Rheological behavior of physicochemical sludges during methanogenesis suppression and hydrogen production at different organic loading rates

Abstract

This study investigated the rheological behavior of raw physicochemical sludges and sludges that were digested at different organic loading rates (OLRs) (1, 5, 10 and 15 gVS L(-1) d(-1)) during methanogenesis suppression to produce hydrogen anaerobically. The Herschel-Bulkley model was used to describe the rheology of these sludges with specific properties. The results indicate that the Herschel-Bulkley model adequately described the rheology (τ0 ≠ 0) of this type of fluids (R(2) > 0.98). In addition, the raw physicochemical sludges and those that were digested at different OLRs had dilatant behaviors (n > 1), which increased with increasing OLR. These results identified the apparent viscosity, yield stress, pH and OLR conditions that allow for the production and suppression of methane, as well as the conditions that guarantee the production of hydrogen.

Influence of anaerobic biotransformation process of agro-industrial waste with Lactobacillus acidophilus on the rheological parameters: case of study of pig manure

“…The viscosity curves in Fig. 7 show that at the beginning of the process the uid thins as the viscosity decreases, which is typical in uids of this type [15], but after increasing the stress rate it recovers its initial state, or, the viscosity increases slightly at the end of the fermentation process, a case similar to that reported by Ahmad et al, [49] who analyzed the production of exopolysaccharides (EPS) and observed that the viscosity tends to increase due to the presence of these compounds, giving a mucilaginous appearance, the same behavior has been observed with different substrates and microorganisms classi ed as LAB such as Lactobacillus ke ranofaciens [49], Peanibacillus edaphicus [50], Lactobacillus plantarum C70 [51], which would indicate that the formation of macromolecules of this type using LAB prolonging the operation time after 30 h [49,51] and with different substrates rich in carbon sources such as glucose, lactose, galactose or fructose [52], which in this case is justi ed by the presence of molasses.…”

“…And establish bioprocess control conditions through rheological monitoring where living organisms intervene to predict behaviors for the application and use of organic waste and determine operating requirements and characteristics of the substrate [13], consider mixing strategies that ensure the most signi cant mass exchange on a larger scale [14,15]. Therefore, the rheological properties of PM were monitored to analyze changes in the substrate during the biotransformation process with Lactobacillus acidophilus with two rheological models: Herschel-Bulkley and Ostwald-de Waele; in addition, the cell growth, carbohydrate consumption and LA production considering three kinetic models: Logistic, Gompertz and Generalized Gompertz.…”

Recent Progresses in Application of Membrane Bioreactors in Production of Biohydrogen

“…Mohan [86] found pH values between 5.5 and 7.5 as the optimum pH range for hydrogen production, showing lower production rate outside the aforementioned optimum range. However, in the literature various studies revealed that the optimum pH range may vary depending on the physiological characteristics of substrate and composition of microbial population [11,97].…”