Over the past two years we have been involved in a drinking water treatment project in the Vendée department in western France, successfully removing disinfection by-products (DPBs) notably trihalomethane (THM).
The area uses surface water for its drinking water supplies and it is transferred to popular coastal towns via lengthy pipelines. This challenging delivery process, combined with the extreme seasonality in the region’s population, thanks to its status as a leading holiday destination, meant that THM was a particular issue affecting water quality. This was especially true during the period immediately following the peak tourist season. The THM is formed from the reaction between chlorine, which is added to the water as a disinfectant, and residual organic matter remaining in the water, as a consequence of it being surface water.
Puragen water treatment expert, Eric Racofier, was recommended by a leading French water treatment OEM back in 2022, to start discussion with the local water Syndicate on how best to resolve this THM issue. From the customer’s side, the discussions were lead by Network & Works Service Manager Francois Lemaire.
The customer decided to install fixed activated carbons filters, each with a capacity of 7 tonnes, initially at two water treatment sites in the region. The work was completed in 2023, with a third site being added earlier this year, 2024.
The activated carbon selected was OxPure® AQM® 1240C, a coconut-shell based activated carbon that has been optimised for the removal of chlorine-containing contaminants such as THM. Laboratory testing confirmed that this was the ideal grade of GAC for this application.
The customer has reported very good results in the removal of THM from these sites and we continue to work with them on regular changeout of the media. In addition, the spent carbon can be safely and economically recycled via thermal reactivation, in a process we refer to as REACT-Sys®. The carbon footprint saving associated with reactivating spent carbon in this way is >90%.
