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

Abstract

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.•Equilibrium Equation (9) (m 3 kmol −1 ) •Equilibrium Equation (10) (−) K 100 Concentration of H 2 S or pH at which the uptake rate is decreased 100 times (kmol m −3 ) K 2 Concentration of H 2 S or pH at which the uptake rate is decreased twice (kmol m −3 ) K a, acid Acid-base equilibrium coefficient (kmol m −3 ) K A/B Acid-base kinetic parameter (m 3 kmol −1 d −1 ) K H Henry's law coefficient (kmol m −3 bar −1 ) K I Inhibition coefficient by undissociated H 2 S (kmol m −3 ) K P2 Competitive product inhibition coefficient in Equation (30) (kg m −3 ) K S Half saturation value (kg COD_S i · m −3 ) K S * Half saturation value in absence of inhibitor in Equation (30) kg m −3 K SO4 Half saturation value for sulfates (kmol m −3 ) EL Barrera et al. K W Water equilibrium constant (kmol m −3 ) L n− Organic ligand (−) p H2S Hydrogen sulfide partial pressure (bar) pH LL Lower pH limits where the groups of microorganism are 50% inhibited (−) pH UL Upper pH limits where the groups of microorganism are 50% inhibited (−) pH 0 pH of the maximum growth rate of Thiobacillus ferrooxidans (−) r Reaction rate (kmol m −3 s −1 ) S Concentration of soluble components (for hydrogen ions, sulfates, sulfides and its ionized forms units are in kmol m −3 ) (kg COD_S i m −3 ) S I Inhibitor concentration (undissociated H 2 S) (kmol m −3 ) T Temperature ( • C) t Time (s) X Particulate component (kg VSS m −3 ) x Distance from gas-liquid interface (m) Y Yield of biomass on the substrate (kg VSS kg COD_S i −1 ) Greek letters α LL-α UL Positive values which affect the steepness of the curve (−) ρ A Acid-base kinetic rate (kmol m −3 d −1 ) ρ uptake Kinetic rate of substrate uptake (kg COD_S i m −3 d −1 ) ρ growth Kinetic rate of bacterial growth (kg VSS m −3 d −1 ) ρ decay Kinetic rate of bacterial ...

Modeling the anaerobic digestion of cane-molasses vinasse: Extension of the Anaerobic Digestion Model No. 1 (ADM1) with sulfate reduction for a very high strength and sulfate rich wastewater

“…Concerning the calibration of the sulfate reduction parameters, the yield coefficients, the Monod maximum specific uptake rates and the half saturation coefficients were found in the range of values found in the literature (Barrera et al, 2013). However, the 50% inhibitory concentrations of free H 2 S (Appendix A) were lower than the values used to calibrate the sulfate reduction processes (Barrera et al, 2013), but similar to experimental values reported as inhibitory (150 mg S L À1 (0.0047 kmol m À3 )) for methanogens and SRB (except for propionate degraders, which is 70 mg S L À1 (0.0022 kmol m À3 )) (Rinzema and Lettinga, 1988).…”

“…The biological degradation processes are described using Monod kinetics, while the extracellular processes (disintegration and hydrolysis) and the biomass decay are described using firstorder kinetics. The ADM1 extension with sulfate reduction for high strength and sulfate rich wastewater was implemented in MatLab/Simulink 2008b following the original ADM1 (Batstone et al, 2002) and the approaches discussed by Barrera et al (2013). The model was implemented as a set of ordinary differential equations using the ODE 15s as numerical solver.…”

“…Vinasse obtained from ethanol distillation in the sugar cane industry (cane-molasses vinasse) is a typical example of very high strength and sulfate rich liquid substrate (Barrera et al, 2013). Hence, the anaerobic digestion of vinasse promotes the activity of sulfate reducing bacteria (SRB) producing sulfide.…”

Vinasse from Sugarcane Ethanol Production: Better Treatment or Better Utilization?

“…Due to the high sulfur composition of vinasse, AD produces a sulfur-rich biogas (Barrera et al, 2013), which could be highly corrosive to the burners by the production of SO2. Removal of SOx from biogas can be accomplished, among other technologies, through physical processes, such as sulfur-specific membrane filters, or through biological processes (Barrera et al, 2014).…”

Sequential fermentative and phototrophic system for hydrogen production: An approach for Brazilian alcohol distillery wastewater

“…The process generates solid and liquid residues, e.g., sugarcane bagasse and vinasse, respectively. Vinasse is also known as distillery wastewater, stillage, distillery spent wash and thin stillage; its main characteristics include a high chemical oxygen demand (COD), acidity (pH 3.5e5.5) and sulfate richness (2.1e15.8 kg m À3 ) [18,19]. Each liter of ethanol produced generates 13 L of vinasse [20].…”