The sulfur chain in biogas production from sulfate-rich liquid substrates: a review on dynamic modeling with vinasse as model substrate

Vinasse is a sulfate-rich liquid substrate, from which high levels of hydrogen sulfide in biogas can be obtained due to the sulfate reduction process under anaerobic conditions. Hydrogen sulfide is corrosive and toxic and must be removed for any utilization of the biogas. Mathematical models have been developed to study separately sulfate reduction in anaerobic digestion and sulfide removal from biogas streams. However, the levels of hydrogen sulfide produced in the anaerobic digestion stage have an effect on the sulfide removal processes in the next stage. As a method to study both processes and their interaction, a new approach is introduced and reviewed in the present article: the sulfur chain in biogas production. The necessity of studying the sulfate reduction processes in vinasse as a typical sulfate-rich substrate to predict hydrogen sulfide concentrations in the gas phase, as well as the best model approach to that aim are established here. In addition, the approaches to model sulfide removal based on direct conversion processes, the models' capability to predict the removal of hydrogen sulfide from the biogas (at levels between 20 000 and 30 000 ppm(v)) as well as the concentration profile of the reactants in this removal processes are discussed. (c) 2013 Society of Chemical Industry