Effect of oxygen dosing point and mixing on the microaerobic removal of hydrogen sulphide in sludge digesters

Economic analysis of microaerobic removal of H2S from biogas in full-scale sludge digesters

“…Fdz-Polanco et al (2009) achieved efficiencies of H 2 S removal higher than 99% in sewage sludge digesters (200 L) by injecting limited amounts of pure O 2 , thereby maintaining H 2 S concentrations of 50-500 mg/N m 3 , while the biogas production, CH 4 yield and volatile solids (VS) removal remained stable. Moreover, they reported dissolved sulfide removal when biogas recirculation was implemented, which was indeed consistent with Díaz et al (2011). Under equivalent oxygenation rates, Díaz et al (2010) reached similar efficiencies of H 2 S removal with both air and pure O 2 .…”

“…The results of Díaz et al (2011) and Ramos et al (2014) indicate that this is the optimal dosing point. The dose of every reactant was obtained from Ramos et al (2014) and increased by 20% (Table 1), assuming that less efficient mass transfer conditions were maintained at industrial scale.…”

“…Variation (b) was proposed in order to consider the geographical variability in the price of this commodity, and (c) was included due to the fact that Ramos et al (2014) observed fluctuations in the H 2 S concentration in biogas of approximately 100%. Finally, the NPV of the most profitable MA scenario was evaluated for a period of 20 yr, assuming that maintenance was performed every 6 and 8 yr. 40% of the S 0 production was considered to accumulate in the digesters (Díaz et al, 2011). Thus, the effect of the cleaning interval on the profitability of this alternative was studied.…”

“…During their lab-pilot-scale investigation, Díaz et al (2011) found that, under microaerobic conditions, S 0 was deposited all over the gas space of the sewage sludge digester, where different SOB developed, independently of the dosing point of the oxidative reactant (headspace or liquid phase) and the mixing method (sludge or biogas recirculation). Accordingly, the main drawback of the microaerobic treatment for gaseous sulfide control is the accumulation of S 0 in the gas space, which reduces the volume of this area and could cause clogging problems, thereby shortening the cleaning interval of digesters.…”

The Influence of Micro-Oxygen Addition on Desulfurization Performance and Microbial Communities during Waste-Activated Sludge Digestion in a Rusty Scrap Iron-Loaded Anaerobic Digester

“…The bands B17, B18 and B19 affiliated to the Epsilonproteobacteria class, Epsilonproteobacteria class and Gammaproteobacteria class were assigned to the Uncultured Arcobacter species, Uncultured Epsilonproteobacterium and Uncultured Acinetobacter species (Table 5), which are capable of oxidizing sulphide. Band B17 was found in the headspace of microaerobic digesters treating sewage sludge [57]. Band B18 was described by Kodama and Watanabe [58] as a chemolithoautotrophic SOB capable of oxidizing H 2 S, S 0 and S 2 O 3 2− under microaerobic conditions.…”