Phytoremediation of cyanide containing steel industrial wastewater by <i>Eichhornia crassipes</i>

Water pollution has become one of the serious problems of today's civilization. Free cyanide and complex cyanide, including HCN and CN− is the most reactive and toxic substance of all industrial pollutants. R&D, Tata Steel preliminary investigation reports have established that cyanide in the blast furnace (BF) blows down water above permissible limit. Presently, chemical treatment has been applied to attenuate the cyanide level 0.2 ppm (permissible limit of free cyanide as per environmental norms). From the economic point of view, phytoremediation could be an attractive technology in dealing with this dangerous pollutant. Cyanide BF blow down water could possibly be removed by the water hyacinth because of its high biomass production, and tolerance to cyanide (CN). This investigation is related to the study of the potential of water hyacinth on the cyanide ion pollutant removal from BF water using cost-effective biological technology—Phytoremediation. The experimental results have shown that about 95% removal of cyanide from blast furnace water could be achieved by water hyacinth in 3 days in 6 L and also in 100 L water. Water hyacinth is also effective for reducing biochemical oxygen demand (BOD) and chemical oxygen demand (COD). This aquatic plant is also capable of reducing ammonia, TDS, and hardness of water.