Modelling assisted phytoextraction of heavy metals from tannery origin leachate

The toxic tannery solid waste leachate (TSWL) containing heavy metals is generated after the percolation of rainwater in openly dumped tannery solid waste (TSW) which poses a serious threat to the surroundings by leaching down and bioaccumulation. For its management, the phytoextraction potential of Pistia stratiotes L. and Spirodela polyrhiza L. Schleid. was analyzed by growing them individually and combining them in different dilutions of TSWL (0%, 5%, 10%, 15%, and 20%) for 30 days. The removal efficiency of metal content was 79.04% (Cr), 78.49% (Cd), and 88.11% (Cu) in P. stratiotes, 72.55% (Cr), 80.12% (Cd), and 77.70% (Cu) in S. polyrhiza while in the mixture it was 88.39% for Cr, 92.57% for Cd, and 90% for Cu. The translocation factor of all the metals for every plant was greater than 1 indicating that all the plants used in the study proved to be hyperaccumulators. The Langmuir model more efficiently described experimental data for Cd and Cu while the phytoextraction of Cr was explained by the Freundlich model. The R_L and 1/n were <1 for the above-mentioned metals indicating the favourable and active absorption of metals in plants. Therefore, based on the modelling-assisted phytoextraction findings it is suggested that the use of hyperaccumulator plants is a cost-effective and sustainable approach for managing the toxic TSWL.