, which were 1.75 and 1.04 mg L day, respectively. Our results suggested that plant uptake was the main pathway for nitrogen removal in FTWs, and P. australis was a suitable emergent plant species for use in FTW construction in a cold temperate zone. [ABSTRACT FROM AUTHOR]

With the purpose to study a solution based on Sustainable Urban Drainage Systems (SUDS) to reduce and treat stormwater runoff in urban areas, a bioretention pond (BP) was realized in the Agripolis campus of the University of Padova, Italy. The BP collected overflow water volumes of the rainwater drainage system of a 2270 m2 drainage area consisting almost entirely of impervious surfaces. Sixty-six Tech-IA® floating elements, supporting four plants each, were laid on the water surface. Eleven species of herbaceous perennial helophyte plants, with ornamental features, were used and tested. The early growth results of the BP functioning showed that nearly 50% of the total inflow water volume was stored or evapotranspirated, reducing the peak discharge on the urban drainage system. Among plants, Alisma parviflora, Caltha palustris, Iris ‘Black Gamecock’, Lysimachia punctata ‘Alexander’, Oenanthe javanica ‘Flamingo’, Mentha aquatica, Phalaris arundinacea ‘Picta’, and Typha laxmannii had the best survival and growth performances. A. parviflora and M. aquatica appeared interesting also for pollutant reduction in runoff water.

The Living-Filter is a novel floating emergent treatment wetland design that combines a hydroponic plant-bed with curtains and baffles. Thames Water Utilities and AquaticEngineering UK designed and installed the Living-Filter in Farmoor II reservoir, Oxfordshire, UK, in July 2012. The aim is to reduce the phytoplankton biomass prior to the water treatment works intake. The plant-bed (1 m H × 21 m W × 10 m L) supports plants of Phragmites australis , Phalaris arundinacea and Carex acutiformis , with a combined system of curtains and baffles that aid the water to flow through the Living-Filter. All the water treated at the water treatment works has passed through the Living-Filter. The roots and a plastic fabric increase the surface area for biofiltration processes and the rhizosphere provides refuge for zooplankton. The research attempts to answer the question: Can the Living-Filter be used as an in-reservoir pre-treatment filtration process for reducing the phytoplankton biomass onto the water treatment works? Weekly surveys were carried out from July to October 2013 at sixteen sampling sites to measure physico-chemical and biological variables. The results for the first year of study show: (1) Soluble manganese, dissolved inorganic nitrogen and nitrites were significantly lower after treatment through the Living-Filter. (2) Chlorophyll- a removal efficiency was up to 45% during the first seven weeks. (3) Zooplankton abundance was more stable within the rhizosphere than in the water column. (4) The aerial shoots of the plants developed well, but based on root development only Phalaris and Carex should be considered for future designs. This work highlights the potential of the Living-Filter for phytoplankton reduction, but it also addresses questions that will further improve the system. [ABSTRACT FROM AUTHOR]

Nitrogen is widely recognized as a chronic urban stormwater pollutant. In the United States, wet retention ponds have become widely used to treat urban runoff for quantity and quality. While wet ponds typically function well for the removal of sediments, nitrogen removal, performance can be inconsistent due to poor design and/or lack of maintenance. Retrofitting ponds to improve their nitrogen capture performance, however, is often expensive. By hydroponically growing macrophytes on wet ponds, floating treatment wetlands (FTW) may provide a cheap, sustainable means of improving nitrogen removal efficiency of aging stormwater ponds. Few studies have been performed on the effectiveness real-world stormwater systems, however. In this study, we investigated the nitrogen and sediment capture performance of a 50m2 floating treatment wetland deployed for 137 days on a stormwater wet pond located within an urban university campus near Washington, D.C. A total of 2684 g of biomass was produced, 3100 g of sediment captured, and 191 g of nitrogen removed from the pond. Although biomass production was relatively low (53 g/m2), we found that nitrogen uptake by the plants (0.009 g/m2/day) was comparable to contemporary FTW studies. [ABSTRACT FROM AUTHOR]

A pilot hybrid constructed wetland (subsurface flow line (SSL, 15 m 2 ) + floating treatment wetland line (FTWL, 90 m 2 )) treating digestate liquid fraction (DLF) in northeast Italy was monitored to determine its depuration efficiency in treating COD, total nitrogen (TN), ammonia nitrogen (NH 4 -N), nitrate nitrogen (NO 3 -N), total phosphorus (TP) and orthophosphate (PO 4 -P). CO 2 , CH 4 , and N 2 O emissions were also measured in SSL beds. The system was fed with diluted DLF (0.7 m 3 day −1 ) containing high COD (4580–6000 mg L −1 ) and TN (378.0–657.5 mg L −1 ). Removal efficiency was 57.9% for COD, 64.6% for TN, 65.1% for NH 4 -N, 35.6% for NO 3 -N, 49.2% for TP, 45.1% for PO 4 -P in SSL and of 89.2% for COD, 90.0% for TN, 89.0% for NH 4 -N, 93.8% for NO 3 -N, 50.3% for TP, 49.9% for PO 4 -P in FTWL. SSL showed a higher areal load reduction than FTWL. The carbon emitted (CO 2 -C + CH 4 -C) was always below 100% of C removed from digestate as COD, showing that during monitored periods SSL acted as C sink. The results indicate that the set-up composed by a sequence of vertical subsurface, horizontal subsurface and floating wetland represent a valid solution as secondary treatment for DLF. [ABSTRACT FROM AUTHOR]

Stormwater wet detention ponds hold a permanent pool of water and offer many beneficial uses including flood mitigation, pollution prevention, downstream erosion control, increased aesthetics, and recreational uses. The reduction efficiency of nutrients is generally low in stormwater wet detention ponds in many urban areas. To enhance nutrient reduction, floating treatment wetlands (FTWs), which are a new best management practice (BMP) in stormwater management, can be installed in wet detention ponds to offer an innovative solution toward naturally removing excess nutrients and aiding in stormwater management. This study assesses nutrient reduction in three Floridian stormwater wet detention ponds where FTWs have recently been installed. Both episodic (storm event) and routine (nonstorm event) sampling campaigns were carried out at the three ponds located in Ruskin, Gainesville, and Orlando. Most notably, nutrient reduction rates after installation of the FTWs reached levels of 33% for total nitrogen at the Ruskin pond during storm events, 71% for total phosphorus at the Gainesville pond during storm events, and 17% for total nitrogen at the Orlando pond during nonstorm events. [ABSTRACT FROM AUTHOR]

Floating Treatment Wetland (FTW) systems are purpose-built devices designed to replicate the water treatment processes that occur in and around naturally occurring floating vegetated islands. FTWs can be used to improve the water quality of water storage ponds by contributing to water treatment processes through adhesion, filtration, nutrient uptake (direct use by plants), and sequestration. This paper presents the results of a twelve-month investigation into the pollution removal performance of a FTW receiving stormwater runoff from a 7.46 ha urban residential catchment. As anticipated, there was a high degree of variation in FTW treatment performance between individual rainfall events. Overall pollution removal performance was calculated to be 80% for Total Suspended Solids (TSS), 53% for Total Phosphorous (TP), and 17% for Total Nitrogen (TN) for a FTW footprint of 0.14% of the contributing catchment. TSS and TP concentrations were found to be significantly reduced after FTW treatment. The minimum FTW footprint to catchment size ratio required to achieve regulated nutrient removal rates was calculated to be 0.37%. Sum of loads calculations based on flow resulted in pollution load reductions of TSS 76%, TP 55%, and TN 17%. Pollution treatment performance (particularly for TN) was found to be affected by low influent concentrations, and highly-variable inflow concentrations. The study demonstrated that FTWs are an effective treatment solution for the removal of pollution from urban stormwater runoff. [ABSTRACT FROM AUTHOR]

Stormwater wet detention ponds hold a permanent pool of water and offer many beneficial uses including flood mitigation, pollution prevention, downstream erosion control, increased aesthetics, and recreational uses. Although the removal of nutrients is generally low for stormwater wet detention ponds in urban areas, floating treatment wetlands (FTWs) can be installed to offer an innovative solution toward naturally removing excess nutrients and aiding in stormwater management. To improve the stormwater reuse potential, this study assessed nutrient, microcystin, and chlorophyll-a interactions in three Florida stormwater wet detention ponds with recently implemented FTWs. Both episodic (storm events) and routine (non-storm events) sampling campaigns were carried out at the three ponds located in Ruskin, Gainesville, and Orlando. The results showed a salient negative correlation between total phosphorus and microcystin concentrations for both storm and non-storm events across all three ponds. The dominant nutrient species in correlation seemed to be total phosphorus, which correlated positively with chlorophyll-a concentrations at all ponds and sampling conditions, with the exception of Orlando non-storm events. These results showed a correlation conditional to the candidate pond and sampling conditions for microcystin and chlorophyll-a concentrations. [ABSTRACT FROM AUTHOR]

The combination of floating treatment wetland (FTW) and sediment microbial fuel cell (SMFC) has drawn increasing interest as an economical, effective, and environmentally sustainable method for energy recovery, remediation of contaminated sediments, and wastewater treatment. In this study, a novel FTW-SMFC system with vertical floating biocathodes was developed to evaluate the performance and mechanism of plants, substrates, and bio-electrochemical systems for treating low-strength surface water. Experiments were operated in batch mode and conducted in microcosms with the following six treatments: control system only containing water and sediment (CS), normal SMFC (SMFC), only plant system (PS), SMFC with plants (PSMFC), SMFC with substrates (S-SMFC), and SMFC with plants and substrates (S-PSMFC). The results show that introducing plants into SMFCs could increase the power density by 32.9–42.5%, proving that plants played an important role in enhancing bioelectricity production. The alkaline substrates reduced the cathode potential and made the cathode inefficient. The presence of plants and substrates greatly improved the removal of nitrogen and phosphorus. The removal efficiency of total nitrogen and total phosphorus increased by 8.3–27.8% and 3.5–13.9% under electrochemical treatment. There existed competition between electrochemical and plant removal approaches for nitrogen in FTW-SMFC, and electrochemical removal was prior to plant removal. Phosphorus removal was mainly through plant uptake and substrate-mediated adsorption and precipitation. The electrochemical process promoted the removal of phosphorus by enhancing the conversion of non-reactive phosphorus (NRP) to reactive phosphorus, providing 5.0–6.9% additional NRP conversion. This study furthers our understanding of the contribution and interaction of each component in the FTW-SMFC system to pollutant removal and bioenergy generation, which will contribute to the performance enhancement of FTW and further facilitate the application of FTW-SMFC technology for in-situ remediations of the polluted surface water body. • The contribution and interaction of components in FTW-SMFC were studied. • Plants enhanced the power density by 33–43% while alkaline substrates lowered it. • Increased current density promoted TN removal but limited TP removal. • Electrogenesis limited nitrogen removal by plants but raised the RP use by plants. • Electrogenesis provided 5.0–6.9% additional NRP conversion. [ABSTRACT FROM AUTHOR]

The floating treatment wetland (FTW) is an innovative hydroponic device which can be installed on the surface of a stormwater retention pond to improve its pollutant removal efficiency. Limited full-scale experiments have been published, and no design or maintenance guidelines have been developed to date to promote their use. This paper presents implementation and maintenance considerations developed based on the monitoring of three full-scale ponds retrofitted with FTWs. Results suggest that the size and relative surface cover of the FTW, the relative root depth, and the capability of the plants to tolerate periodic anaerobic conditions are crucial factors to promote good removal across a spectrum of pollutants. Special attention to the location and anchorage of the FTW are thought to promote good performance and facilitate FTW maintenance. While zinc and copper sediment concentrations were unlikely to cause undue aquatic impacts after 2 years of operation, more frequent sediment removal will be needed than in conventional retention ponds to maintain adequate storage capacity in the permanent pool because of enhanced sedimentation. Given proper installation and maintenance, FTWs can enhance aesthetic and water quality benefits of stormwater ponds. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the feasibility of using a floating treatment wetland for removal of dissolved metals from urban runoff under full-scale conditions. The study site is a retention pond located in northeast Nantes (France) that receives the storm water runoff from a section of highway (27,000 vehicles/day, basin surface 375 m 2 ). Three floating marshes were anchored in the retention pond, each raft with a surface area of 1.5 m 2 (125 cm × 120 cm) supporting 16 plants (8 Juncus , 8 Carex ). After 4 months, plant samples were harvested, mineralized and analyzed by atomic spectrometry absorption to determine cadmium, nickel and zinc concentrations. Analysis showed Ni concentration in leaves between 23 and 31 μg/g drymatter , and between 113 and 131 μg/g in roots. Accumulation of Zn was 45–80 μg/g in leaves and 168–210 μg/g in roots. The root/leaf ratio, between 2.6 and 5.7 for Ni and Zn respectively, highlights the important function of roots in heavy metal accumulation. No cadmium accumulation was detected in plants. All three metals were also present in the biofilm on roots. Moreover, roots demonstrated a capacity to filter particulates. This study shows that floating marshes can effectively remove some metals from stormwater ponds. [ABSTRACT FROM AUTHOR]

Floating treatment wetlands (FTWs) were employed to improve the water quality of aquaculture. Four kinds of FTWs, with different carriers (polyethylene foam board and combined carrier) and different vegetation coverage ratios of water surface (one-third and two-thirds), were designed to monitor the performance on water quality improvement for loach (Misgurnus anguillicaudatus) cultivation. Compared to the FTW with one-third vegetation coverage ratio, two-thirds vegetation coverage ratio FTW performed higher production of vegetation (7.48±0.48 kg m'2), 21.1% higher transparency, and 29.6% lower TN concentration in the cultivation water (O .05).The FTWs with different carriers performed similar removal efficiencies of TN and TP, but 24.0% higher DO concentration was provided by the FTW with combined carrier (P<0.05).As a result, FTW could improve the transparency and TN removal in loach cultivation water, two-thirds vegetation coverage, and combined carrier FTW would be a priority choice in the practice for loach cultivation. [ABSTRACT FROM AUTHOR]