Assessment of autochthonous aquatic macrophytes with phytoremediation potential for dairy wastewater treatment in floating constructed wetlands

Sustainable treatment of combined industrial wastewater: synergistic phytoremediation with Eichhornia crassipes, Pistia stratiotes, and Arundo donax in biofilm wetlands

This study investigates the treatment of combined wastewater from Hattar Industrial Estate using Biofilm Wetlands (BW) planted with monoculture species: Eichhornia crassipes (EAC), Pistia stratiotes (WL), and Arundo donax (GR). Each species showed distinct capabilities in organic degradation, metal uptake, and pH stabilization. BW2, planted with EAC, achieved the highest total solids (TS) and total suspended solids (TSS) removal efficiencies of 66% and 65%, respectively. GR effectively reduced initial COD concentrations from 232 mg/L to 58.67 mg/L, while EAC and WL reached reductions to 72.78 mg/L and 70.67 mg/L, respectively. Overall, the plant efficiency ranking was EAC > GR > WL. These findings underscore the potential of these plant species in synergistic BW systems, highlighting their role as natural solutions for remediating complex industrial effluents. This research contributes to advancing eco-friendly wastewater treatment approaches, suggesting promising applications for sustainable practices in industrial contexts.RESEARCH HIGHLIGHTSThis research assessed the effectiveness of phytoremediation using Eichhornia crassipes, Pistia stratiotes, and Arundo donax for removing pollutants i.e. heavy metals (Cd, Pb, Ni, K, Ca, Mg, Na, Fe, Hg) nitrates, phosphates and sulfates from combined industrial wastewater of Hattar Industrial Estate Pakistan.It highlighted the potential of selected plant species' as natural treatment systems, providing crucial insights into their efficiency.Findings contribute to understanding nature-based solutions for complex industrial effluents.

Floating treatment wetlands to improve the water quality of the Hang Bang canal, Ho Chi Minh City, Vietnam: Effect of plant species

Floating treatment wetlands (FTWs) are artificial platforms that allow aquatic emergent plants to grow in water. Aquatic macrophytes and microorganisms attached to plant roots contribute to the remediation of the contaminated water through physicochemical and biological processes. The pollutant removal treatment performance is affected by various factors, including the plant species. In this study, several plant species, i.e. Canna generalis, Phragmites australis, Pennisetum purpureum, Cyperus alternifolius rottb, Kyllinga brevifolia rottb, and Cyperus ordoratus were investigated for their potential to clean-up water from the Hang Bang canal in Ho Chi Minh City (Vietnam). Canna generalis, Phragmites australis, and Cyperus alternifolius were found to be suitable for FTWs with the highest performance compared to that of other plant species investigated. The organic and nitrogen removal rates amounted to 48-70 g COD m-3 d-1 and 0.7-1.2 g N m-3 d-1, respectively, whereas the reduction of pathogens was around 1.86-3.00 log. Furthermore, FTW systems bring other benefits such as improving ecosystem functioning and biodiversity, producing value-added products from plant biomass, as well as attracting the attention of communities, thus increasing social acceptance of environmental technology interventions.

Nutrient dynamics in wetland systems associated with hydrological and anthropogenic variations in the south of Samborombón Bay, Argentina

Wetlands provide numerous ecosystem services to the environment, such as nutrient removal and storage. The aim of this work is to evaluate the nutrient dynamics in different sectors within wetland systems in the south of the Samborombón Bay (Argentina) based on hydrological and/or anthropogenic variations. For this purpose, the hydrological features of the wetland were defined through the analysis of satellite images, precipitation and tidal data, and field surveys. Three sectors were identified in the wetland: one with tidal influence, another which is dependent on rainfall, and another that receives inputs from rainfall and from a sewage effluent treatment plant. In order to analyze the nutrient dynamics, samples of surface water, groundwater, and sediments were collected from these sectors. Measurements of pH and electrical conductivity were determined in situ in water samples, while the concentration of inorganic forms of phosphorus and nitrogen, soluble reactive silica, and organic carbon were determined through laboratory analysis. Also, bioavailable phosphorus, organic matter, pH, and electrical conductivity were determined in the sediment samples collected. Statistical analysis of the data reveals differences between the sectors and allows the interpretation of the dynamics of the studied components in the wetland. Electrical conductivity distinguishes the intertidal sectors of the wetland while components associated with P and N discriminate the sectors with inputs from the sewage effluent treatment plant. On the other hand, soluble reactive silica, organic carbon, and organic matter do not seem to be influenced by the tide or effluent discharge. This study demonstrates that the studied wetland works as a nutrient retention area, providing ecosystem services to local inhabitants. Although these services can be utilized, they require a continuous monitoring over time to provide an early warning in case the variations in P and N cycles could lead to eutrophication or wetland degradation.

Industrial wastewater treatment using floating wetlands: a review

Industrial wastewater generated from various production processes is often associated with elevated pollutant concentrations and environmental hazards, necessitating efficient treatment. Floating wetlands (FWs) have emerged as a promising and eco-friendly solution for industrial wastewater treatment, with numerous successful field applications. This article comprehensively reviews the removal mechanisms and treatment performance in the use of FWs for the treatment of diverse industrial wastewaters. Our findings highlight that the performance of FWs relies on proper plant selection, design, aeration, season and temperature, plants harvesting and disposal, and maintenance. Well-designed FWs demonstrate remarkable effectiveness in removing organic matter (COD and BOD), suspended solids, nutrients, and heavy metals from industrial wastewater. This effectiveness is attributed to the intricate physical and metabolic interactions between plants and microbial communities within FWs. A significant portion of the reported applications of FWs revolve around the treatment of textile and oily wastewater. In particular, the application reports of FWs are mainly concentrated in temperate developing countries, where FWs can serve as a feasible and cost-effective industrial wastewater treatment technology, replacing high-cost traditional technologies. Furthermore, our analysis reveals that the treatment efficiency of FWs can be significantly enhanced through strategies like bacterial inoculation, aeration, and co-plantation of specific plant species. These techniques offer promising directions for further research. To advance the field, we recommend future research efforts focus on developing novel floating materials, optimizing the selection and combination of plants and microorganisms, exploring flexible disposal methods for harvested biomass, and designing multi-functional FW systems.

Knowledge Atlas on the Relationship between Water Management and Constructed Wetlands—A Bibliometric Analysis Based on CiteSpace

Water management is a crucial resource conservation challenge that mankind faces, and encouraging the creation of manmade wetlands with the goal of achieving long-term water management is the key to long-term urban development. To summarise and analyse the status of the research on the relationship between water management and constructed wetlands, this paper makes use of the advantages of the bibliometric visualization of CiteSpace to generate country/region maps and author-collaboration maps, and to analyse research hotspots and research dynamics by using keywords and literature co-citations based on 1248 pieces of related literature in the core collection in the Web of Science (WoS) database. The existing research shows that the research content and methods in the field of constructed-wetland and water-management research are constantly being enriched and deepened, including the research methods frequently used in constructed wetlands in water management and in the research content under concern, the functions and roles of constructed wetlands, the relevant measurement indicators of the purification impact of constructed wetlands on water bodies, and the types of water bodies treated by constructed wetlands in water management. We summarise the impact pathways of constructed wetlands on water management, as well as the impact factors of constructed wetlands under water-management objectives, by analysing the future concerns in the research field to provide references for research.

The Dynamics of NO3- and NH4+ Uptake in Duckweed Are Coordinated with the Expression of Major Nitrogen Assimilation Genes

Duckweed plants play important roles in aquatic ecosystems worldwide. They rapidly accumulate biomass and have potential uses in bioremediation of water polluted by fertilizer runoff or other chemicals. Here we studied the assimilation of two major sources of inorganic nitrogen, nitrate (NO3- ) and ammonium (NH4+), in six duckweed species: Spirodela polyrhiza, Landoltia punctata, Lemna aequinoctialis, Lemna turionifera, Lemna minor, and Wolffia globosa. All six duckweed species preferred NH4+ over NO3- and started using NO3- only when NH4+ was depleted. Using the available genome sequence, we analyzed the molecular structure and expression of eight key nitrogen assimilation genes in S. polyrhiza. The expression of genes encoding nitrate reductase and nitrite reductase increased about 10-fold when NO3- was supplied and decreased when NH4+ was supplied. NO3- and NH4+ induced the glutamine synthetase (GS) genes GS1;2 and the GS2 by 2- to 5-fold, respectively, but repressed GS1;1 and GS1;3. NH4+ and NO3- upregulated the genes encoding ferredoxin- and NADH-dependent glutamate synthases (Fd-GOGAT and NADH-GOGAT). A survey of nitrogen assimilation gene promoters suggested complex regulation, with major roles for NRE-like and GAATC/GATTC cis-elements, TATA-based enhancers, GA/CTn repeats, and G-quadruplex structures. These results will inform efforts to improve bioremediation and nitrogen use efficiency.

Recent developments and applications of floating treatment wetlands for treating different source waters: a review

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.

Application of floating treatment wetlands for stormwater runoff: A critical review of the recent developments with emphasis on heavy metals and nutrient removal

Floating treatment wetlands (FTWs) are increasingly gaining popularity due to a set of valuable features like wastewater remediation under varied conditions, ecosystem quality preservation, landscape conservation, and aesthetic benefits. FTW is a phyto-technology in which macrophytes grow on a floating raft with their roots in permanent contact with water and remove pollutants via several physicochemical-biological processes. FTW is highly capable of overcoming technical and operational challenges that come way in stormwater treatment due to the erratic nature of hydrologic and input pollutant loads because this innovative buoyant hydroponic design can move up and down with fluctuating water levels in the stormwater pond and can treat highly variable flows. Plants and biofilms attached to the roots hanging beneath the floating mat play a pivotal role in FTWs. The present review encompasses the concept of FTWs, their structural designs, relevance in stormwater management, and mechanism of plant uptake for pollutant removal. The role of FTWs to remove heavy metals and nutrients is also critically analyzed. Understanding hydraulics and other parameters of FTW is vital to effective design. Hence, the role of vegetation coverage, vegetation type, sorption media, aeration frequency, and intensity, and plant density to enhance system efficiency is also highlighted. Due to their operational flexibility and environmentally friendly working with no additional burden on existing urban land use, FTWs entice broad international interest and offer a coherent solution for stormwater management. MAIN FINDINGS: The review delivers state-of-the-art analysis of the current understanding of hydraulics and other parameters of FTWs, and associated mechanisms to enhance the treatment efficiency of FTWs for nutrients and heavy metals removal.

Implementation of Floating Treatment Wetlands for Textile Wastewater Management: A Review

The textile industry is one of the most chemically intensive industries, and its wastewater is comprised of harmful dyes, pigments, dissolved/suspended solids, and heavy metals. The treatment of textile wastewater has become a necessary task before discharge into the environment. The textile effluent can be treated by conventional methods, however, the limitations of these techniques are high cost, incomplete removal, and production of concentrated sludge. This review illustrates recent knowledge about the application of floating treatment wetlands (FTWs) for remediation of textile wastewater. The FTWs system is a potential alternative technology for textile wastewater treatment. FTWs efficiently removed the dyes, pigments, organic matter, nutrients, heavy metals, and other pollutants from the textile effluent. Plants and bacteria are essential components of FTWs, which contribute to the pollutant removal process through their physical effects and metabolic process. Plants species with extensive roots structure and large biomass are recommended for vegetation on floating mats. The pollutant removal efficiency can be enhanced by the right selection of plants, managing plant coverage, improving aeration, and inoculation by specific bacterial strains. The proper installation and maintenance practices can further enhance the efficiency, sustainability, and aesthetic value of the FTWs. Further research is suggested to develop guidelines for the selection of right plants and bacterial strains for the efficient remediation of textile effluent by FTWs at large scales.