Research on reducing residue of fipronil pesticide by vetiver grass in constructed wetland - a case study in Quangnam province, Vietnam

Tóm tắt

In this study, a survey of pesticides in Quang Nam Province illustrates that the best-selling and the highest frequency of use is Regent 800 WG, of which the main component is Fipronil, with 95% and 82% respectively. Thus, that the residue of Fipronil, a chemical substance in “Group C that can cause cancer in humans” according to the U.S. EPA, in the soil and groundwater is inevitable. The results have proven that the concentration of Fipronil in groundwater at farmers’ households, which are closed to the paddy field, is around 1.0 mgL to 2.0 mg/L. Therefore, this study aims to examine the absorptive capacity of constructed wetland system in which vetiver grass is the selective plant. The pilot of constructed wetland is designed in 36 L tank with the density of vetiver grass of 100 plants/m2. The vetiver grass is 20 cm long with bushy roots. The results show that the fipronil, which reduces efficiency of the constructed wetland by vetiver grass,reaches 72% with the optimal velocity and hydraulic retention time (HRT) of 3.30*10-6 m/s and 7.58 hours, respectively.