Autotrophic perchlorate reduction kinetics of a microbial consortium using elemental sulfur as an electron donor

The perchlorate reduction kinetic parameters of a microbial consortium using elemental sulfur (S-0) as an electron donor were investigated in batch experiments. Standard Monod substrate utilization and biomass accumulation models were employed to fit the experimental data for microbial perchlorate reduction. The maximum observed yield coefficient for the microbial consortium was 0.19 mg dry weight (DW) mg(-1) ClO4-, suggesting that the microbial consortium had a slow growth rate using S0 as the electron donor. The maximum specific substrate utilization rate (q(max)) and half saturation constant (K-s) for microbial perchlorate reduction were 0.14 mg ClO(4)(-)mg(-1) DW day(-1) and 5.71 mg L-1, respectively, which indicated that the microbial consortium could effectively utilize perchlorate as an electron acceptor. The variation of qmax with pH was described well by using a Gaussian peak equation, and the maximal value of qmax was obtained at pH 6.7. The presence of nitrate in perchlorate-contaminated water delayed the onset of sulfur autotrophic perchlorate reduction. The modified Gompertz equation could adequately describe the formation of Cl-and SO42- during the process of sulfur autotrophic perchlorate reduction. The SO42- production exceeded the theoretical SO42- production due to S-0 disproportionation. The kinetic parameters for microbial perchlorate reduction are essential to design biological treatment systems, as well as to predict and evaluate their performance.