Removal of natural organic matter and trihalomethanes from the drinking water of Ankara city

The effectiveness of granular activated carbon (GAC) adsorption for the removal of natural organic matter (NOM) and trihalomethanes (THM) from the drinking water treated at Ivedik Water Treatment Plant in Ankara City is investigated. Freundlich Isotherm constants K and n were determined as 17.61 (mg/g)(L/mg)1/n and 1.66 respectively to determine the carbon capacity. Bench-scale GAC columns were run with empty bed contact times (EBCT) varying from 0.40 to 2.67 min to evaluate adsorption performance and to investigate the effect of EBCT on service life. The treated volumes of water increased with EBCT, showing a linear increase in GAC service life. A five-fold increase in EBCT resulted in an almost 16-fold increase in service life. Correspondingly, the carbon usage rate (CUR) decreased and the optimum bed depth was observed to be 10 cm. The capacities calculated by the isotherm equation and achieved in columns were also compared. The column capacities were within 43-65% of the isotherm capacities at complete breakthrough. However, they were only within 8-17% of the isotherm capacities at 50% breakthrough.