AWWA ACE61618

This paper discusses enhanced removal of dissolved natural organic matter (DOM) by modified granular activated carbon (GAC). GAC was modified by high temperature ammonia and steam treatment, respectively. Both techniques increased the carbon mesoporosity and surface basicity. Adsorption isotherms indicated that ammonia- and steam-treated carbons exhibited higher dissolved organic matter (DOM) uptake than the precursor mainly due to the enlargement of carbon pores. Rapid small scale column tests (RSSCTs) showed that steam treatment almost doubled the volume of treated water to reach 50% breakthrough compared to the virgin GAC. Several iron impregnation methods were used to load iron species on the carbon surface. Surface-area normalized isotherms showed that some iron impregnated carbons had higher DOM uptake due to the presence of iron species on the carbon surface. However, not all the iron species were favorable for the adsorption. Iron oxidation state and particle size appear to be important. GAC with higher mesoporosity and proper iron dispersion on the surface was expected to exhibit higher DOM uptakes from natural waters. Includes 12 references, tables, figures.