An Integrated Ecological Floating-bed Employing Plant,Freshwater Clam and Biofilm Carrier for Purification of Eutrophic Water

摘要

Planted floating-bed can be used for treating eutrophicated water in a simple and cost-effective manner,the performance of which however is unavoidably restricted by the growth rate and limited stand biomass of the plant.We report here,a novel approach to enhance the performance of traditional planted floating-bed with the introduction of filterfeeding bivalve and biofilm carrier.The integrated ecological floating-bed (IEFB) concurrently employing plant (Ipomoea aquatica),freshwater clam (Corbicula fluminea) and biofilm carrier (an artificial semi-soft assembly medium) performed better than the other two kinds of floating-beds,one of which was constructed with freshwater clam and biofilm carrier,while the other one consisted of plant and biofilm carrier.Moreover,percentage reductions of pollutants increased with extended water exchange period.With a water exchange period of 7 d,the removal efficiencies of IEFB for total nitrogen (TN),ammonium nitrogen (NH4+-N),total phosphorus (TP),total organic carbon (TOC),chlorophyll-α (Chl-α),total microcystin-LR and extracellular microcystin-LR were 52.7％,33.7％,54.5％,49.2％,80.2％,77.4％ and 68.0％,respectively.