组合式水生植物净化系统对Cu、Pb和Cd的去除与生物富集特征

选取再力花、美人蕉、水烛、旱伞草、梭鱼草、慈姑、菖蒲、水葫芦和大藻9种植物作为实验植物，构建成以高效净化重金属污染水体为主要功能的组合式水生植物高效净化系统（人工湿地＋生态浮床＋水生植物塘3个处理单元串联而成），研究不同处理单元中水生植物对重金属Cu、Pb和cd的去除能力及富集特征。结果表明，该净化系统经过为期60d的连续运行，对Cu、Pb和Cd的去除率较为稳定，可分别达到Cu93．5％～96．1％、Ph94．5％～95．2％和Cd95．6％～97．4％，3种重金属出水浓度均可达到GB3838-2002Ⅲ类水排放要求；其中人工湿地单元对重金属去除贡献率最高，Cu、Pb和Cd分别为54．15％、33．61％和44．84％，其次为生态浮床处理单元，Cu、Pb和Cd的去除贡献率分别为38．61％、51．42％和38．56％，而水生植物塘主要起到深度处理作用，对Cu、Pb和cd的去除贡献率分别为7．24％、14．97％和16．6％。9种植物在系统运行期间，生长状况良好，且重金属累积量较高，尤其是生物塘系统中的水葫芦和大藻，实验期间其重金属生物富集系数（BCF）均在200以上。所选植物不同部位对3种重金属的吸收富集能力均表现为根最强。

Removal efficiency and accumulation characteristics of Cu,Pb and Cd in combined purification systems

The removal efficiency and accumulation characteristics of Cu, Pb and Cd from simulated wastewater of metals were investigated in combined purification systems （CPS） , which was comprised of three treatment units of constructed wetlands （ CW）, ecological floating-bed （EFB） and purifying pond （ PP）, inclu- ding nine aquatic plant species of Thalia dealbata, Canna indica, Typha angustifolia Linn, Cyperus ahernifolius, Pontederia cordata, Sagittaria sagittifolia, Acorus calamus, Eichhornia crassipes and Pistia stratiotes. The results suggested that total metal concentrations in the effluent were complied with the third environmental quality stand- ards of GB3838-2002 after 60 days of treatments,and the removal efficiencies for Cu, Pb and Cd were 93.5% 96.1% ,94.5% - 95.2% and 95.6% - 97.4% , respectively, during the period of operating in the CPS （60 days） ,where the CW had the highest capabilities to remove metals （for Cu, Pb, Cd as 54. 15% ,51.42% and 44.84% ,respectively） ,followed by EFB （for Cu,Pb,Cd as 38.61% ,33.61% and 38.56% ） and subsequent PP of advanced treatment （ for Cu, Pb, Cd as 7.24% , 14.97% and 16.6% ）. During the operation of the CPS, all aquatic plant species grew well and accumulated high amounts of metals,especially for Eichhornia crassipes and Pistia stratiotes,exhibiting the bioconcentration factor （BCF） as more than 200. Furthermore,the characteristics of metal accumulation in tissues of plant species all showed the descending sequences of roots, stems and leaves.