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Sulfide removal by natural mix of chemotrophic sulfide oxidizing bacteria in anaerobic conditions

Amirfakhri, J ; Sharif University of Technology | 2006

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  1. Type of Document: Article
  2. Publisher: 2006
  3. Abstract:
  4. Most sulfide oxidizing bioreactors are based on pure cultures or artificial mixes of microorganisms with strict requirements for growth, which make the system unstable and do not guarantee their long term performance. The ultimate goal of this study is to develop a natural mix of chemotrophic bacteria that may be applied anaerobically for the treatment of sour gas. Activated sludge from local municipal wastewater treatment plant that was maintained in endogenous anaerobic conditions for one year was used in this study. Total suspended solids (TSS) and volatile suspended solids (VSS) of the sludge was 22 gl-1 and 14.3 gl-1, respectively. A glass culture vessel had a volume of 0.65 L was used as a batch reactor. The experiments included thiosulfate and sulfide removal. Because soluble sulfide is toxic to microorganisms, thiosulfate (10gl-1) was used as an energy source in the first step. In addition most of the chemolithotrophic sulfide oxidizing bacteria (CSOB) which consume sulfide can use thiosulfate as an energy source. Results showed that thiosulfate was consumed and sulfate was produced as a major end product. First step showed that this sludge contained CSOB. After this step the reactor was filled with 600 ml of sulfide medium that contained 0.2 gl-1 S-2 in form of Na2S.7-9H2O and then it was inoculated with 5 ml of the sludge. Throughout the experiment temperature was fixed at 30°C. As a result after 6days, 92.5% of inlet sulfide was consumed by bacteria and pH decreased from 8 to 7.6. Sulfate was a major end product which its concentration increased to 615 mg 1-1 at the end of experiment. Results of the experiment show that this natural mix of CSOBs can use for the treatment of effluent which contains sulfide
  5. Keywords:
  6. Bacteria ; Bioreactors ; Growth kinetics ; Removal ; Activated sludge ; Anaerobic conditions ; Sulfide removal ; Sulfur compounds
  7. Source: CHISA 2006 - 17th International Congress of Chemical and Process Engineering, Prague, 27 August 2006 through 31 August 2006 ; 2006 ; 8086059456 (ISBN); 9788086059457 (ISBN)