Abstract
In order to remove pesticides from raw water, an injection guideline of powdered activated carbon (PAC) was investigated. We set up an objective value which should be under 0.4μg · l-1 in the total concentration of pesticides in purified water. On the baises of the analytical data of 70 pesticides found in raw water and purified water with PAC treatment for two years (1996∼1997) in our water treatment plant, the adequate injection rates of PAC for various concentrations of total pesticides in raw water to satisfy the objective pesticide value were determined and then applied to purification of water in our plant in 1998. The injection of PAC based on the guideline resulted in approximately 87% removal of total pesticides from raw water, and consequently the concentration of pesticides in purified water almost cleared the objective value (0.4μg · l-1) during the investigation except only a few days, in which the increase in the injection rate of PAC corresponding to the suddenly increased pesticides in raw water might be delayed.
