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 S(0) 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 ClO4 (-) 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 q max with pH was described well by using a Gaussian peak equation, and the maximal value of q max 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 SO4(2-) during the process of sulfur autotrophic perchlorate reduction. The SO4(2-) production exceeded the theoretical SO4(2-) 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.