WATERPLANT PURIFICATION OF EUTROPHICATED WATER IN MESOCOSM SYSTEM WITH LONG-TERM OBSERVATION

Abstract

To compare the ability of water purification as N, P, COD and Chl.a removal, 8 mesocosm systems were observed for 4 years. As results, 1) In all treated mesocosm system, Aoko did not appear, 2) CaO sprinkling treatment showed the most effect for water purification with P-elution controlling in long- term observation, but bio-diversity of phytoplankton and zooplankton became poor because of surplus purification, 3) MgO sprinkling treatment showed long-term effective P-elution control, and phytoplankton flora was not so poor as that in CaO sprinkling treatment, 4) Large size zooplankton were observed in water glass purification system with the structure of water plant roots for rich niche construction, 5) The diversity index of phytoplankton flora was higher under complicated community structure such as phytoplankton, zooplankton and water plants, 6) Water plant purification system was disturbed by immigration birds that ate water plants and supply their excrement to water, so positive maintenance is important to keep this system in order, and 7) Hybrid treatment system did not show the hybrid effect on water purification, so it considered important that environmental improvement level should be optimized.