Media Selection of Artificial Soil Filtration System for Stormwater Runoff Treatment in Beijing

摘要

Filter media is the most pivotal element of artificial soil filtration system and directly impact the reduction of contaminants in runoff. Four typical filtration materials including sand soil, boiler slag, furnace cinder and ceramsite are selected and studied in laboratory scale in Beijing. The experiment is carried by two stages. One is selection of filtration media. Firstly, different materials' physical properties such as the percentage of moisture, apparent density and permeability coefficient are studied in the stage. Then their removal effects for pollutions are researched under static and dynamic conditions in turn. Results show that although ceramsite has the highest permeability coefficient and percentage of moisture, it couldn't remove the pollutants by adsorption and it wouldn't be solely used as filtration media for its low apparent density. Sand soil had the lowest permeability coefficient and the highest apparent density. It could hardly remove pollutants by adsorption. Apparent density and permeability coefficient of furnace cinder are close to boiler slag, but while its percentage of moisture is much higher than that of boiler slag. Both boiler slag and furnace cinder all could remove pollutants effectively in dynamic condition. Based on the first experimental results, boiler slag is selected as filtration media of faculty and its removal effects for various pollutants are further studied under dynamic condition in the second stage. The removal rates of the faculty for CODcr, turbidity and total nitrogen are 50%~70%, 50%~85% and 40%~60% respectively.