Synergistic phytoremediation effect by Sorghum bicolor, citric acid, biochar, and Vermiwash amendment for the remediation of a mine-contaminated soil

Abstract

Abstract Phytoremediation technology is an eco-friendly technology for the treatment of a polluted environment. In contrast, it has been demonstrated that both natural and synthetic amendments can enhance the process of phytoremediation of heavy metals (HMs) from polluted soils through the utilization of bioenergy crops. This work assessed the synergistic impact of two tested biochar (BC) from data palm (B1) and Prosopis (B2)/ citric acid (CA) and Vermiwash (VW) to enhance phytoremediation of tested HMs (Zn, Pb, Cd, Ni, Cu, Mn, and Fe) from mine-contaminated soil by Sorghum (Sorghum bicolor). The BC and CA amendments alone and combined with VW significantly augmented the proliferation and survival of sorghum grown in mine-contaminated soil. Considering the individual and combined applications of VW and BC, the influence on plant growth followed this order: K > VW > B2 > B1 > B1 + VW > B2 + VW > CA > CA + VW. Applying tested BC/ CA and VW significantly increased chlorophyll compared to unamended soil. The outcomes revealed a substantial elevation in HM absorption in both shoot and root (p ≤ 0.05) with all tested treatments compared to the untreated soil (K). The combined application of CA and VW resulted in the highest uptake of HMs in both the root as well as the shoot. This study highlights the efficacy of combining CA/BC with VW as a more viable option for remediating mine-contaminated soil compared to individual amendments.