用于污水处理的人工湿地的基质、植物及其配置

Screen Plants and Substrates of the Constructed Wetland for Treatment of Wastewater

从工程角度探讨了人工湿地中基质与植物的筛选以及配置问题。基质是人工湿地不可缺少的组成部分,大部分物理、化学和生物反应等都在基质中进行。不同基质对污染物的净化能力存在明显差异,筛选对污染物净化能力强的当地材料作为人工湿地基质,不但能提高人工湿地的净化能力和使用寿命,还能减少人工湿地的投资成本。植物在人工湿地中有着重要的作用,包括直接吸收氮、磷和重金属等污染物质,提高人工湿地的渗透系数,增强根际微生物活性和输送氧气到根际增加根际的溶解性氧含量等,但不同植物对污染物的净化能力也存在很大差异,选用本地区净化力强的植物用于人工湿地,一方面可以提高人工湿地对污染物的去除效率,另一方面可以减少引用外来植物的投资成本,还可以避免引用外来植物造成的生物入侵危险。在筛选人工湿地基质和植物的基础上合理的配置基质和植物是提高人工湿地净化效率的重要保障。

The key techniques of the constructed wetlands including choose substrates and vegetations, and combination substrates with plants was discussed in this paper from point of view engineering. Substrates were main components in constructed wetlands, and purification capacity and lifetime of constructed wetlands were directly influenced by substrates. However, Phosphorus（P） sorption capacity of different substrates was significantly different. P sorption capacity of furnace slag was the highest, followed by fly ash, and that of sand Ⅱ was the lowest. In terms of maximum P sorption of the substrates tested, furnace slag was 68.4 times as compare with the sand Ⅱ, and the sand Ⅰ was 2.2 times as compared with the sand Ⅱ. The purification capacity of constructed wetland was influenced by filter coefficient of substrates and low purification capacity and clogging phenomena in constructed wetlands might be happen resulted from low filter coefficient of substrates. However, filter coefficient of the substrates tested was also obviously different. Filter coefficient of fine - clay kaolinitic thermic typic plinthuduhs was lower than that of sand and furnace slag. The filter coefficients for the 3 substrates was that the sand＇ s （ 184.2 m^3/（ m^2·d） ） was more than that of furnace slag （ 153.7 m^3/（ m^2·d） ） and fine - clay kaolinitic thermic typic plinthuduhs（0.03 m^3/ （m^2·d））. Due to the different characteristics for different section, the local substrates with the high purifying capacity were usually screen and used for the constructed wetland to reduce the constructed cost and improve the purifying efficiency and increase the lifetime of the constructed wetland. Plants were the important components in constructed wetlands and played an import role in constructed wetlands to purify wastewater, which had the important function, such as direct uptake nitrogen（ N）, P and heavy metal, enhance filter coefficient of constructed wetlands, improved microbial activity and dissolve oxygen content in rhizosphere by transport secretion and oxygen from plant photosynthesis. Many plants might be used in constructed wetland, such as Cyperus rotundus, Salix chaenomeloides, Phragmites austrail, Zizanira caduciflora Juncus effucus, Nymphaea terragona, Brasenia schreberi, Vallianeria, verticillata, Eichhirnia crasslpes, Pistia stratiotes and Azolla imbricata. However, the capacity to purify wastewater for different plants greatly varied. The capacity of N and P uptake by Eichhirnia crasslpes, Canna chinesesis and Coix lacrymajobi was higher than that of Acorus calamus and Sambucus chiemesis. The ideal plants for constructed wetlands to remove N and P should have the following characteristics of quick growth, high biomass, high content of N and P in plant, no significant pest and disease, high tolerance to stress, high uptake and removal of N and P, The local plants with the high purifying capacity were usually screened and used in constructed wetlands to enhance the purifying efficiency, to reduce the constructed cost, and to prevent invasive species. In engineering, the purification capacity of constructed wetland was influenced by type of substrates and plants, and type of combination substrates with plants. Substrates of the constructed wetland should be chosen according to type of contamination to treat and wetland to construct. Plants of the constructed wetland should be chosen according to climate and type of substrate. In addition, the rationally plants and substrates chosen, and combination plants and substrates were insured to improve purifying efficiency of the constructed wetlands.