Sulfur balance in the treatment of sulfur-containing wastewater in a biotrickling reactor

Biological sulfite reduction was studied in a laboratory-scale anaerobic biotrickling reactor packed with ceramic granule for biomass attachment. Inoculated with the Sulfate-reducing Bacteria isolated from landfill leachate, the reactor was operated for 72h per cycle at room temperature with a sulfite loading rate of 1360 mg/L. The sulfite removal efficiency reached 97% after 9.5h. However, the total sulfur and Chemical Oxygen Demand (COD) reduction were 40% and 48.2% respectively at that time. To quantify various sulfur speciations, calculation of sulfur balance was performed, which revealed that up to 76% of sulfite removed was converted to elemental sulfur. In addition, the Oxidation-reduction potential (ORP) maintained within the range of -61mv to -20mv, which is different from the widely reported value: lower than -1000mv. It is effective to treat sulfur-contining waste water using biotrickling reactor.