Contaminant removal from low-concentration polluted river water by the bio-rack wetlands

The bio-rack is a new approach for treating low-concentration polluted river water in wetland systems.A comparative study of the efficiency of contaminant removal between four plant species in bio-rack wetlands and between a bio-rack system and control system was conducted on a small-scale （500 mm length × 400 mm width × 400 mm height） to evaluate the decontamination effects of four different wetland plants.There was generally a significant difference in the removal of total nitrogen （TN）,ammonia nitrogen （NH 3-N） and total phosphorus （TP）,but no significant difference in the removal of permanganate index （COD Mn） between the bio-rack wetland and control system.Bio-rack wetland planted with Thalia dealbata had higher nutrient removal rates than wetlands planted with other species.Plant fine-root （root diameter 3 mm） biomass rather than total plant biomass was related to nutrient removal efficiency.The study suggested that the nutrient removal rates are influenced by plant species,and high fine-root biomass is an important factor in selecting highly effective wetland plants for a bio-rack system.According to the mass balance,the TN and TP removal were in the range of 61.03-73.27 g/m^2 and 4.14-5.20 g/m^2 in four bio-rack wetlands during the whole operational period.The N and P removal by plant uptake constituted 34.9%-43.81% of the mass N removal and 62.05%-74.81% of the mass P removal.The study showed that the nitrification/denitrification process and plant uptake process are major removal pathways for TN,while plant uptake is an effective removal pathway for TP.

再力花/菖蒲生物湿地床去除河水中氮磷的试验

采用再力花和菖蒲构建湿地床,以考察其对污染河水的净化效果。6个月的连续试验表明:在水力负荷为0.24 m3/(m2.d)、植物种植密度大于158株/m2的条件下,2种植物存活率均大于93%,说明植物能适应低污染负荷、高种植密度的无土培养环境;再力花和菖蒲湿地床月均去除率分别为:总氮(TN),48.22%～78.53%和43.23%～72.42%;总磷(TP),77.62%～85.67%和58.07%～80.77%。再力花湿地床对TN、TP的净化效果好于菖蒲湿地床;2种植物吸收N、P含量分别占去除总量的比例:N为44.14%、37.75%,P为73.43%、62.05%。湿地床技术可有效去除来水中的TN、TP,通过植物吸收作用累积N、P含量较高,不同种类的植物构建湿地床对污染河水中N、P去除效果存在显著差异,且硝化反硝化和植物吸收是去除N的主要途径,而植物吸收是去除P的有效手段。

再力花生物湿地床氮磷去除过程中根系微生物群落结构解析

生物湿地床作为富营养化水体生态修复技术的重要组成部分,具有良好的发展潜能,其应用的关键是优选适宜的植物种类,并维持较高的污水净化能力。目前,国内外对湿地床根系微生物的群落结构与优势种群组成及变化研究甚少。本文利用变性梯度凝胶电泳技术(DGGE)对再力花湿地床不同根系微生物群落结构进行了解析。结果表明,腐根和黄根间具有较高相似度种群,而黄根、腐根与幼根相似度较低。微生物种类在腐根根系最为丰富,幼根最少。Clavibacter、Clostridium、Mesoflavibacter、Brevundimonas、Chromobacterium在生物湿地床去除污染物的过程中起到重要作用,为主要功能菌群。研究结果对应用生物湿地床净化水体中氮、磷具有一定的参考价值和理论意义。