Phytoremediation of the Toxic Effluent Generated During Recovery of Precious Metals from Polymetallic Sea Nodules

Abstract

Recovery of metals from the polymetallic sea nodules at the pilot plant at National Metallurgical Laboratory, Jamshedpur, India has generated a highly toxic effluent. This effluent contains several metals like Mn, Cu, Zn, Fe, Pb, Cr, and Cd that pollute the neighboring water bodies when discharged. Hence detoxification of this effluent was practiced using two plants: Lemna minor and Azolla pinnata for 7 days. During investigation A. pinnata removed 96% of Mn, 97% of Cu, 98% of Zn, 70% of Fe, 96% of Pb, 93% of Cr, 78% of Cd, and was comparatively more effective than L. minor which removed 94% of Mn, 86% of Cu, 62% of Zn, 74% of Fe, 84% of Pb, 63% of Cr, 78% of Cd. During the 7 days of experiment chlorophyll content decreased by 51% and 59% in A. pinnata and L. minor respectively. Based on our findings we can suggest that these two plants have wide range of metal retention potentialities hence can be of routine use for purification of toxic effluents.

KEY WORDS::

• Azolla pinnata
• detoxification
• heavy metals
• Lemna minor
• polymetallic sea nodules (PMN)
• phytoremediation

ACKNOWLEDGMENTS

This work was supported by the Department of Ocean development, Government of India. The senior author thanks to University Grant Commission for providing a Junior Research Fellowship and also to Dr Virendra Kumar Mishra, Department of Chemical Engineering, Institute of Technology, Banaras Hindu University, Varanasi, India, for providing his valuable suggestions.