几种人工湿地基质净化磷素的机理

 研究了砂子、沸石、蛭石、黄褐土、下蜀黄土、粉煤灰和矿渣7种人工湿地基质材料净化污水磷素的机理,并初步评价了其作为人工湿地基质可能导致的磷素二次污染的风险.结果表明,矿渣、粉煤灰有很好的磷素去除效果,蛭石、黄褐土和下蜀黄土次之,沸石和砂子的去除效果较差.上述人工湿地基质净化磷素的机理主要为化学机理,表现为基质全钙、氧化钙、水溶性钙的含量越高,其固定形成的磷酸钙盐越多,在pH值较高的情况下,主要形成难溶性的磷酸八钙和磷酸十钙,有利于磷素的净化;基质中游离氧化铁、铝和胶体氧化铁、铝含量越高,其固定形成的磷酸铁盐和磷酸铝盐数量越多,基质净化磷素的能力越强.除砂子外,上述基质磷素饱和吸附后,磷素释放比例很低.加强人工湿地基质管理,其基质吸附的磷素一般不会对水体环境造成二次污染.

Mechanism of phosphorus purification in some kinds of substrates constructed wetland systems

The mechanism of sewage phosphorus purification by 7 kinds of substrate materials (sand, zeolite, vermiculite yellow-cinnamon soil, Xiashu loess, fly ash and flag) in constructed wetland was studied. Flag and fly ash had very good removal effect of phosphorus, followed by vermiculite, yellow-cinnamon soil and xiashu loess, the zeolite and sand had the less effect. The mechanism as mentioned above was mainly chemical mechanism, so the more the content of total, oxidized and water soluble Ca, the more the solidified calcium phosphate. Under the condition of higher pH, the solidified calcium phosphate was mainly the phosphates of octo and ten calcium hard to dissolve, so favorable to phosphorus purification. The more contents of free oxides of Fe, Al, as well as of colloid oxides of Fe, Al in substrate, the more amounts of solidification phosphates of Fe, Al; the phosphorus purification capacity of the substrate was more strange. The ratio of desorption and saturated adsorption of phosphorus as mentioned above was very low except sand substrate. Strengthening the substrate management in constructed wetland, the second time pollution of phosphorus on waters environment would not be formed generally in constructed wetland.