Sodium oleate 82

To investigate the impact of sulfite on the thiosulfate-reducing SBR biomass, incubations with initial concentrations of sodium sulfite of 2.5, 5, 7.5, 10, and 25 mM were performed with 1 mM sodium oleate 82% (Sigma-Aldrich, St. Louis, MI) added as electron donor and carbon source. A bioreactor sample from the 58th day of operation was used as inoculum. Experiments were conducted in triplicates and cultures were incubated statically at 30°C. Activity was monitored every 4 days by sulfide production and pH dynamics.

To determine the inhibitory oleate concentration to the enriched microorganisms, elemental sulfur- and thiosulfate-reducing enrichments (using the 4th transfer biomass inoculated to the bioreactors) were incubated with sodium oleate 82% (Sigma-Aldrich, St. Louis, MI) in a concentration range from 1 to 10 mM, exceeding the reported inhibitory concentrations for anaerobic microorganisms (Hwu and Lettinga, 1997 (link); Sousa et al., 2013 (link); Silva et al., 2016 (link)). Experiments were conducted in triplicates and the bottles were incubated statically at 30°C. Activity was monitored every 4 days by sulfide production and pH dynamics.