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bioRxiv · 10.1101/2022.03.21.484299

Use of Fe3O4 nanoparticles in reactor co-digestion of residues from 1G2G ethanol biorefinery: microbiological routes and operational aspects

Volpi, M. P. C.·Mockaitis, G.·Bruant, G.·Tremblay, J.·Moraes, B.
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Abstract

The co-digestion of residues from the sugarcane industry has already proven to be a highly attractive process for biogas production through anaerobic digestion (AD). The use of residues such as vinasse (1G) filter cake (1G) and deacetylation liquor (2G) in CSTR operation showed the potential for integrating 1G and 2G ethanol biorefineries through AD in previous work by our research group. The use of nanoparticles (NP) is a favorable way to optimize AD processes, as these additives allow the introduction of nutrients to the process more assertively concerning the distribution and interaction with microorganisms. The present work proposed the optimization of the co-digestion of vinasse, filter cake, and deacetylation liquor in a continuous reactor by adding Fe3O4 NP, comparing the results with a previous reactor operation without NP. Initially, tests were carried out in batches with different NP concentrations, resulting in 5 mg L-1 as the best concentration to be added in the continuous reactor along the increments of the applied organic rate load (ORL). CH4 production reached a maximum value of 2.8 {+/-} 0.1 NLCH4 gVS-1 and the organic matter removal reached 71 {+/-} 0.9%, in phase VI (ORL of 5.5 gVS L-1 day-1). This production was 90% higher than the reactor co-digestion operation without NP. The pH and alkalinity results indicated the methanogenesis stabilization within 60 days of operation: 30 days before when there was no NP added. The AD development was stable, presenting low variations in the oxidation-reduction potential (ORP) and stable organic acid (OA) concentrations, which indicated the propionic acid route to produce CH4 was predominant. The main methanogenic Archeae identified was Methanoculleus, indicating that the predominant metabolic route was that of acetate (SAO) coupled with hydrogenotrophic methanogenesis. The use of Fe3O4 NP managed to improve the AD from the 1G2G ethanol production residues and stimulated the microbial community growth, not modifying the preferable metabolic pathways.

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Volpi, M. P. C., Mockaitis, G., Bruant, G., Tremblay, J., Moraes, B.. 2022-03-21. Use of Fe3O4 nanoparticles in reactor co-digestion of residues from 1G2G ethanol biorefinery: microbiological routes and operational aspects. https://doi.org/10.1101/2022.03.21.484299

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