基于径流污染控制的生物滞留设施填料优化研究

为实现对径流污染的有效控制,对生物滞留设施种植土层之下的人工填料层组成优化进行了系统性研究,在静态条件下考察了9组填料对氮磷营养物的吸附性能。结果显示,蛭石和沸石对氨氮的吸附性能较好,对氨氮的吸附量分别为3.7和3.2 mg/g,并且粒径越小,吸附性能越好;蛭石和麦饭石对磷酸盐的去除效果较好,磷酸盐去除量分别为0.13和0.1 mg/g。由此筛选出对污染物净化效果较好的1~3 mm沸石和蛭石、2~3 mm麦饭石作为去除污染物的功能性填料。动态水力循环试验显示,相同体积的蛭石和沸石对氨氮的吸附效果接近,水力停留时间(HRT)为60 min时,对氨氮的去除率均接近100%,此时麦饭石对氨氮的去除率为93%。对磷酸盐吸附效果的优劣排序为蛭石>麦饭石>沸石,当HRT为60 min时,对磷酸盐的去除率分别为78.8%、53%和19.7%。填料掺混体积比为沸石∶蛭石∶麦饭石∶砂=3∶7∶1∶6的组合系统对氨氮、磷酸盐和COD的去除效果最好,且下覆5 cm砂层有利于降低出水颗粒物导致的浊度。在此填料配比条件下,当填料层厚度在30~50 cm之间时,对氮、磷和COD的综合去除效果最好。

Optimization of Bioretention Facility Filler Based on Runoff Pollution Control

A systematic study was carried out on the optimization of the composition of artificial filler layers under the soil layer of bioretention facilities in order to achieve effective control of runoff pollution.The adsorption properties of nine groups of fillers to nutrients of nitrogen and phosphorus under static conditions were investigated.Vermiculite and zeolite had good ammonia nitrogen adsorption performance with adsorption capacity of 3.7 mg/g and 3.2 mg/g,respectively,and the smaller the particle size,the better the adsorption performance.Vermiculite and medical stone had good effect on phosphate removal,and the removal amount of phosphate was 0.13 mg/g and 0.1 mg/g,respectively.Thus,zeolite(1-3 mm),vermiculite(1-3 mm)and medical stone(2-3 mm)with good purification effect of pollutants were selected as the functional fillers.The dynamic hydraulic cycle test showed that the same volume of vermiculite and zeolite had similar adsorption effect on ammonia nitrogen.When the hydraulic retention time(HRT)was 60 min,the removal rate of ammonia nitrogen by vermiculite and zeolite was close to 100%,and that by medical stone was 93%.The order of phosphate adsorption performance was vermiculite,medical stone and zeolite.When HRT was 60 min,the phosphate removal rates were 78.8%,53%,and 19.7%,respectively.The combined system with the mixture volume ratio of zeolite∶vermiculite∶medical stone∶sand=3∶7∶1∶6 had the best removal effect on ammonia nitrogen,phosphate and COD,and underlying 5 cm sand layer was beneficial to reduce the turbidity caused by effluent particles.When the optimal filler volume ratio was adopted and the thickness of the filler layer was between 30 cm and 50 cm,the comprehensive removal effect of nitrogen,phosphorus and COD was the best.