| Based on the characteristics of arsenic hyperaccumulation of Pteris vittata L., aspecial process called subsurface flow constructed wetland (SSFW) was constructedto be used in testing its effect on treating As-containing wastewater. During theresearch, four constructed wetland systems, based on two plants and two substrates,i.e. ceramsite-Pteris vittata L. constructed wetland system, cobble-Pteris vittata L.constructed wetland system, cobble-Canna indiaca constructed wetland system andcobble constructed wetland system were formulated to test their ability on theremoval of arsenic in the artificially mixed wastewater. The results of theinvestigation were as the following:When the concentration of the artificially mixed wastewater was As 0.25mg/L,the removal efficiencies of As in four systems (ceramsite-Pteris vittata L.system,cobble-Pteris vittata L.system, Cobble-Canna indiaca and cobble system) were76.13％, 79.01％, 69.45％and 66.20％respectively,When the concentration of theartificially mixed wastewater was As 0.5mg/L, the average removal efficiencies ofAs in four systems were 78.23％, 80.32％, 67.79％and 65.92％respectively, Whenthe concentration of the artificially mixed wastewater was As 1mg/L, the averageremoval efficiencies of As in four systems were 76.06％, 78.49％, 66.60％and64.79％respectively.When the concentration of the artificially mixed wastewater was As 1mg/L, thecontent of As uptaken by Pteris vittata L. in ceramsite system increased from 82.78μg/g to 503.02μg/g, while the content of As uptaken by Pteris vittata L. incopple-Pteris vittata L.system increased from 85.86μg/g to 521.61μg/g, and thecontent of As uptaken by Canna indiaca in copple-Canna indiaca system increasedfrom 25.71μg/g to 78.45μg/g.When the concentration of the artificially mixed wastewater was COD 150mg/L,their removal efficiencies of COD in four systems were 67.81％, 70.48％, 74.36％and55.68％respectively, When the concentration of the artificially mixed wastewater wasCOD 250mg/L, their removal efficiencies of COD in four systems were 63.30％, 65.16％, 68.78％and 57.42％respectively.When the concentration of the artificially mixed wastewater was NH4+-N10mg/L, their removal efficiencies of NH4+-N in four systems were 60.83％, 63.38％,67.25％and 50.30％respectively, When the concentration of the artificially mixedwastewater was NH4+-N 20mg/L, their removal efficiencies of NH4+-N in foursystems were 54.87％, 57.52％, 61.12％and 48.93％respectively.When the concentration of the artificially mixed wastewater was TP 2mg/L,cobble-Canna indiaca system had the highest TP removal efficiency that was 65.19％,followed by in the copple-Pteris vittata L.system, 60.94％, copple system, 57.42％,and ceramsite system had the lowest removal efficiency of 57.30％. When theconcentration of the artificially mixed wastewater was TP 4mg/L, the averageremoval efficiencies of TP in four systems (ceramsite-Pteris vittata L.system,cobble-Pteris vittata L. system, cobble-Canna indiaca and cobble system) were56.15％, 59.43％, 63.40％and 56.28％respectively.From the result of the research, subsurface flow constructed wetland system,especially the cobble-Pteris vittata L. system, was an ideal treatment process to solvethe As-containing wastewater problems. Four constructed wetland systems treatedwastewater of As, of COD and of NH4+-N, the removal efficiencies of combination ofplant and substrate in dfferent constructed wetland systems were higher than ofsubstrate in constructed wetland system.
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