Improvement of Water Quality by Constructed Submerged Plant Bed

The constructed submerged plant bed(CSPB),with aquatic macrophytes being vegetated on a constructed submerged bed and artificial filling,is a biologic-ecological technique of water body restoration at virgin position for polluted water body,and its core is still aquatic macrophytes.The purification of aquatic macrophytes of CSPB for polluted water is a complicated physical,chemical and biologic process,the mechanism contains: 1.absorption of nutrient elements and enrichment of heavy metal;2.removal of SS and macromolecule organic matter by physical adsorb adsorption;3.enhance of Do in water by releasing oxygen;4.controlling the growth of algal and bacteria by means of biochemical effect;5.providing carrier and O2 for microorganism and forming plant-microbiology cooperating purification.Nevertheless,because aquatic macrophytes be vegetated directly under water in previous studies,the utilization of aquatic macrophytes,especially of submerged aquatic vegetation,is restricted by diaphaneity and depth of water,it becomes a important limit for aquatic macrophytes to be applied for restoring grievously polluted water with low diaphaneity and large depth.Contrarily,the CSPB technology can artificially adjust the depth of aquatic macrophytes under water by means of rising or sinking down the vegetation bed,so,it can eliminate the limit of diaphaneity and depth to the growth of aquatic vegetation.moreover,the CSPB technology is convenient for the scheme of species and community construction of aquatic macrophytes,as well as for the management and maintenance of aquatic vegetation.It should provide a new idea for water quality improvement by utilizing aquatic macrophytes in grievously polluted water body with low diaphaneity and large depth.