Phenanthrene regulates metabolic pathways for hydrogen accumulation in sludge alkaline dark fermentation

The influence of phenanthrene (PHE), a general polycyclic aromatic hydrocarbon in waste activated sludge, on sludge alkaline dark fermentation for hydrogen accumulation was investigated prospectively. The yield of hydrogen was 16.2 mL/g TSS with 50 mg/kg TSS PHE, which was 1.3-fold greater than that of the control. Mechanism research demonstrated that hydrogen production and the abundance of functional microorganisms were facilitated, whereas those of homoacetogenesis were reduced. The activity of pyruvate ferredoxin oxidoreductase in the conversion of pyruvate to reduced ferredoxin for hydrogen production was promoted by 57.2%, and that of carbon monoxide dehydrogenase and formyltetrahydrofolate synthetase, closely associated with hydrogen consumption, was suppressed by 60.5% and 55.9%, respectively. Moreover, the encoding genes involved in pyruvate metabolism were significantly up-regulated, while genes related to consuming hydrogen to reduce carbon dioxide and produce 5-methyltetrahydrofolate were down-regulated. This study notably illustrates the effect of PHE on hydrogen accumulation from metabolic pathways.

Automated summary

This prospective study investigated the influence of phenanthrene (PHE), a general polycyclic aromatic hydrocarbon found in waste activated sludge, on sludge alkaline dark fermentation for hydrogen accumulation. The yield of hydrogen increased by 1.3-fold compared to the control when PHE concentration was 50 mg/kg TSS, reaching 16.2 mL/g TSS. Mechanism research revealed that PHE promoted hydrogen production and the abundance of functional microorganisms, while reducing homoacetogenesis.