Biofilm-driven H₂S biotransformation in a high-surface-area biofilter packed with KOH-modified biochar and FeCO₃-modified CLC waste inoculated with pseudomonas spp.

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DOI:

https://doi.org/10.3846/enviro.2026.1604

Abstract

This study provides an in-depth mechanistic assessment of H₂S biodegradation in a thermally and hydraulically controlled vertical biofilter (1.0 m height, 0.14 m width) packed with KOH-activated sewage-sludge biochar (BET 471.54 m².g–1; pore volume 0.22 cm³.g–1) and FeCO₃-functionalized Cellular Lightweight Concrete (CLC) waste. Pseudomonas spp. were aerobically cultivated for 24 h at 30 °C to 10⁷ cells.g–1, then uniformly inoculated onto the media. The system was operated continuously for 144 h under 30 ± 1°C, 45–60% water-holding capacity, Empty Bed Retention Time (EBRTs) between 15–60 s, and inlet H₂S concentrations of 100–2000 ppmv, corresponding to inlet loading rates of 50–200 g.m–3h–1. Fluorescence microscopy (DAPI/SYPRO) demonstrated rapid early-stage attachment on biochar, with biomass increasing 4.1-fold within 72 h (1.4×10⁶ → 5.8×10⁶ cells.g–1/sample). Dense, protein-rich Extracellular Polymeric Substance (EPS) matrices in stages 3–4 match the highest H₂S concentrations and maximal gas–liquid interfacial area. Hybrid biochar–CLC packing enhanced mass transfer via simultaneous physisorption, FeCO₃-mediated catalytic oxidation, and high-turnover enzymatic oxidation mediated by Pseudomonas spp. Peak removal performances were Removal Efficiency (RE) = 92–95% and Elimination Capacity (EC) = 18–22 g.m–3h–1 at 0.2–0.5 L.min–1. Breakthrough remained negligible up to 120 h, demonstrating strong microbial–material synergy and high redox stability. FeCO₃-CLC promoted downstream S⁰ → SO₄²– conversion, stabilizing sulfur speciation under elevated loading. These findings position Pseudomonas–biochar systems as high-flux, kinetically resilient bio-catalytic platforms for intensified biogas desulfurization in detail.

Keywords:

hydrogen sulfide biodegradation, Pseudomonas spp. biofiltration, KOH-activated sewage-sludge biochar, FeCO₃-functionalized CLC media, biogas desulfurization

How to Cite

Mohammadi, K., & Vaiškūnaitė, R. (2026). Biofilm-driven H₂S biotransformation in a high-surface-area biofilter packed with KOH-modified biochar and FeCO₃-modified CLC waste inoculated with pseudomonas spp. International Conference “Environmental Engineering”, 13, 1–9. https://doi.org/10.3846/enviro.2026.1604

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Published

2026-05-06

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Section

Environmental Protection and Water Engineering