Phytoefficacy of Eicchornia crassipes (Mart.) Solms-Laub for aqua-remediation of hexavalent chromium in chromite mine effluent of South Kaliapani, Odisha, India.

Abstract

A huge quantity of toxic hexavalent chromium (Cr-VI or Cr6+) was released into the environment through mine effluent at the South Kaliapani chromite mining area during different mining activities. The present in situ bioremediation approach was conducted to assess the remediation potential of a well-known aquatic weed water hyacinth (Eichhornia crassipes (Mart.) Solms-Laub) for attenuating Cr(VI) from mine wastewater. The study correlates the bio-concentration factors (BCF) of Cr with the reduction percentage. The percent reduction of Cr content in mine effluent was maximum (53.5%) at 100days after treatment (DAT) followed by 40.7% at 75 DAT after passage through 2000 sq. ft area covering four water hyacinth-populated (1350 plants) ponds. Reduction in Cr content of OMC discharged mine effluent varies with plant age as well as with the distance of passage. A constant increase in root biomass was recorded with increased passage distance and days of treatment of contaminated mine effluent. The plants could not survive after 125days of treatment but could show an increasing trend in shoot biomass up to 100 DAT. After 75days of treatment, it was noted that Cr concentration in roots decreased from 200 to 148ppm and from 76 to 21ppm in shoots after passage through the 2000sq.ft area at 100 DAT. Water hyacinth roots exhibit maximum Cr bioaccumulation at 75 DAT, whereas this was highest in shoots at 100 DAT.