Urban growth and development negatively affect nearby natural water systems. For example, increases in impervious land areas decrease rainfall infi ltration, increase runoff rates and volumes, and decrease runoff travel time. In addition, detrimental water quality changes in stormwater runoff accompany land-use changes that coincide with urbanization [1].In addition, due to human activities, atmospheric deposition, and other factors, a large number of pollutants accumulate and are discharged into the municipal stormwater sewer by stormwater runoff fl ushing, then enter the receiving waterbody [2]. Although low concentrations of some heavy metals such as copper (Cu) and zinc (Zn) are essential to plants, humans, and animals, high heavy metal concentrations are toxic [3]. Lead (Pb), on the other Pol. J. Environ. Stud. Vol. 27, No. 1 (2018), 163-173 Original Research Study of Bioretention System on AbstractBioretention is a typical low-impact development (LID) technology. This work used four different fi ller combinations of bioretention tank pilot test devices. Experiments on infl uence factors and intermittent operation were conducted. A continuous-run experiment was also performed to determine the purifi cation ability of bioretention system on heavy metals. Results showed that the removal effi ciency of heavy metals by fl y ash tank was the most effi cient, with a removal rate reaching 85.57%. The removal effect on highinfl uent concentrations in fi lter was better than that in low-infl uent concentrations. With increased rainfall time intervals (antecedent dry time), heavy-metal removal effi ciency improved. Temperature did not affect the removal effi ciency of heavy metals on the whole based on the long duration of intermittent operation experiments. Moreover, the effl uent heavy-metal concentration presented a descending trend during each simulation rainfall runoff event. During continuous operation test, heavy metals did not reach the exhaustion point in the experimental tanks, while the effl uent concentration increased with increased water volume. According to PLS regression analysis, rainfall time interval was the most important factor affecting Zn removal rate, followed by fi ller characteristics, infl uent volume, and infl uent concentration.