Adsorption and desorption processes of trihalomethanes on different granulated activated carbons in a full-scale advanced water treatment plant

Abstract

Trihalomethanes (THMs) are one of the main disinfection by-products generated in drinking water (DW). To control health risks caused by THMs several countries have established a maximum content of these chemicals in DW. THMs can be removed by granular activated carbon (GAC) and their adsorption processes have been studied by different authors. However, there are few studies on their desorption from GAC and no data are available on their desorption at a full scale. This paper summarises the results obtained in the monitoring of the adsorption and desorption processes of THMs at a full-scale DW plant considering different types and stages of GACs, as well as several types of influent waters. This research was carried out during 3 years in a full-scale advanced DW plant (6.25 m3·h−1) that can use four different pre-oxidants. An increase on THMs concentration in the outlet of the AC filters due to desorption processes were checked, although the obtained doses were always far below the established European limit (100 μg/L). HIGHLIGHTS Data on the real performance of activated carbon filters in a drinking water treatment plant under different conditions were provided.; Performance of different activated carbons and different ages of these carbons were compared.; Adsorption varies with the characteristics of water inlet, pretreatment applied and GAC type.; Desorption capacity depends on the type and previous usage of the GAC.; Desorption process was verified, for two different types of carbons, when the pre-oxidant was changed, and ozone was used instead of chlorine.;

Keywords

• activated carbon
• desorption
• drinking water
• full-scale
• trihalomethanes