Removal Characteristics of High Concentrations of Perchlorate Using a "Heterotrophic Sulfur Autotrophic" Combination Process

Abstract

The heterotrophic-autotrophic reactor including two chambers, that is, the lower part of the heterotrophic zone and the upper part of the autotrophic zone, was used to remove highly concentrated perchlorate (ClO4-) wastewater. The reduction characteristics of ClO4- and the effluent sulfur (SO42-) concentration were investigated using different influent ClO4- concentrations and C/Cl ratios. By adjusting the influent C/Cl ratio from 2 to 1, the reactor was started up successfully within 36 d. The microorganisms tolerated the high concentration of ClO4- (250-400 mg·L-1) and the ClO4- removal efficiency was higher than 95%. By adjusting the C/Cl ratio to 1.2, the ClO4- load in the autotrophic zone was reduced and the SO42- concentration in the effluent was controlled below 250 mg·L-1. The result show that tryptophan and tyrosine materials in soluble microbial products led to the TOC increase in the effluent of the autotrophic zone. The sludge yield was reduced because of heterotrophic and autotrophic processes. The alkalinity produced by the heterotrophic process was used as carbon source for the autotrophic process and to neutralize the acidity produced by the autotrophic process, representing the complementary function and avoiding the addition of alkalinity in the autotrophic process.