THE EFFECT OF Fe(III) ON THE RATE OF MICROBIAL SULFATE- REDUCTION

The effect of threevalent iron (Fe(OH)3) on microbial dissimilatory sulfate-reduction was studied in batch conditions with use of three different donors of electrons - Na-lactate, Na-acetate and solid organic matter (cow manure, spent mushroom compost and sawdust). The inoculum (mixed culture of sulfate-reducing and other metabolically related groups of microorganisms) was received from anaerobic cell for treatment of acid mine drainage. It was found maximal rate of the process sulfate reduction (147 mg SO4 2- /l.d) when lactate was used as sole source of carbon and energy. The Fe(III) reduction was prevalent process with acetate as donor of electrons (the rate of sulfate-reduction was only 13 mg SO4 2- /l.d). It was found that in the conditions, typical for anaerobic passive treatment, the rate of reduction of threevalent iron also is higher than the rate of sulfate- reduction. A part from reduced iron precipitated in the form of FeS. The concentrations of soluble Fe 2+ when using solid organic matter increased to rates above 1g/l after two months of the start of the experiment.