Adaption of sulfate-reducing bacteria to sulfide exposure

“Sulfate-reducing bacteria (SRB) can beneficially be applied to domestic wastewater treatment. In general, formed
sulfide will stay in liquid phase, resulting in an elevated sulfide content, which might have inhibiting effects on the
SRB. To study effects of environmental conditions on the SRB resistance against sulfide, two sequencing batch
reactors fed with artificial domestic wastewater were operated at sulfate-reducing conditions. Required sulfide
concentration within the reactor was achieved by adding 400 or 800 mg COD/L (acetate and propionate), the latter
resulting in proportionally more sulfide production. Batch tests revealed that sulfide inhibited the rate of sulfate
reduction by 50% at a concentration of 200 mg/L sulfide for biomass from the reactor fed with 400 mg COD/L.
After adaptation to a feed of 800 mg COD/L, resulting in higher sulfide exposures, sulfide was less inhibitive to
SRB. Complete COD removal was achieved in the reactor fed with 800 mg COD/L, and the SRB population
changed from one (Desulfotalea arctica) to two (Desulfobacter postgatei and Desulfocapsa sulfexigens) dominant
species. Results indicate that SRB are capable of adapting to higher sulfide exposure. Therefore, the SRB can also
be applied to treat wastewater with higher COD levels, blackwater for instance.”
(Citaat: van den Brand, T.P.H., Roest, K., Chen, G.H., Brdjanovic, D., van Loosdrecht, C.M. Adaption of sulfate-reducing bacteria to sulfide exposure – Environmental Engineering science 33(2016)4, p.242-249)