Remediation of potentially toxic elements -containing wastewaters using water hyacinth - a review

For a long time, water hyacinth has been considered a very stubborn and troublesome weed. However, research has shown that it can be used to remove many pollutants from water. Among the different pollutants, potentially toxic elements (PTE) or their ions have been found to be very toxic for humans, animals, and plants. Among the many conventional methods for removing PTE from wastewaters, phytoremediation has several advantages. This method is highly eco-friendly, cost-effective, and can remove a wide range of metal pollutants and organic pollutants. Both, living and non-living water hyacinth plants, can be used for remediation - either entirely or their parts. Study on mechanisms and different factors involved in the process would help to effectively use water hyacinth for remediation. This review presents different studies conducted in the past thirty years for the removal of PTEs. Detailed analysis of the work done in this field showed that in spite of the main advantages provided by the plant, not much has been done to increase the efficiency of the remediation process and for reusing the water hyacinth biomass for other applications after desorption of the PTE. Hence, the section on scope for future work highlights these prospective ideas. Novelty statement: Water hyacinth, which is a very stubborn weed and has a negative impact on the environment, can be constructively used to remove potentially toxic elements (PTEs) along with other pollutants from wastewaters. Different parts of the water hyacinth plant like roots, leaves, and stems or the entire plant can be used. Further, either the live plant or its other forms, such as dried powder, biochar, or activated carbon can be used. This review focuses on different forms of water hyacinth plant used, the advantages and limitations associated with these methods and the scope for future work.