Influences of pipe materials and hydraulic conditions on the process of trihalomethanes formation in water distribution network

In this paper, the influences of different pipe materials and hydraulic conditions on the formation process of trihalomethanes (THMs) were investigated. Water used in this research was taken from a Chinese water treatment plant in the northeastern part of China. The results showed that, under the same condition, the ranking of THM concentration in different pipe materials was: PVC> stainless steel>ductile iron, while it was different for chlorine decay. The variation of THMs in distribution system simulator is consistent with that of bulk water experiment. THM amount is only slightly higher in water distribution system simulator. The trend is not as distinct as that of chlorine decay. A higher flow velocity of water is associated with higher THM concentration, but it was not obvious compared with the decay of chlorine. For the same distance, different flow velocities and diameters, THM concentration was dependent on the influential degree of retention time and flow velocity. For the same distance and different flow velocities, THM concentration increased with the increase of pipe diameter. THM levels in real water distribution networks are dependent on various influences.