AWWA WQTC55142

Various water quality and treatment characteristics were evaluated under controlled chlorination conditions to determine their influences on the formation and distribution of nine haloacetic acids (HAA9) and four trihalomethanes (THM4). Raw waters were sampled from five water utilities and were coagulated with alum and fractionated with XAD-8 resin. The resulting four fractions--raw and coagulated water, and hydrophobic and hydrophilic extracts--were then chlorinated at pH 6 and 8, and stored at 20 degrees C for various contact times. The results show that increasing pH from 6 to 8 increased THM4 formation but decreased trihaloacetic acid (X3AA) formation, with little effect on dihaloacetic acid (X2AA) formation. More THM4 were formed than HAA9 at pH 8, while the reverse was true at pH 6. Hydrophobic fractions always gave higher HAA and THM formation potentials than their corresponding hydrophilic fractions, but hydrophilic carbon also played an important role in DBP formation for waters with low humic content. The bromine-containing species comprised a higher molar proportion of THM4 than HAA9. Hydrophilic fractions (with more aliphatic moieties) were more reactive with bromine than hydrophobic fractions (with more aromatic moieties). Coagulation generally removed more HAA precursors than THM precursors. Higher SUVA waters were more susceptible to coagulation. Evidence suggested that HAA precursors might be more aromatic than THM precursors. Includes 26 references, tables, figures.