To predict the fate of haloacetic acids (HAAs) in natural or engineered sys
tems, information is needed concerning the types of reactions that these co
mpounds undergo, the rates of those reactions, and the products that are fo
rmed. Given that many drinking water distribution systems consist of unline
d cast iron pipe, reactions of HAAs with elemental iron (Fe-0) may play a r
ole in determining the fate of HAAs in these systems. In addition, zerovale
nt iron may prove to be an effective treatment technology for the removal o
f HAAs from chlorinated drinking water and wastewater. Thus, batch experime
nts were used to investigate reactions of four trihaloacetic acids, trichlo
roacetic acid (TCAA), tribromoacetic acid (TBAA), chlorodibromoacetic acid
(CDBAA), and bromodichloroacetic acid (BDCAA), with Fe-0. All compounds rea
dily reacted with Fe-0, and investigation of product formation and subseque
nt disappearance revealed that the reactions proceeded via sequential hydro
genolysis. Bromine was preferentially removed over chlorine, and TBAA was t
he only compound completely dehalogenated to acetic acid. In compounds cont
aining chlorine, the final product of reactions with Fe-0 was monochloroace
tic acid. Halogen mass balances were 95-112%, and carbon mass balances were
62.6-112%. The pseudo-first-order rate constants for trihaloacetic acid de
gradation were as follows: BDCAA (10.6 +/- 3.1 h(-1)) > COBAA(1.43 +/- 0.32
h(-1)) approximate to TBAA (1.41 +/- 0.28 h(-1)) much greater than TCAA (0
.08 +/- 0.02 h(-1)).