Electrochemical regeneration of natural organic matter (NOM) loaded granular activated carbon

Abstract

Granular activated carbon (GAC) is used in municipal drinking water treatment plants for the removal of organic compounds (natural and synthetic), taste and odour compounds, as well as for the removal of disinfection by-products (DBPs). Many alternative technologies for GAC regeneration, such as bioregeneration, chemical regeneration, chemical desorption regeneration, and steam regeneration, have been tested in attempts to overcome the shortcomings of thermal regeneration. In this study, the suitability of electrochemical regeneration for municipal drinking water systems was investigated. Three different sample types were obtained; virgin, field spent and field-thermally reactivated GAC. The field spent samples were electrochemically regenerated at 10, 50, 100 and 200mA in a divided cell electrochemical reactor for 5 h. The virgin, the thermal and the electrochemical regenerated samples were analysed for aqueous NOM adsorption, iodine number, surface chemistry, pore size distribution and surface area to evaluate the regeneration efficiency and to characterize the regeneration. The electrochemical reactor was able to regenerate 8--15% of the adsorption capacity of the field spent GAC compared to approximately 100% regeneration efficiency for the thermally regenerated samples. (Abstract shortened by UMI.)