Mechanism of microcystin removal from eutrophicated source water by aquatic vegetable bed

摘要

For purifying raw water for tap water treatment, the aquatic vegetable bed (AVB) experiment has been carried out in a hypertrophic waterfront of Taihu Lake, China. The average removal rates of total microcystin-RR and microcystin-LR are 63.0% and 66.7%, respectively. Experiments indicate that Ipomoea aquatica can absorb microcystin by using enzyme-linked immunosorbent assay (ELISA), and the roots absorb more toxins than leaves and stems. Fluorescence in situ hybridization (FISH) is used to analyze the density of microcystin degrading bacteria in the AVB sediment. Two species of microcystin degrading bacteria are detected, which indicate that microcystin bio-degradation process happened in the AVB. Protozoa and metazoa are abundant in root spheres. Aspidisca sp., Vorticella sp., Philodina sp., and Lecane sp. are dominant species. The predation functions of protozoa and metazoa have a positive effect on the removal of cyanobacteria and microcystin.