Photoautotrophic removal of hydrogen sulfide from biogas using purple and green sulfur bacteria
Martin Struk, Cristian A. Sepúlveda-Muñoz, Ivan Kushkevych, Raúl Muñoz
Abstract
Biogas desulfurization based on anoxygenic photosynthetic processes represents an alternative to physicochemical technologies, decreasing the risk of O 2 and N 2 contamination. This work aimed at assessing the potential of Allochromatium vinosum and Chlorobium limicola for biogas desulfurization under different light intensities (10 and 25 klx) and H 2 S concentrations (1 %, 1.5 % and 2 %) in batch photobioreactors . In addition, the influence of rising biogas flow rates (2.9, 5.8 and 11.5 L d -1 in stage I, II and III, respectively) on the desulfurization performance in a 2.3 L photobioreactor utilizing C. limicola under continuous mode was assessed. The light intensity of 25 klx negatively influenced the growth of A. vinosum and C. limicola , resulting in decreased H 2 S removal capacity. An increase in H 2 S concentrations resulted in higher volumetric H 2 S removal rates in C. limicola (2.9–5.3 mg L -1 d -1 ) tests compared to A. vinosum (2.4–4.6 mg L -1 d -1 ) tests. The continuous photobioreactor completely removed H 2 S from biogas in stage I and II. The highest flow rate in stage III induced a deterioration in the desulfurization activity of C. limicola . Overall, the high H 2 S tolerance of A. vinosum and C. limicola supports their use in H 2 S desulfurization from biogas.