Influence of hydraulic retention time and sulfide toxicity on sulfidogenic FBR

摘要

The influence of hydraulic retention time (HRT) and sulfide toxicity on ethanol and acetate oxidation were studied in a sulfate-reducing fluidized-bed reactor (FBR) treating acidic metal-containing waste-water. Incomplete acetate oxidation restricted the operation of the FBR at HRTs below 6.5 h, since the alkalinity produced by acetate oxidation is necessary for wastewater neutralization. At a HRT of 6.5 h, Zn and Fe precipitation rates were over 600 mg l~(-1)d~(-1) and 300 mg l~(-1)d~(-1), respectively, and the alkalinity produced by substrate utilization increased the wastewater pH from 3 to 7.9-8.0. Both uncompetitive and noncompetitive inhibition models described well the sulfide inhibition of the sulfate-reducing culture. Dissolved sulfide inhibition constants (K;) for ethanol and acetate oxidation were 225-248 mg S l~(-1) and 338-356 mg S l~(-1), respectively, and the corresponding K_i values for H_2S were 76-84 mgS l~(-1) and 118-124 mg S l~(-1).