Pilot-scale assessment of modified activated carbon for minimizing disinfection by-products in freshwater

Abstract

Water purification is essential to ensuring access to drinking water and safeguarding the health of both livestock animals and humans. One of the most common methods to purify water in drinking water treatment plants (DWTPs) is chlorination and chlorine dioxide. However, these processes can produce undesirable and potentially harmful by-products, such as chlorite (ClO2 - ) and chlorate (ClO3 - ). While granulated activated carbon (GAC) is classically and effectively employed to eliminate many hazardous contaminants, it exhibits inadequate efficiency in the removal of ClO2 - and ClO3 - . In an attempt to improve the current methods, a GAC has been here modified with an alkylquaternary ammonium-based surfactant, the 1-hexadecylpyridinium chloride monohydrate (CPC). Upon the selection of the best reaction conditions in terms of surfactant functionalization, reaction time and the prevention of pellets breakage, the synthesis of the modified carbon (CPC@GAC) was successfully scaled up to kilograms. Then, a pilot scale experiment was performed in a DWTP filling a 0.21 m3 -column bed with the CPC@GAC material. When using real water flows (with corresponding to empy bed contact times-EBTC of 3.9, 5.2, 7.8 and 15.5 min), the time to reach 50 % of saturation (t50 %) was 6.0, 22.9, 22.0 and 54.8 days, respectively. These values surpass those obtained with non-modified GAC, thereby demonstrating the practical applicability of this modified adsorbed in water disinfection treatments.