Phytoremediation of the coalmine effluent.

Coal mine effluent was subjected to detoxification by phytoremediation using two macrophytes Azolla pinnata and Lemna minor. Both plants were kept separately in the effluents for 7 day. The initial concentration (mg L⁻¹) of eight metals: Fe, Mn, Cu, Zn, Ni, Pb, Cr and Cd investigated in the effluent were 22.91±0.02, 9.61±1.6, 2.04±0.23, 1.03±0.15, 0.86±0.19, 0.69±0.11, 0.18±0.007 and 0.06±0.008 respectively. The initial fresh biomass of each plant was 100g. After one week, metals removed in A. pinnata-phytoremediated effluent were in the order: Mn (98%)>Fe (95.4%)>Zn (95%)>Cu (93%)>Pb (86.9%)>Cd (85%)>Cr (77.7%)>Ni (66.2%) and metal decrease in L. minor-phytoremediated effluent were: Mn (99.5%)>Cu (98.8%)>Zn (96.7%)>Ni (94.5%)>Fe (93.1%)>Cd (86.7%)>Pb (84%)>Cr (76%). Due to metal toxicity the total chlorophyll and protein contents of L. minor decreased by 29.3% and 38.55% respectively. The decrease of these macromolecules in A. pinnata was 27% and 15.56% respectively. Also, the reduction in biomass of L. minor was greater than that for A. pinnata. Based on the finding we could suggest that both the plants are suitable for bioremediation of mine effluent at the contaminated sites. However, attention for quick disposal of these metal loaded plants is urgently required.