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 longterm 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.