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The remediation of heavy metals contaminated soils is increasingly a global problem with serious implications for human health. This study aimed to evaluate the in-situ remediation performance of multi element contaminated soil by the electrokinetic. To achieve this, the effects of chelating agents (water, ethylenediamine tetraacetic acid (EDTA), diethylenetriamine pentaacetic acid (DTPA)), potential gradient (0, 1, and 2 V cm− 1), and position of soil in electrokinetic cell on metals fractions and metals removal were investigated. The results revealed that the electric potential difference and application of EDTA or DTPA electrolyte generally enhanced heavy metals removal efficiency and for Ni and Pb the interactions effects of these factors were significantly positive. Results showed that Ni, Zn, Cd, and Pb removal efficiency is highest with DTPA, DTPA, EDTA and EDTA electrolytes, respectively. In particular, the usage of electric current remarkably shifted the soil-metal bonds from stable (residual) to a less stable (mobile and mobilisable) fraction. The optimum electric current for the removal of Zn, Cd, and Ni was 1, 1, and 2 V cm− 1, respectively, which removed 44, 47 and 41% of the average of these heavy metals in soil, respectively. Results of present study demonstrated that removal efficiency was highly metal-dependent; and the order of metals removal was Cd > Ni > Zn > Pb.

Immobilization is an efficient method in the remediation of heavy metal-polluted soils. A greenhouse experiment is conducted to investigate the influence of fish scale powder, chitin, and chitosan on the growth and chemical composition of rice grown on a soil contaminated with Zn, Pb, Cd, and Ni. Results showed that the application of fish scale powder, chitin, and chitosan significantly increased root and shoot dry matter yield of rice, but decreased Pb phytoextraction efficiency. Further, the translocation factor of Ni decreased following the application of fish scale powder and chitosan. Application of fish scale powder decreased Ni, Cd, Zn, and Pb bioavailability in soil. The addition of chitosan reduced Ni and Pb concentration in rice shoots. Among different amendments, only the application of chitosan had a significant effect on the reduction of Zn content in rice root. Considering that the translocation factors were less than one in all treatments, it can be concluded that biostabilization of the studied metals has occurred. based on the obtained results fish scale derivatives including fish scale powder and chitosan play an important role in the removal of heavy metals due to having suitable functional groups. Therefore, it can be deduced that due to the economic feasibility, environmentally friendly, and high metal removal capability of chitosan and fish scale powder, these two amendments are highly recommendable to be applied in multi-metal polluted soils for increasing metals removal and hence decreasing their phytotoxicity.