Characterization of the sulfate reduction process in the anaerobic digestion of a very high strength and sulfate rich vinasse

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 248; pp. 383 - 393
• Main Authors: Barrera, Ernesto L., Spanjers, Henri, Romero, Osvaldo, Rosa, Elena, Dewulf, Jo
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.07.2014
• Subjects: Anaerobic digestion; Bacteria; Biogas production; Chemical oxygen demand; Dynamic behavior; High strength; Inhibition; Propionic acid; Reduction; Sulfate reduction; Sulfates; Sulfur compound; Vinasse; Sulfate reduction; Dynamic behavior; Inhibition; Biogas production; Sulfur compound; Vinasse
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2014.03.057

•Sulfate reduction of a very high strength and sulfate rich vinasse was characterized.•Close mass balances indicated that the data were suitable for dynamic modeling.•Variations in biogas quality (by H2Sgas) were highest at a SO42−/COD ratio of 0.05.•H2Saq and [H2S]free inhibited methanogens and SRBs at SO42−/COD ratios ⩾0.10.•Propionate uptake at SO42−/COD ratios ⩽0.10 suggested strong contribution of pSRB. This article characterizes the sulfate reduction process in the anaerobic digestion of a very high strength and sulfate rich vinasse, where chemical oxygen demand (COD) and sulfate (SO42−) pulses were applied at different SO42−/COD ratios to obtain dynamical responses. The results showed an increase in H2Sgas of up to 33%, when influent COD (inf_COD) and influent SO42− (inf_SO42−) increased at a SO42−/COD ratio of 0.05. A decrease of inf_COD together with an increase of inf_SO42− caused propionic acid degradation (up to 90%), suggesting strong contribution of propionate degrading sulfate reducing bacteria at SO42−/COD ratios ⩽0.10, in contrast to literature results. The inf_COD and inf_SO42− fluctuations at a SO42−/COD ratio of 0.10 caused inhibition by H2Saq, [H2S]free and propionic acid to sulfate reducing bacteria (SRBs), methanogens or both. At a SO42−/COD ratio of 0.20 this inhibition became severe for methanogens and SRBs, leading to reactor failure. Mass balance calculations showed COD and sulfur recoveries from 90% to 98% in most cases. Increments of inf_COD within a constant SO42−/COD ratio (0.05 or 0.10) accumulated as effluent COD rather than as COD_CH4gas, showing deterioration of the anaerobic digestion, while the sulfur was displaced to the gas phase at a SO42−/COD ratio of 0.05 or to the liquid phase at SO42−/COD ratios ⩾0.10. Based on the closed mass balances results, the data presented here are considered reliable for calibrating mathematical models, when sulfate reduction in the anaerobic digestion of a very high strength and sulfate rich vinasse is of primary interest.