What is the best approach for feeding powdered activated carbon (PAC)?

The best approach for feeding powdered activated carbon (PAC) is after filtration. When PAC is introduced into the water treatment process after filtration, it effectively adsorbs contaminants and impurities that may have escaped the initial filtration process. This step allows PAC to interact with dissolved organic compounds and taste and odor compounds that are typically not captured by standard filtration methods.

Feeding PAC after filtration means that the water has already been clarified of larger particulate materials, which allows for optimal contact between the PAC and dissolved substances. This maximizes the effectiveness of the PAC in removing unwanted pollutants from the water, which is crucial for maintaining water quality and ensuring safety for consumption.

If PAC were fed before filtration, the large particles and sediments would predominantly trap the PAC, potentially leading to lower contact time with specific contaminants. Feeding during filtration could also lead to issues with filter clogging and reduced efficiency in the filtration system. Feeding at any time would not provide the systematic approach required for optimal contaminant removal, as the timing can significantly affect the interaction between the PAC and the targeted impurities.