Removal of heavy metals from industrial effluents by water hyacinth (Eichornia crassipes)

摘要

A study was carried out using water hyacinth as a pollution monitor for the simultaneous removal of heavy metals such as copper (Cu), cadmium (Cd), iron (Fe), zinc (Zn), lead (Pb), chromium (Cr) and aluminium (Al). Effluents were collected from eight industries including paint, textiles, aluminium, galvanizing and battery industries situated in Lagos State, Nigeria. After cultivation of the plant for seven days in a plastic bowl containing each effluent, while sampling was carried out from the bowl everyday, the collected samples were analyzed for Pb, Fe, Zn, Cr and Cu at wavelengths 248.3, 213.7, 357.9 and 324.9 nm respectively using atomicabsorptionspectrophotometry. Aluminium was determined using UVspectrophotometryand potassiumwasdetermined using a flame photometer. The results of the analysis indicated that the range of the heavy metal in the effluents before the cleaning process were Pb (0.1 to 4.4 ppm), Cr(0.39 to 0.5 ppm), Cu (0.08 to 1.65 ppm), Zn (0.7 to 8.7 ppm), Fe (1.2 to 7.5 ppm), Al (0.15 to 1.05 ppm) and Ni (0.6 to 49.2 ppm) while Cd was not detected innone ofthe effluents. The values were higher than the Federal Ministry of Environment and the World Health Organization effluent limitation guidelines recommended levels. The cleaning experiment showed that water hyacinth has the ability to clean-up the effluents of their heavy metals content by removing about 70 to 90% of their initial concentrations within four to six days of the experimental set-up.