关键词: 活性炭, 生物膜, 过滤, 有机化合物

Abstract: Chlorothalnial and chlorpyrifos are widely used in China, so they are likely to be present in source water, but the traditional drinking water treatment process cannot removal them well. In view of the polluted water sources, there has been a number of new drinking water treatment technologies, and among them bioactive rapid filter (BARF) has the vast application prospect in China. There are few reports about chlorothalonil and chlorpyrifos removal from drinking water by BARF, so the effect and mechanism of chlorothalnial and chlorpyrifos removal by BARF were studied in this paper with a pilot test device of BARF, and raw water was simulated effluent of settling tank of traditional drinking water treatment process, empty bed contact time (EBCT) is a key design parameter for BARF. The experiments for the influence of EBCT were conducted in the temperature range of 24℃ to 27℃, and the results showed that BARF could remove chlorothalonil and chlorpyrifos significantly when EBCT was in the range of 7.5 min to 30 min. Chlorothalonil removal rate ranged from 66.7% to 86.2%, chlorpyrifos removal rate ranged from 69.6% to 93.0%. Increasing EBCT tended to increase removal rates of the two substances, but the increase was not obvious beyond 15min. Water temperature may have seasonal change, so chlorothalonil and chlorpyrifos removal by BARF was investigated in three temperature ranges (15—20℃, 10—15℃, <5℃) when EBCT was 15 min. Removal rates of chlorothalonil were 84.2%, 79.3%, 59.8%, and removal rates of chlorpyrifos were 92.7%, 91.4%, 80.3% respectively. It was shown that a low temperature seemed to be unfavorable for the removal of the two substances and water temperature affect chlorothalonil removal more intensely. In general, BARF could remove chlorothalonil and chlorpyrifos effectively. For test water quality, when temperature of raw water was above 15℃ and EBCT was 15 min, the concentrations of chlorothalnial and chlorpyrifos of effluent could meet the current water quality standard for drinking water of China. Adsorption tests showed that activated carbon used in this study could adsorb chlorothalonil and chlorpyrifos well, contributing to high removal rates of the two substances at the start of BARF pilot test. When biofilm was stabilized, biological function played a greater role in chlorothalonil and chlorpyrifos removal.

Key words: activated carbon, biofilm, filtration, organic compounds