Phytoextraction of heavy metals and ultrastructural changes of Ricinus communis L. grown on complex organometallic sludge discharged from alcohol distillery

The safe disposal and eco-friendly management of distillery sludge discharged after anaerobic digestion of spent wash have become a serious global concern. The present paper aims to investigate the heavy metal phytoextraction potential of Ricinus communis L. thrive on dumped distillery sludge, which was slightly contaminated by heavy metals and organometallic co-pollutants. The results of physicochemical analyses of distillery sludge revealed the presence of high amounts of Fe (62856.32 mg kg(-1)), Zn (178.64 mg kg(-1)), Cu (648.39 mg kg(-1)), Cr (2.32 mg kg(-1)), Cd (1.89 mg kg(-1)), Mn (121.42 mg kg(-1)), Ni (14.32 mg kg(-1)), and Pb (18.51 mg kg(-1)) along with complex co-pollutants. The major recalcitrant organic pollutants detected by GC-MS/MS technique were octadecadienoic acid, 2,3-bis[(TMS)oxy]propyl ester; stigmasterol TMS ether; beta-sitosterol TMS ether; docosanoic acid, TMS ester; and heptadecane, 2,6,10,15-tetramethyl. The phytoextraction potential revealed higher accumulation of Fe followed by Cu, Zn, Mn, Ni, and Pb, in root and shoot of R. communis L. It was also noted that the bioaccumulation factor (BAF) and translocation factor (TF) of all tested metals were found to be <1 and >1, respectively which showed strong evidence for high hyperaccumulation and translocation capabilities of this plant. Furthermore, the ultrastructural study of root tissues of R. communis L. showed the formation of multi-vacuoles, multi-nucleolus, and deposition of metal granules in the cell wall and on the plasma membrane's periphery of roots as adaptive characteristics of plants thriving at organometallic contaminated sludge dumping site. Thus, the study showed a strong indication for the application of Ricinus communis L. as a biotechnological tool for in-situ phytoextraction and restoration of organometallic contaminated sites. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the phytoextraction potential of Ricinus communis L. on slightly contaminated distillery sludge, revealing high accumulation of heavy metals in the plant. Results showed strong evidence of hyperaccumulation and translocation capabilities in the plant, indicating its potential as a biotechnological tool for in-situ phytoextraction and restoration of organometallic contaminated sites.