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

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 activated carbon (AC) and their adsorption processes have been studied by different authors. However, there are few studies on their desorption from AC and no data are available on their desorption at a real 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 ACs, as well as several types of influent waters. This research has been 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 filter due to desorption processes has been verified, although their doses have always been far below the established European limit (100 μg/L).