Application of zero valence iron for anaerobic digestion of skim latex wastewater: advantages and challenges
Abstract Aqueous sulfide, a product of the sulfate-reducing process in undissociated form, is a potent inhibitor of methanogens. Furthermore, the biogas generated from the anaerobic digestion of skim latex wastewater (SLW) typically contains > 10,000 ppm H2S. In this study, we investigated the ro...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
SpringerOpen
2025-06-01
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| Series: | Applied Water Science |
| Subjects: | |
| Online Access: | https://doi.org/10.1007/s13201-025-02528-9 |
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| Summary: | Abstract Aqueous sulfide, a product of the sulfate-reducing process in undissociated form, is a potent inhibitor of methanogens. Furthermore, the biogas generated from the anaerobic digestion of skim latex wastewater (SLW) typically contains > 10,000 ppm H2S. In this study, we investigated the role of zero-valent iron (ZVI) as a sink for both sulfides generated from the reduction of sulfate in SLW and CO2 from acetoclastic methanogenesis. The ZVI-based anaerobic digestion was performed in a fed-batch reactor fed with SLW for 30 days at an organic loading rate (OLR) of 2.34 g COD/L d and a COD/SO4 2− ratio of around 3. The concentrations of undissociated sulfide in the reactor added with ZVI were 9.1 ± 3.3 mg/L S2−. In contrast, the concentrations of undissociated sulfide in a control reactor were 157.2 ± 44.4 mg/L S2−, which were closer to the levels that can be toxic to methanogens. The ZVI addition promoted the precipitation of iron sulfide and carbonate at a medium pH of 7.9. The biogas generated from the ZVI-based reactor had 94–96% CH4, 4–6% CO2, and undetectable amounts of H2S. However, the methane production in the ZVI-based anaerobic digester decreased by 7.9%, possibly due to the buildup of partial pressure of H2 and subsequent propionate accumulation. |
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| ISSN: | 2190-5487 2190-5495 |