Inside Cover: The cover image presents a lotus and a piece of duckweed floating on water surface, with the outmost cymbiform petals of the lotus half immersed in water. This indicates a new support ...method in photocuring 3D printing process in which partially cured resin material is used as weak support to fabricate overhang structures or even completely suspended parts, while the weak support is easy to design, fabricate, and remove. Further details can be found in the article 2100613 by Longqiu Li and co‐workers.
Over the past 50 years, different strategies have been developed for the remediation of polluted air, land and water. Driven by public opinion and regulatory bottlenecks, ecological based strategies ...are preferable than conventional methods in the treatments of chemical effluents. Ecological systems with the application of microbes, fungi, earthworms, plants, enzymes, electrode and nanoparticles have been applied to varying degrees in different media for the remediation of various categories of pollutants. Aquatic macrophytes have been used extensively for the remediation of pollutants in wastewater effluents and aquatic environment over the past 30 years with the common duckweed (L. minor) as one of the most effective macrophytes that have been applied for remediation studies. Duckweed has shown strong potentials for the phytoremediation of organic pollutants, heavy metals, agrochemicals, pharmaceuticals and personal care products, radioactive waste, nanomaterials, petroleum hydrocarbons, dyes, toxins, and related pollutants. This review covers the state of duckweed application for the remediation of diverse aquatic pollutants and identifies gaps that are necessary for further studies as we find pragmatic and sound ecological solutions for the remediation of polluted environment for sustainable development.
•Several tonnes of chemicals are produced annually from the global chemical industry.•Many of these chemicals are released into the environment after their domestic or industrial application.•These chemicals are difficult to remediate using conventional wastewater treatment methods.•Lemna minor is an effective macrophyte for the treatment of chemicals in the environment using constructed wetlands.
The phyto-Fenton process, which generates hydroxyl radicals through Fenton and Fenton-like reactions using plant-derived hydrogen peroxide (H2O2) and ferrous iron (Fe (II)) can degrade organic ...pollutants. Duckweed, an aquatic plant, is promising for a co-beneficial phytoremediation process that combines wastewater treatment and biomass production for biofuel feedstock. However, the phyto-Fenton process using duckweed has not been extensively studied. Because sulfamethoxazole (SMX), a major antibiotic, is distributed widely and is an emerging contaminant, its effective removal from contaminated water is necessary. The present study investigated the possibility of the simultaneous efficient removal of SMX from polluted water and biomass production for fuel feedstock by the phyto-Fenton process using duckweed. This is the first attempt to demonstrate the co-benefits of SMX removal and biomass production using duckweed. Intracellular H2O2 was produced using four duckweeds, Lemna aequinoctialis, L. minor, Landolina punctata, and Spirodela polyrhiza, in the range of 16.7–24.6 μ mol g−1 fresh weight, and extracellular H2O2 was released into the water phase. Consequently, duckweed could be used as an H2O2 supply source for the phyto-Fenton process. Specifically, 0.5 g fresh duckweed almost completely eliminated 1 mg L−1 SMX after 5 d in 50 mL sterile modified Hoagland solution containing 10 mM Fe (II). Fe (II)-dependent elimination of SMX indicated the occurrence of phyto-Fenton reaction. The phyto-Fenton process using duckweed effectively removed SMX. S. polyrhiza duckweed similarly removed 1 mg L−1 SMX even in sewage effluent containing other organic contaminants. During this treatment, duckweed biomass was generated at 7.95 g dry weight m−2 d−1, which was converted into methane at 353 normal liters CH4 kg−1 volatile solids by anaerobic digestion. For the first time, this study clearly demonstrates the potential for simultaneous SMX removal and biomass production from SMX-contaminated wastewater using duckweed.
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•Duckweed produced H2O2 and released it to water phase.•Duckweed supplied enough H2O2 for the phyto-Fenton process.•Sulfamethoxazole (SMX) was efficiently removed by the phyto-Fenton process.•Duckweed biomass (7.95 g-dry weight) m−2 d−1 was produced during SMX removal.•Duckweed biomass was converted to 353 NL methane kg−1 volatile solids.
•The CM particle electrode with rich in N, P was prepared using duckweed.•Ru catalyst was dispersed uniformly on CM-650 with amorphous.•The Ru/CM-650 exhibited high activity for electrocatalytic ...dechlorination of DCF.
In order to improve degradation efficiency and reduce electrode cost, carbon microspheres (CM) particle electrode was prepared from readily available duckweed as a raw material for electrocatalytic hydrodechlorination. The surface structures and chemical characteristics of the CM were regulated by adjusting the pyrolysis temperature. When pyrolysis was performed at 650 °C, carbon microspheres (CM-650) with large surface areas that are rich in heteroatoms (N, P) and show high electrical conductivity are obtained. After the Ru catalyst was supported, the Ru/CM-650 as particle electrode forming a three-dimensional (3D) electrochemical reaction system exhibits high electrocatalytic performance for diclofenac (DCF) hydrodechlorination with dechlorination efficiency of more than 90% in 150 min. Furthermore, the Ru/CM-650 has good stability for repeated use, which is attributed to the synergistic interaction between N and P elements improving the stability of the catalyst.
Microplastics in the environment occur in different sizes and shapes and are made of various polymers. Therefore, they also considerably differ in their properties and ecotoxicity. However, the ...majority of microplastics research uses pre-made spherical microplastics, which practically do not exist in the environment. Our work focused on a comprehensive study of six different types of microplastic that were prepared to simulate common microplastics found in the environment. All types of microplastics where chemically and physically characterized using Fourier-transform infrared spectroscopy, thermal analysis, field-emission scanning electron microscopy, optical microscopy and laser diffraction analysis. The specific surface area was determined using the BET method. Furthermore, effects of microplastics and microplastic leachates on a common duckweed (Lemna minor) were evaluated. All tested microplastics did not affect specific growth rate and chlorophyll a content in duckweed, while microplastics with a rough surface and sharp edges caused a significant reduction of duckweed root length. Microplastics made of Bakelite also showed an intensive leaching, which increased their ecotoxicity potential. Natural particles used as a control did not have any negative effect on duckweed. Overall, microplastic particles have significantly different ecotoxicity profiles depending on their physico-chemical properties. Therefore, the testing of environmentally relevant particles and their proper characterization, as well as the testing of microplastic leaching properties, is crucial for understanding of microplastics ecotoxicological potential.
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•MPs with rough surface and sharp edges had negative impact on duckweed's root length.•MPs made of Bakelite had negative impact on root length due to leaching of chemicals.•Natural particles, used as control, showed no negative impact on duckweed.
Nature-based solutions have been proven in recent decades as a reliable and cost-effective technology for the treatment of wastewaters. Different plant species have been studied for this purpose, but ...particular attention has been given to duckweeds, the smallest flowering plant in the world. Duckweed-based systems for simultaneous wastewater treatment and nutrient recovery have the potential to provide sustainable and cost-effective solutions to reduce water pollution and increase nutrient efficiency at catchment level. However, despite being considered a seemingly simple technology, the performance of wastewater treatment systems using duckweed depends on environmental and operational conditions not very well understood. For that reason, careful consideration must be given to such environmental factors controlling duckweed biomass growth but the evidence in published literature is scare and dispersed. This study employs a systematic review approach to conduct a meta-analysis of the effect of environmental conditions on duckweed growth by means of standardised IQ-scores. The results suggest that duckweed biomass growth rates reach a maximum within specific ranges for temperature (11.4–32.3 °C), daily light integral (DLI) (5–20 mol m−2), and nitrogen (>5 mg N L−1) and phosphorus (>1 mg P L−1) concentrations; DLI was found to be a better parameter to assess the overall effect of light (photoperiod and intensity) on duckweed growth and that the effect of nitrogen and phosphorus supply should consider the nitrogen species available for plant growth and its ratio to phosphorus concentrations (recommended N:P ratio = 15:1). By establishing the optimal range of culture conditions for duckweed, this study provides important insights for optimizing engineered wastewater treatment systems that rely on duckweed for nutrient control and recovery, which is primarily mediated by duckweed growth.
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•A meta-analysis with standardised scores can help to compare duckweed growth studies.•Different duckweed genera have different temperature optima.•The daily light integral is a useful parameter for assessing the impact of light on duckweed growth.•There is no clearly defined preference for N source.•The ratio of N:P has important effects on growth rates.
High concentration of Cu2+ in swine wastewater raises concerns about its potential adverse effects on nutrient removal by aquatic plants like duckweed. In this work, the effects of copper ions on ...nutrient removal and release of dissolved organic matter (DOM) were investigated in duckweed systems. Results showed that the removal performance of ammonia nitrogen (NH3N) and total phosphorus (TP) increased at 0.1–1.0 mg/L of Cu2+, while dropped at 2.0–5.0 mg/L of Cu2+. A novel kinetic model in which Cu2+ was taken into account was then developed which was used to optimize Cu2+ concentration at 0.96 mg/L for nutrient removal in duckweed systems. NADH, detected in DOM by the parallel factor (PARAFAC) analysis, exhibited high capacities of binding copper ions, so it played an important role on the decrease of Cu2+ concentrations in duckweed systems. The principle component analysis (PCA) showed that the dominant DOM were lower molecular weight compounds at 1.0 mg/L of Cu2+ and higher molecular weight compounds at 2.0–5.0 mg/L of Cu2+. The bonds of CH (humic-like), NO (NO3−) and ArH (tyrosine) in DOM were responsible for not only the fastest binding with Cu2+ from the result of the two-dimensional Fourier transform infrared correlation spectroscopy (2D-FTIR-CoS) but also the variations of DOM conformations at a critical concentration of 0.5 mg/L Cu2+ from the perturbation correlation moving window two-dimensional (PCMW2D) analysis. These findings lead to a better understanding on the environmental behaviors and mechanisms of Cu2+ in duckweed systems.
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•The optimal Cu2+ concentration was 0.96 mg/L for the removal of NH3N and TP.•NADH in DOMs was detected with high metal binding abilities with Cu ions.•The molecular weight of released DOMs was different at various Cu2+ concentrations.•The bonds of CH, NO and ArH were responsible for the fastest binding with Cu2+.•The conformational variation of DOMs was at a critical concentration 0.5 mg/L Cu2+.
In this study, two native duckweeds (Lemna minor and Azolla pinnata) were cultivated in Palm Oil Mill Effluent (POME) to extract nutrients from the effluent. Five grams of A. pinnata and 2 g of ...L. minor were transferred to 2 L POME (Initial concentrations: 198 mg/L COD, 4.3 mg/L nitrates, pH 9.53, 4 mg/L phosphate, 2.98 mg/L ammonia) with four different dilutions (2.5%, 5%, 10%, 15%) under greenhouse conditions. Samples of POME were taken every two days up to 10 days. Growth parameter, phosphate, ammonia, nitrates, pH, and COD were monitored within 10 days to select the most suitable growth medium for both plants. Results showed that 2.5% POME dilution had positive effect on L. minor growth and A. pinnata (wet weight increased by 8.7 g and 9.8 g, respectively), with all plants able to survive until the final day of exposure. The highest removal of ammonia was accomplished in 5% POME dilution by A. pinnata (98%) and L. minor (95.5%). The maximum phosphate removal was obtained in 10% POME dilution with 93.3% removal by A. pinnata and 86.7% by L. minor. Significant COD removal in 15% POME was obtained by L. minor (78%) and A. pinnata (66%). Both plants responded positively to the phytoremediation process, especially for A. pinnata which showed significant decreases in all parameters. The nutrient extraction by both plants from POME showed a positive effect on growth parameter, which has further promising potential to be used as animal feedstock.
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•This is the first report on POME - Azolla pinata - Lemna minor - livestock interaction.•Palm oil mill effluent (POME) gave positive effect on A. pinata and L. minor growth.•POME enhanced the carbohydrate and protein content in A. pinata and L. minor.•Potential of A. pinata and L. minor as a livestock after treating POME were reported.
Catfish is one of the fish that is in demand for cultivation activities because it has high market absorption, adequate nutrition, and is relatively easy to maintain. The research aims to analyze the ...hematological response of Sangkuriang catfish (Clarias sp.) after being given a feed substitute made from Duckweed flour (Lemna minor). The research was conducted in Palangka Raya City, Central Kalimantan Province. Feed from each treatment A (Commercial feed, feed without the addition of duckweed meal), B (Feed with 0% duckweed meal: 100% soybeans), C (Feed with 50% duckweed meal: 50% soybeans), D (Feed with 75% duckweed meal: 25% soybeans), and treatment E (Feed with 25% duckweed meal: 75% soybeans) was weighed at 5% of each fish's weight in the treatment container. The hematological response of Sangkuriang catfish given feed substitution made from Duckweed flour (Lemna minor) with parameters of hematocrit, leukocrit, hemoglobin, and blood plasma of Sangkuriang catfish for 45 days of research had a positive impact on fish health in this condition due to the content of Duckweed flour (Lemna minor). can help control the health of sangkuriang catfish.
Duckweed-based ponds (DP), as a modified type of waste stabilization ponds (WSP) are receiving growing attention due to the sustainable production of high-quality duckweed biomass. However, the ...comprehensive effects of duckweed cover on nutrient removal, greenhouse gas emission and microbial community of the WSP have rarely been studied. In this study, two pilot-scale WSP (12 m2) with (DP) and without (OP) a duckweed mat on the surface were compared over 1 year to determine the effects. The results showed that, compared to OP, DP had higher TP, but lower TN and NH4+-N removal efficiencies, and lower pH, dissolved oxygen (DO) and sedimentation rate of settling detritus. For both nitrogen and phosphorus removal, the dominant pathway was duckweed uptake (66.95% and 93.18%, respectively) in DP; however, it became other pathways (mainly nitrification/denitrification, 82.27%) and sedimentation (87.65%), respectively, in OP. Meanwhile, DP had lower N2O, but higher CH4 emission fluxes than OP, resulting in comparable global warming potential between OP and DP (approximately 2800 g CO2/m2/yr). Microbial community analysis indicated that the greater nitrogen removal and N2O emission in OP could be attributed to higher abundance of ammonia-oxidizing bacteria in the water and denitrifiers in the sediment, supported by higher DO and settling organic carbon, respectively. Meanwhile, the greater CH4 emission in DP could be attributed to higher abundance of methanogens and syntrophic methanogenic bacteria in the sediment. Thus, despite favourable effects on nutrient recovery and phosphorus removal mainly attributed to duckweed uptake, duckweed cover had unfavourable effects on nitrogen removal and CH4 emission reduction of the WSP mainly attributed to microbial taxa which were influenced by environmental conditions (such as DO and settling detritus) in the WSP. These findings help to clarify the influencing mechanism of duckweed cover, providing overall insight into the function and application of the DP.
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•Two pilot-scale ponds with (DP) and without (OP) duckweed were compared over 1 year.•Duckweed had favourable effects on N, P recovery and P removal due to plant uptake.•Duckweed had unfavourable effects on N removal and CH4 emission reduction.•More AOB and denitrifiers supported greater N removal and N2O emission of OP.•More methanogens and syntrophic bacteria supported greater CH4 emission of DP.
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