FORMATION OF TRIHALOMETHANES DURING CHLORINATION OF RAINWATER IN CISTERN

This study was to explore the formation of trihalomethanes (THMs) during chlorination of cistern water, an important drinking water source in Guizhou karst area of China. It was found that chloroform (CF) typically accounted for most of the total formation potentials (FP) of 4 THMs, suggesting that bromide was lacking in the cistern water. CF concentration formed during chlorination of cistern water varied from 14.5 to 69.5 mu g/L, and total organic halogen (TOX) concentrations ranged between 89.6 and 387.9 mu g/L. The levels for precursors of THMs in cistern water of Guizhou karst area was significantly lower than that in surface water sources. However, the mean percentage (14.8%) of CF in TOX formed during chlorination of cistern water was slightly higher than that in surface water sources. Dissolved organic carbon (DOC) from atmospheric dust and Delta UV272 were strongly related to CF concentration in cistern water, which implied the possibility of estimating CF formation by measuring DOC and the reduction in UV272, although it is likely that the precise relationship will be dependent of water cistern quality.