International Journal of Phytoremediation最新文献

Herein, a walnut shell as a biosorbent was applied to remove petroleum compounds from the water medium. The characterization analyses of the walnut shells showed the macro-mesopore structure of the walnut shells, a specific surface area of 26 m²/g, and the presence of various functional groups (-OH, -COOH, -C = O). The CCD design showed that the walnut shell can remove 84.43% of petroleum compounds at pH = 3 (the optimum pH), adsorbent dosage: 2 g/L, and initial concentration of petroleum compounds: 550 mg/L. The study of kinetics and adsorption equilibrium indicated matching the experimental data with the pseudo-second-order kinetic model and Freundlich equilibrium isotherm, respectively. The maximum adsorption ability of walnut shell was 3038.29 mg/g at 45 °C. The ability to regenerate and reuse the walnut shell was investigated in 6 cycles, and the results showed a 21% decrease in adsorption ability after 6 cycles. The obtained data showed that the walnut shells could be a promising adsorbent with high adsorption ability toward petroleum components. Also, the walnut shell is a regenerable adsorbent, low-cost, and environmentally friendly, and can be effective in successive cycles. Therefore, this biosorbent can have a superb influence on wastewater treatment technology and possible applications at an industrial scale.

In this study, rice plants were co-exposed to selenium (Se) and silica (Si) under arsenic (As) stress to evaluate As accumulation in rice grains, associated cancer risk, and its impact on the types and numbers of grain metabolites. A total of 58 metabolites were identified, of which, 19 belong to sugars, and drastically altered during different treatments. Arsenic exposure significantly reduced monosaccharides, i.e., D-glucose (83%) >D-galactose (60%) >D-fructose (57%) >D-ribose (29%) but increased that monosaccharide units which have antioxidant properties (i.e. α-D-glucopyranoside and melibiose). However, the levels of D-galactose, fructose, and ribose were significantly increased during co-supplementation of selenite (Se^IV) and Si under As stress. Other groups of rice grain metabolites, like sugar alcohols, organic acids, polyphenols, carboxylic acids, fatty acids, and phytosterols, were also significantly altered by As exposure and increased in grains of Se^IV and Si supplemented rice compared to alone As exposure. In brief, rice growing in As-affected areas may have a low level of different metabolites. However, supplementation by selenite (Se^IV) with Si not only increased metabolites and amylose/amylopectin ratio but also reduced ∼90% of As accumulation in grains. Thus, the use of Se^IV with Si might be advantageous for the locals to provide a healthy diet of rice and limit As-induced cancer risk up to 10-fold.

Green manure returning can improve soil fertility and crop production, and immobilize heavy metals in the soil. However, limited information is available on the effects of green manure replacing chemical fertilizers on soil properties and crop growth. In this study, we investigated the effects of Chinese milk vetch incorporation with reduced chemical fertilizers on soil properties, rice agronomic traits and cadmium (Cd) accumulation by field experiments, and four treatments were conducted: chemical fertilizer alone (CF), milk vetch alone (MV), milk vetch plus 80% chemical fertilizers (MVCF80), and milk vetch plus 50% chemical fertilizers (MVCF50). The results showed that all milk vetch treatments decreased soil pH and Eh, and increased the SOM, DOC contents and the activities of catalase and urease. The soil DTPA-Cd contents decreased by 20.41%, 18.20%, and 21.22%, and the Cd accumulation in rice root, stem, leaf, and grain decreased by 21.13%-37.62%, 20.74%-39.61%, and 21.91%-43.56% under MV, MVCF80, and MVCF50 treatments, respectively. Additionally, the MVCF80 treatment showed a better rice agronomic traits and grain yield than others. These data revealed the great potential of milk vetch incorporation with chemical fertilizer reduction in decreasing Cd accumulation in rice plants and improving rice quality and yield of Cd-contaminated paddy fields.

The use of organic and inorganic amendments like stilbite-zeolite (SZ) and nano-biochar (NBC) in phytoremediation holds immense promise, long-term stability, and its effectiveness necessitate comprehensive research. This study aimed to evaluate their potential in mitigating heavy metal contamination in soil and plants. Our results shows that SZ and NBC treatments significantly impacted heavy metal levels, notably reducing arsenic (As), nickel (Ni), lead (Pb), cadmium (Cd), and mercury (Hg) accumulation in plant tissues. The treatments exhibited varying degrees of effectiveness in reducing heavy metal levels. Notably, SZ₂ treatment decreased As and Pb levels by 33.33% and 20%, respectively, while NBC₃ achieved even greater reductions, lowering As by 53.33% and Pb by 30%. Moreover, SZ₂, SZ₅, and NBC₃ treatments halved Cd levels, showcasing their potential in mitigating heavy metal contamination in rice. However Hg levels remained largely unaffected, except for NBC₁, which unexpectedly doubled its concentration. In soil, SZ₂ treatment significantly reduced metal concentrations, particularly Cd (66.8% reduction) and Hg (70.7% reduction). Conversely, SZ₃ and SZ₇ treatments increased metal concentrations, suggesting that certain zeolite applications might enhance metal bioavailability. NBC treatments showed varying effectiveness, with NBC₃ being the most effective, substantially reducing As, Pb, and Cd levels.

Cadmium (Cd) has shown toxicity to reduce growth and productivity in different plants. The Present study investigated the efficacy of menadiol diacetate (MD) to reduce Cd stress on growth and yield of summer squash plants. The experiment was performed under saturated Hoagland's nutrient solution (control) while the other group was supplemented with 0.1 mM CdCl₂ (Cd stress). Surface sterilized seeds of summer squash were primed in different concentrations (10, 20 µM) of MD as well as in distilled water for 24 h and sown in the pots. Different morphological and physio-biochemical attributes were determined after 35 d of growth whereas the data for yield attributes was collected after 70 d. Cd concentration was determined in various subcellular compartments i.e., cell walls and cell wall debris, chloroplast, cell membrane and other organelles including vacuoles. The Cd stress decreased photosynthetic pigments, osmoprotectants and ultimately caused reduction in the yield attributes. Further, it increased the secondary metabolites and oxidants (MDA and H₂O₂) in the summer squash tissues. Cd exposure also altered ions accumulation in the summer squash tissues by increasing the root and shoot Ca²⁺ (24-93%) and Fe (4-18%) ions while decreasing the Mg²⁺ (31-39%) ions. The MD-priming, particularly at 10 µM concentration mediated increase in the total phenolics, ascorbic acid, and anthocyanins concentration, and thus enhanced growth and yield attributes of summer squash exposed to Cd toxicity. Further, 10 µM MD-priming facilitated Cd compartmentalization in the subcellular compartments mainly in the cell wall (58%) rather than in the chloroplast (18%), cell membrane (7%) and soluble fractions (18%). In this context, cell wall and vacuole were the key compartments for Cd sequestration. This study highlights MD-priming as a potential strategy to counter Cd toxicity in summer squash plants.

Adsorption is one of the most efficient ways to eliminate hazardous metals. The study evaluated the effectiveness of banana peel biochar as a cheap adsorbent to remove hazardous metals from landfill leachate. The landfill leachate of 100 mg/L was mixed with banana peel biochar (0.50, 1.50, and 3.00 g each) and placed in a water bath for 15, 30, and 45 min at a constant temperature of 30 °C and 35 °C. The adsorption efficiency of banana peel biochar for nickel in the leachate ranged from 98.76% to 98.96% and chromium ranged from 99.71% to 99.77% at a temperature of 30 °C for 15 mins and 99.07% to 99.27% for Ni and 99.71% to 99.73% for Cr at a temperature of 35 °C for 45 min. Banana peel biochar maximum adsorption capacity of nickel ranged from 1.15 × 10^-5 mg/g to 5.27 × 10^-6 mg/g, and 1.05 × 10^-5 mg/g to 6.76 × 10^-6 mg/g for chromium. Adsorbent made from less expensive banana peel can affordably remove nickel and chromium from landfill leachate. To acquire a broad understanding of the adsorbent's application, more adsorptive research utilizing banana peels as an adsorbent to treat various wastes ought to be conducted.

Electrolytic manganese slag (EMR) is a solid waste generated in the manganese hydrometallurgy process. It not only takes up significant land space but also contains Mn²⁺, which can lead to environmental contamination. There is a need for research on the treatment and utilization of EMR. Improved EMR substrate for Pennisetum sinese Roxb growth was determined in pot planting experiments. The study tested the effects of leaching solution, microorganisms, leaf cell structures, and growth data. Results indicated a substrate of 45% EMR, 40% phosphogypsum, 5% Hericium erinaceus fungi residue, 5% quicklime, and 5% dolomite sand significantly increased the available phosphorus content (135.54 ± 2.88 μg·g^-1) by 17.95 times, compared to pure soil, and enhanced the relative abundance of dominant bacteria. After 240 days, the plant height (147.00 ± 0.52 cm), number of tillers (6), and aerial dry weight (144.00 ± 15.99g) of Pennisetum sinese Roxb increased by 5.81%, 200%, and 32.58%, respectively. Analyses of leaves and leaching solution revealed that the highest leaf Mn content (46.84 ± 2.91 μg·g^-1) being 3.38 times higher than in pure soil, and the leaching solution Mn content (0.66 ± 0.13 μg·g^-1) was lowest. Our study suggested P. sinese Roxb grown in an improved EMR substrate could be a feasible option for solidification treatment and resource utilization of EMR.

While phytoremediation has been widely employed for greywater treatment, this system suffers from the transfer of considerable amounts of surfactants to the aquatic environment through partially treated effluent and/or exhausted plant disposal. Hence, this study focuses on greywater phytoremediation followed by recycling the spent plant for preparing an adsorbent material used as post-treatment. P. crassipes was used to operate a phytoremediation unit under 23 °C, 60% relative humidity, plant density (5-30 g/L), dilution (0-50%), pH (4-10), and retention time (3-15 days). The optimum condition was 12.7 g/L density, 34.0% dilution, pH 8.4, and 13 days, giving chemical oxygen demand (COD), surfactant, and NH₄-N removal efficiencies of 94.62%, 90.45%, and 88.09%, respectively. The exhausted plant was then thermally treated at 550 °C and 40 min to obtain biochar used as adsorbent to treat the phytoremediation effluent. The optimum adsorption process was biochar dosage of 1.51 g/L, pH of 2.1, and 137 min, providing a surfactant removal efficiency of 92.56%. The final discharge of this phytoremediation/adsorption combined process contained 8.30 mg/L COD, 0.23 mg/L surfactant, and 0.94 mg/L NH₄⁺-N. Interestingly, this approach could be economically feasible with a payback period of 6.5 years, 14 USD net present value, and 8.6% internal rate of return.

Partially Saturated Vertical Constructed Wetlands (PSV-CWs) are novel wastewater treatment systems that work through aerobic and anaerobic conditions that favor the removal of pollutants found in high concentrations, such as rivers contaminated with domestic wastewater and landfill leachate. The objective of the study was to evaluate the efficiency of PSV-CWs using monocultures and polycultures of Typha latifolia and Heliconia psittacorum to treat river waters contaminated with leachates from open dumps and domestic wastewater. Six experimental units of PSV-CWs were used; two were planted with Typha latifolia monoculture, two with Heliconia psittacorum monoculture and two with polycultures of both plants. The results indicated better organic matter and nitrogen removal efficiencies (p < 0.05) in systems with polycultures (TSS:95%, BOD₅:83%, COD:89%, TN:82% and NH₄₊:99%). In general, the whole system showed high average removal efficiencies (TSS:93%, BOD₅:79%, COD:85%, TN:79%, NH₄₊:98% and TP:85%). Regarding vegetation, both species developed better in units with monocultures, being Typha latifolia the one that reached a more remarkable development. However, both species showed high resistance to the contaminated environment. These results showed higher removals than those reported in the literature with conventional Free Flow Vertical Constructed Wetlands (FFV-CWs), so PSV-CWs could be a suitable option to treat this type of effluent.

This study aimed to examine the potential of soil amendment-assisted phytoremediation using ryegrass in reclaiming abandoned gold mine soil in southwestern Ghana, with a specific focus on the soil contamination hazards associated with metals and metalloids. A pot experiment lasting 60 days was carried out to assess the efficacy of soil amendments, such as compost, iron oxide, and poultry manure, in mitigating environmental hazards. Three soil contamination indices (soil contamination = CF, enrichment factor = ER, and pollution load index = PLI) were used to calculate the extent of soil contamination, enrichment, and pollution of the sites with Co, Hg, Ni, Mo, Se, Sb, and Pb. The findings show that Hg made the greatest contribution (with a maximum soil CF of 18.0) to the overall PLI, with a maximum value of 74.4. The sites were averagely and consequently enriched with toxic elements in the decreasing order: Ni (ER = 33.3) > Mo (20.5) > Sb (14.1) > Pb (11.0) > Hg (7.9) > Se (2.1). The bioaccumulation factor (BCF > 1) suggests that ryegrass has the ability to phytostabilize Co, Hg, Mo, and Ni. This means that the plant may store these elements in its roots, potentially decreasing their negative effects on the environment and human health. Ultimately, the addition of combined manure with iron oxides might have augmented the sequestration of these metals in the root. The elements may have accumulated through sorption on manure or Fe surfaces, dissolution from watering the plants in the pot, or mineralization of organic manure. Thus, ryegrass has shown potential for phytostabilisation of Co, Hg, Mo, and Ni when assisted with a combination of manure and iron oxides; and can consequently mitigate the environmental and human health impacts.