Evaluation of drinking water quality produced by ultrafiltration membranes in distribution systems

Abstract

The final quality of the drinking water in the consumers’ tap depends on the purification treatment applied, but also on its route through the drinking water distribution system (DWDS). This study assesses the quality of water treated by ultrafiltration membranes in a DWDS at a pilot scale in order to determine how possible network fouling affects drinking water quality, with special interest in natural organic matter, trihalomethanes (THM) and biofilm. Two different configurations were tested: an initial stage with an ultrafiltration (UF) system and a subsequent stage with coagulation-hydraulic flocculation (CF) pretreatment coupled to the UF. Although CF pretreatment helped reduce the dissolved organic matter (DOM) of the effluent that passed through the UF system, the high concentration of DOM promoted the fouling of the DWDS by organic matter deposits. This, together with the increase in water temperature in DWDS, allowed the adhesion of bacteria on the inner pipeline surface, encouraging the formation of a biofilm. Finally, despite the high concentration of DOM, THM generation was negligible throughout the study.