Influence of pH and Nitrate on Perchlorate Biological Reduction

Abstract

The pH and nitrate effect on the anaerobic biological reduction of perchlorate using acetate as carbon source was studied. Perchlorate reduction occurred throughout the pH range from 6.0 to 9.0. However, initiation of perchlorate reduction was rapid under neutral pH conditions. At initial pH 7, perchlorate reduction followed pseudo-first-order with the reaction rate constants was 0.3732 d-1 and the half-life time was 1.85 d. In the absence and presence of nitrate, the kinetics of perchlorate reduction with the reaction rate constants were 0.3229 d-1 and 0.2307 d-1 (after a lag phase for 3 d), the half-life time were 2.1 d and 6 d. With multiple additions of nitrate, perchlorate removal was observed with a longer lag period, the consequent production of high level nitrite may delay perchlorate degradation.