Impact of petroleum versus bio-based nano/microplastics on fermentative biohydrogen production from sludge

Biohydrogen production via dark fermentation offers a promising route for waste-to-bioenergy. The impact of emerging contaminants like microplastics (MPs) and nanoplastics (NPs) in the waste on fermentative hydrogen production has not been thoroughly examined. Notably, a systematic comparison between petroleum-based and bio-based MPs/NPs in the hydrogen fermentation process has not yet been explored. We investigated the effects of petroleum-derived polyethylene MPs, polyvinyl chloride MPs, polystyrene NPs, and bio-based polyhydroxy butyrate and polylactic acid MPs, at low and high concentrations, on hydrogen production from primary sludge. Inhibition of hydrogen production ranged from 8.2% to 82.4%, with high concentrations of petro-based MPs/NPs causing more significant inhibition. Bio-based MPs exhibited lower inhibition compared to petro-based MPs/NPs. PsNPs at 0.3 mg/L exhibited the highest inhibition, accompanied by the highest increase (77.3%) in reactive oxygen species compared to the control. High levels of MPs/NPs increased extracellular polymeric substance production, indicating a protective response to toxicity. These findings highlight the importance of studying how emerging MPs/NPs pollutants in wastewater sludge impact fermentative hydrogen production and sludge properties.