Phytoremediation of nickel and chromium-containing industrial wastewaters by water lettuce (Pistia stratiotes)

Abstract

This study was conducted to assess the phytoremediation potential ofPistia stratiotesfor post-treatment of Ni(II) and Cr(III)-containing industrial wastewater effluents in mono (synthetic waste-water) and bimetallic systems (real wastewater). Differences were seen in metal uptake, growthperformance, and metal accumulation of the plants. In the monometallic system, the highestremoval efficiency was calculated as 77.50% for Cr(III) and 70.79% for Ni(II) at 5 mg L 1concentra-tion. At 1.25 mg L 1concentration, the bioconcentration factor ofP. stratioteswas calculated as734.2 for Ni(II) and 799.0 for Cr(III). To assess the effects of metal stress on plants, photosyntheticpigments and percent growth rates were also investigated. The percent growth rate increasedfrom 38.22 to 81.74% for Ni and decreased from 87.53 to 43.18% for Cr(III) when the metal con-centrations increased from 1.25 to 5 mg L 1. Toxicity symptoms were less severe in plants exposedto low Ni concentrations. The greatest reduction in chlorophyll was observed at 5 mg L 1Ni con-centration.P. stratiotesshowed better performance in the monometallic system. It was concludedbased on present findings thatP. stratiotescould potentially be used for the post-treatment ofwastewaters containing Ni and Cr.