7种人工湿地填料对污水中营养盐吸附能力的评价

Performance Evaluation of Nutrient Removal by Seven Substrates Used in Constructed Wetlands

为筛选对污水中氮、磷吸附效果较好的填料,选取7种在污水处理中较常用到的填料(煤渣、火山岩、活性炭、沸石、牡蛎壳、钢渣和河沙)作为研究对象,考察其吸附、解吸特性。结果表明,Langmuir和Freundlich方程均能较好地拟合填料对氨氮(NH_4^+-N)和磷酸盐(PO_4^(3-))的吸附特征。通过Langmuir模型计算,沸石、活性炭、火山岩和牡蛎壳对NH_4^+-N的理论饱和吸附量较大;钢渣、牡蛎壳、沸石和煤渣对PO_4^(3-)盐的理论饱和吸附量较大。在动力学特征研究中,沸石和钢渣分别对NH_4^+-N和PO_4^(3-)保持了较高的吸附速率,同时其解吸风险也较其他填料大。综合评价填料对NH_4^+-N与PO_4^(3-)的等温吸附过程、吸附动力学特征及解吸风险,发现沸石和钢渣分别对NH_4^+-N和PO_4^(3-)具有很强吸附能力,可针对不同浓度含氮、磷废水进行适当选择及搭配使用,牡蛎壳对NH_4^+-N和PO_4^(3-)同时具有较强的吸附能力,是作为人工湿地填料的较好选择。

In the paper, seven kinds of substrate materials in constructed wetland including cinder, volcanic rock, activated carbon, zeolite, oyster shell, steel slag and river sand were utilized to investigate the adsorption and desorption performance to ammonia nitrogen （NH4＋-N） and phosphate （po43-）. The results showed that the behaviors of NH4 ＋-N and PO43- adsorption by substrates used in this study were well fitted to both Langmuir and Freundlich isothermal adsorption equations. Calculated by Langmuir equation, the NH4＋-N adsorption capacity of zeolite, activated carbon, volcanic rock and oyster shell and the PO43- adsorption capacity of steel slag, oyster shell, zeolite and cinder were larger than other substrates. In the study of kinetic characteristics, the adsorption rate of PO43- and NH4＋-N were maintained at a high level of zeolite and steel slag, respectively, synchronously the desorption risk were also greater than that of other substrates. Through comprehensive evaluation of the isothermal adsorption process, adsorption kinetic characteristics and desorption risk of NI-h＋-N and PO43- by substrates, we can find that zeolite and steel slag had a strong adsorption capacity of NH4＋-N and PO43-, which can be used in wastewater treatment with high concentrations of nutrients combined with other substrates; additionally, the oyster shell performed well in NH4＋-N and PO43- adsorption, and it is a proper candidate for constructed wetland.