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Neonicotinoid insecticides are among the most used insecticides and their residues are frequently found in surface water due to their persistence and mobility. Neonicotinoid insecticides exhibit toxicity to a wide range of aquatic invertebrates at environmentally relevant levels, and therefore their contamination in surface water is of significant concern. In this study, we investigated the spatiotemporal distribution of six neonicotinoids in a large wetland system, the Prado Wetlands, in Southern California, and further evaluated the wetlands' efficiency at removing these insecticides. Total neonicotinoid concentrations in water ranged from 3.17 to 46.9 ng L-1 at different locations within the wetlands, with imidacloprid and dinotefuran among the most detected. Removal was calculated based on concentrations as well as mass flux. The concentration-based removal values for a shallow pond (vegetation-free), moderately vegetated cells, densely vegetated cells, and the entire wetland train were 16.9%, 34.2%, 90.2%, and 61.3%, respectively. Principal component analysis revealed that pH and temperature were the primary factors affecting neonicotinoids removal. Results from this study demonstrated the ubiquitous presence of neonicotinoids in surface water impacted by urban runoff and wastewater effluent and highlighted the efficiency of wetlands in removing these trace contaminants due to concerted effects of uptake by wetland plants, photolysis, and microbial degradation.

This article examines the utilization and advancements of constructed wetlands (CWs) in South Asia (SA), focusing on their roles, costs, and efficacy enhancements through pre- and post-treatment units for various pollutants. Notable findings include Phragmites and Canna species as commonly used macrophytes, achieving high removal rates for various pollutants. CWs consistently remove total suspended solids, biochemical oxygen demand, chemical oxygen demand, emerging contaminants, and antimicrobial resistant bacteria at substantial rates. Anaerobic baffled reactors are effective pretreatment devices for high-strength wastewater. Moreover, CWs exhibit lower operational and maintenance costs compared to conventional treatment methods. However, the bibliometric analysis reveals limited regional cooperation in SA. Key challenges identified include the absence of guidelines for media, vegetation, and maintenance. The review underscores the necessity for further research in optimizing CWs' efficiency through land area management, plant selection, and enhanced design and operation and maintenance protocols. [ABSTRACT FROM AUTHOR]

The increasing volume of wastewater from fish farming poses a serious environmental threat. This study investigated a novel treatment method for butter catfish (Ompok bimaculatus) wastewater using a constructed wetland-microbial fuel cell (CW-MFC) integrated with the water fern Azolla microphylla. The system was effective in removing pollutants like electrical conductivity (EC), total dissolved solids (TDS), ammonium, nitrate, nitrite, and phosphate were evaluated. Additionally, the electricity generation capabilities were measured. The CW-MFC system achieved significant removal rates: 67.65% for EC, 61.67% for TDS, 100% for ammonium, 75.00% for nitrate, 81.25% for nitrite, and 70.00% for phosphate. Furthermore, the system generated a maximum open-circuit voltage (OCV) of 690±90 mV, a current density (CD) of 7.29±0.43 mA/m2 and a power density (PD) of 0.37±0.04 mW/m2. Analysis of the microbial community revealed a diverse root consortium dominated by bacterial genera, including Phreatobacter, Emticicia, and Rhodobacter, along with fungal genera such as Strelitziana, Ramularia, Cladosporium, Trichomerium, Cercospora, Erythrobasidium and Fusarium. These findings suggest that CW-MFC systems integrated with A. microphylla offer a promising approach for sustainable and efficient treatment of wastewater from catfish farming while simultaneously generating bioelectricity. [ABSTRACT FROM AUTHOR]

The terrestrial environment generally serves as an important carbon pool. This study mainly assessed the properties and carbon storage capabilities of soils from different urban land uses. Soil samples from roads/highways, parks, institutional areas, and constructed wetlands were collected to assess the effects of soil sealing on the characteristics and carbon content of urban soils. Soil sealing and compaction greatly influenced urban soil properties by altering the mass-balance, thereby resulting in a disproportionate amount of inflow and outflow of compounds in the soil strata. Using the Walkley-Black and loss-on-ignition (LOI) methods of soil organic carbon (SOC) analysis demonstrated that LOI-based analysis yielded up to 26 times higher SOC values than the wet-oxidation method due to the high weight losses prompted by the volatilization of hygroscopic and structural water and thermal decomposition of carbonate-containing minerals. Further analyses indicated that open soils contain 5% to 78% higher percentage of organic carbon as compared with their sealed counterparts and top soil layers tend to have higher amounts of SOC due to the continuous deposition of carbon-containing compounds from external sources. Generally, the results of this inquiry can serve as a baseline for formulating strategies to augment pedologic carbon stocks in urban environments. [ABSTRACT FROM AUTHOR]

The escalating demand for water and the increasing pollution of natural water bodies necessitate innovative solutions for wastewater treatment and reuse. This study investigated the potential of a horizontal subsurface flow (HSSF) constructed wetland to treat aquaculture wastewater for reuse. The system, planted with Taro (Colocasia esculenta) and sugarcane (Saccharum officinarum L.), received effluent from a recirculating aquaculture system (RAS) producing African Catfish (Clarias gariepinus). The study assessed the impact of varying hydraulic retention times (1-3 days) and flow rates (11-108 L/min) on water quality parameters, including dissolved oxygen, electrical conductivity, salinity, total dissolved solids, temperature, and pH. Results showed significant increase in dissolved oxygen (4.25-5.52 mg/L), while electrical conductivity (491-677 µS/cm), salinity (0.23-0.32 ppt), and total dissolved solids (237-332 mg/L) decreased considerably. Temperature (29.28-31.07 °C) and pH (7.57-7.59) remained stable and within acceptable ranges for reuse in African Catfish production. However, retention time and flow rate did not significantly affect treatment efficiency within the tested parameters. Further research is recommended to explore the impact of longer retention times, wider flow rate ranges, different plant species and substrate types, and microbial community analysis to optimize the system's performance and promote sustainable aquaculture practices. [ABSTRACT FROM AUTHOR]

The study aimed to treatment of high organic matter concentration in leachate produced by municipal waste in developing countries. The average properties of the raw leachate were investigated, including chemical oxygen demand (COD), biochemical oxygen demand (BOD5), and total suspended solids (TSS), which were found to be 55,058.7, 34,500, and 8080 mg/L, respectively. The study evaluated the performance of integrated systems consisting of modified septic tanks (MST) and horizontal flow subsurface flow constructed wetland (HF-SFCW) to treat this type of leachate. The maximum removal efficiencies for COD, BOD5, and TSS were 61.18%, 55.07%, and 64.6% for MST, and 67.93%, 61.90%, and 71.11% for HF-SFCW. Also, the percentage phosphorus removal was 35.41% for MST and 54.16% for HF-SFCW, while the efficiency of nitrogen compound removal was reported differently for the two methods. MST showed an increase in ammonium concentration due to anaerobic conditions and denitrification, while HF-SFCW showed a significant decrease in ammonium concentration and a slight increase in nitrate and nitrite concentrations. The study concluded that MST and HF-SFCW planted with Phragmites australis exhibited good phytoremediation performance in heavily polluted leachate. [ABSTRACT FROM AUTHOR]

This study developed a novel constructed wetland (CW) coupled with a magnetic field for treating domestic wastewater, and the magnetic field distribution was solved and optimised by the finite element method. Herein, we investigated the effects of optimising magnetic field optimisation and studied its impact on CW treatment performance and the responses of a microbial community. The optimisation results showed that the average magnetic field strength of the CW unit increases from 3 to 8 mT, and the proportion of areas with magnetic field strength greater than 5 mT also increases from 30% to 74%. The water quality analysis results showed that the removal of chemical oxygen demand (COD) and NH4+-N (p < 0.01) was significantly increased by the magnetic field (average 3 mT), increasing by 12.2% and 8.49%, respectively. Moreover, the removal of COD and NH4+-N (p < 0.01) was more significantly increased by M-VFCW(O) (average 8 mT), increasing by 15.58% and 49.1%, respectively. The magnetic field application shifted significantly the abundance of dominant bacteria in CWs. Relative abundance of dominant bacteria such as Proteobacteria (63.3%), Firmicutes (4.72%) and Actinobacteria (2.11%) that played an important role in organics removal and nitrification and denitrification-related bacteria such as Nitrospirae (1.48%) and Planctomycetes (9.58%) significantly promoted in M-VFCW(O). These results suggest that introducing a magnetic field into CWs may improve organics and nitrogen removal via the biological process, and the optimisation of the magnetic field was significant in enhancing the performance of VFCWs. [ABSTRACT FROM AUTHOR]

Fish ponds are reliable food supply in local scale. However, they have adverse environmental impacts due to discharging pollution to the surface waters. To quantify the sustainability of this industry with the perspective of environment-food nexus, the-state-of-the-art index of food environmental footprint (FEF) is used and calculated for trout ponds (TPs). For this purpose, an integrated method is developed for accounting the environmental impacts of TPs by including grey water footprint (GWF) in Recipe, a tool for life cycle impact assessment (LCIA). GWF stands for the embedded water consumption and LCIA combines the potential health and ecological impacts. Here, water quality data of multiple pollutants, BOD, COD, TSS, NO2, NO3, NH4, TN, PO4, DO and Cu+2, in the influent and effluent of Iranian TPs was obtained by field experiments and discussed with data from 9 countries. Results showed that TSS and NH4 are critical pollutants and the average GWF is about 16 m3/kg. Moreover, human health impacts are relatively greater than ecological damages. Nevertheless, FEF is calculated 0.17 and verifies TP sustainability (< 1). Based on environment-food nexus perspective; it means that the positive value of food production dominates TPs' negative environmental damages. In addition, this study reviewed the efficiency of constructed wetlands for low-strength wastewater treatment. Due to its potential on TSS and NH4 removal, this system can reduce the GWF and added environmental damages of TPs 85% and 58%, respectively. Consequently, FEF decreases to 0.023 showing the very sustainability (< 0.1) of TPs by wastewater treatment. [ABSTRACT FROM AUTHOR]

Traditional wastewater treatment plants (WWTPs) consume a significant amount of energy to clean wastewater. However, for medium‐ and small‐scale WWTPs, it is crucial to have an energetically self‐sustained treatment. In this regard, novel low‐energy demand treatment systems, such as nature‐based solutions (NBS), are highly suitable alternatives. Constructed wetlands coupled with microbial fuel cells (MFC), referred to as electrowetlands (EWs), are NBS able to treat wastewater while recovering electricity. In this study, initially, various granular carbon materials were tested as anode materials in laboratory‐scale MFCs, and anthracite was selected due to its higher electrochemical activity. Then, pre‐pilot scale tests were conducted, evaluating different EW configurations. The one consisting in a horizontal anode yielded the best wastewater treatment efficiencies (chemical oxygen demand [COD] degradation greater than 90%) and electricity production (11 mW m−2; 260 mWh day−1 m−2). Finally, a 50 m2 pilot was constructed in Valladolid, studying its performance under real conditions for 1 year. The pilot showed robust and stable performance, achieving high wastewater treatment efficiencies (COD degradation >85%, outflow COD of 100 ppm) and generating 115 Wh in 1 year (power density of 0.4 mW m−2). [ABSTRACT FROM AUTHOR]

This study aimed to determine the concentrations of hazardous heavy metals in the Naseri Wetland of southern Khuzestan province and to investigate constructed wetlands for the treatment of agricultural runoffs. In this regard, the length of the constructed wetlands was divided into three equal segments (3.5 km in length, 1.2 km in width, and 0.5 m in depth) and the beginning of each segment was considered a sampling station as ST1, ST2, and ST3. The concentrations of major heavy metals such as Hg, Pb, Cr, Cd, and As were monitored at different stations over a period of 1 year (2020–2021). The results showed a direct correlation between pollutant concentrations in the wetland bottom sediments and those in the agricultural runoff. ST3 had the highest removal efficiency (RE%) of heavy metals compared to ST1 and ST2 (RE = 100% for all heavy metals examined). The meaning of 100% efficiency and zero concentration is that the pollutant concentration was so low that it was undetectable. In contrast, ST1, the closest station to the entry point, had the lowest RE with averages 29.99, 13.34, 21.24, 34.23, and 24.80% for Hg, Pb, Cr, Cd, and As, respectively. As a result, this system has been successful in bringing the quality of agricultural runoff to the desired standard for discharge into the environment and for agricultural purposes. Overall, in Khuzestan and other regions with similar climates, the development of constructed wetland as an environmentally friendly technology could represent a practical strategy for reclaiming agricultural runoff, although their design and operation need to be well-engineered. [ABSTRACT FROM AUTHOR]

The ever-increasing population and expansion of development activities regardless of the quantitative and qualitative management of water resources in most of the countries located in the dry belt areas have led to the aggravation of the water crisis, especially in Iran. Wastewater is one of the types of non-conventional water that can be put back into the consumption cycle if its pollutants and impurities are removed. In this research, the performance of the artificial wetland systems with vertical and horizontal subsurface flows under the cultivation of reed and typha plants for the treatment of the wastewater of Rasht city were simulated by the HYDRUS-2D model. The values of the statistical index of the normalized root-mean-square error (NRMSE) in wetlands without plants, under Reed and Typha cultivation were 6.5, 9.8 and 14.8%, respectively, which in comparison with the classification of Jaminson et al. (1991). The HYDRUS model has excellent (less than 10%) and good (10 and 20%) accuracy in simulating total dissolved solids in artificial wetlands. Therefore, the HYDRUS model recommends for the design of reducing the total dissolved solids of artificial wetlands. [ABSTRACT FROM AUTHOR]

This research investigates the effects of treated piggery effluent from cassava peel-based biochar-amended constructed wetlands on the growth of the Okra plant (Abelmoschus esculentus). A batch-fed pilot-scale Horizontal subsurface flow constructed wetland (HSSFCW) planted with Vertiveria zizanioides was operated with a 3-day Hydraulic Retention Time (HRT). Four different substrates comprising sharp sand SS, quarry dust QD, sharp sand amended with biochar (SS+B), and quarry dust amended with biochar (QD+B). Using standard procedures, the biochar and piggery effluent were characterized before and after treatment in the HSSFCW. The treated effluents from the four systems were applied to the Okra plant, and growth parameters of Leave area index LAI, Plant height Ph, and stem diameter QD were measured and analyzed for five consecutive weeks. The results show that substrate types have a significant effect on LAI and QD but insignificant for Ph. The highest measured LAI, Ph, and QD were 13.02, 316.7, and 12.3 mm, respectively for SS; 12, 323, and 14 mm for QD, 25, 307 and 14 mm for SS+B and 27, 325 and 17 mm for QD+B. The biochar-amended quarry dust CWs effluent is recommended as the best for the treated effluent irrigation for okra plant cultivation. [ABSTRACT FROM AUTHOR]

The growing mining industry has led to environmental pollution, primarily from mining waste known as acid mine drainage (AMD). To effectively address AMD, a combination of constructed wetland and biochar treatment is necessary. This study aims to assess the ability of biochar in combination with wetland sediment to reduce sulfate and cadmium (Cd) heavy metals in AMD. The research method involved a laboratory-scale constructed wetland in a microcosmos and a treatment of: T1, biochar mixed with wetland sediment; T2, sediment; T3, biochar; and T4, control with no treatment. Observations included sulfate content, pH determination, heavy metal concentration, and scanning electron microscope (SEM) analysis of the biochar. Results after 30 days of observation showed that T1 reduced sulfate concentration by 72.03%, compared to 63.33% for T2, 63.33% for T3, and 2.50% for T4. The reduction in sulfate was accompanied by a consecutive increase in pH, with T1 at pH 6.9, T2 at pH 6.6, T3 at pH 6.4, and T4 at pH 3.6 after 30 days. T1 treatment reduced heavy metal Cd by 80.16% after 30 days, while T2 of 55.46%. T3 of 65.83% and T4 of 2.31%. This indicates that the constructed wetland method, combined with biochar, is more effective in reducing sulfate and the heavy metal Cd in AMD, compared to using only biochar or wetland sediment treatment. [ABSTRACT FROM AUTHOR]

An integrated constructed wetland-microbial electrolysis cell (ICW-MEC) system was investigated for nitrogen removal under different pollution loads, hydraulic loads (HLRs), and aeration conditions. The treatment performance of each unit and the microbial community characteristics for nitrogen removal were elucidated. The results showed that, on average, 80% of NH4+-N, around 70% of nitrate nitrogen (NO3−-N), and 70% of total nitrogen (TN) were removed by the system under three pollution loads, with less influence by pollution loads. The high removal efficiencies of NH4+-N (81.8%), NO3−-N (71.4%), and TN (72.8%) indicated tolerable to high HLRs. The intermittent aeration negatively affected NH4+-N removal, while increasing NO3−-N and TN removals by 3.2–13.0% and 3.7–16.7%. The contribution efficiencies of the secondary unit to the removal of NH4+-N, NO3−-N, TN, and total organic carbon (TOC) reached 47.4%, 55.0%, 45.9%, and 38.8%, respectively. The distinct microbial communities existed in various units of the ICW-MEC system, which were strongly affected by environmental factors and shaped by diverse fillers and structures of the system. The dominant bacteria contributed to the efficient nitrogen removal performance of the ICW-MEC system. The three units exerted their advantages to ensure efficient and stable system operation. [ABSTRACT FROM AUTHOR]

The increasing volume of wastewater from fish farming poses a serious environmental threat. This study investigated a novel treatment method for butter catfish (Ompok bimaculatus) wastewater using a constructed wetland-microbial fuel cell (CW-MFC) integrated with the water fern Azolla microphylla. The system was effectiveness in removing pollutants like electrical conductivity (EC), total dissolved solids (TDS), ammonium, nitrate, nitrite, and phosphate was evaluated. Additionally, the electricity generation capabilities were measured. The CW-MFC system achieved significant removal rates: 67.65% for EC, 61.67% for TDS, 100% for ammonium, 75.00% for nitrate, 81.25% for nitrite, and 70.00% for phosphate. Furthermore, the system generated a maximum open-circuit voltage (OCV) of 690±90 mV, a current density (CD) of 7.29±0.43 mA/m³and a power density (PD) of 0.37±0.04 mW/m³. Analysis of the microbial community revealed a diverse root consortium dominated by bacterial genera including Phreatobacter, Emticicia and Rhodobacter, along with fungal genera such as Strelitziana, Ramularia, Cladosporium,Trichomerium, Cercospora, Erythrobasidium and Fusarium. These findings suggest that CW-MFC systems integrated with A. microphylla offer a promising approach for sustainable and efficient treatment of wastewater from catfish farming while simultaneously generating bioelectricity.

The escalating demand for water and the increasing pollution of natural water bodies necessitate innovative solutions for wastewater treatment and reuse. This study investigated the potential of a horizontal subsurface flow (HSSF) constructed wetland to treat aquaculture wastewater for reuse. The system, planted with Taro (Colocasia esculenta) and sugarcane (Saccharum officinarum L.), received effluent from a recirculating aquaculture system (RAS) producing African Catfish (Clarias gariepinus). The study assessed the impact of varying hydraulic retention times (1-3 days) and flow rates (11-108 L/min) on water quality parameters, including dissolved oxygen, electrical conductivity, salinity, total dissolved solids, temperature, and pH. Results showed significant increase in dissolved oxygen (4.25-5.52 mg/L), while electrical conductivity (491-677 µS/cm), salinity (0.23-0.32 ppt), and total dissolved solids (237-332 mg/L) decreased considerably. Temperature (29.28-31.07 °C) and pH (7.57-7.59) remained stable and within acceptable ranges for reuse in African Catfish production. However, retention time and flow rate did not significantly affect treatment efficiency within the tested parameters. Further research is recommended to explore the impact of longer retention times, wider flow rate ranges, different plant species and substrate types, and microbial community analysis to optimize the system's performance and promote sustainable aquaculture practices.

Fly ash is the primary residue produced in huge amounts by coal combustion in thermal power plants, which needs to be utilized appropriately. In this connection, an experimental study was conducted with fly ash alone and in combination with soil for the treatment of simulated dumpsite leachate in constructed wetland (CW) (vertical flow) systems containing Canna+ Typha plants. The study revealed that the fly ash + soil mixture as a CW substrate showed better removal efficiency of chemical oxygen demand (COD), phosphate (), total nitrogen (TN), and chloride (Cl–) by 97.3, 99.4, 94.5, and 89.6%, respectively, in comparison to the fly ash alone which was shown to yield the corresponding values of 88.5, 94.1, 84, and 73.2% of the efficiency in the removal of these pollutants from simulated dumpsite leachate. [ABSTRACT FROM AUTHOR]

This article presents the authors’ perspectives on modelling best practices for nature-based solutions (NBS). The authors led a workshop on NBS modelling as part of the 8th IWA Water Resource Recovery Modelling Seminar (WRRmod2022+) in January 2023, where the discussion centred around the design, use cases, and potential applications of NBS models. Four real-world case studies, encompassing an aerated lagoon, a biofilm-enhanced aerated lagoon, a stormwater basin, and a constructed wetland were reviewed to demonstrate practical applications and challenges in modelling NBS systems. The initial proposed modelling framework was derived from these case studies and encompassed eight sub-models used for these NBS types. The framework was subsequently extended to include eight additional NBS categories, requiring a total of 10 sub-models. In a subsequent step, with a different perspective, the framework was refined to focus on 13 primary use cases of NBS, identifying 10 sub-models needed or potentially required for these specific NBS applications. These frameworks help to identify the necessary sub-models for the NBS system at hand or the use case. This article also discusses the benefits and challenges of applying water resource recovery modelling best practices to NBS, along with recommendations for future research in this area. HIGHLIGHTS Data scarcity is a primary challenge to NBS modelling, with limited data available for model calibration and validation.; The numerous use cases and categories of NBS technologies complicate the development of a broad and flexible modelling framework.; Inspired by four NBS case studies, the paper addresses diverse objectives and challenges in NBS modelling.; The proposed frameworks offer a structured approach to NBS modelling, considering various categories, use cases, and essential sub-models.;

In rural areas grappling with recurring water scarcity during dry periods, the imperative for water conservation becomes evident. This research centers on Green Infrastructure (GI), showcasing its substantial potential for better water management practices, specifically in the realms of rainwater harvesting and greywater treatment. We implemented an integrated household-scale rainwater harvesting system (RWH) coupled with greywater processing using a constructed wetland (CW). The constructed wetland, filled with sands and gravels and adorned with Napier grass (Pennisetum purpureum), served as a filtration medium for both greywater and rainwater before channelling them into a fishpond. The project was conducted at the ITB research station in Haurngombong village, Pamulihan sub-district, Sumedang, West Java. The project exemplified an effective synergy between the RWH system and a constructed wetland for greywater treatment, benefiting both plant irrigation and fishpond utilization. The demonstrated approach holds significant potential added value for communities, serving as a reservoir for crop irrigation, supporting fish farming, and facilitating greywater treatment through an integrated aquaponic system.

BACKGROUND AND OBJECTIVES: Domestic wastewater pollution in Thailand presents challenges due to limited space and a high concentration of point source effluents. This phenomenon often leads to domestic wastewater exceeding the capacity of local treatment systems. This study aims to expand the knowledge gained from The King’s Royally Initiated Laem Phak Bia Environmental Research and Development Project by evaluating the treatability of municipal wastewater. It utilizes a constructed wetland system in conjunction with a transfer and point source system. After the implementation of this primary system, the reduction in highly contaminated domestic wastewater could enhance the treatment loading of other secondary treatment systems or even facilitate its release into natural pathways.METHODS: In the sampling collection process, the dynamics of the collection points were categorized into three different zones: 1) the point sources of domestic wastewater within a municipality, where 15 sample points were selected to represent the municipality; 2) the collection pond within the municipality and the transfer pipeline, comprising three collection points of the system; 3) the constructed wetland treatment system, where five water samples were collected in relation to the length of the existing 100-meter plot. The water samples were collected using four 1-liter polyethylene bottles. The analysis parameters were the biological oxygen demand, total nitrogen, nitrate, total phosphorous and phosphate, and other parameters related to domestic wastewater treatment efficacy.FINDING: This study reveals that the domestic wastewater in Phetchaburi Province initially has a high organic content, leading to a biochemical oxygen demand: nitrogen: phosphorous ratio of 100:2.5:0.2 favoring anaerobic degradation. This ratio shifts in the constructed wetland system, located 18.5 kilometers away, to 100:10.5:2.3, promoting anaerobic treatment. The system shows high efficacy, with 81.4, 50.0, and 58.3 percent removal rates for biochemical oxygen demand, nitrogen, and phosphorus, respectively. This efficacy corresponds to a notable reduction in average biochemical oxygen demand from 740.0 to 9.7 milligrams per liter. Moreover, changes are observed in total nitrogen content, shifting from 20.8 to 2.8 milligrams per liter, in the system’s effluent. While lastly, the total phosphorous decreased from 2.75 to 0.60 milligrams per literCONCLUSION: This treatment method can be effectively applied to small-scale constructed wetland systems within households. The recommended hydraulic retention time is between 29 and 60 hours under anaerobic conditions and 3 days under aerobic conditions. The changes in the composition of municipal wastewater, which is highly organic, support the use of both degradation processes. The knowledge and application of the constructed wetland system could be suggested for the primary treatment system of domestic wastewater within municipalities, given that this system would provide support to the central wastewater treatment system for enhanced efficacy.

The elements of landscape-based water treatment design are reviewed in this work. The paper examines the most commonly utilized elements, such as Vegetated swale/Bio-swale and Constructed wetland, as well as their benefits and possibilities for treating water for various purposes, such as irrigation and domestic usage. This paper also reviews the literature on determining the potential of plants used for pollution removal, particularly the capacity of Vetiver grass to remove pollutants from waste water.

Constructed wetlands are an environmentally friendly and cost-effective option for treating leachate. They rely on aquatic plants and microorganisms to efficiently remove contaminants. Temperature plays a crucial role in the performance of wetlands, as it improves overall efficiency. Oxygen accumulation in the wetland, either through photosynthesis or from the atmosphere, is essential for organic matter decomposition and nitrification. The growth of macrophytes, supported by sunlight and temperature, enhances wetland efficiency. Scientific observations confirm that macrophytes' performance depends on biomass production and oxygen fixation in the rhizosphere during the growing season. The reviewed results showed that there is a noticeable trend is that tropical climate areas tend to exhibit higher efficiency in leachate treatment across various parameters such as TSS, COD, BOD, TN, TP, and others.These macrophytes excel in tropical and temperate regions with temperatures above 30°C with the removal percentage above 90%. The review of the literature confirms that wetlands are a low-cost, eco-friendly, and efficient solution for removing various contaminants. Furthermore, the efficiency of wetlands is enhanced by approximately 20-30% in tropical and temperate regions due to higher temperatures.

Constructed wetlands (CW) are well known nature-based systems for water treatment. This study evaluated the efficiency and effectiveness of seven domestic wastewater treatment systems based on horizontal flow CWs in Jarabacoa, the Dominican Republic. The results showed that the CWs were efficient in reducing the degree of contamination of wastewater to levels below the Dominican wastewater discharge standards for parameters such as the 5-day biochemical oxygen demand (BOD5) and chemical oxygen demand, but not for the removal of phosphorus and fecal coliforms. In addition, a horizontal flow subsurface wetland in the peri-urban area El Dorado was evaluated in terms of the performance of wastewater treatment in tropical climatic conditions. The concentrations of heavy metals, such as zinc, copper, chromium, and iron, were found to decrease in the effluent of the wetland, and the concentrations for nickel and manganese tended to increase. The levels of heavy metals in the effluent were lower than the limit values of the Dominican wastewater discharge standards. The construction cost of these facilities was around 200 USD per population equivalent, similar to the cost in other countries in the same region. This study suggested some solutions to the improved performance of CWs: selection of a microbial flora that guarantees the reduction of nitrates and nitrites to molecular nitrogen, use of endemic plants that bioaccumulate heavy metals, combination of constructed wetlands with filtration on activated carbon, and inclusion of water purification processes that allow to evaluate the reuse of treated water.

Untreated domestic wastewater from rural areas poses significant risks to ecosystems and human health. Constructed wetlands (CWs) are a viable alternative for this wastewater treatment, enhancing nitrogen removal using substrates as carbon sources. This process is particularly beneficial for wastewater with low carbon-to-nitrogen (C/N) ratios, making the treated water suitable for agricultural irrigation. In this study, a Horizontal Subsurface Flow CW (HSF-CW) was evaluated using Canna hybrids and a mixed substrate of gravel and endocarp from oil palm fruit (EOP) as a carbon source to leverage its abundance in the region. It was also determined that the effluent complies with the permissible limits set by Resolution 1207 of 2014 from the Colombian Ministry of Environment and Sustainable Development, which establishes environmental standards for wastewater treatment to ensure environmental protection and enable safe reuse in agricultural irrigation. The key parameters analyzed included organic contaminants, heavy metals, nutrients, and microbiological indicators. Removal efficiencies of up to 91%, 94%, 98%, 52%, 73%, 78%, and 75% were achieved for BOD, TSS, total phosphorus, nitrates, nitrites, ammonium, and total nitrogen, respectively, demonstrating the CW's strong performance in contaminant removal and meeting most standards for agricultural irrigation. Although the carbon source was not highly efficient, the overall system performance supports its viability for improving water quality and promoting sustainable agricultural practices in rural areas. [ABSTRACT FROM AUTHOR]

This study of constructed wetland design investigated relationships between macrophyte species selection and planting density for water quality improvement. A lab-scale wetland was compared against a pilot-scale wetland in San Antonio, Texas, at Mitchell Lake to measure differences in effluent water quality improvement using three native macrophyte species. Using a novel, two-phase method, a targeting macrophyte was identified from among Olney's bulrush (Schoenoplectus americanus), hardstem bulrush (Schoenoplectus acutus), and California bulrush (Schoenoplectus californicus), based on its marked capability for improving water quality factors, then it was planted in varied majority densities to compare differences in treatment effectiveness. The results showed that the planting density with 50% giant bulrush, 25% Olney's bulrush, and 25% hardstem improved conductivity removal by 34% and increased dissolved oxygen by 3713% as compared to the Mitchell Lake pilot-scale results. The 70% and 90% majority density plantings (giant bulrush) were not shown to be as effective for the tested parameters, indicating diminishing returns as the vegetation density increasingly becomes a monoculture within the system. The results of this study showed that this complementary approach to wetland design displayed significant improvement in certain treatment parameters than the evenly planted species distribution of the pilot study. These findings demonstrate that the constructed wetland design can be optimized by selecting and planting macrophytes based on their effectiveness in targeting site-specific water quality concerns by capitalizing on their individual traits within complex wetland systems. [ABSTRACT FROM AUTHOR]

Sludge treatment reed bed planted (STRB) with Phragmites australis (P.australis) and Arundo donax (A.donax) was assessed in the presence of Eisenia fetida under control condition during the dry season. Worm-planted units were fed with mixed sewage sludge (dry and volatile solids of 29.44 g DS.L−1 and 24.23 g VS.L−1). Sludge loading rates (SLR) of 50, 60, and 70 kg DS m−2 year−1 were examined to assess dewatering efficiency. Surface layers in units with P.australis and A.donax achieved DS of 80 and 81% at a loading rate of 50 kg DS m−2 year−1, while their subsurface DS were 41 and 25%, respectively. Units with A.donax experienced plant loss when subjected to SLR exceeding 60 kg DS m−2 year−1. More than 10 cm of residual sludge accumulated on the top of units after a 2-month final rest. Evapotranspiration was greater in the unit with P.australis (5.23 mm day−1) compared to the unit with A.donax (4.24 mm day−1) while both were fed with 70 kg DS m−2 year−1. Water loss contributions from residual sludge layer, drained water, and evapotranspiration were 3, 46, and 51%, respectively. Units with P.australis indicated 20% higher water loss compared to units with A.donax. Although the drained water quality improved over time, it did not meet standard limits. The residual sludge layer contained macro and micronutrients, and heavy metals with a significant elemental order of N > Ca > P > S > mg > K (N:P:K = 31:8:1), Fe > Na > B > Mn > Mo and Zn > Cr > Cu > Pb > Ni > Cd. Overall, STRB could be a sustainable alternative technology to conventional sewage sludge management techniques. [ABSTRACT FROM AUTHOR]

This study comparatively evaluated effluent reuse from two TWs—a horizontal subsurface flow (HF) and a vertical subsurface flow (VF)—used for rural wastewater treatment in Central Chile during the initial operation stage. The two TWs were planted with Zantedeschia aethiopica and were operated for 10 months at a pilot scale. The water quality of the influent and effluents was measured and compared with reuse regulations. The results showed similarities in the behavior of the effluents from the two TWs, presenting differences only in the chemical oxygen demand (COD) and different forms of nitrogen, suggesting the necessity of complementary treatment stages or modifications to the operation. The effluents from the HF better fulfilled the reuse standards for irrigation, as the VF faced problems associated with its size. However, a complementary disinfection system is necessary to improve pathogen removal in the effluents coming from the two TWs, especially to be reused as irrigation water for crops. Finally, this work showed the potential for applying subsurface TWs for wastewater treatment in rural areas and reusing their effluents as irrigation water, practice that can contribute to reducing the pressure on water resources in Chile, and that can be used as an example for other countries facing similar problems. [ABSTRACT FROM AUTHOR]

In order to understand the effect of subsurface flow constructed wetland on the treatment of aquaculture tail water, we constructed three subsurface flow wetlands (Ipomoea aquatica, Eichhornia crassipes, philoxeroides) to compare the effects on tail water purification of grass carp ponds, and analyzed the mechamism of microorganisms. The effects of treatment of ponds for tail water of ponds with different hydraulic loads, drainage, suspension and drainage conversion were discussed, and the diversity and composition of microbial community of subsurface flow constructed wetland were also discussed. The results showed that in Ipomoea aquatica, Eichhornia crassipes, philoxeroides groups, the removal rates of TP, NH+4-N and CODMn was the highest respectively, for 24. 7%, 25. 1% and 25%; When the system was shut down, the removal rates of NH+4-N was the lowest in in Ipomoea aquatica, Eichhornia crassipes, philoxeroides groups, for - 526. 07%, - 871. 08%, and -1 196. 46%; When the system was under the low hydraulic load (5. 76 m 3/d), in Ipomoea aquatica, Eichhornia crassipes, philoxeroides groups, the removal rates of CODMn, NH+4 and TP was the highest respectively, for 30. 4%, 42. 5% and 22. 1%. For the microbial community diversity, the Shannon, Ace and Chao 1 index of Ipomoea aquatica groups were the highest, while for Simpson index, the Alternanthera philoxeroides groups was the highest. A total of 5131 samples were identified from the samples of the three aquatic plants groups, which were annotated to 45 phyla, 293 orders and 974 genera. And total of 5 021 OTU samples were obtained from the Ipomoea aquatica groups in drainage, suspension and drainage conversion period, including 47 phyla, 294 orders and 953 genera. The study has shown that aquatic plant subsurface flow constructed wetland had a certain purification effect on aquaculture tail water, while the purification effect will reduce when the water shut down, and the purification effect of low hydraulic load was greater than that of high and medium. The diversity and composition of microbial communities affected the purification effect of subsurface flow constructed wetland on the tail water of aquaculture ponds. [ABSTRACT FROM AUTHOR]

This research aims to analyze the efficiency of processing liquid waste from the laundry industry using the Free Water Surface Constructed Wetland (FWS) system with Azolla microphylla plants. The research method used is experimental research by manipulating independent variables and controlling other relevant variables, as well as observing the effect on the dependent variable. Laundry waste samples were taken from Berkah Laundry, Puri Gading, Bekasi. The results showed that the biomass of Azolla microphylla plants increased significantly from day 0 to day 12, with a growth rate between 0.0289 - 0.0477 grams/day and plant density between 185.19 ind/m2 - 277.78 ind/m2. The influent BOD concentration of laundry liquid waste during the acclimatization stage ranged from 5.89 - 10.54 mg/L, while the effluent BOD ranged from 4.35 - 6.98 mg/L, with the highest efficiency reaching 33.8%. The constructed wetland system with Azolla microphylla plants has proven to be effective in reducing pollutant content in liquid waste, with a BOD removal efficiency of 11.1% - 17.7% and COD of 14.5% - 39%. The conclusion of this research is that the use of artificial wetlands with Azolla microphylla plants can be an effective and environmentally friendly alternative solution for processing liquid waste from the laundry industry. The implications of this research show the potential for applying constructed wetland technology in the clothes washing industry to reduce the negative impact of waste on the environment. [ABSTRACT FROM AUTHOR]

Simple Summary: In this study, we investigated the seasonal effects of constructed wetlands on water quality characteristics in a gate dam lake. The research reveals pronounced seasonal changes in the lake's water environment index. During winter, nitrate nitrogen and BOD5 interact significantly, jointly becoming the primary factors restricting lake water quality. In summer, the constructed wetlands effectively improve TN levels. Furthermore, water depth plays a regulatory role in Chl-a content, ammonia–nitrogen, and nitrite–nitrogen by influencing light penetration and water temperature. Urban lakes commonly suffer from nutrient over-enrichment, resulting in water quality deterioration and eutrophication. Constructed wetlands are widely employed for ecological restoration in such lakes but their efficacy in water purification noticeably fluctuates with the seasons. This study takes the constructed wetland of Jinshan Lake as an example. By analyzing the water quality parameters at three depths during both summer and winter, this study explores the influence of the constructed wetland on the water quality of each layer during different seasons and elucidates the potential mechanisms underlying these seasonal effects. The results indicate that the constructed wetland significantly enhances total nitrogen (TN) concentration during summer and exhibits the capacity for nitrate–nitrogen removal in winter. However, its efficacy in removing total phosphorus (TP) is limited, and may even serve as a potential phosphorus (P) source for the lake during winter. Water quality test results of different samples indicated they belong to Class III or IV. Restrictive factors varied across seasons: nitrate–nitrogen and BOD5 jointly affected water quality in winter, whereas TP predominantly constrained water quality in summer. These results could provide a reference for water quality monitoring and management strategies of constructed wetlands in different seasons in Jiangsu Province. [ABSTRACT FROM AUTHOR]

Traditionally constructed wetlands face significant limitations in treating tailwater from wastewater treatment plants, especially those associated with sugar mills. However, the advent of novel modified surface flow constructed wetlands offer a promising solution. This study aimed to assess the microbial community composition and compare the efficiencies of contaminant removal across different treatment wetlands: CW1 (Brick rubble, lignite, and Lemna minor L.), CW2 (Brick rubble and lignite), and CW3 (Lemna minor L.). The study also examined the impact of substrate and vegetation on the wetland systems. For a hydraulic retention time of 7 days, CW1 successfully removed more pollutants than CW2 and CW3. CW1 demonstrated removal rates of 72.19% for biochemical oxygen demand (BOD), 74.82% for chemical oxygen demand (COD), 79.62% for NH4 +-N, 77.84% for NO3--N, 87.73% for ortho phosphorous (OP), 78% for total dissolved solids (TDS), 74.1% for total nitrogen (TN), 81.07% for total phosphorous (TP), and 72.90% for total suspended solids (TSS). Furthermore, high-throughput sequencing analysis of the 16S rRNA gene revealed that CW1 exhibited elevated Chao1, Shannon, and Simpson indices, with values of 1324.46, 8.8172, and 0.9941, respectively. The most common bacterial species in the wetland system were Proteobacteria, Spirochaetota, Bacteroidota, Desulfobacterota, and Chloroflexi. The denitrifying bacterial class Rhodobacteriaceae also had the highest content ratio within the wetland system. These results confirm that CW1 significantly improves the performance of water filtration. Therefore, this research provides valuable insights for wastewater treatment facilities aiming to incorporate surface flow-constructed wetland tailwater enhancement initiatives. [ABSTRACT FROM AUTHOR]

A demonstration-scale outdoor constructed wetland (CW) wastewater treatment system was evaluated for about two years for its effectiveness in treating septic system effluents. The system included three treatment cells: an anaerobic cell, an aerated cell, and a basic oxygen furnace slag (BOFS)-based phosphorus (P) treatment cell. High removal efficiencies were achieved, with reductions of >99% for PO4-P, >83% for NH3-N, >99% for cBOD5, and >76% for COD, with influent concentrations averaging 6, 48, 63, and 143 mg L−1, respectively. Additionally, pathogens removal were high, with an over 99% decrease in E. coli and total coliform levels. The BOFS cell was critical, elevating effluent pH to 10.9 ± 1.5, which effectively inactivated pathogens. Environmental safety before discharge was ensured by CO2(g) sparging to adjust the pH and a zero-valent iron layer in the BOFS cell to control dissolved metal concentrations. Analytical techniques (FESEM-EDX, FTIR, and XANES) confirmed the formation of Ca carbonate and Ca phosphate on spent BOFS, highlighting their role in the treatment process. This study highlights the potential of integrating complementary technologies in constructed wetlands for sustainable and efficient wastewater management. [ABSTRACT FROM AUTHOR]

Synthetic wastewater was treated in lab-scale constructed wetlands (CWs) in sequencing batch mode to evaluate roles of aquatic plants for removing an azo dye: Reactive Yellow 86 (RY86). Under hydraulic retention time (HRT) of 5 days, removal by unplanted CWs was less than 20% for RY86 of 10–50 mg/L. The CWs planted with cattail and papyrus demonstrated RY86 removal of 50–68% and 73–84%, respectively. For wastewater containing 50 mg/L RY86, removal in the unplanted CW was <12%, even under a 15 day HRT, although it was 22–71% in CWs planted with cattail and 34–81% in CWs planted with cattail, with increasing values under HRTs of 1 day to 15 days. Both cattail and papyrus grew well, extending their roots in the CWs for 90 days. RY86-decolorizing microorganisms were detected in CW effluent. Overall, RY86 removal was positively correlated with evapotranspiration in the CWs, indicating the plant uptake as the main removal mechanism. Papyrus and cattail, especially the former, are suitable plants for CWs intended to treat RY86-containing wastewater. [ABSTRACT FROM AUTHOR]

The effects of salinity gradients (500–4000 mg·L−1 NaCl) on electricity generation, nitrogen removal, and microbial community were investigated in a constructed wetland-microbial fuel cell (CW-MFC) system. The result showed that power density significantly increased from 7.77 mW m−2 to a peak of 34.27 mW m−2 as salinity rose, indicating enhanced electron transfer capabilities under saline conditions. At a moderate salinity level of 2000 mg·L−1 NaCl, the removal efficiencies of NH4+–N and TN reached their maximum at 77.34 ± 7.61% and 48.45 ± 8.14%, respectively. This could be attributed to increased microbial activity and the presence of critical nitrogen-removal organisms, such as Nitrospira and unclassified Betaproteobacteria at the anode, as well as Bacillus, unclassified Rhizobiales, Sphingobium, and Simplicispira at the cathode. Additionally, this salinity corresponded with the highest abundance of Exiguobacterium (3.92%), a potential electrogenic bacterium, particularly at the cathode. Other microorganisms, including Geobacter, unclassified Planctomycetaceae, and Thauera, adapted well to elevated salinity, thereby enhancing both electricity generation and nitrogen removal. [ABSTRACT FROM AUTHOR]

Owing to the impact of the effluent C/N from the secondary structures of urban domestic wastewater treatment plants, the denitrification efficiency in constructed wetlands (CWs) is not satisfactory, limiting their widespread application in the deep treatment of urban domestic wastewater. To address this issue, we constructed enhanced CWs and conducted orthogonal experiments to investigate the effects of different factors (C/N, fillers, and plants) on the removal of conventional pollutants and the reduction of greenhouse gas (GHG) emission. The experimental results indicated that a C/N of 8, manganese sand, and calamus achieved the best denitrification efficiencies with removal efficiencies of 85.7%, 95.9%, and 88.6% for TN, NH4+-N, and COD, respectively. In terms of GHG emission reduction, this combination resulted in the lowest global warming potential (176.8 mg/m2·day), with N2O and CH4 emissions of 0.53 and 1.25 mg/m2·day, respectively. Characterization of the fillers revealed the formation of small spherical clusters of phosphates on the surfaces of manganese sand and pyrite and iron oxide crystals on the surface of pyrite. Additionally, the surface Mn (II) content of the manganese sand increased by 8.8%, and the Fe (III)/Fe (II) and SO42−/S2− on pyrite increased by 2.05 and 0.26, respectively, compared to pre-experiment levels. High-throughput sequencing indicated the presence of abundant autotrophic denitrifying bacteria (Sulfuriferula, Sulfuritalea, and Thiobacillus) in the CWs, which explains denitrification performance of the enhanced CWs. This study aimed to explore the mechanism of efficient denitrification and GHG emission reduction in the enhanced CWs, providing theoretical guidance for the deep treatment of urban domestic wastewater. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigated the distribution and binding affinity of dissolved copper (Cu) and organic carbon (OC) in size-fractioned dissolved organic matter (DOM) in a constructed wetland (CW). Two sites were studied: one at the inflow (P-1) and one within the wetland (P-2). The DOMs (<0.45 μm) were separated into six size fractions using a cross-flow ultrafiltration system. In the wetland (P-2), the concentrations of dissolved organic carbon (DOC) increased while the concentrations of Cu decreased. The high molecular weight fraction (1 kDa–0.45 μm, HMW) contained most of the OC mass (57.4–71.2% averages). On the other hand, Cu was almost equally distributed in HMW and low molecular weight fractions (<1 kDa, LMW) with mean HMW percentages of 50.3–51.3%. The mean Cu binding affinity to DOM ratios (CuBADOM) was 74.9 ± 24.0 μmol/g-C at site P-1 and 17.3 ± 2.6 μmol/g-C at site P-2. The CuBADOM ratios were decreased in wetlands of bulk and size-fractioned DOM (p < 0.001 to p = 0.073). The SUVA254 values for bulk DOM solution were 2.54 ± 0.15 and 1.68 ± 0.18 L/mg-C/m, and humidification index (HIX) values were 1.74 ± 0.16 and 2.09 ± 0.19 for sites P-1 and P-2, respectively. Optical indicators suggested that the wetland process decreased aromaticity but increased the humification degree of DOM. Furthermore, the CuBADOM ratios positively correlated with SUVA254 and HIX within the constructed wetland DOM but not in the influent DOM. Understanding the Cu distribution and binding affinity to size-fractioned DOM makes it possible to develop strategies to mitigate the potential effects of copper pollution in wetlands. [ABSTRACT FROM AUTHOR]

In response to the problems of insufficient denitrification and poor denitrification effect of traditional constructed wetlands for the treatment of livestock biogas slurry, in this study Chlorella sorokiniana was used as an additional carbon source for the construction of C. sorokiniana - constructed wetland systems to treat piggery biogas slurry. The effect of the system on the removal of water quality of piggery biogas slurry and the change rule of the dissolved organic matters (DOMs) through the addition of C. sorokiniana under different concentrations (0, 0.25, 0.5 and 1.0 g/L) were investigated, and the mechanism of en- hanced nitrogen removal was explored from the perspective of microorganisms. The results showed that compared with the constructed wetland without the addition of C. sorokiniana, the removal of total nitrogen was obviously increased up to 70.24%, and the removal of nitrate nitrogen reached up to 93.45%. Based on the three-dimensional fluorescence parallel factor analysis, the three components in DOMs were fulvic acid/humic acid-like substances, polymer aromatic substances and humic acid-like substances, while the addition of C. sorokiniana enhanced the removal of DOMs from piggery biogas slurry and reduced the content of humic acid-like substances. The addition of C. sorokiniana evidently increased the Alpha diversity of microorganisms in the constructed wetland. Particularly, at the phylum level the relative abundance of dominant bacteria related to denitrification (Proteobacteria) increased obviously, while at the genus level the genera Nitrosomonas and Limnobacter played important roles in the ammonia oxidation and denitrification processes of the system. This study provides theoretical support for the use of C. sorokiniana as an additional carbon source to enhance nitrogen and phosphorus removal in constructed wetlands. [ABSTRACT FROM AUTHOR]

Recent advancements in constructed wetlands (CWs) have highlighted the imperative of enhancing nitrogen (N) removal efficiency. However, the variability in influent substrate concentrations presents a challenge in optimizing N removal strategies due to its impact on removal efficiency and mechanisms. Here we show the interplay between influent substrate concentration and N removal processes within integrated vertical-flow constructed wetlands (IVFCWs), using wastewaters enriched with NO3−-N and NH4+-N at varying carbon to nitrogen (C/N) ratios (1, 3, and 6). In the NO3−-N enriched systems, a positive correlation was observed between the C/N ratio and total nitrogen (TN) removal efficiency, which markedly increased from 13.46 ± 2.23% to 87.00 ± 2.37% as the C/N ratio escalated from 1 to 6. Conversely, in NH4+-N enriched systems, TN removal efficiencies in the A-6 setup (33.69 ± 4.83%) were marginally 1.25 to 1.29 times higher than those in A-3 and A-1 systems, attributed to constraints in dissolved oxygen (DO) levels and alkalinity. Microbial community analysis and metabolic pathway assessment revealed that anaerobic denitrification, microbial N assimilation, and dissimilatory nitrate reduction to ammonium (DNRA) predominated in NO3−-N systems with higher C/N ratios (C/N ≥ 3). In contrast, aerobic denitrification and microbial N assimilation were the primary pathways in NH4+-N systems and low C/N NO3−-N systems. A mass balance approach indicated denitrification and microbial N assimilation contributed 4.12–47.12% and 8.51–38.96% in NO3−-N systems, respectively, and 0.55–17.35% and 7.83–33.55% in NH4+-N systems to TN removal. To enhance N removal, strategies for NO3−-N dominated systems should address carbon source limitations and electron competition between denitrification and DNRA processes, while NH4+-N dominated systems require optimization of carbon utilization pathways, and ensuring adequate DO and alkalinity supply.

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a large class of toxic contaminants. Nutrients are closely related to the ecological health of aquatic systems. Both have received widespread global attention. This study investigated the concentrations, compositions, and spatial distributions of PFAS and nutrients in surface water from two constructed wetlands and the nearby drinking water treatment plants (DWTPs). We explored the natural environmental factors and human activities that affect the composition and distribution of pollutants in wetlands and assessed the ability of the DWTPs to remove contaminants. Concentrations of ∑32PFAS varied from 153 to 405 ng/L. Hexafluoropropylene oxide trimer acid (HFPO-TA) was the predominant substance accounting for 45 % of ∑32PFAS concentrations. It might originate from the emissions of indirect sources of PFAS related manufacturers. The detection rate of 6:2 fluorotelomer carboxylic acid (6:2 FTCA) was 100 % with concentrations ranging from 0.915 to 19.7 ng/L 6:2 FTCA might come from the biotransformation of indirect sources in the air. Concentrations of total nitrogen (TN) and total phosphorus (TP) were from 1.47 to 3.54 mg/L, and non-detect (ND) to 0.323 mg/L, respectively. Constructed wetlands could effectively remove PFAS under nutrient stress, however, the removal of PFAS depends on the characteristics of specific compounds and their sources. The removal rates for PFAS and nutrients could be promoted through artificial dredging. But wetland bioremediation could have two opposing effects. On the one hand, plants can take up pollutants from water via roots, leading to pollutant removal and purification. On the other hand, plants may also absorb precursor intermediates from the air through leaves and release them into the water, leading to increased pollutant concentrations. Thirty-two emerging PFAS were identified by high resolution mass spectrum. The drinking water treatment process removed PFAS and nutrients below the drinking water quality standards of China, however, 9 non-target PFAS compounds were still found in tap water. These results provide case support and a theoretical basis for the pollution control and sustainable development of typical ecological wetlands used as drinking water sources.

【Objective】 Nonpoint source pollution poses a significant threat to the surface water environment, particularly in agricultural systems. Reconstructed wetlands are an environmentally friendly method to mitigate nonpoint source pollution. This paper investigates the efficacy of plants and their growing medium in removing pollutants from farmland receding water. 【Method】 The experiment was conducted in a subsurface-flow wetland and an ecology surface flow wetland at Bapaigan region along the bank of Duliujian River. We measured the impact of aquatic plant species, planting density, matrix materials and filling rate, and hydraulic retention time of water in the wetland on purification of the water. 【Result】 Among all treatments we compared, the combination of plant species of Scirpus tabernaemontani+ Iris tectorum and matrix of zeolite+ volcanic rock was most effective to purify the receding water, as they nurtured a microbial community which increased denitrification and dephosphorization. Keeping the hydraulic retention time 3 day and running 10 consecutive cycles can remove ammonia nitrogen, total phosphorus and chemical oxygen demand (COD) contents by 95.74%, 49.94% and 89.03%, respectively. 【Conclusion】 Following the implementation of the Bapaigan constructed wetland, the plants, substrate medium and their associated microbiome were effective to remove the pollutants from the receding water, with the effluent water quality reaching Class V standard for surface water. These findings have important implications for remediating farmland runoff using constructed wetlands in north China.