What is the most probable cause of tastes and odors persisting or worsening when using PAC?

The most probable cause of tastes and odors persisting or worsening when using powdered activated carbon (PAC) is related to the proximity in which PAC and chlorine are added to the treatment process. When PAC and chlorine are mixed too closely together, the effectiveness of both substances can be compromised.

PAC is used to adsorb organic compounds and contaminants that contribute to undesirable tastes and odors in water. However, when chlorine is added immediately after PAC, it can react with the organic compounds that PAC has not yet fully adsorbed. This interaction may lead to the formation of chlorinated byproducts, which can have unpleasant tastes and odors themselves. If the PAC has not had enough time to adsorb the contaminants effectively before the chlorine treatment occurs, it reduces the overall effectiveness of the water treatment process.

By ensuring an appropriate time interval between the addition of PAC and chlorine, operators can enhance the adsorption process and reduce the likelihood of negative tastes and odors resulting from chemical reactions in the treatment system. Proper operational practices are crucial in maintaining water quality and the effectiveness of treatment chemicals.