Title : Water hyacinths as phytoremidation and cyanobacterial bloom control
Cyanobacterial blooms, one of the main characteristics of eutrophic waters, is harmful to aquatic ecosystems and poses risks to public health, especially when the bloom-forming species can release toxins. Phytoremediation is considered to be an emerging green technology in which plants are used for to removal of nutrients, organic compounds, toxic metals and cyanobacteria from wastewaters. It has advantages because plants are solar-driven, economical, and helpful to achieve a sustainable environment. Water hyacinths are free-floating perennial aquatic macrophytes with long and dense hairy root systems which are conducive to absorbing nutrients and a medium for the filtering out and attachment of particulate matter including cyanobacteria. In general, due to a wide tolerance to environmental conditions, water hyacinths grow well even in heavily polluted waters. Therefore, they can be well used for harmful cyanobacterial bloom control and phytoremediation in algae dominated waters. An eco-engineering project with water hyacinths planted in large-scale enclosures was conducted as meteorological and hydrographical conditions in Lake Dianchi, and the results confirmed the great potential to use water hyacinths for phytoremidation and cyanobacterial bloom control in lakes with great amount of algae. Additionally, the pilot test suggested that water hyacinths achieved high efficiencies (over 90%) on algal and chlorophyll a removal from urban wastewater by using self-designed experimental devices. Furthermore, over 80% cyanobacterial N could be assimilated by water hyacinths. These results show a new strategy for cyanobacterial bloom control, phytoremidation and environmental restoration in eutrophic waters.