Metal removal from and microbial property improvement of a multiple heavy metals contaminated soil by phytoextraction with a cadmium hyperaccumulator Sedum alfredii H.

Four clones of short rotation coppice (SRCs) were investigated for phytoextraction of soil contaminated by risk elements (REs), especially Cd, Pb and Zn. As a main experimental factor, the influence of rotation length on the removal of REs was assessed. The field experiment with two Salix clones (S1 – (Salix schwerinii × Salix viminalis) ×S. viminalis; S2 – S. × smithiana) and two Populus clones (P1 – Populus maximowiczii × Populus nigra; P2 – P. nigra) was established in April 2008 on moderately contaminated soil. For the first time, all clones were harvested in February 2012 (20124y) after 4 years. Subsequently each plot was equally split into halves. The first half of the SRC clones was harvested in February 2014 after 2 years (20142y) and again it was harvested in February 2016 after further 2 years (20162y). The second half was harvested in February 2016 after 4 years (20164y). The results showed that the biomass production for the second 4-year harvest period was significantly higher for all clones but the metal concentration was lower in the mentioned period. 4-year rotation seems to be more advantageous for the phytoextraction than two 2-year rotations. The highest metal removal presented by remediation factors (RFs) per 4 years for Cd (6.39%) and for Zn (2.55%) were found for S2 in the harvest 20164y treatment. Removal of Pb was the highest by P1 clone with very low RF per 4 years (0.04%). Longer rotation is also economically superior.

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A polymer – zeolite composite for mixed metal removal from aqueous solution

Water Science & Technology ◽

10.2166/wst.2021.057 ◽

2021 ◽

Author(s):

Merve Yıldız Yiğit ◽

Esra Sultan Baran ◽

Çiğdem Kıvılcımdan Moral

Keyword(s):

Heavy Metals ◽

Heavy Metal ◽

Metal Uptake ◽

Metal Removal ◽

Low Cost ◽

Heavy Metal Removal ◽

Heavy Metal Concentration ◽

Low Flow ◽

Zeolite Composite ◽

Multiple Heavy Metals

Abstract Heavy metals become inevitable pollutants that are toxic to life. Lots of treatment methods are available; adsorption is a cheap option. Metals are mostly found as mixtures in wastewaters. Taking this into account, a natural composite adsorbent aims to remove multiple heavy metals (Pb2+, Cu2+, Cd2+). Alginate was combined with clinoptilolite to form alginate – clinoptilolite (A–C) beads. First, factors influencing the removal efficiency of metals were investigated. Then, continuous column experiments were performed to evaluate the real application potential of the adsorbent. A–C beads preferably adsorbed Pb2+. Batch experiments showed metal uptake reached equilibrium after 24 hours and kinetics were compatible with the first-order. Also, pH values near neutral levels were observed to increase heavy metal removal. On the other hand, adsorption equilibrium was well described by the Langmuir model for Cu2+ and Cd2+ and by the Freundlich model for Pb2+. The highest heavy metal uptake was calculated as 2,145 mg /g A–C beads for Pb2+. Continuous column operations were suggested to apply low flow rates (<2 mL/min) and heavy metal concentration (<10 mg/L) for effectiveness. A–C beads can be a good candidate for mixed heavy metal removal composed of environmentally friendly and low-cost materials.

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Bioremediation of heavy metals from artisanal crude oil refinery (Kpo-Fire) impacted soil using Bacillus flexus and Pseudomonas aeruginosa in Ngie Community, Degema Local Government Area, Rivers State, Nigeria

Journal of Applied Sciences and Environmental Management ◽

10.4314/jasem.v24i12.6 ◽

2021 ◽

Vol 24 (12) ◽

pp. 2049-2054

Author(s):

C.J. Ugboma ◽

T. Sampson ◽

N.E. Mbonu

Keyword(s):

Heavy Metals ◽

Heavy Metal ◽

Pseudomonas Aeruginosa ◽

Contaminated Soil ◽

Metal Removal ◽

Heavy Metal Removal ◽

Oil Refinery ◽

Experimental Setup ◽

Strong Positive Correlation ◽

Bacillus Flexus

The existence of heavy metals in “kpo-fire” impacted soil creates significant risks to human health and the ecosystem. In this study, the efficacy of the elimination of heavy metal from “kpo-fire” impacted soil was evaluated using bacterial treatments. The organisms (Bacillus flexus and Pseudomonas aeruginosa) used in the bioremediation setup were isolated from the impacted soil. Heavy metal analysis was carried out using an Atomic Absorption Spectrophotometer. The experimental setup involved the recreation of the contaminated soil sample in three (3) vessels labeled as: Flask A containing 300g of un-amended sample (control) to monitor natural process; Flask B containing 300g of sterilized sample; Flask C containing 300g of sample with Pseudomonas aeruginosa and Bacillus flexus. Soil baseline physicochemical composition was determined to have a pH of 6.18, Temperature of 29.2oC, Total Organic Carbon 7.58 mg/kg and Phosphate concentration 37.56 mg/kg. At the end of the investigation, experimental setup C, containing bacterial inocula was observed to possess the best bio-removal rates for Mercury (99.32%), Cadmium (77.59%), Boron (72.84%) and Arsenic (93.43%) after a 42-day period of study. Also, the concentrations declined from 1.05264mg/kg to 0.00621mg/kg for Mercury; Cadmium declined from 5.93mg/kg to 1.16mg/kg; Boron declined from 3.61mg/kg to 0.82mmg/kg and Arsenic declined from 2.78mg/kg to 0.16mg/kg. Molecular characterization revealed the contaminated soil had predominance of isolates with genomic molecular weight of 1,500 bp and the phylogenetic construct showed the bacterial isolates were Pseudomonas aeruginosa (MT023359), Bacillus flexus (MT023375) and Lysinibacillus macroides (MT023377). Statistical analysis revealed a strong positive correlation between the bacterial biomass and heavy metal removal. The synergistic parts played by bacterial consortia in the bio-removal of heavy metals from the polluted soil have been established and these potentials can be harnessed as a roadmap for eco-recovery of impacted environment in the Niger Delta. Bacillus flexus and Pseudomonas aeruginosa in consortium are efficient in remediation of kpo-fire contaminated soil.

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