Search Results (848)

Advanced treatment of plant effluent (tailwater) is critical for mitigating agricultural non-point source pollution; however, plant–substrate synergy in vertical-flow constructed wetlands (VFCWs) remains poorly understood under subtropical conditions. This one-year pilot study evaluated the effects of substrate type (zeolite vs. gravel) and P. australis presence on nutrient removal, seasonal performance stability, and microbial community assembly in tailwater treatment. Methodologically, twelve VFCWs were operated across seasons, and their performance was assessed via water quality monitoring and high-throughput sequencing. The results indicate that all configurations consistently met stringent discharge standards. Planted treatments significantly outperformed unplanted controls in removing TN, COD, and TP (p < 0.05), while no significant difference emerged between zeolite- and gravel-planted systems, confirming vegetation’s dominance over substrate selection under low-concentration loads. Seasonal analysis revealed temperature-dependent TN removal (p < 0.01), whereas TP, COD, and NH₄⁺-N removal remained stable. Microbial analysis showed P. australis selectively enriched functional taxa driving N and organic matter mineralization despite a shared core microbiome at the genus level. Gravel-planted VFCWs exhibited superior long-term resilience compared to the transient sorption of zeolites. We considered that vegetation-driven biological pathways offer a resilient design for polishing nutrients in tailwater, showing potential for agricultural irrigation and nutrient interception. Full article

Constructed wetlands (CWs) are widely used as an ecological technology for wastewater treatment. However, the accumulation of microplastics (MPs) in their substrates may impair long-term performance and threaten the operational sustainability of these nature-based treatment systems. To elucidate the transport behaviour of MPs in wetland substrates, this study developed a numerical model based on the lattice Boltzmann method (LBM) to simulate advection, hydrodynamic dispersion, and reversible first-order adsorption/desorption of MPs in saturated porous media. The model incorporates a salinity-dependent non-linear attachment rate coefficient, which captures the compression of the electrical double layer and the enhanced attachment efficiency with increasing salinity. Pore-scale flow is solved using the LBM with an Ergun-type drag term to represent the resistance of the porous matrix. The model was validated against experimental breakthrough curves from column studies using quartz sand and coastal wetland soils under five salinity levels (0–35 PSU) reported in the literature. Quantitative validation yielded coefficients of determination (R²) ranging from 0.782 to 0.960 (RMSE = 0.024–0.045) for calibration cases and 0.741 to 0.946 (RMSE = 0.027–0.048) for independent validation cases across both substrates, excluding the soil cases at 3.5 and 35 PSU. Here, both observed and simulated effluent concentrations were identically zero, resulting in the statistically forced R² = 1.000 and RMSE = 0, which are mathematical artefacts rather than indicators of predictive performance. The simulations reproduce the observed reduction in peak relative concentration by over 50% in sand and near-complete retention (C/C₀ ≈ 0) in soil at high salinities (3.5 and 35 PSU). Results demonstrate that the model successfully reproduces the differences in MP breakthrough behaviour across different substrate types and salinity levels. By linking salinity-enhanced retention to the risk of irreversible clogging and shortened wetland lifespan, the model provides a predictive tool for evaluating the sustainability of CWs under saline stress. This study offers a scientific basis for optimizing hydraulic management (e.g., flushing strategies) to mitigate microplastic pollution and enhance the long-term sustainability and resilience of constructed wetlands in coastal and saline environments. Full article

Constructed wetland has evolved into an effective treatment method of effluent, an important consideration in mitigating the escalating problem of antibiotic resistance in environmental and human health contexts. This study evaluated the performance of a 21-acre horizontal flow constructed wetland (HFCW) located at the Nicholls State University Farm for reducing nutrients, fecal coliform bacteria, and antibiotics, in water originating from Bayou Folse receiving treated sewage wastewater. Water samples were collected monthly in triplicate from input and output sites from January 2025 to February 2026. Water quality parameters, such as nitrate, phosphate, ammonia, sulfate, COD and antibiotic concentrations and fecal coliform abundance were analyzed to evaluate treatment efficiency. Significant reductions in sulfate (99.2%) and phosphate (40%) concentrations were observed, along with reduction in other nutrients, between input and output sites over the 14-month study period, indicating nutrient attenuation within the wetland. Antibiotic analysis revealed significant decreases in amoxicillin (81.81%), erythromycin (62.96%), sulfamethoxazole (62.02%), trimethoprim (68.72%), bacitracin (69.77%), tetracycline (69.94%), and penicillin (88.14%) concentrations. Fecal coliform bacterial numbers decreased from input to output site with 32.77% reduction. Overall, the results demonstrated that the constructed wetland effectively reduced nutrients, antibiotics concentration, and fecal coliforms. This study highlights the potential of HFCWs as sustainable mitigation tools for improving water quality. Full article

Global water scarcity is mainly due to climate change, population growth, excessive use of water resources and inadequate water management. Alternative sources such as reusing greywater are promising in urban environments. In this context, phytoremediation, the direct use of plants to remove soil and water pollution, could be an encouraging alternative nature-based solution to traditional reuse methods. While constructed wetlands are the most common method for greywater phytoremediation, their limited feasibility in cities makes green roofs and walls a practical urban alternative. This review examines studies conducted over the last 20 years. The combination of greywater treatment through phytoremediation with urban greenery would help close the water cycle as well as make cities more sustainable. However, for this solution to be viable, several challenges must be addressed, including limited roof or wall surface area compared to traditional systems, the precise volume of water to be managed, and the selection of suitable substrates and plants essential for effective phytoremediation. This work reviews the main mechanisms and factors that drive the phytoremediation process in constructed wetlands, and based on this knowledge, delves into the challenges of applying this process to the urban context through green roofs and facades on buildings. Full article

Animal activity plays an important role in regulating soil methane (CH₄) and nitrous oxide (N₂O) emissions. As a global invasive gastropod, golden apple snail (GAS, Pomacea canaliculata) has established great populations in wetlands, which has disturbed the soil ecological process. However, the impact of GAS activities on greenhouse gas (GHG) emissions is still unclear. A 25-day mesocosm experiment was conducted to examine CH₄ and N₂O fluxes, soil properties, microbial community, and GHG-related functional genes under low-density (GASL), high-density (GASH) and control (CK, without snail) treatments. Results showed that GASL significantly increased soil porosity and total nitrogen content by 18.6% and 7.6% on the 25th day. GASH significantly increased soil urease and sucrase activities by 18.1% and 30.0%. GASH significantly decreased the CH₄ emission flux by 18.7% and increased the N₂O emission flux by 33.1% on the 25th day. The 25-day cumulative CH₄ and N₂O emissions from female and male snail accounted for 0.002% and 2.3% of the total CH₄ and N₂O emissions in the GASH treatment, respectively. Moreover, GAS altered the soil microbial community composition. GASL significantly decreased the relative abundance of the phylum Chloroflexota by 11.3%, and increased the relative abundance of the family Nitrospiraceae by 24.5%. Compared with CK, GASH reduced the abundance of functional genes of mcrA, AOA-amoA, and nosZ by 16.9%, 19.7%, and 21.1%, respectively, while increasing the abundance of pmoA, AOB-amoA, and nirS by 18.4%, 65.3%, and 54.2%, respectively. These findings indicate that GAS disturbs soil physiochemical and microbial properties, and the conclusions are limited to a short-term mesocosm experiment. Full article

Municipal wastewater is a major pathway for the continuous release of microplastics into aquatic environments, making the development of efficient and reusable capture materials essential for advanced water treatment. In this study, a multifunctional ZIF-67/g-C₃N₄/CS nanocomposite was designed by integrating cobalt-based zeolitic imidazolate framework ZIF-67 with graphitic carbon nitride (g-C₃N₄) and a chitosan (CS) biopolymer matrix. The novelty of this material lies in combining the high porosity and tunable surface chemistry of ZIF-67, the π-rich layered structure of g-C₃N₄, and the hydrophilic, amino-rich chitosan framework into a single adsorptive platform for simultaneous removal of chemically different microplastics. The nanocomposite achieved high removal efficiencies for polystyrene (PS), polypropylene (PP), and polyethylene (PE) microplastics with particle sizes of 20–25 μm, reaching 97.4%, 92.1%, and 90.3%, respectively, at pH 7.6 within 25 min. The higher affinity toward PS is attributed to additional π–π interactions between the aromatic PS chains and the conjugated domains of g-C₃N₄/ZIF-67, whereas PP and PE removal is mainly governed by hydrophobic adhesion, surface trapping, and interfacial interactions with the chitosan-supported porous framework. The equilibrium data were well described by both Langmuir and Freundlich models, with maximum adsorption capacities of 97.69, 94.86, and 93.67 mg g⁻¹ for PS, PP, and PE, respectively. The nanocomposite retained high recyclability, maintaining 95–97 ± 3.1% removal after five adsorption–desorption cycles. These findings demonstrate that ZIF-67/g-C₃N₄/CS is a durable and high-performance adsorbent for microplastic remediation, with strong potential for application in municipal wastewater treatment, constructed wetlands, and advanced water-polishing systems. Full article

Emerging contaminants (ECs), including pharmaceuticals, endocrine disruptors, pesticides, PFAS, and microplastics, are increasingly detected in aquatic environments due to their persistence, bioactivity, and limited removal by conventional treatment processes. These challenges are intensified in hyper-arid regions where desalination and wastewater reuse dominate water supply, concentrating contaminants and creating unique exposure pathways. The Arabian Gulf is one of the most environmentally stressed marine systems, characterized by hypersalinity, extreme temperatures, dense coastal development, and strong petrochemical influence. Despite its major role in global petrochemical and plastic production, the region lacks coordinated monitoring and regulatory frameworks, creating significant gaps in understanding EC occurrence, fate, and risks. Treatment systems designed for temperate climates often underperform under Gulf conditions, enabling contaminants to persist, accumulate in sediments, and enter marine food webs. This review examines the occurrence, behaviour, and removal challenges of ECs in the Gulf, where concentrations frequently exceed international benchmarks due to wastewater reuse, desalination brine discharge, maritime activities, and oil-related pollution. Regional factors such as hypersalinity, high temperatures, and petrochemical interactions further influence contaminant persistence and toxicity. Conventional treatments show reduced efficiency, while alternatives such as halophyte-based wetlands and brine valorisation show promise. However, key gaps remain in nanoplastics, PFAS speciation, and cumulative exposure, requiring coordinated monitoring and unified GCC regulations. Full article

Bolboschoenus planiculmis is a dominant clonal sedge in saline–alkaline wetlands of the Songnen Plain, and its corms provide important food resources for migratory waterbirds. However, its growth mechanism under saline alkali conditions is still unclear. We combined a field survey with a greenhouse experiment that decoupled saline–alkaline stress into two associated constraints, physiological drought and nitrogen deficiency. Six treatments were established: control, nitrogen deficiency, PEG-induced physiological drought, their combination, moderate saline–alkaline stress, and severe saline–alkaline stress. In the field, soil electrical conductivity and pH increased synchronously, whereas inorganic nitrogen availability was heterogeneous. In the greenhouse, compared with the CK, moderate and severe saline–alkaline stress reduced total biomass by approximately 47% and 51%, respectively, and inhibited leaf growth, root expansion, and corm biomass. It also increased SOD and CAT activities, and ${\mathrm{H}}_2$${\mathrm{O}}_2$ and MDA accumulated. ¹⁵N tracing further showed reduced nitrogen enrichment and lower nitrogen input into corms under saline–alkaline stress, despite partial maintenance of corm allocation. Integrated trait analyses suggested that growth limitation was associated with oxidative damage, restricted morphological development, defense costs, and reduced nitrogen acquisition. These findings provide a plant-level perspective that may inform future assessments of belowground food-resource conditions in migratory waterbird stopover habitats. Full article

Wastewater treatment remains a major challenge in rural and peri-urban areas, where conventional centralized infrastructure is often unavailable or insufficient. In this context, Nature-Based Solutions (NBS) have emerged as cost-effective and energy-efficient alternatives for decentralized wastewater treatment. This review presents a comprehensive and multidimensional assessment of 15 NBS types, evaluating their technical performance, economic viability, environmental sustainability, and social dimensions. The analysis indicates that NBS can achieve pollutant removal efficiencies comparable to those of conventional treatment systems, particularly for organic matter and, in some cases, emerging contaminants. However, their performance is strongly influenced by system design and operational conditions. The main limitations of NBS include relatively low hydraulic and pollutant loading capacities, as well as substantial land requirements, ranging from 0.45 to 840 m²·PE⁻¹. These constraints limit their applicability in densely populated areas while making them particularly well suited for rural and low-density settings. From both economic and environmental perspectives, NBS offer significant advantages, including construction cost reductions of up to 66% and substantially lower energy consumption than conventional technologies. Nevertheless, their successful implementation depends not only on technical performance but also on social acceptance, stakeholder engagement, and the establishment of appropriate governance frameworks. Overall, NBS constitute a flexible and sustainable approach to wastewater treatment, whose effectiveness ultimately depends on site-specific conditions and the integration of complementary treatment components. Full article

This Editorial introduces the Special Issue “Emerging Technologies for Waste Treatment, Pollution Control and Resource Recovery”, which examines how contemporary environmental engineering is moving beyond conventional end-of-pipe treatment toward integrated, circular, and systems-oriented approaches. The collected contributions address sustainability innovation in textile manufacturing, life-cycle-informed PFAS removal from landfill leachate, fishbone-derived hydroxyapatite adsorbents for heavy metal removal, and constructed wetlands for azo dye degradation. Together, these studies demonstrate that effective waste treatment must be evaluated not only in terms of pollutant removal efficiency, but also by material circularity, secondary environmental burdens, operational feasibility, and long-term contaminant fate. This Editorial highlights key cross-cutting themes, including the valorization of residual materials, the importance of realistic matrices and field validation, and the need to integrate life cycle assessment, techno-economic analysis, and mechanistic investigation early in technology development. It further identifies major research gaps concerning spent media management, regeneration, toxicity, transformation products, and scale-up under variable operating conditions. Overall, this Special Issue proposes a framework in which emerging waste treatment technologies are understood as multifunctional environmental systems that support pollution control, resource recovery, and resilient circular economies. Full article

Increasing water scarcity and pollution have intensified the need for low-cost wastewater treatment in developing regions. Constructed wetlands (CWs) offer a nature-based solution for pollutant removal but often fail, on their own, to meet discharge and reuse standards. This study evaluated four CW systems planted with Cyperus latifolius, Juncus effusus, Phragmites mauritianus, and Pennisetum purpureum, integrated with banana fibre filtration as a polishing step. The CWs alone achieved ammonium removal of 74–83%, nitrate 78–85%, phosphorus 86–91%, and COD 78–83%. Banana fibre filtration enhanced overall removal efficiencies to 93–96%, 94–96%, 81–88%, and 82–87% for ammonium, phosphorus, nitrate, and COD, respectively. Pennisetum purpureum had the highest aboveground nitrogen accumulation (74.4 g N/m²), with its coupled system achieving the highest nitrate removal, whereas Juncus effusus had the highest phosphorus accumulation (93.1 g P/m²), with its coupled system showing the best overall removal of ammonium, phosphorus, and COD. The integrated system reduced fecal coliforms and Escherichia coli by 6–8 log and eliminated detectable Salmonella and Shigella. Treated effluent met FAO irrigation, Rwanda discharge, and European Union (EU) standards for all evaluated parameters except phosphorus, which remained above the stricter EU limit. Despite bench-scale operation over four months, these findings demonstrate a low-cost, nature-based treatment approach suitable for decentralized wastewater treatment and reuse, with harvested wetland biomass offering additional potential for animal feed, energy, or fibre valorization. Full article

Constructed wetlands operated in plateau habitats may experience constrained biological treatment because low temperature, low atmospheric pressure, and low-carbon wastewater can jointly limit microbial metabolism. This 80-day pilot screening study evaluated three nonreplicated modular constructed wetland configurations (MCW1-MCW3) containing different sequences of zeolite, ceramsite, and quartz sand and planted with Veronica anagallis-aquatica. Each configuration consisted of one independent treatment train; therefore, the comparisons were interpreted as configuration-specific and exploratory rather than as statistically generalizable treatment effects. Pollutant-removal performance and microbial community succession were evaluated through repeated water-quality monitoring and 16S rRNA gene sequencing. MCW1 showed the highest observed mean NH₄⁺-N removal efficiency (88.6%), whereas MCW3 showed the highest observed mean TP and COD removal efficiencies (79.56% and 47.40%, respectively) and an NH₄⁺-N removal efficiency of 85.51%. TN removal by MCW3 remained limited at 20.49%, consistent with carbon limitation of denitrification. Under the naturally low-temperature plateau laboratory conditions, the observed COD reduction indicated partial mineralization or retention of organic pollution loads, potentially supported by substrate biofilms and cold-adapted microbial assemblages. Apparent module-contribution analysis suggested that zeolite contributed substantially to NH₄⁺-N reduction, whereas ceramsite contributed to TP and COD removal under the tested sequences. Because plant biomass and tissue nutrient contents were not measured, nitrogen and phosphorus removal could not be attributed quantitatively to hydrophyte uptake. Overall, substrate sequence influenced pollutant-removal patterns and microbial community assembly, providing preliminary evidence for habitat-adapted optimization of modular constructed wetlands for plateau domestic wastewater. Full article

The presence of antibiotic resistance genes (ARGs) in wastewater and their dissemination into aquatic ecosystems represents a significant threat to ecological integrity and public health. This study focuses on the Batuco Lagoon Natural Sanctuary (receiving effluents from a WWTP) and on irrigation canals used for agriculture (without WWTP influence). The aim was to analyze seasonal ARG dynamics and relate their occurrence to water physicochemical characteristics. Five sampling campaigns were conducted, during which physicochemical analyses and molecular detection were performed to identify the blaTEM, sul1, tetW, and ermB genes. Dissolved oxygen ranged from 2.8 to 5.0 mg/L, COD in untreated wastewater reached 287.84 mg/L, and the lagoon exhibited hypereutrophic conditions with total nitrogen averaging 4.56 mg/L (BL1) and 4.39 mg/L (BL2). blaTEM was the most prevalent gene, detected in 71% of samples, followed by sul1 (63%) and tetW (50%). ermB was the least prevalent, present in only 25% of samples. Significant seasonal variations were observed: 33% of samples were ARG-positive in winter, 38% in spring, 50% in fall, and 88% in summer, with all four genes detected during the latter. Seasonal factors, especially summer temperatures and human activity, may increase ARG dissemination, highlighting the need for better WWTP effluent management. Full article

Aquatic ecosystems are increasingly impacted by anthropogenic pressures, including nutrient over-enrichment, industrial discharge and physical habitat alteration, resulting from industrialization, urbanization, agricultural intensification and population growth. In recent years, microalgae have been extensively studied in engineered and controlled systems for their potential role in aquatic ecosystem restoration, owing to their capacity to assimilate nutrients, sequester contaminants and interact with microbial consortia, alongside valuable biomass generation. While most of the existing studies are based on ex situ systems, such as high-rate algal ponds, wastewater treatment reactors, algal–bacterial granular sludge, constructed wetlands and aquaculture effluent treatment units, these processes provide mechanistic insights relevant to aquatic ecosystem restoration. Hence, this review critically evaluates the emerging role of microalgae in aquatic ecosystem restoration, mainly through two implementation pathways, namely ex situ engineered systems and in situ applications, based on the current state of the art in microalgae-driven processes, with particular emphasis on nutrient uptake pathways and mechanisms. Furthermore, key challenges and future directions associated with the translational potential of microalgae-based approaches, including field-scale validation, ecological performance assessment, operational stability and regulatory integration, essential for real-world aquatic ecosystem restoration, are discussed. Despite the limitations in direct field-scale restoration, microalgae-based strategies are promising and sustainable platforms for aquatic ecosystem rehabilitation, which align with Sustainable Development Goals 6 and 14. Full article

To clarify the effects of precipitation changes on greenhouse gas (CO₂, CH₄, N₂O) emissions from the lakeshore wetland ecosystem of Qinghai Lake, this study establishes five precipitation treatments (D25%, D75%, CK, I25%, I75%) using a rainfall manipulation device. During the growing season, greenhouse gas fluxes were measured via the static chamber–gas chromatography method, while soil temperature, moisture, total carbon (TC), total nitrogen (TN), pH, electrical conductivity (EC), and aboveground and belowground biomass were simultaneously monitored. The results showed that at 11:00, both increased and decreased precipitation inhibited CO₂ and CH₄ emissions (with D25 showing the strongest inhibition for CO₂ and I75 for CH₄); however, increased precipitation promoted N₂O emissions (I75 strongest), while decreased precipitation suppressed them (D25 strongest). At 15:00, only D25 inhibited CO₂ emissions, whereas all other treatments promoted them (I75 strongest). CH₄ fluxes under all treatments were higher than those in CK, indicating a promoting effect (I25 strongest). N₂O emissions responded to precipitation changes as follows: wetting promoted emissions (I25 optimal), while drying suppressed them (D75 stronger). Correlation analyses revealed treatment- and time-specific patterns. At 11:00, significant negative correlations between CO₂ and soil temperature and significant positive correlations between CH₄ and soil temperature were observed only under I75; soil moisture was significantly positively correlated with CH₄ under D25; TN significantly inhibited all three gases under wetting treatments; and TC showed a highly significant negative correlation with N₂O under I75 (p < 0.01). At 15:00, soil temperature generally promoted CO₂ and CH₄ emissions (except for CO₂ under D75); soil moisture promoted CH₄; TC was negatively correlated with both CO₂ and N₂O; pH was positively correlated with CO₂ only under CK; the correlation between EC and CO₂ shifted from positive (CK) to negative (I75); aboveground biomass suppressed CO₂ under I25 and I75 but promoted N₂O under D25. In summary, precipitation changes significantly modulate greenhouse gas emissions and their relationships with soil factors, with strong temporal and treatment dependencies. Future studies should integrate long-term observations and process-based models to further quantify the comprehensive effects of precipitation changes on the greenhouse gas budget of this wetland ecosystem. Full article