Hydrogen and organic acid production from dark fermentation of sugarcane vinasse without buffers in mesophilic and thermophilic conditions

Abstract

BACKGROUND Sugarcane vinasse has a low pH and several studies report that alkalinity supplementation is essential to the stability of its dark fermentation (DF). In the context of biorefineries, the reduction, or even elimination, of alkalinizing agents could be extremely environmentally and economically advantageous. The main objective of this study was to evaluate the valorisation of vinasse DF through bioH2 and value‐added metabolite production without buffers in two similar Upflow Anaerobic Sludge Blanket (UASB) under mesophilic (U30) and thermophilic (U55) conditions. RESULTS Average organic acid yields of 376 ± 52 and 248 ± 122 mg‐CODOA.g−1CODtin, and productivities of 17 396 ± 5220 and 14 024 ± 1642 mg‐CODOA.L−1 day−1 were obtained for U30 and U55 reactors, respectively, with only vinasse as substrate (CODOA stands for organic acids chemical oxygen demand (COD) and CODin influent COD). BioH2 production was feasible with sucrose as substrate and pH below 3.0, but it ceased with substrate replacement by vinasse along with a natural pH increase. A change in microbial community was also observed: Ethanoligenens, Clostridium sensu stricto 12, and Liquorilactobacillus (using sucrose and with a pH <3.0) were replaced by Prevotella, Megasphaera, Pectinatus, Clostridium sensu stricto 11, and Lactobacillus using vinasse (with a pH > 4.0). CONCLUSION Results showed that DF of sugarcane vinasse without any buffering addition might be a promising approach for the valorization of real wastewater through the production of organic acids. Nevertheless, bioH2 production was not favored and further strategies would be needed to maintain hydrogen‐producing bacteria when sucrose is replaced by real effluent with a natural pH increase. © 2021 Society of Chemical Industry (SCI).

Techno-Economic Assessment of Biohydrogen Production from Dark Fermentation of Wastewater Sludge

“…to the modeled results, and a discrepancy between 15 to 20% has been observed in the biohydrogen production, [18], [19], [33], [67], and for organic acid production, a variation of about 10 to 17% has been observed. The reason behind this discrepancy might be the following:…”

“…The key advantage of this green technique includes simple operational requirements, stable hydrogen production, and minimal energy consumption [18]. More importantly, this method can utilize various non-economic biomass as feedstock such as the wastewater and organic fraction of municipal waste, providing enormous economic and environmental benefits over conventional techniques through clean energy supply and reduction in the cost of municipal wastewater and solid waste management [19]. The management of waste imposes a financial strain on the state; employing waste as raw material for hydrogen production could potentially ease this burden while concurrently creating value as a byproduct.…”

Avaliação da produção de biohidrogênio e ácidos orgânicos em reatores acidogênicos a partir de soro de queijo e vinhaça de cana-de-açúcar sem ajuste de pH e de água residuária rica em proteínas gerada em indústria de processamento de atum

“…Esta etapa do trabalho encontra-se presente no artigo Hydrogen and organic acid production from dark fermentation of sugarcane vinasse without buffers in mesophilic and thermophilic conditions(RIBEIRO et al, 2021).…”