When activated carbon is used for water purification, the method of application varies significantly depending on the application scenario (large-scale treatment in water plants, small-scale household purification) and the type of activated carbon (powdered, granular). The specific operational procedures and precautions are as follows:
Large-scale treatment in water plants
Powdered activated carbon (emergency + regular pre-treatment): There are two feeding methods: wet and dry. The wet method involves first preparing the activated carbon into a slurry of approximately 10%, which is uniformly mixed in a stirring tank and then accurately delivered to the feeding point by a metering pump. This method ensures good mixing uniformity but has high equipment and operational costs. The dry method uses quantitative feeding equipment to directly send the carbon powder into a water injector, which then delivers it to the target location. This method has simple equipment and easily guaranteed feeding accuracy. The feeding location is usually before the coagulation tank; in emergency situations, it can be switched to before the filtration tank. Samples are taken 5-10 minutes after feeding to observe the effect. The regular feeding amount needs to be adjusted based on water quality monitoring data, and can be increased to 10-30mg/L in case of sudden pollution.
Granular activated carbon (advanced treatment): It is mostly used in the form of adsorption beds such as fixed beds, with a carbon bed thickness typically of 1.0-2.0m and an activated carbon particle size of 1-2mm. A common process is granular carbon adsorption following regular treatment; some processes are combined with ozone oxidation to form an ozone-granular activated carbon process. During operation, the filtration rate is controlled at 8-20m/h, and backwashing is required every 24-72 hours, which can be done by water alone or a combination of air and water. The water flushing speed is approximately 28-32m/h, lasting 4-10 minutes, to prevent the adsorption effect from being affected by impurity accumulation in the carbon bed.
