Effect of pH on the Anaerobic Fermentation of Fruit/Vegetables and Disposable Nappies Hydrolysate for Bio-hydrogen Production

Τσίγκου, Κωνσταντίνα; Tsafrakidou, Panagiota; Athanasopoulou, Sofia; Zafiri, Constantina; Kornaros, Michael

doi:10.1007/s12649-019-00854-z

Cited by 28 publications

(28 citation statements)

References 41 publications

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“…Accumulation of lactic acid, as an intermediate product, was observed at pH 5.0 (8.86 g lactic acid/L), whereas at higher pH it was metabolized during the process and thus not detected at the end of each batch test (Figure 2b). Lactate accumulation at pH 5.0 accompanied by low or no H2 production has been also observed during the dark fermentation of municipal solid wastes using mixed culture as inoculum [41,42]. As depicted in Figure 2b, the distribution of main soluble end-products was similar at all pH values, apart from pH 5.0.…”

Section: Effect Of Phsupporting

confidence: 53%

“…In order to enhance H 2 production and avoid inhibition, pH maintenance with an optimum range is of great importance. On the other hand, as various inhibitors of dark fermentation have been identified, co-fermentation of several feedstocks could control or even minimize inhibition by factors such as nutrients, organic load [42] or toxic compounds [44].…”

Section: Effect Of Phmentioning

confidence: 99%

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Dark Fermentation of Sweet Sorghum Stalks, Cheese Whey and Cow Manure Mixture: Effect of pH, Pretreatment and Organic Load

et al. 2021

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The aim of this study was to determine the optimal conditions for dark fermentation using agro-industrial liquid wastewaters mixed with sweet sorghum stalks (i.e., 55% sorghum, 40% cheese whey, and 5% liquid cow manure). Batch experiments were performed to investigate the effect of controlled pH (5.0, 5.5, 6.0, 6.5) on the production of bio-hydrogen and volatile fatty acids. According to the obtained results, the maximum hydrogen yield of 0.52 mol H2/mol eq. glucose was measured at pH 5.5 accompanied by the highest volatile fatty acids production, whereas similar hydrogen productivity was also observed at pH 6.0 and 6.5. The use of heat-treated anaerobic sludge as inoculum had a positive impact on bio-hydrogen production, exhibiting an increased yield of 1.09 mol H2/mol eq. glucose. On the other hand, the pretreated (ensiled) sorghum, instead of a fresh one, led to a lower hydrogen production, while the organic load decrease did not affect the process performance. In all experiments, the main fermentation end-products were volatile fatty acids (i.e., acetic, propionic, butyric), ethanol and lactic acid.

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Section: Effect Of Phsupporting

confidence: 53%

Section: Effect Of Phmentioning

confidence: 99%

Dark Fermentation of Sweet Sorghum Stalks, Cheese Whey and Cow Manure Mixture: Effect of pH, Pretreatment and Organic Load

et al. 2021

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“…A simultaneous decrease in the pH value of the effluent from 6.14 to 3.51 was observed, which is considered a key factor concerning the pH influence on fermentative hydrogen production. It is acknowledged that anaerobic fermentative hydrogen production is suppressed by both low and high pH values because the pH is a crucial parameter for bioprocesses [46], while the greatest hydrogen yields are usually presented when pH values close to 5-6 prevail [30,[46][47][48]. According to Dareioti et al [49], low pH values result in inhibition of the hydrogenase activity, whereas controlled pH conditions also affect the soluble end-products distribution.…”

Section: Cheese Whey Treatmentmentioning

confidence: 99%

Assessment of Single- vs. Two-Stage Process for the Anaerobic Digestion of Liquid Cow Manure and Cheese Whey

et al. 2021

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The growing interest in processes that involve biomass conversion to renewable energy, such as anaerobic digestion, has stimulated research in this field in order to assess the optimum conditions for biogas production from abundant feedstocks, like agro-industrial wastes. Anaerobic digestion is an attractive process for the decomposition of organic wastes via a complex microbial consortium and subsequent conversion of metabolic intermediates to hydrogen and methane. The present study focused on the exploitation of liquid cow manure (LCM) and cheese whey (CW) as noneasily and easily biodegradable sources, respectively, using continuous stirred-tank reactors for biogas production, and a comparison was presented between single- and two-stage anaerobic digestion systems. No significant differences were found concerning LCM treatment, in a two-stage system compared to a single one, concluding that LCM can be treated by implementing a single-stage process, as a recalcitrant substrate, with the greatest methane production rate of 0.67 L CH4/(LR·d) at an HRT of 16 d. On the other hand, using the easily biodegradable CW as a monosubstrate, the two-stage process was considered a better treatment system compared to a single one. During the single-stage process, operational problems were observed due to the limited buffering capacity of CW. However, the two-stage anaerobic digestion of CW produced a stable methane production rate of 0.68 L CH4/(LR·d) or 13.7 L CH4/Lfeed, while the total COD was removed by 76%.

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“…DF is a biological approach for hydrogen (H 2 ) production in the absence of light, through the decomposition and transformation of the organic material, not only to H 2 , but also to other metabolites such as volatile fatty acids (VFAs), lactate, and ethanol. The aforementioned metabolites are associated with metabolic pathways that are followed by microflora in the used inoculum and their possible synergistic (or antagonistic) interactions [23,24]. Additionally, various factors could affect the H 2 and other metabolites' efficiency, such as the pH, the temperature, the organic loading, the inhibitor's concentration, the nitrogen or phosphorus concentration, or the amounts of metals [25].…”

Section: Introductionmentioning

confidence: 99%

“…Concerning the macronutrients nitrogen and phosphorus, both are able to significantly affect the process, and for this reason, the optimum wide ranges of C/N (5-200) and C/P (up to 1000) have been proposed in the literature [25][26][27]. DF can be considered a waste valorization method, as except the clean energy generation through H 2 production, there is an option for further exploitation of the other metabolites for methane, bio-plastics, or biodiesel production [24,28]. DF has been widely used for the exploitation and valorization of several waste and wastewater streams such as sugarcane, wheat, rice, corn, and other crop residues, the organic fraction of municipal wastes (usually kitchen and food wastes), wastes of animal origin, and industrial residues such as cheese whey, brewery, and citric acid wastewaters [27,29].…”

Section: Introductionmentioning

confidence: 99%

Thermophilic Dark Fermentation of Olive Mill Wastewater in Batch Reactors: Effect of pH and Organic Loading

2022

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In recent decades, olive oil consumption has almost tripled worldwide. Olive oil production is linked with the production of enormous amounts of olive mill wastewater, the main by-product derived from three-phase olive mills. Due to the environmental risks of olive mill wastewater disposal, the management and valorization of the specific waste stream is of great importance. This work focuses on the thermophilic dark fermentation of olive mill wastewater in batch reactors, targeting pH optimization and the organic loading effect. A series of experiments were performed, during which the organic load of the substrate remained at 40 g/L after dilution with tap water, and the pH was tested in the range of 4.5 to 7.5. The maximum yield in terms of produced hydrogen was obtained at pH 6.0, and the yields were 0.7 mol H2/mol glucose or 0.5 L H2/Lreactor. At the same conditions, a reduction of 62% of the waste’s phenols was achieved. However, concerning the effect of organic loading at the optimized pH value (6.0), a further increase in the organic load minimized the hydrogen production, and the overall process was strongly inhibited.

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Effect of pH on the Anaerobic Fermentation of Fruit/Vegetables and Disposable Nappies Hydrolysate for Bio-hydrogen Production

Cited by 28 publications

References 41 publications

Dark Fermentation of Sweet Sorghum Stalks, Cheese Whey and Cow Manure Mixture: Effect of pH, Pretreatment and Organic Load

Dark Fermentation of Sweet Sorghum Stalks, Cheese Whey and Cow Manure Mixture: Effect of pH, Pretreatment and Organic Load

Assessment of Single- vs. Two-Stage Process for the Anaerobic Digestion of Liquid Cow Manure and Cheese Whey

Thermophilic Dark Fermentation of Olive Mill Wastewater in Batch Reactors: Effect of pH and Organic Loading

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