Phytoremediation of polychlorobiphenyls (PCB’s) in landfill e-waste leachate with water hyacinth (E.Crassipes)

Abstract

The presence of e-waste in a landfill can release persistent organic pollutants (POPs) including polychlorinated biphenyls (PCBs), into the environment. PCBs are a family of more than 200 chemical compounds (congeners), each of which consists of two benzene rings and one to ten chlorine atoms. This study investigated use of water hyacinth (Eichhornia crassipes) for phytoremediation of landfill leachate waste containing PCB. Landfill leachate was simulated in the laboratory by spiking water samples with PCB to obtain concentrations of 5, 10 and 15 μg/L, which were in one to two orders of magnitude above the US Environmental Protection Agency (EPA) limit of 0.5 μg/L or 0.5 ppb. Water hyacinth plants were grown in 2 L samples of the PCB spiked water for 15 days and evaluated for tolerance and bioaccumulation of PCB. Phytoremediation of PCB spiked water by the plants was evaluated by measuring the change in concentration of PCB. The plants tolerated PCB concentrations in the range of 5 to 15 μg/L without depicting any serious adverse effect except for change in root color and an initial wilting of peripheral leaves. Water hyacinth reduced the concentration of PCBs in the leachate over 15 days from 15 to 0.42 μg/L for the 15 μg/L initial concentration sample and to below the GC/MS detection limit of 0.142 μg/L for the 10 and 5 ug/L initial concentration samples. Bioaccumulation of PCB in the plant tissue was evaluated through solid phase extraction and testing of samples for PCB with GC/MS. Bioaccumulation of PCBs at a concentration of 0.179 μg/g was observed in the water hyacinth roots for the 15 μg/L sample but none was detected for the lower initial PCB concentration and shoots. The study demonstrated potential of water hyacinth plants in phytoremediation of PCBs in e-waste leachate.