Uptake of perfluoroalkyl substances PFOS and PFOA by free-floating hydrophytes Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms

The phytoremediation potential of floating aquatic plants to accumulate and remove two common PFAS from contaminated water was investigated. Free-floating hydrophytes Eichhornia crassipes and Pistia stratiotes were grown in water spiked with 0.5, 1, or 2 ppm perfluorooctanoic acid (PFOA) or perfluorooctanesulfonic acid (PFOS) for seven days. Both species were able to accumulate PFOA and PFOS in this time frame, with translocation factors (TF) ranging from 0.13 to 0.57 for P. stratiotes and 0.18 to 0.45 for E. stratiotes, respectively. E. crassipes accumulated a greater amount of PFOA and PFOS than P. stratiotes, with 178.9 ug PFOA and 308.5 ug PFOS removed by E. crassipes and 98.9 ug PFOA and 137.8 ug PFOS removed by P. stratiotes at the highest concentrations. Root tissue contained a higher concentration of PFOA and PFOS than shoot tissue in both species, and the concentration of PFOS was generally significantly higher than PFOA in both E. crassipes and P. stratiotes, with concentrations of 15.39 and 27.32 ppb PFOA and 17.41 and 80.62 ppb PFOS in shoots and roots of P. stratiotes and 12.59 and 37.37 ppb PFOA and 39.92 and 83.40 ppb PFOS in shoots and roots of E. crassipes, respectively. Both species may be candidates for further phytoremediation studies in aquatic ecosystems.

Are cysteine, glutathione and phytochelatins responses of Myriophyllum alterniflorum to copper and arsenic stress affected by trophic conditions?

The aim of this article is to study the impact of both copper (Cu²⁺) and arsenic (As (V)) at 100 µg/L, with each element being combined with trophic conditions at the level of glutathione, cysteine and phytochelatins in the aquatic macrophyte Myriophyllum alterniflorum, whose potential for bioindication and phytoremediation of metal/metalloid pollution has already been demonstrated. To achieve this goal, a synthetic medium, of a composition similar to the water found in the Vienne River in France's Limousin Region and modified for eutrophic or oligotrophic conditions, is prepared. The analysis of cysteine, glutathione and phytochelatins is performed at 0, 3, 7, 14 and 21 days. Our results indicate that the eutrophic medium without contaminant only induces a significant increase in the glutathione level when compared to the oligotrophic medium. However, the joint presence of As (V) and Cu is able to increase the synthesis of cysteine, glutathione and phytochelatins (PC2 and PC3) under both eutrophic and oligotrophic conditions, with a significant increase in the eutrophic medium compared to the oligotrophic one. Phytochelatins (PC2 and PC3) are induced after as little as 3 days of exposure to copper and arsenic under both trophic conditions. Copper induces the synthesis of more PC3 than PC2, unlike arsenic. Our results confirm the potential use of phytochelatins as a specific biochemical biomarker for metal/metalloid stress. In conclusion, the eutrophic condition combined with copper or arsenic does change the response of Myriophyllum alterniflorum by enhancing its antioxidative defense. Thus, M. alterniflorum phytochelatins represent a potential dedicated biomarker to monitor water quality in terms of metal/metalloid stress regardless of the trophic level.

The physiological mechanism of the tolerance of Eichhornia crassipes (Mart.) Solms to cadmium

The tolerance of plants to Cd is a scientific and interesting issue for phytoremediation. In the current study, we attempt to reveal the physiological mechanism of the tolerance of Eichhornia crassipes to cadmium (Cd) by using hydroponic experiments. The results showed that the Cd absorption of E. crassipes was dose-dependent and the absorbed Cd was mainly maintained in the root. The fresh weight was greatly affected by Cd in the early stage of aquatic cultivation. The negative effect of Cd on E. crassipes is dose-dependent, but E. crassipes might adapt to moderate Cd pollution over time. The Cd stimulated the opening of the stomata, and the cell tightness ratio of E. crassipes increased with rising Cd concentrations. The administration of moderate levels of Cd stimulated the release of soluble protein, free proline, malondialdehyde, and soluble polysaccharide. Cd administration also stimulated the activity of superoxide dismutase, peroxidase (POD), catalase, and ascorbic acid peroxidase of E. crassipes, except for POD activity at the highest Cd concentration. This indicates that the physiological mechanism of the tolerance of E. crassipes to Cd depends on osmotic regulation, reduction of lipid peroxidation, improvement of antioxidant properties, increasing palisade tissue while decreasing sponge tissue, and increasing stomatal conductance.

Efficiency of Pb, Zn, Cd, and Mn Removal from Karst Water by Eichhornia crassipes

This study experimentally investigated heavy metal removal and accumulation in the aquatic plant Eichhornia crassipes. Pb, Zn, Cd, and Mn concentrations, plant morphology, and plant functional groups were analyzed. Eichhornia crassipes achieved high removal efficiency of Pb and Mn from karst water (over 79.5%), with high proportion of Pb, Zn, and Cd absorption occurring in the first eight days. The highest removal efficiencies were obtained at initial Pb, Zn, Cd, and Mn concentrations of 1 mg/L, 2 mg/L, 0.02 mg/L, and 0.2 mg/L, respectively. Eichhornia crassipes exhibited a high bioconcentration factor (Mn = 199,567 > Pb = 19,605 > Cd = 3403 > Zn = 1913) and a low translocation factor (<1). The roots accumulated more Pb, Zn, Cd, and Mn than the stolons and leaves due to the stronger tolerance of roots. The voids, stomas, air chambers, and airways promoted this accumulation. Pb, Cd, Zn, and Mn likely exchanged with Mg, Na, and K through the cation exchange. C≡C, C=O, SO₄²⁻, O-H, C-H, and C-O played different roles during uptake, which led to different removal and accumulation effects.

Estimation of equilibrium times and maximum capacity of adsorption of heavy metals by E. crassipes (review)

Cellulose emerges as an alternative for the treatment of water contaminated with heavy metals due to its abundant biomass and its proven potential in the adsorption of pollutants. The aquatic plant Eichhornia crassipes is an option as raw material in the contribution of cellulose due to its enormous presence in contaminated wetlands, rivers, and lakes. The efficiency in the removal of heavy metals is due to the cation exchange between the hydroxyl groups and carboxyl groups present in the biomass of E. crassipes with heavy metals. Through different chemical and physical transformations of the biomass of E. crassipesThe objective of this review article is to provide a discussion on the different mechanisms of adsorption of the biomass of E. crassipes to retain heavy metals and dyes. In addition to estimating equilibrium, times through kinetic models of adsorption and maximum capacities of this biomass through equilibrium models with isotherms, in order to design one biofilter for treatment systems on a larger scale represented the effluents of a real industry.

Estimation of equilibrium times and maximum capacity of adsorption of heavy metals by E. crassipes (review)

Cellulose emerges as an alternative for the treatment of water contaminated with heavy metals due to its abundant biomass and its proven potential in the adsorption of pollutants. The aquatic plant Eichhornia crassipes is an option as raw material in the contribution of cellulose due to its enormous presence in contaminated wetlands, rivers, and lakes. The efficiency in the removal of heavy metals is due to the cation exchange between the hydroxyl groups and carboxyl groups present in the biomass of E. crassipes with heavy metals. Through different chemical and physical transformations of the biomass of E. crassipesThe objective of this review article is to provide a discussion on the different mechanisms of adsorption of the biomass of E. crassipes to retain heavy metals and dyes. In addition to estimating equilibrium, times through kinetic models of adsorption and maximum capacities of this biomass through equilibrium models with isotherms, in order to design one biofilter for treatment systems on a larger scale represented the effluents of a real industry.

Phytoremediation of landfill leachate waste contaminants through floating bed technique using water hyacinth and water lettuce

In the present study, the effectiveness of water hyacinth and water lettuce was tested for the phytoremediation of landfill leachate for the period of 15 days. Fifteen plastic containers were used in experimental setup where aquatic plants were fitted as a floating bed with the help of thermo-pole sheet. It was observed that both plants significantly (p < 0.05/p < 0.01/p < 0.001) reduce the physicochemical parameters pH, TDS, BOD, COD and heavy metals like Zn, Pb, Fe, Cu and Ni from landfill leachate. Maximum reduction in these parameters was obtained at 50% and 75% landfill leachate treatment and their removal rate gradually increased from day 3 to day 15 of the experiment. The maximum removal rate for heavy metals such as for Zn (80-90%), Fe (83-87%) and Pb (76-84%) was attained by Eichhornia crassipes and Pistia stratiotes. Value of bioconcentration and translocation factor was less than 1 which indicates the low transport of heavy metals from roots to the above-ground parts of the plants. Both these plants accumulate heavy metals inside their body without showing much reduction in growth and showing tolerance to all the present metals. Therefore, results obtained from the study suggest that these aquatic plants are suitable candidate for the removal of pollution load from landfill leachate.

Optimization process of organic matter removal from wastewater by using Eichhornia crassipes

This study aimed to determine the optimal conditions for organic matter removal from wastewater by Eichhornia crassipes (E.C). As a matter of fact, a complete factorial design was used to determine the effect of residence time (X₁), plant density (X₂) and initial chemical oxygen demand (COD) concentration (X₃) on the phytoremediation process. The process's performance was measured on COD (Y₁), NH₄⁺ (Y₂) and PO₄^3- (Y₃), with the results indicating a reduction of 8.59-81.71% of COD (Y₁); 22.53-95.81% of NH₄⁺ (Y₂) and 0.54-99.35% of PO₄^3- (Y₃). Then, the first-order models obtained for COD, NH₄⁺ and PO₄^3- removal were validated using different statistical approaches such as statistical and experimental validation. Moreover, multi-response optimization was carried out through different scenarios. On the whole, the results obtained indicated that two serial ponds are required for an optimum organic matter removal by Eichhornia crassipes. Indeed, for the first pond, a residence time of 15 days is needed with a plant density of 60 ft/m² and an initial concentration of about 944 mg/L. The second was the same residence time as the first with similar plant density of 60 ft/m² and an initial load 192 mg/L (> 200 mg/L). Optimal organic matter removal from wastewater using Eichhornia crassipes requires two ponds arranged in chain.

The efficiency of Eichhornia crassipes in the removal of organic and inorganic pollutants from wastewater: a review

Water is a basic necessity of life, but due to overextraction and heavy input of nutrients from domestic and industrial sources, the contamination level of water bodies increase. In the last few decades, a potential interest has been aroused to treat wastewater by biological methodologies before discharge into the natural water bodies. Phytoremediation using water hyacinth is found to be an effective biological wastewater treatment method. Water hyacinth (Eichhornia crassipes), a notorious weed, being the most promising plant for removal of contaminants from wastewater is studied extensively in this regard. It has been successfully used to accumulate heavy metals, dyes, radionuclides, and other organic and inorganic contaminants from water at laboratory, pilot, and large scale. The plant materials are also being used as sorbent to separate the contaminant from water. Other than phytoremediation, the plant has been explored for various other purposes like ethanol production and generation of biogases and green manures. Such applications of this have been good support for the technocrats in controlling the growth of the plant. The present paper reviews the phytoremedial application of water hyacinth and its capability to remove contaminants in produced water and wastewater from domestic and isndustrial sources either used as a whole live plant grown in water or use of plant body parts as sorbent has been discussed.

Absorption and translocation of copper and arsenic in an aquatic macrophyte Myriophyllum alterniflorum DC. in oligotrophic and eutrophic conditions

The aim of this study is to evaluate copper and arsenic accumulation and translocation at a concentration of 100 μg/L of a submersed macrophyte Myriophyllum alterniflorum. The trophic level (eutrophic and oligotrophic conditions) of the medium was also considered. To achieve this goal, plants were incubated for 21 days in the presence of 100 μg/L of Cu or AsV. The heavy metal transfers from the contaminated medium to plants and into plant tissues was discussed in terms of the bioconcentration factor (BCF) and the translocation factor (TF). Malondialdehyde (MDA) content in tissues was analyzed in order to study the toxicity of these two contaminants. Our results show that copper was more accumulated in shoots, than roots, whereas the opposite trend was observed for arsenic. In addition, the two contaminants were more accumulated in oligotrophic than eutrophic medium. The BCF of copper in shoots was 1356 in oligotrophic condition, while that of arsenic was higher in roots about 620 in the same condition. The TF was less than 1 for arsenic, and higher than 1 for copper, indicating that watermilfoil restrains the translocation of arsenic to shoots, while it has a low capacity to control the translocation of an essential micronutrient like copper. An increase in MDA content was observed under Cu and As stress. On the basis of this experiment, M. alterniflorum has a higher accumulation potential of copper and arsenic, and therefore, it can be a good candidate for the phytofiltration of these two contaminants from water.