几种人工湿地基质净化磷素污染性能的分析

Analysis on the Removal Efficiency of Phosphorus in Some Substrates Used in Constructed Wetland Systems

通过基质磷素等温吸附、净化磷素污染效果和基质磷素饱和吸附后磷素释放实验 ,研究了砂子、沸石、蛭石、黄褐土、下蜀黄土、粉煤灰和矿渣 7种人工湿地基质净化磷素污染效果和影响因素 ,并评价了基质磷素饱和吸附后磷素释放可能造成的二次污染风险 .结果表明 :Freundlich和Langmuir等温吸附曲线方程均能很好地描述上述基质磷素吸附过程 ,其磷素理论饱和吸附量依次为矿渣 >粉煤灰 >蛭石 >表土 >下蜀黄土 >沸石 >砂子 .磷素的净化能力依次为矿渣 >粉煤灰 >蛭石 >表土 >下蜀黄土 >沸石 >砂子 ,模拟污水磷素净化实验也证实矿渣、粉煤灰、蛭石净化磷素污染效果较好 ,表土和下蜀黄土次之 ,沸石和砂子净化磷素污染效果较差 .矿渣和粉煤灰等钙素含量较高的碱性基质 ,影响磷素吸附净化效果的主要因素是基质的全钙含量 ,碱性条件下 ,基质全钙含量越高 ,其吸附的磷素越多 ,净化磷素污染的效果越好 .砂子、沸石、下蜀黄土、黄褐土和蛭石等活性胶体氧化铁铝含量较多的中性基质 ,影响其磷素吸附净化效果的主导因素是其胶体氧化铁的含量 ,胶体氧化铁能促进基质吸附磷素效应 ,提高磷素净化能力 .基质磷素饱和吸附后磷素释放实验也表明 :除砂子基质磷素释放比例较高以外 ,其它基质磷素释放的比例很低 ,加强人工湿地基质的?

Constructed wetlands are widely used to purify wastewater in some developing countries. As filter substrates in such wetland, these substrates play important role on removal of pollutants from wastewater. Selecting suitable substrates is one of the effective ways to improve the performance of constructed wetland on treating wastewater. In this study the phosphorus adsorption capacities of sand, zeolite, vermiculite, two clay soils, two industrial by-products named steel slag and fly ash are examined for their potential use as substrate in constructed wetland. Both Freundlich and Langmuir adsorption isotherms are very fit for describing the adsorption characteristics of these substrates. Two industrial by-products including steel slag and fly ash have higher phosphorus adsorption capacity, which had 50490 and 17934 mg·kg -1 respectively.Followed vermiculite, two clay soils named yellow cinnamon and xiashu loess with phosphorus adsorption capacity of 3473, 1893.7 and 1582 mg·kg -1 respectively. The zeolite and sand had the least phosphorus adsorption capacity with 813.7 and 302 mg·kg -1 respectively. The experiments on purifying phosphorus from synthesize domestic sewage using these substrates also demonstrate this conclusion. The ability of removal phosphorus of these substrates have closely relationship with their makeup and chemical properties such as pH, total calcium and reactive calcium, reactive Fe, Al including poorly coastal and amorphous Fe, Al oxide. The steel slag and fly ash with higher reactive Ca, such as calcium oxide, have better adsorption capacity of phosphorus than other substrates, and the substrates which contained more reactive Fe also have a better ability of adsorption phosphorus than others. To assess the environmental risk for using these substrates above, the phosphorus de- sorption characteristics of these substrates are also studied. The process of phosphorus desorption quickly reached equilibrium in no more than 4 hours in the experiments, the ratio of desorption and adsorption of phosphorus in substrates above is lower except sand. To take suitable measures to manage substrates above, the risk of pollution of phosphorus form these substrates will be controlled.