人工湿地复合基质深度净水除磷实验

Phosphorus removal efficiency of constructed wetland with different compound substrates treating pre-treated wastewater

通过垂直上升流人工湿地模拟柱实验,研究了泥炭、蛭石、砾石以不同体积比(柱1比例1:1:3,柱2比例1:1:2, 柱3比例1:1:1,柱4全为砾石)组成的复合基质对人工湿地出水的深度除磷效果．结果表明,填充复合基质的柱1-3对总磷和正磷酸盐的处理效果较好,去除率分别达到了77％和90％以上,明显优于填充单一基质砾石的柱4(27％和 21％);蛭石、泥炭价格远高于砾石,从经济、有效的原则出发,用蛭石、泥炭、砾石以1:1:3的体积比例混合作为复合填料比较合理;该复合基质适合于水质深度净化,在进水总磷浓度不超过0．1 mg／L的情况下,除磷效果相当稳定,可以保证 0．02mg／L以下的出水浓度(地表Ⅲ类水质标准),并达到80％左右的去除率;遇到高浓度磷污染负荷冲击时,磷去除率会降低;该复合基质的除磷机制主要为吸附净化,单独使用易吸附饱和,而与人工湿地中与湿地植物的吸收净化衔接起来,就能形成稳定持久的除磷效果．

In order to select suitable substrates to treat pre-treated wastewater by constructed wetland, the removal efficiencies of phosphorus of compound substrates which consisted of peat, vermiculite and gravel was investigated through the experiment of vertical up-flow simulation system. The composition of the substrates in four systems were 1 ： 1 ： 3, 1 ： 1 ： 2, 1 ： 1 ： 1 and all gravel, respectively. The removal efficiency of TP and PO4^3- -P in system 1 - 3 which were filled with compound substrates was up to 77% and 90% ,apparently better than system 4（27% and 21% ）. The substrates was suitable for profound purification. When the concentration of TP in inflow was lower than 0.1 mg/L, the removal effect was very stable, it can make sure that the concentration of TP in outflow was lower than 0.02 mg/L and the removal efficiency was about 80%. When it was struck by the inflow with high concentration phosphorus, the removal efficiency would decrease. The price of peat and vermiculite was much higher than gravel, so the composition of 1 ： 1 ： 3 was a reasonable choice for economy and efficiency. The phosphorus removal mechanism of compound substrates was mainly adsorption, which couldn＇t work effectively by itself. But it could form stable and sustainable phosphorus removal efficiency that having it work together with macrophyte in wetland.