Water hyacinth systems are very efficient in pollutant removal from waste water. Efficiency of nitrogen removal ranges from 10 to 90% . Results from Iron Bridge water hyacinth system in Florida, USA demonstrated that phosphorus removal was from 35 to 80%. The same facility successfully removed about 60% of BODs and 43% of suspended materials from waste water. These systems can also remove heavy metals like chlorine, cadmium, copper and other effectively. In an experiment 72% of cadmium was removed from waste water by water hyacinth. Aquatic plants remove pollutants by Directly assimilating them into their tissue and by providing a suitable environment for microorganisms to transform pollutants and reduce their concentrations. Such biochemical/ physio-chemical processes functioning in these systems include nitrification/ denitrification and ammonia volatization. Accumulated nutrients and heavy metals are removed from aquatic systems by plant harvesting and sediment dredging. Thus water hyacinth effectively removes nutrient waste water.