Evaluation of electro-assisted phytoremediation (EAPR) system for heavy metal removal from synthetic leachate using Pistia stratiotes

Novelty statement EAPR greatly reduced heavy metals, BOD, color, and turbidity of synthetic leachate. The use of water lettuce in EAPR could be another plant alternative for potential remediation of real leachate which is extremely difficult to be treated. The highest waste generated in Malaysia is composed of municipal solid waste, which is mainly managed by landfilling. Heavy metals in leachate generated from landfill could have caused hazardous effects to human and environment. EAPR has been increasingly applied to treat soil and wastewater. This technique serves as a potential tool for remediation of real leachate. Metals (Mn, Cd, Fe, Ni, Pb, Zn) uptake by Pistia stratiotes were evaluated via flame atomic adsorption spectrophotometer. Pb and Fe could be the elements that were more efficiently removed by P. stratiotes in the EAPR system. The removal efficiency was 59.86 +/- 9.98 and 56.56 +/- 18.08% for Pb and Fe, respectively. EAPR significantly reduced the BOD (9.37 +/- 2.36 mg/L), color (120.00 +/- 5.77 PtCo), and turbidity (25.50 +/- 11.96 NTU) of synthetic leachate. An obvious accumulation of heavy metals was observed at roots based on BCF and TF values. BCF values of Pb (18,999.06 +/- 8,321.76) and Fe (16,090.81 +/- 5,844.36) in the EAPR system were more than 10(3), which indicates that P. stratiotes is a hyperaccumulator. Further study on the upregulated genes is needed to comprehend the molecular basis of heavy metal stress tolerance.

Automated summary

EAPR effectively reduced heavy metals, BOD, color, and turbidity in synthetic leachate. Water lettuce could be an alternative plant for remediating difficult-to-treat real leachate. Further research on upregulated genes is needed to understand the molecular basis of heavy metal stress tolerance.