Activated carbon pH acidity

Steam activated or reactivated carbons can have pH and alkalinity spikes of significant duration when put into service. The pH increase and duration depend on the type of activated carbon and the chemical composition of the treated water. The pH of the effluent can rise to a value exceeding 9 or 10 for 200 to 500 bed volumes and can lead to the leaching of aluminium from the activated carbon,  as well as the leaching of manganese and other transition metals from reactivated carbon in drinking water applications.

The leaching pH (DSTM 11, based on ASTM 6851) allows activated carbon users and producers to predict the effect that an activated carbon will have on the initial pH of the treated water in contact with the activated carbon. Therefore, contact pH is also called leaching pH.