Abstract:In order to improve the purification effect of bioretention systems, the adsorption properties of special fillers such as zeolite, vermiculite, activated carbon and perlite to the pollutants such as ammonia nitrogen, total nitrogen, total phosphorus, chemical oxygen demand in the road runoff of rainwater were studied. The adsorption capacity of fillers to various pollutants was studied by static shaking experiments, and the isothermal adsorption models of the fillers were established. The results showed that the comprehensive adsorption performance of the zeolite was better, followed by the activated carbon. The fitting results of isothermal adsorption process of the four fillers basically conform to Langmuir adsorption model. The bench-scale test results of zeolite as the special filler indicated that the load reduction rate of bioretention systems to ammonia nitrogen, total nitrogen, total phosphorus and chemical oxygen demand could reach 70. 59%, 85. 83%, 79. 98% and 66. 02%, respectively. Considering the purification performance and economy, zeolite can be selected as the special filler for bioretention system.