Characterization of trihalomethanes (THM) and their precursors patterns in a drinking water conveyance network in Tunisia

The objective of this study is to characterize the spatial and temporal distribution of trihalomethanes (THMs) in a drinking water network in Tunisia and to propose treatment guidelines for improvement. The presence of THM was studied in the raw water treatment plant and during the transfer through the network. Monitoring was done over three 10-day periods, corresponding to three seasons, to search for THM species and their main precursors. The average concentration of THMs at the end of the water conveyance network during the three study periods was estimated at 95.5 μg/l. The results showed that at the end of the network, chloroform was the species predominantly formed during the warm season. Dichlorobromomethane was the compound found mostly during the cold and temperate seasons. Dibromochloromethane and bromoform only accounted for a small percentage of the total THMs during all three study periods. Better management of the treatment plant and the chlorination are proposed as keys to reduce THMs formation.