Iron particles lower than 10 µm in drinking water dominate particle catalysis effect on disinfection byproduct formation.

ABSTRACT

Iron particles could catalyze disinfection by-product (DBP) formation in drinking water distribution systems (DWDS), but the catalytic effects of iron particles considering size effects have not been focused. Here, we first found that fine particles (lower than 10 µm) dominated the particle catalysis effect of the iron particles on the formation of DBPs containing multiple Cl atoms (DBP-3Cl), especially those with aromatic structure and containing multiple N atoms (DBP-3N). The loose deposit particles were filtered through 50 µm (F50), 10 µm (F10) and 1 µm (F10) membranes, and their turbidity values were 231.6, 53.4 and 1.1 NTU, respectively. In mass ratio, F50, F10 and F1 accounted for 84 %, 15 % and 1 % of unfiltered samples. Notably, the lower mass F10 generated more DBP-3Cl and DBP-3N than F50. Metal crystals and natural organic matters showed little difference among different sizes. The high catalytic activity of particles in F10 due to size effect was proved to be the essential mechanism. F1 contained few particles to affect DBP formation. In toxicity evaluation, the toxicity of F10 was even higher than F50. Therefore, fine particles with sizes lower than 10 µm may play a dominate role in the catalytic effect on DBP transformation in DWDS.