Evaluation of enhanced soil washing process with tea saponin in a peanut oil–water solvent system for the extraction of PBDEs/PCBs/PAHs and heavy metals from an electronic waste site followed by vetiver grass phytoremediation

Abstract

BACKGROUND: Problems associated with PBDEs/PCBs/PAHs and heavy metals mixed contaminated sites have received wide attention. To address the associated environmental concerns, innovative remediation techniques are urgently needed. RESULTS: 5.0 mL L −1 peanut oil and 5.0 g L −1 tea saponin were found to be effective in extracting 94.6%, 97.1%, 95.1%, 83.5%, and 87.1% of PBDEs, PCBs, PAHs, Pb, and Ni, respectively, after two successive washing cycles. Cultivation of vetiver grass and addition of nutrients for 4 months further degraded 45.1%, 36.2%, and 40.2% of the residual PBDEs, PCBs and PAHs, respectively. Pb and Ni removal efficiencies by phytoextraction were 4.1% and 2.0%, respectively. The combined treatment partially restored the microbiological functions of washed soil, as indicated by a significant increase in the number, biomass C, N, and functioning diversity of soil microorganisms (P < 0.05). After treatment, the residual organic pollutants and heavy metals mainly existed as very slowly desorbing fractions and residual fractions, as evaluated by Tenax extraction combined with a first-three-compartment model and sequential extraction. The secondary environmental risk of residual mixed pollutants in the remediated soil was limited. CONCLUSION: The proposed combined cleanup strategy proved to be effective and environmentally friendly. Statistical analysisStatistical analysis was performed using SPSS 14.0. Equation (1) was calculated using SigmaPlot 10.0 software. Mean values were compared by least significant difference at probability level ≤ 5%. The removal rates of pollutants were subsequently calculated. 21

Tea saponins: effective natural surfactants beneficial for soil remediation, from preparation to application

“…The helpful inuences of tea saponins in the leaching remediation of soils have also been investigated and conrmed. [30][31][32][33] Although the mechanism of tea saponins improving the bioavailability of pollutants in contaminated soils is not yet fully understood, and the application of tea saponins has been investigated with only a few heavy metals and organic pollutants, the results of existing studies suggest that tea saponins deserve in-depth and extensive researches, not just on their sources, structures and properties, but also on their preparation, effects and mechanisms. This will be greatly benecial to fully utilize the resources of Camellia plants and increase the bioremediation efficiency of contaminated soils.…”

The ability of Achromobacter sp. KW1 strain to biodegrade isomers of chlorotoluene

“…High levels of emission of these hydrocarbons leads to contamination of soil and water, in particular close to factories that use chlorotoluenes . With growing awareness of the need to protect the natural environment, much effort has been devoted to developing methods of removing hydrocarbons from the environment . Many techniques exist for the removal of organic pollutants from contaminated soil and water.…”

“…Many techniques exist for the removal of organic pollutants from contaminated soil and water. One of them is bioremediation – an environmentally friendly, cheap and efficient method based on the activity of microorganisms that metabolize chemicals into less harmful forms . Factors affecting the bioremediation process have been the subject of interest of many authors, and are described in many published papers .…”

“…One of them is bioremediation -an environmentally friendly, cheap and efficient method based on the activity of microorganisms that metabolize chemicals into less harmful forms. 15 -20 Factors affecting the bioremediation process have been the subject of interest of many authors, and are described in many published papers. 16,17,21 -24 One of the important factors affecting bioremediation is long-term contact between microorganisms and chemicals which are usually toxic to them.…”

Sustainable Options for Mitigation of Major Toxicants Originating from Electronic Waste

“…Bioaccumulation/uptake of 0.179 g g -1 was observed for initial 15 g l -1 of PCB. Ye et al 23 have tested the phytoremediation efficiency of vetiver grass for PBDEs/ PCBs/PAHs and heavy metals (Pb and Ni) after washing of e-waste contaminated soil with tea saponin and peanut oil for extraction of contaminants. Soil washing using the above amendments resulted in 94.6%, 97.0%, 95.1%, 83.5% and 87.1% removal of PBDEs, PCBs, PAHs, Pb and Ni respectively.…”