Factors influencing the formation and relative distribution of haloacetic acids and trihalomethanes in drinking water.

TLDR: Experimental evidence suggests that haloacetic acid precursors have a higher aromatic content than trihalomethane precursor, and Waters with higher specific ultraviolet absorbance values were more amenable to removal of organic material by coagulation than waters with low specific ultraviolet absorbsance values.

Abstract: 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 and four trihalomethanes in drinking water Raw waters were sampled from five water utilities and were coagulated with alum and fractionated with XAD-8 resin The resulting four fractionsraw and coagulated water and the hydrophobic and hydrophilic extractswere then chlorinated at pH 6 and 8 and held at 20 °C for various contact times The results show that increasing pH from 6 to 8 increased trihalomethane formation but decreased trihaloacetic acid formation, with little effect on dihaloacetic acid formation More trihalomethanes were formed than haloacetic acids at pH 8, while the reverse was true at pH 6 Hydrophobic fractions always gave higher haloacetic acid and trihalomethane formation potentials than their corresponding hydrophilic fractions, but hydrophilic carbon also played an important role in disinfe