Phosphorus removal rules of duckweed plants in eutrophication water

Phosphorus, the cause of most eutrophication cases, is often the limiting factor of algae proliferation. The key point toward restoration of eutrophicated water body is phosphorus removal. Based on studies of phosphorus-absorption kinetics and dynamic absorption characteristics among three kinds of duckweed, the suitable one was identified for water bodies with various eutrophic levels. Experiment results indicated that kinetic characteristics of phosphorus-absorption of certain duckweed plants can be described by the Michaelis-Menten equation.? In addition, it was found that Lemna minor has the highest value of 1/Km and is suitable for restoring water bodies slightly eutrophicacted. Spirodela polyrhiza, with the highest value of Vmax among the three, which can be used for restoration of the heavily eutrophicated water bodies. While Spirodela oligorrhiza, with low absorption rate and slow growth, is therefore unqualified for purification purpose.