下水汚泥に潜む光明：揮発性脂肪酸(A silver lining in sewer sludge: volatile fatty acids)

2025-09-16 ワシントン大学セントルイス校

＜関連情報＞

• https://source.washu.edu/2025/09/a-silver-lining-in-sewer-sludge-volatile-fatty-acids/
• https://engineering.washu.edu/news/2025/A-silver-lining-in-sewer-sludge-volatile-fatty-acids.html
• https://www.sciencedirect.com/science/article/pii/S0043135425011364?via%3Dihub

光刺激による過酸化水素の抑制が嫌気性消化過程におけるメタン生成を阻害し、揮発性脂肪酸（VFAs）生産を促進 Light stimulated H2O2 inhibition on methanogenesis during anaerobic digestion towards enhanced VFAs production

Jiasi Sun, Zhen He
Water Research  Available online 14 July 2025
DOI:https://doi.org/10.1016/j.watres.2025.124229

Graphical abstract

Highlight

• Light accelerates H₂O₂ inhibition for methanogenesis towards VFAs production
• Light reduces H₂O₂ dosage from 380 to 80 mg L⁻¹ for complete inhibition
• The inhibition results in over 11 g COD L⁻¹ VFAs accumulation
• Oxidative stress by H₂O₂ promotes Firmicutes while inactivating 95 % of methanogens
• NH₄⁺ and PO₄³⁻ are simultaneously enriched by 1.44- and 5.26-fold

Abstract

Producing volatile fatty acids (VFAs) from anaerobic digestion (AD) of sewage sludge is of strong interest and can be realized via arresting methanogens. Herein, in situ hydrogen peroxide (H₂O₂) dosage has been demonstrated to be an effective approach to suppress methanogenesis and promote VFAs accumulation in the presence of illumination. Two AD reactors operating under different conditions produced average VFAs concentrations of 11,456.5 mg COD L⁻¹ (R_Light, 80 mg L⁻¹ H₂O₂) and 11,896.5 mg COD L⁻¹ (R_Dark, 380 mg L⁻¹ H₂O₂). The comparable VFAs concentrations indicated that methanogenic activity was effectively inhibited under both conditions, thereby preventing further conversion of VFAs to methane. However, visible light significantly reduced the H₂O₂ dosage level from 380 to 80 mg L⁻¹ to achieve complete methane inhibition, likely due to light-activated H₂O₂ producing ·OH. The light-exposed H₂O₂ elevated intracellular reactive oxygen species (ROS) levels, leading to a sharp decline in methanogen abundance (only 5.02 % remained compared to the inoculum). Firmicutes became dominant, increasing from 14.03 % (inoculum) to 52.35 % under high oxidative stress. Metagenomic functional predictions inferred microbial communities that tended to mitigate oxidative stress by reducing ROS generation, as shown by the relative gene abundance reduced from 0.0577 to 0.0472 %. A side-effect of H₂O₂ inhibition was the enrichment of NH₄⁺ and PO₄³⁻, increased by 1.44 and 5.26 times, respectively; those nutrient compounds could be potentially recovered.